Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

180 files changed, 43863 insertions, 0 deletions

diff --git a/widget/cocoa/AppearanceOverride.h b/widget/cocoa/AppearanceOverride.h
new file mode 100644
index 0000000000..c826323c51
--- /dev/null
+++ b/widget/cocoa/AppearanceOverride.h
@@ -0,0 +1,19 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef AppearanceOverride_h
+#define AppearanceOverride_h
+
+#import <Cocoa/Cocoa.h>
+
+// Implements support for the browser.theme.toolbar-theme pref.
+// Use MOZGlobalAppearance.sharedInstance.effectiveAppearance
+// in all places where you would like the global override to be respected. The effectiveAppearance
+// property can be key-value observed.
+@interface MOZGlobalAppearance : NSObject <NSAppearanceCustomization>
+@property(class, readonly) MOZGlobalAppearance* sharedInstance;
+@end
+
+#endif
diff --git a/widget/cocoa/AppearanceOverride.mm b/widget/cocoa/AppearanceOverride.mm
new file mode 100644
index 0000000000..3f3d5e38e9
--- /dev/null
+++ b/widget/cocoa/AppearanceOverride.mm
@@ -0,0 +1,100 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "AppearanceOverride.h"
+
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_browser.h"
+#include "mozilla/StaticPrefs_widget.h"
+
+#include "nsXULAppAPI.h"
+#include "SDKDeclarations.h"
+
+static void ToolbarThemePrefChanged(const char* aPref, void* aUserInfo);
+
+@interface MOZGlobalAppearance ()
+@property NSInteger toolbarTheme;
+@end
+
+@implementation MOZGlobalAppearance
+
++ (MOZGlobalAppearance*)sharedInstance {
+  static MOZGlobalAppearance* sInstance = nil;
+  if (!sInstance) {
+    sInstance = [[MOZGlobalAppearance alloc] init];
+    if (XRE_IsParentProcess()) {
+      mozilla::Preferences::RegisterCallbackAndCall(
+          &ToolbarThemePrefChanged,
+          nsDependentCString(mozilla::StaticPrefs::GetPrefName_browser_theme_toolbar_theme()));
+    }
+  }
+  return sInstance;
+}
+
++ (NSSet*)keyPathsForValuesAffectingAppearance {
+  return [NSSet setWithObjects:@"toolbarTheme", nil];
+}
+
+- (NSAppearance*)appearance {
+  if (@available(macOS 10.14, *)) {
+    switch (self.toolbarTheme) {  // Value for browser.theme.toolbar-theme pref
+      case 0:                     // Dark
+        return [NSAppearance appearanceNamed:NSAppearanceNameDarkAqua];
+      case 1:  // Light
+        return [NSAppearance appearanceNamed:NSAppearanceNameAqua];
+      case 2:  // System
+      default:
+        break;
+    }
+  }
+  // nil means "no override".
+  return nil;
+}
+
+- (void)setAppearance:(NSAppearance*)aAppearance {
+  // ignored
+}
+
+- (NSApplication*)_app {
+  return NSApp;
+}
+
++ (NSSet*)keyPathsForValuesAffectingEffectiveAppearance {
+  if (@available(macOS 10.14, *)) {
+    // Automatically notify any key-value observers of our effectiveAppearance property whenever the
+    // pref or the NSApp's effectiveAppearance change.
+    return [NSSet setWithObjects:@"toolbarTheme", @"_app.effectiveAppearance", nil];
+  }
+  return [NSSet set];
+}
+
+- (NSAppearance*)effectiveAppearance {
+  if (@available(macOS 10.14, *)) {
+    switch (self.toolbarTheme) {  // Value for browser.theme.toolbar-theme pref
+      case 0:                     // Dark
+        return [NSAppearance appearanceNamed:NSAppearanceNameDarkAqua];
+      case 1:  // Light
+        return [NSAppearance appearanceNamed:NSAppearanceNameAqua];
+      case 2:  // System
+      default:
+        // Use the NSApp effectiveAppearance. This is the system appearance.
+        return NSApp.effectiveAppearance;
+    }
+  }
+  // Use aqua on pre-10.14.
+  return [NSAppearance appearanceNamed:NSAppearanceNameAqua];
+}
+
+@end
+
+static void ToolbarThemePrefChanged(const char* aPref, void* aUserInfo) {
+  MOZ_RELEASE_ASSERT(XRE_IsParentProcess());
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  MOZGlobalAppearance.sharedInstance.toolbarTheme =
+      mozilla::StaticPrefs::browser_theme_toolbar_theme();
+}
diff --git a/widget/cocoa/CFTypeRefPtr.h b/widget/cocoa/CFTypeRefPtr.h
new file mode 100644
index 0000000000..185355777e
--- /dev/null
+++ b/widget/cocoa/CFTypeRefPtr.h
@@ -0,0 +1,194 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef CFTypeRefPtr_h
+#define CFTypeRefPtr_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/DbgMacro.h"
+#include "mozilla/HashFunctions.h"
+
+// A smart pointer for CoreFoundation classes which does reference counting.
+//
+// Manual reference counting:
+//
+// UInt32 someNumber = 10;
+// CFNumberRef numberObject =
+//     CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &someNumber);
+// // do something with numberObject
+// CFRelease(numberObject);
+//
+// Automatic reference counting using CFTypeRefPtr:
+//
+// UInt32 someNumber = 10;
+// auto numberObject =
+//      CFTypeRefPtr<CFNumberRef>::WrapUnderCreateRule(
+//        CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &someNumber));
+// // do something with numberObject
+// // no CFRelease
+
+template <class PtrT>
+class CFTypeRefPtr {
+ private:
+  void assign_with_CFRetain(PtrT aRawPtr) {
+    CFRetain(aRawPtr);
+    assign_assuming_CFRetain(aRawPtr);
+  }
+
+  void assign_assuming_CFRetain(PtrT aNewPtr) {
+    PtrT oldPtr = mRawPtr;
+    mRawPtr = aNewPtr;
+    if (oldPtr) {
+      CFRelease(oldPtr);
+    }
+  }
+
+ private:
+  PtrT mRawPtr;
+
+ public:
+  ~CFTypeRefPtr() {
+    if (mRawPtr) {
+      CFRelease(mRawPtr);
+    }
+  }
+
+  // Constructors
+
+  CFTypeRefPtr() : mRawPtr(nullptr) {}
+
+  CFTypeRefPtr(const CFTypeRefPtr<PtrT>& aSmartPtr)
+      : mRawPtr(aSmartPtr.mRawPtr) {
+    if (mRawPtr) {
+      CFRetain(mRawPtr);
+    }
+  }
+
+  CFTypeRefPtr(CFTypeRefPtr<PtrT>&& aRefPtr) : mRawPtr(aRefPtr.mRawPtr) {
+    aRefPtr.mRawPtr = nullptr;
+  }
+
+  MOZ_IMPLICIT CFTypeRefPtr(decltype(nullptr)) : mRawPtr(nullptr) {}
+
+  // There is no constructor from a raw pointer value.
+  // Use one of the static WrapUnder*Rule methods below instead.
+
+  static CFTypeRefPtr<PtrT> WrapUnderCreateRule(PtrT aRawPtr) {
+    CFTypeRefPtr<PtrT> ptr;
+    ptr.AssignUnderCreateRule(aRawPtr);
+    return ptr;
+  }
+
+  static CFTypeRefPtr<PtrT> WrapUnderGetRule(PtrT aRawPtr) {
+    CFTypeRefPtr<PtrT> ptr;
+    ptr.AssignUnderGetRule(aRawPtr);
+    return ptr;
+  }
+
+  // Assignment operators
+
+  CFTypeRefPtr<PtrT>& operator=(decltype(nullptr)) {
+    assign_assuming_CFRetain(nullptr);
+    return *this;
+  }
+
+  CFTypeRefPtr<PtrT>& operator=(const CFTypeRefPtr<PtrT>& aRhs) {
+    assign_with_CFRetain(aRhs.mRawPtr);
+    return *this;
+  }
+
+  CFTypeRefPtr<PtrT>& operator=(CFTypeRefPtr<PtrT>&& aRefPtr) {
+    assign_assuming_CFRetain(aRefPtr.mRawPtr);
+    aRefPtr.mRawPtr = nullptr;
+    return *this;
+  }
+
+  // There is no operator= for a raw pointer value.
+  // Use one of the AssignUnder*Rule methods below instead.
+
+  CFTypeRefPtr<PtrT>& AssignUnderCreateRule(PtrT aRawPtr) {
+    // Freshly-created objects come with a retain count of 1.
+    assign_assuming_CFRetain(aRawPtr);
+    return *this;
+  }
+
+  CFTypeRefPtr<PtrT>& AssignUnderGetRule(PtrT aRawPtr) {
+    assign_with_CFRetain(aRawPtr);
+    return *this;
+  }
+
+  // Other pointer operators
+
+  // This is the only way to get the raw pointer out of the smart pointer.
+  // There is no implicit conversion to a raw pointer.
+  PtrT get() const { return mRawPtr; }
+
+  // Don't allow implicit conversion of temporary CFTypeRefPtr to raw pointer,
+  // because the refcount might be one and the pointer will immediately become
+  // invalid.
+  operator PtrT() const&& = delete;
+  // Also don't allow implicit conversion of non-temporary CFTypeRefPtr.
+  operator PtrT() const& = delete;
+
+  // These let you null-check a pointer without calling get().
+  explicit operator bool() const { return !!mRawPtr; }
+};
+
+template <class PtrT>
+inline bool operator==(const CFTypeRefPtr<PtrT>& aLhs,
+                       const CFTypeRefPtr<PtrT>& aRhs) {
+  return aLhs.get() == aRhs.get();
+}
+
+template <class PtrT>
+inline bool operator!=(const CFTypeRefPtr<PtrT>& aLhs,
+                       const CFTypeRefPtr<PtrT>& aRhs) {
+  return !(aLhs == aRhs);
+}
+
+// Comparing an |CFTypeRefPtr| to |nullptr|
+
+template <class PtrT>
+inline bool operator==(const CFTypeRefPtr<PtrT>& aLhs, decltype(nullptr)) {
+  return aLhs.get() == nullptr;
+}
+
+template <class PtrT>
+inline bool operator==(decltype(nullptr), const CFTypeRefPtr<PtrT>& aRhs) {
+  return nullptr == aRhs.get();
+}
+
+template <class PtrT>
+inline bool operator!=(const CFTypeRefPtr<PtrT>& aLhs, decltype(nullptr)) {
+  return aLhs.get() != nullptr;
+}
+
+template <class PtrT>
+inline bool operator!=(decltype(nullptr), const CFTypeRefPtr<PtrT>& aRhs) {
+  return nullptr != aRhs.get();
+}
+
+// MOZ_DBG support
+
+template <class PtrT>
+std::ostream& operator<<(std::ostream& aOut, const CFTypeRefPtr<PtrT>& aObj) {
+  return mozilla::DebugValue(aOut, aObj.get());
+}
+
+// std::hash support (e.g. for unordered_map)
+namespace std {
+template <class PtrT>
+struct hash<CFTypeRefPtr<PtrT>> {
+  typedef CFTypeRefPtr<PtrT> argument_type;
+  typedef std::size_t result_type;
+  result_type operator()(argument_type const& aPtr) const {
+    return mozilla::HashGeneric(reinterpret_cast<uintptr_t>(aPtr.get()));
+  }
+};
+}  // namespace std
+
+#endif /* CFTypeRefPtr_h */
diff --git a/widget/cocoa/CustomCocoaEvents.h b/widget/cocoa/CustomCocoaEvents.h
new file mode 100644
index 0000000000..3c02feb4b0
--- /dev/null
+++ b/widget/cocoa/CustomCocoaEvents.h
@@ -0,0 +1,18 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * This file defines constants to be used in the "subtype" field of
+ * NSEventTypeApplicationDefined type NSEvents.
+ */
+
+#ifndef WIDGET_COCOA_CUSTOMCOCOAEVENTS_H_
+#define WIDGET_COCOA_CUSTOMCOCOAEVENTS_H_
+
+// Empty event, just used for prodding the event loop into responding.
+const short kEventSubtypeNone = 0;
+// Tracer event, used for timing the event loop responsiveness.
+const short kEventSubtypeTrace = 1;
+
+#endif /* WIDGET_COCOA_CUSTOMCOCOAEVENTS_H_ */
diff --git a/widget/cocoa/DesktopBackgroundImage.h b/widget/cocoa/DesktopBackgroundImage.h
new file mode 100644
index 0000000000..2fd7565369
--- /dev/null
+++ b/widget/cocoa/DesktopBackgroundImage.h
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef WIDGET_COCOA_DESKTOPBACKGROUNDIMAGE_H_
+#define WIDGET_COCOA_DESKTOPBACKGROUNDIMAGE_H_
+
+class nsIFile;
+
+namespace mozilla {
+namespace widget {
+
+void SetDesktopImage(nsIFile* aImage);
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // WIDGET_COCOA_DESKTOPBACKGROUNDIMAGE_H_
diff --git a/widget/cocoa/DesktopBackgroundImage.mm b/widget/cocoa/DesktopBackgroundImage.mm
new file mode 100644
index 0000000000..5ebb7ea938
--- /dev/null
+++ b/widget/cocoa/DesktopBackgroundImage.mm
@@ -0,0 +1,68 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Logging.h"
+#include "nsCocoaUtils.h"
+#include "nsIFile.h"
+#include "DesktopBackgroundImage.h"
+
+#import <Foundation/Foundation.h>
+
+extern mozilla::LazyLogModule gCocoaUtilsLog;
+#undef LOG
+#define LOG(...) MOZ_LOG(gCocoaUtilsLog, LogLevel::Debug, (__VA_ARGS__))
+
+namespace mozilla {
+namespace widget {
+
+void SetDesktopImage(nsIFile* aImage) {
+  nsAutoCString imagePath;
+  nsresult rv = aImage->GetNativePath(imagePath);
+  if (NS_FAILED(rv)) {
+    LOG("%s ERROR: failed to get image path", __func__);
+    return;
+  }
+
+  bool exists = false;
+  rv = aImage->Exists(&exists);
+  if (NS_FAILED(rv) || !exists) {
+    LOG("%s ERROR: file \"%s\" does not exist", __func__, imagePath.get());
+    return;
+  }
+
+  NSString* urlString = [NSString stringWithUTF8String:imagePath.get()];
+  if (!urlString) {
+    LOG("%s ERROR: null image path \"%s\"", __func__, imagePath.get());
+    return;
+  }
+
+  NSURL* url = [NSURL fileURLWithPath:urlString];
+  if (!url) {
+    LOG("%s ERROR: null image path URL \"%s\"", __func__, imagePath.get());
+    return;
+  }
+
+  // Only apply the background to the screen with focus
+  NSScreen* currentScreen = [NSScreen mainScreen];
+  if (!currentScreen) {
+    LOG("%s ERROR: got null NSScreen", __func__);
+    return;
+  }
+
+  // Use existing options for this screen
+  NSDictionary* screenOptions =
+      [[NSWorkspace sharedWorkspace] desktopImageOptionsForScreen:currentScreen];
+
+  NSError* error = nil;
+  if (![[NSWorkspace sharedWorkspace] setDesktopImageURL:url
+                                               forScreen:currentScreen
+                                                 options:screenOptions
+                                                   error:&error]) {
+    LOG("%s ERROR: setDesktopImageURL failed (%ld)", __func__, (long)[error code]);
+  }
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/cocoa/GfxInfo.h b/widget/cocoa/GfxInfo.h
new file mode 100644
index 0000000000..0c6e50c04c
--- /dev/null
+++ b/widget/cocoa/GfxInfo.h
@@ -0,0 +1,98 @@
+/* vim: se cin sw=2 ts=2 et : */
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __mozilla_widget_GfxInfo_h__
+#define __mozilla_widget_GfxInfo_h__
+
+#include "GfxInfoBase.h"
+
+#include "nsString.h"
+
+namespace mozilla {
+namespace widget {
+
+class GfxInfo : public GfxInfoBase {
+ public:
+  GfxInfo();
+  // We only declare the subset of nsIGfxInfo that we actually implement. The
+  // rest is brought forward from GfxInfoBase.
+  NS_IMETHOD GetD2DEnabled(bool* aD2DEnabled) override;
+  NS_IMETHOD GetDWriteEnabled(bool* aDWriteEnabled) override;
+  NS_IMETHOD GetDWriteVersion(nsAString& aDwriteVersion) override;
+  NS_IMETHOD GetEmbeddedInFirefoxReality(
+      bool* aEmbeddedInFirefoxReality) override;
+  NS_IMETHOD GetHasBattery(bool* aHasBattery) override;
+  NS_IMETHOD GetWindowProtocol(nsAString& aWindowProtocol) override;
+  NS_IMETHOD GetTestType(nsAString& aTestType) override;
+  NS_IMETHOD GetCleartypeParameters(nsAString& aCleartypeParams) override;
+  NS_IMETHOD GetAdapterDescription(nsAString& aAdapterDescription) override;
+  NS_IMETHOD GetAdapterDriver(nsAString& aAdapterDriver) override;
+  NS_IMETHOD GetAdapterVendorID(nsAString& aAdapterVendorID) override;
+  NS_IMETHOD GetAdapterDeviceID(nsAString& aAdapterDeviceID) override;
+  NS_IMETHOD GetAdapterSubsysID(nsAString& aAdapterSubsysID) override;
+  NS_IMETHOD GetAdapterRAM(uint32_t* aAdapterRAM) override;
+  NS_IMETHOD GetAdapterDriverVendor(nsAString& aAdapterDriverVendor) override;
+  NS_IMETHOD GetAdapterDriverVersion(nsAString& aAdapterDriverVersion) override;
+  NS_IMETHOD GetAdapterDriverDate(nsAString& aAdapterDriverDate) override;
+  NS_IMETHOD GetAdapterDescription2(nsAString& aAdapterDescription) override;
+  NS_IMETHOD GetAdapterDriver2(nsAString& aAdapterDriver) override;
+  NS_IMETHOD GetAdapterVendorID2(nsAString& aAdapterVendorID) override;
+  NS_IMETHOD GetAdapterDeviceID2(nsAString& aAdapterDeviceID) override;
+  NS_IMETHOD GetAdapterSubsysID2(nsAString& aAdapterSubsysID) override;
+  NS_IMETHOD GetAdapterRAM2(uint32_t* aAdapterRAM) override;
+  NS_IMETHOD GetAdapterDriverVendor2(nsAString& aAdapterDriverVendor) override;
+  NS_IMETHOD GetAdapterDriverVersion2(
+      nsAString& aAdapterDriverVersion) override;
+  NS_IMETHOD GetAdapterDriverDate2(nsAString& aAdapterDriverDate) override;
+  NS_IMETHOD GetIsGPU2Active(bool* aIsGPU2Active) override;
+  NS_IMETHOD GetDrmRenderDevice(nsACString& aDrmRenderDevice) override;
+
+  using GfxInfoBase::GetFeatureStatus;
+  using GfxInfoBase::GetFeatureSuggestedDriverVersion;
+
+  virtual nsresult Init() override;
+
+#ifdef DEBUG
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIGFXINFODEBUG
+#endif
+
+  virtual uint32_t OperatingSystemVersion() override { return mOSXVersion; }
+
+ protected:
+  virtual ~GfxInfo() {}
+
+  OperatingSystem GetOperatingSystem() override;
+  virtual nsresult GetFeatureStatusImpl(
+      int32_t aFeature, int32_t* aStatus, nsAString& aSuggestedDriverVersion,
+      const nsTArray<GfxDriverInfo>& aDriverInfo, nsACString& aFailureId,
+      OperatingSystem* aOS = nullptr) override;
+  virtual const nsTArray<GfxDriverInfo>& GetGfxDriverInfo() override;
+
+ private:
+  void GetDeviceInfo();
+  void GetSelectedCityInfo();
+  void AddCrashReportAnnotations();
+
+  uint32_t mNumGPUsDetected;
+
+  uint32_t mAdapterRAM[2];
+  nsString mDeviceID[2];
+  nsString mDriverVersion[2];
+  nsString mDriverDate[2];
+  nsString mDeviceKey[2];
+
+  nsString mAdapterVendorID[2];
+  nsString mAdapterDeviceID[2];
+
+  uint32_t mOSXVersion;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif /* __mozilla_widget_GfxInfo_h__ */
diff --git a/widget/cocoa/GfxInfo.mm b/widget/cocoa/GfxInfo.mm
new file mode 100644
index 0000000000..19944e9c02
--- /dev/null
+++ b/widget/cocoa/GfxInfo.mm
@@ -0,0 +1,495 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <OpenGL/OpenGL.h>
+#include <OpenGL/CGLRenderers.h>
+
+#include "mozilla/ArrayUtils.h"
+
+#include "GfxInfo.h"
+#include "nsUnicharUtils.h"
+#include "nsExceptionHandler.h"
+#include "nsCocoaFeatures.h"
+#include "nsCocoaUtils.h"
+#include "mozilla/Preferences.h"
+#include "js/PropertyAndElement.h"  // JS_SetElement, JS_SetProperty
+
+#include <algorithm>
+
+#import <Foundation/Foundation.h>
+#import <IOKit/IOKitLib.h>
+#import <Cocoa/Cocoa.h>
+
+#include "jsapi.h"
+
+using namespace mozilla;
+using namespace mozilla::widget;
+
+#ifdef DEBUG
+NS_IMPL_ISUPPORTS_INHERITED(GfxInfo, GfxInfoBase, nsIGfxInfoDebug)
+#endif
+
+GfxInfo::GfxInfo() : mNumGPUsDetected(0), mOSXVersion{0} { mAdapterRAM[0] = mAdapterRAM[1] = 0; }
+
+static OperatingSystem OSXVersionToOperatingSystem(uint32_t aOSXVersion) {
+  switch (nsCocoaFeatures::ExtractMajorVersion(aOSXVersion)) {
+    case 10:
+      switch (nsCocoaFeatures::ExtractMinorVersion(aOSXVersion)) {
+        case 6:
+          return OperatingSystem::OSX10_6;
+        case 7:
+          return OperatingSystem::OSX10_7;
+        case 8:
+          return OperatingSystem::OSX10_8;
+        case 9:
+          return OperatingSystem::OSX10_9;
+        case 10:
+          return OperatingSystem::OSX10_10;
+        case 11:
+          return OperatingSystem::OSX10_11;
+        case 12:
+          return OperatingSystem::OSX10_12;
+        case 13:
+          return OperatingSystem::OSX10_13;
+        case 14:
+          return OperatingSystem::OSX10_14;
+        case 15:
+          return OperatingSystem::OSX10_15;
+        case 16:
+          // Depending on the SDK version, we either get 10.16 or 11.0.
+          // Normalize this to 11.0.
+          return OperatingSystem::OSX11_0;
+        default:
+          break;
+      }
+      break;
+    case 11:
+      switch (nsCocoaFeatures::ExtractMinorVersion(aOSXVersion)) {
+        case 0:
+          return OperatingSystem::OSX11_0;
+        default:
+          break;
+      }
+      break;
+  }
+
+  return OperatingSystem::Unknown;
+}
+// The following three functions are derived from Chromium code
+static CFTypeRef SearchPortForProperty(io_registry_entry_t dspPort, CFStringRef propertyName) {
+  return IORegistryEntrySearchCFProperty(dspPort, kIOServicePlane, propertyName,
+                                         kCFAllocatorDefault,
+                                         kIORegistryIterateRecursively | kIORegistryIterateParents);
+}
+
+static uint32_t IntValueOfCFData(CFDataRef d) {
+  uint32_t value = 0;
+
+  if (d) {
+    const uint32_t* vp = reinterpret_cast<const uint32_t*>(CFDataGetBytePtr(d));
+    if (vp != NULL) value = *vp;
+  }
+
+  return value;
+}
+
+void GfxInfo::GetDeviceInfo() {
+  mNumGPUsDetected = 0;
+
+  CFMutableDictionaryRef pci_dev_dict = IOServiceMatching("IOPCIDevice");
+  io_iterator_t io_iter;
+  if (IOServiceGetMatchingServices(kIOMasterPortDefault, pci_dev_dict, &io_iter) !=
+      kIOReturnSuccess) {
+    MOZ_DIAGNOSTIC_ASSERT(false,
+                          "Failed to detect any GPUs (couldn't enumerate IOPCIDevice services)");
+    return;
+  }
+
+  io_registry_entry_t entry = IO_OBJECT_NULL;
+  while ((entry = IOIteratorNext(io_iter)) != IO_OBJECT_NULL) {
+    constexpr uint32_t kClassCodeDisplayVGA = 0x30000;
+    CFTypeRef class_code_ref = SearchPortForProperty(entry, CFSTR("class-code"));
+    if (class_code_ref) {
+      const uint32_t class_code = IntValueOfCFData((CFDataRef)class_code_ref);
+      CFRelease(class_code_ref);
+
+      if (class_code == kClassCodeDisplayVGA) {
+        CFTypeRef vendor_id_ref = SearchPortForProperty(entry, CFSTR("vendor-id"));
+        if (vendor_id_ref) {
+          mAdapterVendorID[mNumGPUsDetected].AppendPrintf(
+              "0x%04x", IntValueOfCFData((CFDataRef)vendor_id_ref));
+          CFRelease(vendor_id_ref);
+        }
+        CFTypeRef device_id_ref = SearchPortForProperty(entry, CFSTR("device-id"));
+        if (device_id_ref) {
+          mAdapterDeviceID[mNumGPUsDetected].AppendPrintf(
+              "0x%04x", IntValueOfCFData((CFDataRef)device_id_ref));
+          CFRelease(device_id_ref);
+        }
+        ++mNumGPUsDetected;
+      }
+    }
+    IOObjectRelease(entry);
+    if (mNumGPUsDetected == 2) {
+      break;
+    }
+  }
+  IOObjectRelease(io_iter);
+
+#if defined(__aarch64__)
+  // If we found IOPCI VGA devices, don't look for AGXAccelerator devices
+  if (mNumGPUsDetected > 0) {
+    return;
+  }
+
+  CFMutableDictionaryRef agx_dev_dict = IOServiceMatching("AGXAccelerator");
+  if (IOServiceGetMatchingServices(kIOMasterPortDefault, agx_dev_dict, &io_iter) ==
+      kIOReturnSuccess) {
+    io_registry_entry_t entry = IO_OBJECT_NULL;
+    while ((entry = IOIteratorNext(io_iter)) != IO_OBJECT_NULL) {
+      CFTypeRef vendor_id_ref = SearchPortForProperty(entry, CFSTR("vendor-id"));
+      if (vendor_id_ref) {
+        mAdapterVendorID[mNumGPUsDetected].AppendPrintf("0x%04x",
+                                                        IntValueOfCFData((CFDataRef)vendor_id_ref));
+        CFRelease(vendor_id_ref);
+        ++mNumGPUsDetected;
+      }
+      IOObjectRelease(entry);
+    }
+
+    IOObjectRelease(io_iter);
+  }
+#endif
+
+  MOZ_DIAGNOSTIC_ASSERT(mNumGPUsDetected > 0, "Failed to detect any GPUs");
+}
+
+nsresult GfxInfo::Init() {
+  nsresult rv = GfxInfoBase::Init();
+
+  // Calling CGLQueryRendererInfo causes us to switch to the discrete GPU
+  // even when we don't want to. We'll avoid doing so for now and just
+  // use the device ids.
+
+  GetDeviceInfo();
+
+  AddCrashReportAnnotations();
+
+  mOSXVersion = nsCocoaFeatures::macOSVersion();
+
+  return rv;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetD2DEnabled(bool* aEnabled) { return NS_ERROR_FAILURE; }
+
+NS_IMETHODIMP
+GfxInfo::GetDWriteEnabled(bool* aEnabled) { return NS_ERROR_FAILURE; }
+
+/* readonly attribute bool HasBattery; */
+NS_IMETHODIMP GfxInfo::GetHasBattery(bool* aHasBattery) { return NS_ERROR_NOT_IMPLEMENTED; }
+
+/* readonly attribute DOMString DWriteVersion; */
+NS_IMETHODIMP
+GfxInfo::GetDWriteVersion(nsAString& aDwriteVersion) { return NS_ERROR_FAILURE; }
+
+NS_IMETHODIMP
+GfxInfo::GetEmbeddedInFirefoxReality(bool* aEmbeddedInFirefoxReality) { return NS_ERROR_FAILURE; }
+
+/* readonly attribute DOMString cleartypeParameters; */
+NS_IMETHODIMP
+GfxInfo::GetCleartypeParameters(nsAString& aCleartypeParams) { return NS_ERROR_FAILURE; }
+
+/* readonly attribute DOMString windowProtocol; */
+NS_IMETHODIMP
+GfxInfo::GetWindowProtocol(nsAString& aWindowProtocol) { return NS_ERROR_NOT_IMPLEMENTED; }
+
+/* readonly attribute DOMString testType; */
+NS_IMETHODIMP
+GfxInfo::GetTestType(nsAString& aTestType) { return NS_ERROR_NOT_IMPLEMENTED; }
+
+/* readonly attribute DOMString adapterDescription; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDescription(nsAString& aAdapterDescription) {
+  aAdapterDescription.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDescription2; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDescription2(nsAString& aAdapterDescription) {
+  if (mNumGPUsDetected < 2) {
+    return NS_ERROR_FAILURE;
+  }
+  aAdapterDescription.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterRAM; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterRAM(uint32_t* aAdapterRAM) {
+  *aAdapterRAM = mAdapterRAM[0];
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterRAM2; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterRAM2(uint32_t* aAdapterRAM) {
+  if (mNumGPUsDetected < 2) {
+    return NS_ERROR_FAILURE;
+  }
+  *aAdapterRAM = mAdapterRAM[1];
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDriver; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriver(nsAString& aAdapterDriver) {
+  aAdapterDriver.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDriver2; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriver2(nsAString& aAdapterDriver) {
+  if (mNumGPUsDetected < 2) {
+    return NS_ERROR_FAILURE;
+  }
+  aAdapterDriver.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDriverVendor; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverVendor(nsAString& aAdapterDriverVendor) {
+  aAdapterDriverVendor.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDriverVendor2; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverVendor2(nsAString& aAdapterDriverVendor) {
+  if (mNumGPUsDetected < 2) {
+    return NS_ERROR_FAILURE;
+  }
+  aAdapterDriverVendor.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDriverVersion; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverVersion(nsAString& aAdapterDriverVersion) {
+  aAdapterDriverVersion.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDriverVersion2; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverVersion2(nsAString& aAdapterDriverVersion) {
+  if (mNumGPUsDetected < 2) {
+    return NS_ERROR_FAILURE;
+  }
+  aAdapterDriverVersion.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDriverDate; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverDate(nsAString& aAdapterDriverDate) {
+  aAdapterDriverDate.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDriverDate2; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverDate2(nsAString& aAdapterDriverDate) {
+  if (mNumGPUsDetected < 2) {
+    return NS_ERROR_FAILURE;
+  }
+  aAdapterDriverDate.AssignLiteral("");
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterVendorID; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterVendorID(nsAString& aAdapterVendorID) {
+  aAdapterVendorID = mAdapterVendorID[0];
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterVendorID2; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterVendorID2(nsAString& aAdapterVendorID) {
+  if (mNumGPUsDetected < 2) {
+    return NS_ERROR_FAILURE;
+  }
+  aAdapterVendorID = mAdapterVendorID[1];
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDeviceID; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDeviceID(nsAString& aAdapterDeviceID) {
+  aAdapterDeviceID = mAdapterDeviceID[0];
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterDeviceID2; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterDeviceID2(nsAString& aAdapterDeviceID) {
+  if (mNumGPUsDetected < 2) {
+    return NS_ERROR_FAILURE;
+  }
+  aAdapterDeviceID = mAdapterDeviceID[1];
+  return NS_OK;
+}
+
+/* readonly attribute DOMString adapterSubsysID; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterSubsysID(nsAString& aAdapterSubsysID) { return NS_ERROR_FAILURE; }
+
+/* readonly attribute DOMString adapterSubsysID2; */
+NS_IMETHODIMP
+GfxInfo::GetAdapterSubsysID2(nsAString& aAdapterSubsysID) { return NS_ERROR_FAILURE; }
+
+NS_IMETHODIMP
+GfxInfo::GetDrmRenderDevice(nsACString& aDrmRenderDevice) { return NS_ERROR_NOT_IMPLEMENTED; }
+
+/* readonly attribute boolean isGPU2Active; */
+NS_IMETHODIMP
+GfxInfo::GetIsGPU2Active(bool* aIsGPU2Active) { return NS_ERROR_FAILURE; }
+
+void GfxInfo::AddCrashReportAnnotations() {
+  nsString deviceID, vendorID, driverVersion;
+  nsAutoCString narrowDeviceID, narrowVendorID, narrowDriverVersion;
+
+  GetAdapterDeviceID(deviceID);
+  CopyUTF16toUTF8(deviceID, narrowDeviceID);
+  GetAdapterVendorID(vendorID);
+  CopyUTF16toUTF8(vendorID, narrowVendorID);
+  GetAdapterDriverVersion(driverVersion);
+  CopyUTF16toUTF8(driverVersion, narrowDriverVersion);
+
+  CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::AdapterVendorID, narrowVendorID);
+  CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::AdapterDeviceID, narrowDeviceID);
+  CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::AdapterDriverVersion,
+                                     narrowDriverVersion);
+}
+
+// We don't support checking driver versions on Mac.
+#define IMPLEMENT_MAC_DRIVER_BLOCKLIST(os, device, features, blockOn, ruleId)          \
+  APPEND_TO_DRIVER_BLOCKLIST(os, device, features, blockOn, DRIVER_COMPARISON_IGNORED, \
+                             V(0, 0, 0, 0), ruleId, "")
+
+const nsTArray<GfxDriverInfo>& GfxInfo::GetGfxDriverInfo() {
+  if (!sDriverInfo->Length()) {
+    IMPLEMENT_MAC_DRIVER_BLOCKLIST(
+        OperatingSystem::OSX, DeviceFamily::RadeonX1000, nsIGfxInfo::FEATURE_OPENGL_LAYERS,
+        nsIGfxInfo::FEATURE_BLOCKED_DEVICE, "FEATURE_FAILURE_MAC_RADEONX1000_NO_TEXTURE2D");
+    IMPLEMENT_MAC_DRIVER_BLOCKLIST(
+        OperatingSystem::OSX, DeviceFamily::Geforce7300GT, nsIGfxInfo::FEATURE_WEBGL_OPENGL,
+        nsIGfxInfo::FEATURE_BLOCKED_DEVICE, "FEATURE_FAILURE_MAC_7300_NO_WEBGL");
+    IMPLEMENT_MAC_DRIVER_BLOCKLIST(OperatingSystem::OSX, DeviceFamily::IntelHDGraphicsToIvyBridge,
+                                   nsIGfxInfo::FEATURE_GL_SWIZZLE,
+                                   nsIGfxInfo::FEATURE_BLOCKED_DEVICE,
+                                   "FEATURE_FAILURE_MAC_INTELHD4000_NO_SWIZZLE");
+    // We block texture swizzling everwhere on mac because it's broken in some configurations
+    // and we want to support GPU switching.
+    IMPLEMENT_MAC_DRIVER_BLOCKLIST(
+        OperatingSystem::OSX, DeviceFamily::All, nsIGfxInfo::FEATURE_GL_SWIZZLE,
+        nsIGfxInfo::FEATURE_BLOCKED_DEVICE, "FEATURE_FAILURE_MAC_GPU_SWITCHING_NO_SWIZZLE");
+
+    // Older generation Intel devices do not perform well with WebRender.
+    IMPLEMENT_MAC_DRIVER_BLOCKLIST(
+        OperatingSystem::OSX, DeviceFamily::IntelWebRenderBlocked, nsIGfxInfo::FEATURE_WEBRENDER,
+        nsIGfxInfo::FEATURE_BLOCKED_DEVICE, "FEATURE_FAILURE_INTEL_GEN5_OR_OLDER");
+
+    // Intel HD3000 disabled due to bug 1661505
+    IMPLEMENT_MAC_DRIVER_BLOCKLIST(
+        OperatingSystem::OSX, DeviceFamily::IntelSandyBridge, nsIGfxInfo::FEATURE_WEBRENDER,
+        nsIGfxInfo::FEATURE_BLOCKED_DEVICE, "FEATURE_FAILURE_INTEL_MAC_HD3000_NO_WEBRENDER");
+
+    // wgpu doesn't safely support OOB behavior on Metal yet.
+    IMPLEMENT_MAC_DRIVER_BLOCKLIST(OperatingSystem::OSX, DeviceFamily::All,
+                                   nsIGfxInfo::FEATURE_WEBGPU, nsIGfxInfo::FEATURE_BLOCKED_DEVICE,
+                                   "FEATURE_FAILURE_MAC_WGPU_NO_METAL_BOUNDS_CHECKS");
+  }
+  return *sDriverInfo;
+}
+
+OperatingSystem GfxInfo::GetOperatingSystem() { return OSXVersionToOperatingSystem(mOSXVersion); }
+
+nsresult GfxInfo::GetFeatureStatusImpl(int32_t aFeature, int32_t* aStatus,
+                                       nsAString& aSuggestedDriverVersion,
+                                       const nsTArray<GfxDriverInfo>& aDriverInfo,
+                                       nsACString& aFailureId,
+                                       OperatingSystem* aOS /* = nullptr */) {
+  NS_ENSURE_ARG_POINTER(aStatus);
+  aSuggestedDriverVersion.SetIsVoid(true);
+  *aStatus = nsIGfxInfo::FEATURE_STATUS_UNKNOWN;
+  OperatingSystem os = OSXVersionToOperatingSystem(mOSXVersion);
+  if (aOS) *aOS = os;
+
+  if (sShutdownOccurred) {
+    return NS_OK;
+  }
+
+  // Don't evaluate special cases when we're evaluating the downloaded blocklist.
+  if (!aDriverInfo.Length()) {
+    if (aFeature == nsIGfxInfo::FEATURE_CANVAS2D_ACCELERATION) {
+      // See bug 1249659
+      switch (os) {
+        case OperatingSystem::OSX10_5:
+        case OperatingSystem::OSX10_6:
+        case OperatingSystem::OSX10_7:
+          *aStatus = nsIGfxInfo::FEATURE_BLOCKED_OS_VERSION;
+          aFailureId = "FEATURE_FAILURE_CANVAS_OSX_VERSION";
+          break;
+        default:
+          *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+          break;
+      }
+      return NS_OK;
+    } else if (aFeature == nsIGfxInfo::FEATURE_WEBRENDER &&
+               nsCocoaFeatures::ProcessIsRosettaTranslated()) {
+      *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+      aFailureId = "FEATURE_UNQUALIFIED_WEBRENDER_MAC_ROSETTA";
+      return NS_OK;
+    }
+  }
+
+  return GfxInfoBase::GetFeatureStatusImpl(aFeature, aStatus, aSuggestedDriverVersion, aDriverInfo,
+                                           aFailureId, &os);
+}
+
+#ifdef DEBUG
+
+// Implement nsIGfxInfoDebug
+
+/* void spoofVendorID (in DOMString aVendorID); */
+NS_IMETHODIMP GfxInfo::SpoofVendorID(const nsAString& aVendorID) {
+  mAdapterVendorID[0] = aVendorID;
+  return NS_OK;
+}
+
+/* void spoofDeviceID (in unsigned long aDeviceID); */
+NS_IMETHODIMP GfxInfo::SpoofDeviceID(const nsAString& aDeviceID) {
+  mAdapterDeviceID[0] = aDeviceID;
+  return NS_OK;
+}
+
+/* void spoofDriverVersion (in DOMString aDriverVersion); */
+NS_IMETHODIMP GfxInfo::SpoofDriverVersion(const nsAString& aDriverVersion) {
+  mDriverVersion[0] = aDriverVersion;
+  return NS_OK;
+}
+
+/* void spoofOSVersion (in unsigned long aVersion); */
+NS_IMETHODIMP GfxInfo::SpoofOSVersion(uint32_t aVersion) {
+  mOSXVersion = aVersion;
+  return NS_OK;
+}
+
+#endif
diff --git a/widget/cocoa/MOZIconHelper.h b/widget/cocoa/MOZIconHelper.h
new file mode 100644
index 0000000000..57783fc674
--- /dev/null
+++ b/widget/cocoa/MOZIconHelper.h
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZIconHelper_h
+#define MOZIconHelper_h
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsRect.h"
+
+class imgIContainer;
+class nsPresContext;
+
+namespace mozilla {
+class ComputedStyle;
+}
+
+@interface MOZIconHelper : NSObject
+
+// Returns an autoreleased empty NSImage.
++ (NSImage*)placeholderIconWithSize:(NSSize)aSize;
+
+// Returns an autoreleased NSImage.
++ (NSImage*)iconImageFromImageContainer:(imgIContainer*)aImage
+                               withSize:(NSSize)aSize
+                            presContext:(const nsPresContext*)aPresContext
+                          computedStyle:(const mozilla::ComputedStyle*)aComputedStyle
+                            scaleFactor:(CGFloat)aScaleFactor;
+
+@end
+
+#endif  // MOZIconHelper_h
diff --git a/widget/cocoa/MOZIconHelper.mm b/widget/cocoa/MOZIconHelper.mm
new file mode 100644
index 0000000000..2af89af2ed
--- /dev/null
+++ b/widget/cocoa/MOZIconHelper.mm
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Creates icons for display in native menu items on macOS.
+ */
+
+#include "MOZIconHelper.h"
+
+#include "imgIContainer.h"
+#include "nsCocoaUtils.h"
+
+@implementation MOZIconHelper
+
+// Returns an autoreleased empty NSImage.
++ (NSImage*)placeholderIconWithSize:(NSSize)aSize {
+  return [[[NSImage alloc] initWithSize:aSize] autorelease];
+}
+
+// Returns an autoreleased NSImage.
++ (NSImage*)iconImageFromImageContainer:(imgIContainer*)aImage
+                               withSize:(NSSize)aSize
+                            presContext:(const nsPresContext*)aPresContext
+                          computedStyle:(const mozilla::ComputedStyle*)aComputedStyle
+                            scaleFactor:(CGFloat)aScaleFactor {
+  bool isEntirelyBlack = false;
+  NSImage* retainedImage = nil;
+  nsresult rv;
+  if (aScaleFactor != 0.0f) {
+    rv = nsCocoaUtils::CreateNSImageFromImageContainer(aImage, imgIContainer::FRAME_CURRENT,
+                                                       aPresContext, aComputedStyle, &retainedImage,
+                                                       aScaleFactor, &isEntirelyBlack);
+  } else {
+    rv = nsCocoaUtils::CreateDualRepresentationNSImageFromImageContainer(
+        aImage, imgIContainer::FRAME_CURRENT, aPresContext, aComputedStyle, &retainedImage,
+        &isEntirelyBlack);
+  }
+
+  NSImage* image = [retainedImage autorelease];
+
+  if (NS_FAILED(rv) || !image) {
+    return nil;
+  }
+
+  int32_t origWidth = 0, origHeight = 0;
+  aImage->GetWidth(&origWidth);
+  aImage->GetHeight(&origHeight);
+
+  // If all the color channels in the image are black, treat the image as a
+  // template. This will cause macOS to use the image's alpha channel as a mask
+  // and it will fill it with a color that looks good in the context that it's
+  // used in. For example, for regular menu items, the image will be black, but
+  // when the menu item is hovered (and its background is blue), it will be
+  // filled with white.
+  [image setTemplate:isEntirelyBlack];
+
+  [image setSize:aSize];
+
+  return image;
+}
+
+@end
diff --git a/widget/cocoa/MOZMenuOpeningCoordinator.h b/widget/cocoa/MOZMenuOpeningCoordinator.h
new file mode 100644
index 0000000000..55dc2b2d59
--- /dev/null
+++ b/widget/cocoa/MOZMenuOpeningCoordinator.h
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZMenuOpeningCoordinator_h
+#define MOZMenuOpeningCoordinator_h
+
+#import <Cocoa/Cocoa.h>
+
+#include "mozilla/RefPtr.h"
+
+namespace mozilla {
+class Runnable;
+}
+
+/*
+ * MOZMenuOpeningCoordinator is a workaround for the fact that opening an NSMenu creates a nested
+ * event loop. This event loop is only exited after the menu is closed. The caller of
+ * NativeMenuMac::ShowAsContextMenu does not expect ShowAsContextMenu to create a nested event loop,
+ * so we need to make sure to open the NSMenu asynchronously.
+ */
+
+@interface MOZMenuOpeningCoordinator : NSObject
+
++ (instancetype)sharedInstance;
+
+// Queue aMenu for opening.
+// The menu will open from a new event loop tick so that its nested event loop does not block the
+// caller. If another menu's nested event loop is currently on the stack, we wait for that nested
+// event loop to unwind before opening aMenu. Returns a handle that can be passed to
+// cancelAsynchronousOpening:. Can only be called on the main thread.
+- (NSInteger)asynchronouslyOpenMenu:(NSMenu*)aMenu
+                   atScreenPosition:(NSPoint)aPosition
+                            forView:(NSView*)aView
+                     withAppearance:(NSAppearance*)aAppearance
+                      asContextMenu:(BOOL)aIsContextMenu;
+
+// If the menu opening request for aHandle hasn't been processed yet, cancel it.
+// Can only be called on the main thread.
+- (void)cancelAsynchronousOpening:(NSInteger)aHandle;
+
+// This field is a terrible workaround for a gnarly problem.
+// It should be set to YES by the caller of -[NSMenu cancelTracking(WithoutAnimation)].
+// This field gets checked by the native event loop code in nsAppShell.mm to avoid calling
+// -[NSApplication nextEventMatchingMask:...] between the call to cancelTracking and the point at
+// which the menu has finished closing and unwound from its tracking event loop, because such calls
+// can interfere with menu closing and get us stuck in the menu event loop forever.
+@property(class) BOOL needToUnwindForMenuClosing;
+
+@end
+
+#endif  // MOZMenuOpeningCoordinator_h
diff --git a/widget/cocoa/MOZMenuOpeningCoordinator.mm b/widget/cocoa/MOZMenuOpeningCoordinator.mm
new file mode 100644
index 0000000000..3ac4d8385f
--- /dev/null
+++ b/widget/cocoa/MOZMenuOpeningCoordinator.mm
@@ -0,0 +1,216 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Makes sure that the nested event loop for NSMenu tracking is situated as low
+ * on the stack as possible, and that two NSMenu event loops are never nested.
+ */
+
+#include "MOZMenuOpeningCoordinator.h"
+
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/StaticPrefs_widget.h"
+
+#include "nsCocoaFeatures.h"
+#include "nsCocoaUtils.h"
+#include "nsMenuX.h"
+#include "nsObjCExceptions.h"
+#include "SDKDeclarations.h"
+
+static BOOL sNeedToUnwindForMenuClosing = NO;
+
+@interface MOZMenuOpeningInfo : NSObject
+@property NSInteger handle;
+@property(retain) NSMenu* menu;
+@property NSPoint position;
+@property(retain) NSView* view;
+@property(retain) NSAppearance* appearance;
+@property BOOL isContextMenu;
+@end
+
+@implementation MOZMenuOpeningInfo
+@end
+
+@implementation MOZMenuOpeningCoordinator {
+  // non-nil between asynchronouslyOpenMenu:atScreenPosition:forView: and the
+  // time at at which it is unqueued in _runMenu.
+  MOZMenuOpeningInfo* mPendingOpening;  // strong
+
+  // An incrementing counter
+  NSInteger mLastHandle;
+
+  // YES while _runMenu is on the stack
+  BOOL mRunMenuIsOnTheStack;
+}
+
++ (instancetype)sharedInstance {
+  static MOZMenuOpeningCoordinator* sInstance = nil;
+  if (!sInstance) {
+    sInstance = [[MOZMenuOpeningCoordinator alloc] init];
+    mozilla::RunOnShutdown([&]() {
+      [sInstance release];
+      sInstance = nil;
+    });
+  }
+  return sInstance;
+}
+
+- (void)dealloc {
+  MOZ_RELEASE_ASSERT(!mPendingOpening, "should be empty at shutdown");
+  [super dealloc];
+}
+
+- (NSInteger)asynchronouslyOpenMenu:(NSMenu*)aMenu
+                   atScreenPosition:(NSPoint)aPosition
+                            forView:(NSView*)aView
+                     withAppearance:(NSAppearance*)aAppearance
+                      asContextMenu:(BOOL)aIsContextMenu {
+  MOZ_RELEASE_ASSERT(!mPendingOpening,
+                     "A menu is already waiting to open. Before opening the next one, either wait "
+                     "for this one to open or cancel the request.");
+
+  NSInteger handle = ++mLastHandle;
+
+  MOZMenuOpeningInfo* info = [[MOZMenuOpeningInfo alloc] init];
+  info.handle = handle;
+  info.menu = aMenu;
+  info.position = aPosition;
+  info.view = aView;
+  info.appearance = aAppearance;
+  info.isContextMenu = aIsContextMenu;
+  mPendingOpening = [info retain];
+  [info release];
+
+  if (!mRunMenuIsOnTheStack) {
+    // Call _runMenu from the event loop, so that it doesn't block this call.
+    [self performSelector:@selector(_runMenu) withObject:nil afterDelay:0.0];
+  }
+
+  return handle;
+}
+
+- (void)_runMenu {
+  MOZ_RELEASE_ASSERT(!mRunMenuIsOnTheStack);
+
+  mRunMenuIsOnTheStack = YES;
+
+  while (mPendingOpening) {
+    MOZMenuOpeningInfo* info = [mPendingOpening retain];
+    [mPendingOpening release];
+    mPendingOpening = nil;
+
+    @try {
+      [self _openMenu:info.menu
+          atScreenPosition:info.position
+                   forView:info.view
+            withAppearance:info.appearance
+             asContextMenu:info.isContextMenu];
+    } @catch (NSException* exception) {
+      nsObjCExceptionLog(exception);
+    }
+
+    [info release];
+
+    // We have exited _openMenu's nested event loop.
+    MOZMenuOpeningCoordinator.needToUnwindForMenuClosing = NO;
+  }
+
+  mRunMenuIsOnTheStack = NO;
+}
+
+- (void)cancelAsynchronousOpening:(NSInteger)aHandle {
+  if (mPendingOpening && mPendingOpening.handle == aHandle) {
+    [mPendingOpening release];
+    mPendingOpening = nil;
+  }
+}
+
+- (void)_openMenu:(NSMenu*)aMenu
+    atScreenPosition:(NSPoint)aPosition
+             forView:(NSView*)aView
+      withAppearance:(NSAppearance*)aAppearance
+       asContextMenu:(BOOL)aIsContextMenu {
+  // There are multiple ways to display an NSMenu as a context menu.
+  //
+  //  1. We can return the NSMenu from -[ChildView menuForEvent:] and the NSView will open it for
+  //     us.
+  //  2. We can call +[NSMenu popUpContextMenu:withEvent:forView:] inside a mouseDown handler with a
+  //     real mouse down event.
+  //  3. We can call +[NSMenu popUpContextMenu:withEvent:forView:] at a later time, with a real
+  //     mouse event that we stored earlier.
+  //  4. We can call +[NSMenu popUpContextMenu:withEvent:forView:] at any time, with a synthetic
+  //     mouse event that we create just for that purpose.
+  //  5. We can call -[NSMenu popUpMenuPositioningItem:atLocation:inView:] and it just takes a
+  //     position, not an event.
+  //
+  // 1-4 look the same, 5 looks different: 5 is made for use with NSPopUpButton, where the selected
+  // item needs to be shown at a specific position. If a tall menu is opened with a position close
+  // to the bottom edge of the screen, 5 results in a cropped menu with scroll arrows, even if the
+  // entire menu would fit on the screen, due to the positioning constraint.
+  // 1-2 only work if the menu contents are known synchronously during the call to menuForEvent or
+  // during the mouseDown event handler.
+  // NativeMenuMac::ShowAsContextMenu can be called at any time. It could be called during a
+  // menuForEvent call (during a "contextmenu" event handler), or during a mouseDown handler, or at
+  // a later time.
+  // The code below uses option 4 as the preferred option for context menus because it's the
+  // simplest: It works in all scenarios and it doesn't have the drawbacks of option 5. For popups
+  // that aren't context menus and that should be positioned as close as possible to the given
+  // screen position, we use option 5.
+
+  if (aAppearance) {
+#if !defined(MAC_OS_VERSION_11_0) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_11_0
+    if (nsCocoaFeatures::OnBigSurOrLater()) {
+#else
+    if (@available(macOS 11.0, *)) {
+#endif
+      // By default, NSMenu inherits its appearance from the opening NSEvent's
+      // window. If CSS has overridden it, on Big Sur + we can respect it with
+      // -[NSMenu setAppearance].
+      aMenu.appearance = aAppearance;
+    }
+  }
+
+  if (aView) {
+    NSWindow* window = aView.window;
+    NSPoint locationInWindow = nsCocoaUtils::ConvertPointFromScreen(window, aPosition);
+    if (aIsContextMenu) {
+      // Create a synthetic event at the right location and open the menu [option 4].
+      NSEvent* event = [NSEvent mouseEventWithType:NSEventTypeRightMouseDown
+                                          location:locationInWindow
+                                     modifierFlags:0
+                                         timestamp:NSProcessInfo.processInfo.systemUptime
+                                      windowNumber:window.windowNumber
+                                           context:nil
+                                       eventNumber:0
+                                        clickCount:1
+                                          pressure:0.0f];
+      [NSMenu popUpContextMenu:aMenu withEvent:event forView:aView];
+    } else {
+      // For popups which are not context menus, we open the menu using [option
+      // 5]. We pass `nil` to indicate that we're positioning the top left
+      // corner of the menu. This path is used for anchored menupopups, so we
+      // prefer option 5 over option 4 so that the menu doesn't get flipped if
+      // space is tight.
+      NSPoint locationInView = [aView convertPoint:locationInWindow fromView:nil];
+      [aMenu popUpMenuPositioningItem:nil atLocation:locationInView inView:aView];
+    }
+  } else {
+    // Open the menu using popUpMenuPositioningItem:atLocation:inView: [option 5].
+    // This is not preferred, because it positions the menu differently from how a native context
+    // menu would be positioned; it enforces aPosition for the top left corner even if this
+    // means that the menu will be displayed in a clipped fashion with scroll arrows.
+    [aMenu popUpMenuPositioningItem:nil atLocation:aPosition inView:nil];
+  }
+}
+
++ (void)setNeedToUnwindForMenuClosing:(BOOL)aValue {
+  sNeedToUnwindForMenuClosing = aValue;
+}
+
++ (BOOL)needToUnwindForMenuClosing {
+  return sNeedToUnwindForMenuClosing;
+}
+
+@end
diff --git a/widget/cocoa/MacThemeGeometryType.h b/widget/cocoa/MacThemeGeometryType.h
new file mode 100644
index 0000000000..559e21d792
--- /dev/null
+++ b/widget/cocoa/MacThemeGeometryType.h
@@ -0,0 +1,21 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef mozilla_widget_ThemeGeometryType
+#define mozilla_widget_ThemeGeometryType
+
+enum MacThemeGeometryType {
+  eThemeGeometryTypeTitlebar = 1,
+  eThemeGeometryTypeToolbar,
+  eThemeGeometryTypeToolbox,
+  eThemeGeometryTypeWindowButtons,
+  eThemeGeometryTypeMenu,
+  eThemeGeometryTypeHighlightedMenuItem,
+  eThemeGeometryTypeTooltip,
+  eThemeGeometryTypeSourceList,
+  eThemeGeometryTypeSourceListSelection,
+  eThemeGeometryTypeActiveSourceListSelection
+};
+
+#endif
diff --git a/widget/cocoa/MediaHardwareKeysEventSourceMac.h b/widget/cocoa/MediaHardwareKeysEventSourceMac.h
new file mode 100644
index 0000000000..da08b8108d
--- /dev/null
+++ b/widget/cocoa/MediaHardwareKeysEventSourceMac.h
@@ -0,0 +1,47 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef WIDGET_COCOA_MEDIAHARDWAREKEYSEVENTSOURCEMAC_H_
+#define WIDGET_COCOA_MEDIAHARDWAREKEYSEVENTSOURCEMAC_H_
+
+#import <ApplicationServices/ApplicationServices.h>
+#import <CoreFoundation/CoreFoundation.h>
+
+#include "mozilla/dom/MediaControlKeySource.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+namespace widget {
+
+class MediaHardwareKeysEventSourceMac final
+    : public mozilla::dom::MediaControlKeySource {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(MediaHardwareKeysEventSourceMac, override)
+  MediaHardwareKeysEventSourceMac() = default;
+
+  static CGEventRef EventTapCallback(CGEventTapProxy proxy, CGEventType type,
+                                     CGEventRef event, void* refcon);
+
+  bool Open() override;
+  void Close() override;
+  bool IsOpened() const override;
+
+  // Currently we don't support showing supported keys on the touch bar.
+  void SetSupportedMediaKeys(const MediaKeysArray& aSupportedKeys) override {}
+
+ private:
+  ~MediaHardwareKeysEventSourceMac() = default;
+
+  bool StartEventTap();
+  void StopEventTap();
+
+  // They are used to intercept mac hardware media keys.
+  CFMachPortRef mEventTap = nullptr;
+  CFRunLoopSourceRef mEventTapSource = nullptr;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif
diff --git a/widget/cocoa/MediaHardwareKeysEventSourceMac.mm b/widget/cocoa/MediaHardwareKeysEventSourceMac.mm
new file mode 100644
index 0000000000..669410018b
--- /dev/null
+++ b/widget/cocoa/MediaHardwareKeysEventSourceMac.mm
@@ -0,0 +1,183 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MediaHardwareKeysEventSourceMac.h"
+
+#import <AppKit/AppKit.h>
+#import <AppKit/NSEvent.h>
+#import <IOKit/hidsystem/ev_keymap.h>
+
+#include "mozilla/dom/MediaControlUtils.h"
+
+using namespace mozilla::dom;
+
+// avoid redefined macro in unified build
+#undef LOG
+#define LOG(msg, ...)                        \
+  MOZ_LOG(gMediaControlLog, LogLevel::Debug, \
+          ("MediaHardwareKeysEventSourceMac=%p, " msg, this, ##__VA_ARGS__))
+
+// This macro is used in static callback function, where we have to send `this`
+// explicitly.
+#define LOG2(msg, this, ...)                 \
+  MOZ_LOG(gMediaControlLog, LogLevel::Debug, \
+          ("MediaHardwareKeysEventSourceMac=%p, " msg, this, ##__VA_ARGS__))
+
+static const char* ToMediaControlKeyStr(int aKeyCode) {
+  switch (aKeyCode) {
+    case NX_KEYTYPE_PLAY:
+      return "Play";
+    case NX_KEYTYPE_NEXT:
+      return "Next";
+    case NX_KEYTYPE_PREVIOUS:
+      return "Previous";
+    case NX_KEYTYPE_FAST:
+      return "Fast";
+    case NX_KEYTYPE_REWIND:
+      return "Rewind";
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid key code.");
+      return "UNKNOWN";
+  }
+}
+
+// The media keys subtype. No official docs found, but widely known.
+// http://lists.apple.com/archives/cocoa-dev/2007/Aug/msg00499.html
+const int kSystemDefinedEventMediaKeysSubtype = 8;
+
+static bool IsSupportedKeyCode(int aKeyCode) {
+  return aKeyCode == NX_KEYTYPE_PLAY || aKeyCode == NX_KEYTYPE_NEXT ||
+         aKeyCode == NX_KEYTYPE_FAST || aKeyCode == NX_KEYTYPE_PREVIOUS ||
+         aKeyCode == NX_KEYTYPE_REWIND;
+}
+
+static MediaControlKey ToMediaControlKey(int aKeyCode) {
+  MOZ_ASSERT(IsSupportedKeyCode(aKeyCode));
+  switch (aKeyCode) {
+    case NX_KEYTYPE_NEXT:
+    case NX_KEYTYPE_FAST:
+      return MediaControlKey::Nexttrack;
+    case NX_KEYTYPE_PREVIOUS:
+    case NX_KEYTYPE_REWIND:
+      return MediaControlKey::Previoustrack;
+    default:
+      MOZ_ASSERT(aKeyCode == NX_KEYTYPE_PLAY);
+      return MediaControlKey::Playpause;
+  }
+}
+
+namespace mozilla {
+namespace widget {
+
+bool MediaHardwareKeysEventSourceMac::IsOpened() const { return mEventTap && mEventTapSource; }
+
+bool MediaHardwareKeysEventSourceMac::Open() {
+  LOG("Open MediaHardwareKeysEventSourceMac");
+  return StartEventTap();
+}
+
+void MediaHardwareKeysEventSourceMac::Close() {
+  LOG("Close MediaHardwareKeysEventSourceMac");
+  StopEventTap();
+  MediaControlKeySource::Close();
+}
+
+bool MediaHardwareKeysEventSourceMac::StartEventTap() {
+  LOG("StartEventTap");
+  MOZ_ASSERT(!mEventTap);
+  MOZ_ASSERT(!mEventTapSource);
+
+  // Add an event tap to intercept the system defined media key events.
+  mEventTap =
+      CGEventTapCreate(kCGSessionEventTap, kCGHeadInsertEventTap, kCGEventTapOptionListenOnly,
+                       CGEventMaskBit(NX_SYSDEFINED), EventTapCallback, this);
+  if (!mEventTap) {
+    LOG("Fail to create event tap");
+    return false;
+  }
+
+  mEventTapSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, mEventTap, 0);
+  if (!mEventTapSource) {
+    LOG("Fail to create an event tap source.");
+    return false;
+  }
+
+  LOG("Add an event tap source to current loop");
+  CFRunLoopAddSource(CFRunLoopGetCurrent(), mEventTapSource, kCFRunLoopCommonModes);
+  return true;
+}
+
+void MediaHardwareKeysEventSourceMac::StopEventTap() {
+  LOG("StopEventTapIfNecessary");
+  if (mEventTap) {
+    CFMachPortInvalidate(mEventTap);
+    mEventTap = nullptr;
+  }
+  if (mEventTapSource) {
+    CFRunLoopRemoveSource(CFRunLoopGetCurrent(), mEventTapSource, kCFRunLoopCommonModes);
+    CFRelease(mEventTapSource);
+    mEventTapSource = nullptr;
+  }
+}
+
+CGEventRef MediaHardwareKeysEventSourceMac::EventTapCallback(CGEventTapProxy proxy,
+                                                             CGEventType type, CGEventRef event,
+                                                             void* refcon) {
+  // Re-enable event tap when receiving disabled events.
+  MediaHardwareKeysEventSourceMac* source = static_cast<MediaHardwareKeysEventSourceMac*>(refcon);
+  if (type == kCGEventTapDisabledByUserInput || type == kCGEventTapDisabledByTimeout) {
+    MOZ_ASSERT(source->mEventTap);
+    CGEventTapEnable(source->mEventTap, true);
+    return event;
+  }
+
+  NSEvent* nsEvent = [NSEvent eventWithCGEvent:event];
+  if (nsEvent == nil) {
+    return event;
+  }
+
+  // Ignore not system defined media keys event.
+  if ([nsEvent type] != NSEventTypeSystemDefined ||
+      [nsEvent subtype] != kSystemDefinedEventMediaKeysSubtype) {
+    return event;
+  }
+
+  // Ignore media keys that aren't previous, next and play/pause.
+  // Magical constants are from http://weblog.rogueamoeba.com/2007/09/29/
+  // - keyCode = (([event data1] & 0xFFFF0000) >> 16)
+  // - keyFlags = ([event data1] & 0x0000FFFF)
+  // - keyState = (((keyFlags & 0xFF00) >> 8)) == 0xA
+  // - keyRepeat = (keyFlags & 0x1);
+  const NSInteger data1 = [nsEvent data1];
+  int keyCode = (data1 & 0xFFFF0000) >> 16;
+  if (keyCode != NX_KEYTYPE_PLAY && keyCode != NX_KEYTYPE_NEXT && keyCode != NX_KEYTYPE_PREVIOUS &&
+      keyCode != NX_KEYTYPE_FAST && keyCode != NX_KEYTYPE_REWIND) {
+    return event;
+  }
+
+  // Ignore non-key pressed event (eg. key released).
+  int keyFlags = data1 & 0x0000FFFF;
+  bool isKeyPressed = ((keyFlags & 0xFF00) >> 8) == 0xA;
+  if (!isKeyPressed) {
+    return event;
+  }
+
+  // There is no listener waiting to process event.
+  if (source->mListeners.IsEmpty()) {
+    return event;
+  }
+
+  if (!IsSupportedKeyCode(keyCode)) {
+    return event;
+  }
+
+  LOG2("Get media key %s", source, ToMediaControlKeyStr(keyCode));
+  for (auto iter = source->mListeners.begin(); iter != source->mListeners.end(); ++iter) {
+    (*iter)->OnActionPerformed(MediaControlAction(ToMediaControlKey(keyCode)));
+  }
+  return event;
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/cocoa/MediaHardwareKeysEventSourceMacMediaCenter.h b/widget/cocoa/MediaHardwareKeysEventSourceMacMediaCenter.h
new file mode 100644
index 0000000000..04a3aeba48
--- /dev/null
+++ b/widget/cocoa/MediaHardwareKeysEventSourceMacMediaCenter.h
@@ -0,0 +1,60 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef WIDGET_COCOA_MEDIAHARDWAREKEYSEVENTSOURCEMACMEDIACENTER_H_
+#define WIDGET_COCOA_MEDIAHARDWAREKEYSEVENTSOURCEMACMEDIACENTER_H_
+
+#include "mozilla/dom/MediaControlKeySource.h"
+
+#ifdef __OBJC__
+@class MPRemoteCommandEvent;
+#else
+typedef struct objc_object MPRemoteCommandEvent;
+#endif
+enum MPRemoteCommandHandlerStatus : long;
+
+namespace mozilla {
+namespace widget {
+
+typedef MPRemoteCommandHandlerStatus (^MediaCenterEventHandler)(MPRemoteCommandEvent* event);
+
+class MediaHardwareKeysEventSourceMacMediaCenter final
+    : public mozilla::dom::MediaControlKeySource {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(MediaHardwareKeysEventSourceMacMediaCenter, override)
+  MediaHardwareKeysEventSourceMacMediaCenter();
+
+  MediaCenterEventHandler CreatePlayPauseHandler();
+  MediaCenterEventHandler CreateNextTrackHandler();
+  MediaCenterEventHandler CreatePreviousTrackHandler();
+  MediaCenterEventHandler CreatePlayHandler();
+  MediaCenterEventHandler CreatePauseHandler();
+
+  bool Open() override;
+  void Close() override;
+  bool IsOpened() const override;
+  void SetPlaybackState(dom::MediaSessionPlaybackState aState) override;
+  void SetMediaMetadata(const dom::MediaMetadataBase& aMetadata) override;
+  // Currently we don't support showing supported keys on the touch bar.
+  void SetSupportedMediaKeys(const MediaKeysArray& aSupportedKeys) override {}
+
+ private:
+  ~MediaHardwareKeysEventSourceMacMediaCenter();
+  void BeginListeningForEvents();
+  void EndListeningForEvents();
+  void HandleEvent(dom::MediaControlKey aKey);
+
+  bool mOpened = false;
+
+  MediaCenterEventHandler mPlayPauseHandler;
+  MediaCenterEventHandler mNextTrackHandler;
+  MediaCenterEventHandler mPreviousTrackHandler;
+  MediaCenterEventHandler mPauseHandler;
+  MediaCenterEventHandler mPlayHandler;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // WIDGET_COCOA_MEDIAHARDWAREKEYSEVENTSOURCEMACMEDIACENTER_H_
diff --git a/widget/cocoa/MediaHardwareKeysEventSourceMacMediaCenter.mm b/widget/cocoa/MediaHardwareKeysEventSourceMacMediaCenter.mm
new file mode 100644
index 0000000000..9637c11d81
--- /dev/null
+++ b/widget/cocoa/MediaHardwareKeysEventSourceMacMediaCenter.mm
@@ -0,0 +1,172 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <MediaPlayer/MediaPlayer.h>
+
+#include "MediaHardwareKeysEventSourceMacMediaCenter.h"
+
+#include "mozilla/dom/MediaControlUtils.h"
+#include "nsCocoaUtils.h"
+
+using namespace mozilla::dom;
+
+// avoid redefined macro in unified build
+#undef LOG
+#define LOG(msg, ...)                        \
+  MOZ_LOG(gMediaControlLog, LogLevel::Debug, \
+          ("MediaHardwareKeysEventSourceMacMediaCenter=%p, " msg, this, ##__VA_ARGS__))
+
+namespace mozilla {
+namespace widget {
+
+MediaCenterEventHandler MediaHardwareKeysEventSourceMacMediaCenter::CreatePlayPauseHandler() {
+  return Block_copy(^MPRemoteCommandHandlerStatus(MPRemoteCommandEvent* event) {
+    MPNowPlayingInfoCenter* center = [MPNowPlayingInfoCenter defaultCenter];
+    center.playbackState = center.playbackState == MPNowPlayingPlaybackStatePlaying
+                               ? MPNowPlayingPlaybackStatePaused
+                               : MPNowPlayingPlaybackStatePlaying;
+    HandleEvent(MediaControlKey::Playpause);
+    return MPRemoteCommandHandlerStatusSuccess;
+  });
+}
+
+MediaCenterEventHandler MediaHardwareKeysEventSourceMacMediaCenter::CreateNextTrackHandler() {
+  return Block_copy(^MPRemoteCommandHandlerStatus(MPRemoteCommandEvent* event) {
+    HandleEvent(MediaControlKey::Nexttrack);
+    return MPRemoteCommandHandlerStatusSuccess;
+  });
+}
+
+MediaCenterEventHandler MediaHardwareKeysEventSourceMacMediaCenter::CreatePreviousTrackHandler() {
+  return Block_copy(^MPRemoteCommandHandlerStatus(MPRemoteCommandEvent* event) {
+    HandleEvent(MediaControlKey::Previoustrack);
+    return MPRemoteCommandHandlerStatusSuccess;
+  });
+}
+
+MediaCenterEventHandler MediaHardwareKeysEventSourceMacMediaCenter::CreatePlayHandler() {
+  return Block_copy(^MPRemoteCommandHandlerStatus(MPRemoteCommandEvent* event) {
+    MPNowPlayingInfoCenter* center = [MPNowPlayingInfoCenter defaultCenter];
+    if (center.playbackState != MPNowPlayingPlaybackStatePlaying) {
+      center.playbackState = MPNowPlayingPlaybackStatePlaying;
+    }
+    HandleEvent(MediaControlKey::Play);
+    return MPRemoteCommandHandlerStatusSuccess;
+  });
+}
+
+MediaCenterEventHandler MediaHardwareKeysEventSourceMacMediaCenter::CreatePauseHandler() {
+  return Block_copy(^MPRemoteCommandHandlerStatus(MPRemoteCommandEvent* event) {
+    MPNowPlayingInfoCenter* center = [MPNowPlayingInfoCenter defaultCenter];
+    if (center.playbackState != MPNowPlayingPlaybackStatePaused) {
+      center.playbackState = MPNowPlayingPlaybackStatePaused;
+    }
+    HandleEvent(MediaControlKey::Pause);
+    return MPRemoteCommandHandlerStatusSuccess;
+  });
+}
+
+MediaHardwareKeysEventSourceMacMediaCenter::MediaHardwareKeysEventSourceMacMediaCenter() {
+  mPlayPauseHandler = CreatePlayPauseHandler();
+  mNextTrackHandler = CreateNextTrackHandler();
+  mPreviousTrackHandler = CreatePreviousTrackHandler();
+  mPlayHandler = CreatePlayHandler();
+  mPauseHandler = CreatePauseHandler();
+  LOG("Create MediaHardwareKeysEventSourceMacMediaCenter");
+}
+
+MediaHardwareKeysEventSourceMacMediaCenter::~MediaHardwareKeysEventSourceMacMediaCenter() {
+  LOG("Destroy MediaHardwareKeysEventSourceMacMediaCenter");
+  EndListeningForEvents();
+  MPNowPlayingInfoCenter* center = [MPNowPlayingInfoCenter defaultCenter];
+  center.playbackState = MPNowPlayingPlaybackStateStopped;
+}
+
+void MediaHardwareKeysEventSourceMacMediaCenter::BeginListeningForEvents() {
+  MPNowPlayingInfoCenter* center = [MPNowPlayingInfoCenter defaultCenter];
+  center.playbackState = MPNowPlayingPlaybackStatePlaying;
+  MPRemoteCommandCenter* commandCenter = [MPRemoteCommandCenter sharedCommandCenter];
+  commandCenter.togglePlayPauseCommand.enabled = true;
+  [commandCenter.togglePlayPauseCommand addTargetWithHandler:mPlayPauseHandler];
+  commandCenter.nextTrackCommand.enabled = true;
+  [commandCenter.nextTrackCommand addTargetWithHandler:mNextTrackHandler];
+  commandCenter.previousTrackCommand.enabled = true;
+  [commandCenter.previousTrackCommand addTargetWithHandler:mPreviousTrackHandler];
+  commandCenter.playCommand.enabled = true;
+  [commandCenter.playCommand addTargetWithHandler:mPlayHandler];
+  commandCenter.pauseCommand.enabled = true;
+  [commandCenter.pauseCommand addTargetWithHandler:mPauseHandler];
+}
+
+void MediaHardwareKeysEventSourceMacMediaCenter::EndListeningForEvents() {
+  MPNowPlayingInfoCenter* center = [MPNowPlayingInfoCenter defaultCenter];
+  center.playbackState = MPNowPlayingPlaybackStatePaused;
+  center.nowPlayingInfo = nil;
+  MPRemoteCommandCenter* commandCenter = [MPRemoteCommandCenter sharedCommandCenter];
+  commandCenter.togglePlayPauseCommand.enabled = false;
+  [commandCenter.togglePlayPauseCommand removeTarget:nil];
+  commandCenter.nextTrackCommand.enabled = false;
+  [commandCenter.nextTrackCommand removeTarget:nil];
+  commandCenter.previousTrackCommand.enabled = false;
+  [commandCenter.previousTrackCommand removeTarget:nil];
+  commandCenter.playCommand.enabled = false;
+  [commandCenter.playCommand removeTarget:nil];
+  commandCenter.pauseCommand.enabled = false;
+  [commandCenter.pauseCommand removeTarget:nil];
+}
+
+bool MediaHardwareKeysEventSourceMacMediaCenter::Open() {
+  LOG("Open MediaHardwareKeysEventSourceMacMediaCenter");
+  mOpened = true;
+  BeginListeningForEvents();
+  return true;
+}
+
+void MediaHardwareKeysEventSourceMacMediaCenter::Close() {
+  LOG("Close MediaHardwareKeysEventSourceMacMediaCenter");
+  SetPlaybackState(dom::MediaSessionPlaybackState::None);
+  EndListeningForEvents();
+  mOpened = false;
+  MediaControlKeySource::Close();
+}
+
+bool MediaHardwareKeysEventSourceMacMediaCenter::IsOpened() const { return mOpened; }
+
+void MediaHardwareKeysEventSourceMacMediaCenter::HandleEvent(MediaControlKey aEvent) {
+  for (auto iter = mListeners.begin(); iter != mListeners.end(); ++iter) {
+    (*iter)->OnActionPerformed(MediaControlAction(aEvent));
+  }
+}
+
+void MediaHardwareKeysEventSourceMacMediaCenter::SetPlaybackState(
+    MediaSessionPlaybackState aState) {
+  MPNowPlayingInfoCenter* center = [MPNowPlayingInfoCenter defaultCenter];
+  if (aState == MediaSessionPlaybackState::Playing) {
+    center.playbackState = MPNowPlayingPlaybackStatePlaying;
+  } else if (aState == MediaSessionPlaybackState::Paused) {
+    center.playbackState = MPNowPlayingPlaybackStatePaused;
+  } else if (aState == MediaSessionPlaybackState::None) {
+    center.playbackState = MPNowPlayingPlaybackStateStopped;
+  }
+  MediaControlKeySource::SetPlaybackState(aState);
+}
+
+void MediaHardwareKeysEventSourceMacMediaCenter::SetMediaMetadata(
+    const dom::MediaMetadataBase& aMetadata) {
+  NSMutableDictionary* nowPlayingInfo = [NSMutableDictionary dictionary];
+  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mTitle)
+                     forKey:MPMediaItemPropertyTitle];
+  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mArtist)
+                     forKey:MPMediaItemPropertyArtist];
+  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mAlbum)
+                     forKey:MPMediaItemPropertyAlbumTitle];
+  // The procedure of updating `nowPlayingInfo` is actually an async operation
+  // from our testing, Apple's documentation doesn't mention that though. So be
+  // aware that checking `nowPlayingInfo` immedately after setting it might not
+  // yield the expected result.
+  [MPNowPlayingInfoCenter defaultCenter].nowPlayingInfo = nowPlayingInfo;
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/cocoa/MediaKeysEventSourceFactory.cpp b/widget/cocoa/MediaKeysEventSourceFactory.cpp
new file mode 100644
index 0000000000..1a5ad93b4c
--- /dev/null
+++ b/widget/cocoa/MediaKeysEventSourceFactory.cpp
@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MediaKeysEventSourceFactory.h"
+
+#include "MediaHardwareKeysEventSourceMac.h"
+#include "MediaHardwareKeysEventSourceMacMediaCenter.h"
+#include "nsCocoaFeatures.h"
+
+namespace mozilla {
+namespace widget {
+
+mozilla::dom::MediaControlKeySource* CreateMediaControlKeySource() {
+  if (nsCocoaFeatures::IsAtLeastVersion(10, 12, 2)) {
+    return new MediaHardwareKeysEventSourceMacMediaCenter();
+  } else {
+    return new MediaHardwareKeysEventSourceMac();
+  }
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/cocoa/NativeKeyBindings.h b/widget/cocoa/NativeKeyBindings.h
new file mode 100644
index 0000000000..6ab885fd95
--- /dev/null
+++ b/widget/cocoa/NativeKeyBindings.h
@@ -0,0 +1,67 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NativeKeyBindings_h
+#define NativeKeyBindings_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/EventForwards.h"
+#include "nsTHashMap.h"
+#include "nsIWidget.h"
+
+struct objc_selector;
+
+namespace mozilla {
+enum class NativeKeyBindingsType : uint8_t;
+
+class WritingMode;
+template <typename T>
+class Maybe;
+
+namespace widget {
+
+typedef nsTHashMap<nsPtrHashKey<objc_selector>, Command>
+    SelectorCommandHashtable;
+
+class NativeKeyBindings final {
+ public:
+  static NativeKeyBindings* GetInstance(NativeKeyBindingsType aType);
+  static void Shutdown();
+
+  /**
+   * GetEditCommandsForTests() returns commands performed in native widget
+   * in typical environment.  I.e., this does NOT refer customized shortcut
+   * key mappings of the environment.
+   */
+  static void GetEditCommandsForTests(NativeKeyBindingsType aType,
+                                      const WidgetKeyboardEvent& aEvent,
+                                      const Maybe<WritingMode>& aWritingMode,
+                                      nsTArray<CommandInt>& aCommands);
+
+  void Init(NativeKeyBindingsType aType);
+
+  void GetEditCommands(const WidgetKeyboardEvent& aEvent,
+                       const Maybe<WritingMode>& aWritingMode,
+                       nsTArray<CommandInt>& aCommands);
+
+ private:
+  NativeKeyBindings();
+
+  void AppendEditCommandsForSelector(objc_selector* aSelector,
+                                     nsTArray<CommandInt>& aCommands) const;
+
+  void LogEditCommands(const nsTArray<CommandInt>& aCommands,
+                       const char* aDescription) const;
+
+  SelectorCommandHashtable mSelectorToCommand;
+
+  static NativeKeyBindings* sInstanceForSingleLineEditor;
+  static NativeKeyBindings* sInstanceForMultiLineEditor;
+};  // NativeKeyBindings
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // NativeKeyBindings_h
diff --git a/widget/cocoa/NativeKeyBindings.mm b/widget/cocoa/NativeKeyBindings.mm
new file mode 100644
index 0000000000..d3e5983259
--- /dev/null
+++ b/widget/cocoa/NativeKeyBindings.mm
@@ -0,0 +1,605 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "NativeKeyBindings.h"
+
+#include "nsTArray.h"
+#include "nsCocoaUtils.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/NativeKeyBindingsType.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/WritingModes.h"
+
+#import <Cocoa/Cocoa.h>
+#import <Carbon/Carbon.h>
+
+namespace mozilla {
+namespace widget {
+
+static LazyLogModule gNativeKeyBindingsLog("NativeKeyBindings");
+
+NativeKeyBindings* NativeKeyBindings::sInstanceForSingleLineEditor = nullptr;
+NativeKeyBindings* NativeKeyBindings::sInstanceForMultiLineEditor = nullptr;
+
+// static
+NativeKeyBindings* NativeKeyBindings::GetInstance(NativeKeyBindingsType aType) {
+  switch (aType) {
+    case NativeKeyBindingsType::SingleLineEditor:
+      if (!sInstanceForSingleLineEditor) {
+        sInstanceForSingleLineEditor = new NativeKeyBindings();
+        sInstanceForSingleLineEditor->Init(aType);
+      }
+      return sInstanceForSingleLineEditor;
+    case NativeKeyBindingsType::MultiLineEditor:
+    case NativeKeyBindingsType::RichTextEditor:
+      if (!sInstanceForMultiLineEditor) {
+        sInstanceForMultiLineEditor = new NativeKeyBindings();
+        sInstanceForMultiLineEditor->Init(aType);
+      }
+      return sInstanceForMultiLineEditor;
+    default:
+      MOZ_CRASH("Not implemented");
+      return nullptr;
+  }
+}
+
+// static
+void NativeKeyBindings::Shutdown() {
+  delete sInstanceForSingleLineEditor;
+  sInstanceForSingleLineEditor = nullptr;
+  delete sInstanceForMultiLineEditor;
+  sInstanceForMultiLineEditor = nullptr;
+}
+
+NativeKeyBindings::NativeKeyBindings() {}
+
+inline objc_selector* ToObjcSelectorPtr(SEL aSel) { return reinterpret_cast<objc_selector*>(aSel); }
+#define SEL_TO_COMMAND(aSel, aCommand) \
+  mSelectorToCommand.InsertOrUpdate(ToObjcSelectorPtr(@selector(aSel)), aCommand)
+
+void NativeKeyBindings::Init(NativeKeyBindingsType aType) {
+  MOZ_LOG(gNativeKeyBindingsLog, LogLevel::Info, ("%p NativeKeyBindings::Init", this));
+
+  // Many selectors have a one-to-one mapping to a Gecko command. Those mappings
+  // are registered in mSelectorToCommand.
+
+  // Selectors from NSResponder's "Responding to Action Messages" section and
+  // from NSText's "Action Methods for Editing" section
+
+  // TODO: Improves correctness of left / right meaning
+  // TODO: Add real paragraph motions
+
+  // SEL_TO_COMMAND(cancelOperation:, );
+  // SEL_TO_COMMAND(capitalizeWord:, );
+  // SEL_TO_COMMAND(centerSelectionInVisibleArea:, );
+  // SEL_TO_COMMAND(changeCaseOfLetter:, );
+  // SEL_TO_COMMAND(complete:, );
+  SEL_TO_COMMAND(copy:, Command::Copy);
+  // SEL_TO_COMMAND(copyFont:, );
+  // SEL_TO_COMMAND(copyRuler:, );
+  SEL_TO_COMMAND(cut:, Command::Cut);
+  SEL_TO_COMMAND(delete:, Command::Delete);
+  SEL_TO_COMMAND(deleteBackward:, Command::DeleteCharBackward);
+  // SEL_TO_COMMAND(deleteBackwardByDecomposingPreviousCharacter:, );
+  SEL_TO_COMMAND(deleteForward:, Command::DeleteCharForward);
+
+  // TODO: deleteTo* selectors are also supposed to add text to a kill buffer
+  SEL_TO_COMMAND(deleteToBeginningOfLine:, Command::DeleteToBeginningOfLine);
+  SEL_TO_COMMAND(deleteToBeginningOfParagraph:, Command::DeleteToBeginningOfLine);
+  SEL_TO_COMMAND(deleteToEndOfLine:, Command::DeleteToEndOfLine);
+  SEL_TO_COMMAND(deleteToEndOfParagraph:, Command::DeleteToEndOfLine);
+  // SEL_TO_COMMAND(deleteToMark:, );
+
+  SEL_TO_COMMAND(deleteWordBackward:, Command::DeleteWordBackward);
+  SEL_TO_COMMAND(deleteWordForward:, Command::DeleteWordForward);
+  // SEL_TO_COMMAND(indent:, );
+  // SEL_TO_COMMAND(insertBacktab:, );
+  // SEL_TO_COMMAND(insertContainerBreak:, );
+  // SEL_TO_COMMAND(insertLineBreak:, );
+  // SEL_TO_COMMAND(insertNewline:, );
+  // SEL_TO_COMMAND(insertNewlineIgnoringFieldEditor:, );
+  // SEL_TO_COMMAND(insertParagraphSeparator:, );
+  // SEL_TO_COMMAND(insertTab:, );
+  // SEL_TO_COMMAND(insertTabIgnoringFieldEditor:, );
+  // SEL_TO_COMMAND(insertDoubleQuoteIgnoringSubstitution:, );
+  // SEL_TO_COMMAND(insertSingleQuoteIgnoringSubstitution:, );
+  // SEL_TO_COMMAND(lowercaseWord:, );
+  SEL_TO_COMMAND(moveBackward:, Command::CharPrevious);
+  SEL_TO_COMMAND(moveBackwardAndModifySelection:, Command::SelectCharPrevious);
+  if (aType == NativeKeyBindingsType::SingleLineEditor) {
+    SEL_TO_COMMAND(moveDown:, Command::EndLine);
+  } else {
+    SEL_TO_COMMAND(moveDown:, Command::LineNext);
+  }
+  SEL_TO_COMMAND(moveDownAndModifySelection:, Command::SelectLineNext);
+  SEL_TO_COMMAND(moveForward:, Command::CharNext);
+  SEL_TO_COMMAND(moveForwardAndModifySelection:, Command::SelectCharNext);
+  SEL_TO_COMMAND(moveLeft:, Command::CharPrevious);
+  SEL_TO_COMMAND(moveLeftAndModifySelection:, Command::SelectCharPrevious);
+  SEL_TO_COMMAND(moveParagraphBackwardAndModifySelection:, Command::SelectBeginLine);
+  SEL_TO_COMMAND(moveParagraphForwardAndModifySelection:, Command::SelectEndLine);
+  SEL_TO_COMMAND(moveRight:, Command::CharNext);
+  SEL_TO_COMMAND(moveRightAndModifySelection:, Command::SelectCharNext);
+  SEL_TO_COMMAND(moveToBeginningOfDocument:, Command::MoveTop);
+  SEL_TO_COMMAND(moveToBeginningOfDocumentAndModifySelection:, Command::SelectTop);
+  SEL_TO_COMMAND(moveToBeginningOfLine:, Command::BeginLine);
+  SEL_TO_COMMAND(moveToBeginningOfLineAndModifySelection:, Command::SelectBeginLine);
+  SEL_TO_COMMAND(moveToBeginningOfParagraph:, Command::BeginLine);
+  SEL_TO_COMMAND(moveToBeginningOfParagraphAndModifySelection:, Command::SelectBeginLine);
+  SEL_TO_COMMAND(moveToEndOfDocument:, Command::MoveBottom);
+  SEL_TO_COMMAND(moveToEndOfDocumentAndModifySelection:, Command::SelectBottom);
+  SEL_TO_COMMAND(moveToEndOfLine:, Command::EndLine);
+  SEL_TO_COMMAND(moveToEndOfLineAndModifySelection:, Command::SelectEndLine);
+  SEL_TO_COMMAND(moveToEndOfParagraph:, Command::EndLine);
+  SEL_TO_COMMAND(moveToEndOfParagraphAndModifySelection:, Command::SelectEndLine);
+  SEL_TO_COMMAND(moveToLeftEndOfLine:, Command::BeginLine);
+  SEL_TO_COMMAND(moveToLeftEndOfLineAndModifySelection:, Command::SelectBeginLine);
+  SEL_TO_COMMAND(moveToRightEndOfLine:, Command::EndLine);
+  SEL_TO_COMMAND(moveToRightEndOfLineAndModifySelection:, Command::SelectEndLine);
+  if (aType == NativeKeyBindingsType::SingleLineEditor) {
+    SEL_TO_COMMAND(moveUp:, Command::BeginLine);
+  } else {
+    SEL_TO_COMMAND(moveUp:, Command::LinePrevious);
+  }
+  SEL_TO_COMMAND(moveUpAndModifySelection:, Command::SelectLinePrevious);
+  SEL_TO_COMMAND(moveWordBackward:, Command::WordPrevious);
+  SEL_TO_COMMAND(moveWordBackwardAndModifySelection:, Command::SelectWordPrevious);
+  SEL_TO_COMMAND(moveWordForward:, Command::WordNext);
+  SEL_TO_COMMAND(moveWordForwardAndModifySelection:, Command::SelectWordNext);
+  SEL_TO_COMMAND(moveWordLeft:, Command::WordPrevious);
+  SEL_TO_COMMAND(moveWordLeftAndModifySelection:, Command::SelectWordPrevious);
+  SEL_TO_COMMAND(moveWordRight:, Command::WordNext);
+  SEL_TO_COMMAND(moveWordRightAndModifySelection:, Command::SelectWordNext);
+  SEL_TO_COMMAND(pageDown:, Command::MovePageDown);
+  SEL_TO_COMMAND(pageDownAndModifySelection:, Command::SelectPageDown);
+  SEL_TO_COMMAND(pageUp:, Command::MovePageUp);
+  SEL_TO_COMMAND(pageUpAndModifySelection:, Command::SelectPageUp);
+  SEL_TO_COMMAND(paste:, Command::Paste);
+  // SEL_TO_COMMAND(pasteFont:, );
+  // SEL_TO_COMMAND(pasteRuler:, );
+  SEL_TO_COMMAND(scrollLineDown:, Command::ScrollLineDown);
+  SEL_TO_COMMAND(scrollLineUp:, Command::ScrollLineUp);
+  SEL_TO_COMMAND(scrollPageDown:, Command::ScrollPageDown);
+  SEL_TO_COMMAND(scrollPageUp:, Command::ScrollPageUp);
+  SEL_TO_COMMAND(scrollToBeginningOfDocument:, Command::ScrollTop);
+  SEL_TO_COMMAND(scrollToEndOfDocument:, Command::ScrollBottom);
+  SEL_TO_COMMAND(selectAll:, Command::SelectAll);
+  // selectLine: is complex, see KeyDown
+  if (aType == NativeKeyBindingsType::SingleLineEditor) {
+    SEL_TO_COMMAND(selectParagraph:, Command::SelectAll);
+  }
+  // SEL_TO_COMMAND(selectToMark:, );
+  // selectWord: is complex, see KeyDown
+  // SEL_TO_COMMAND(setMark:, );
+  // SEL_TO_COMMAND(showContextHelp:, );
+  // SEL_TO_COMMAND(supplementalTargetForAction:sender:, );
+  // SEL_TO_COMMAND(swapWithMark:, );
+  // SEL_TO_COMMAND(transpose:, );
+  // SEL_TO_COMMAND(transposeWords:, );
+  // SEL_TO_COMMAND(uppercaseWord:, );
+  // SEL_TO_COMMAND(yank:, );
+}
+
+#undef SEL_TO_COMMAND
+
+void NativeKeyBindings::GetEditCommands(const WidgetKeyboardEvent& aEvent,
+                                        const Maybe<WritingMode>& aWritingMode,
+                                        nsTArray<CommandInt>& aCommands) {
+  MOZ_ASSERT(!aEvent.mFlags.mIsSynthesizedForTests);
+  MOZ_ASSERT(aCommands.IsEmpty());
+
+  MOZ_LOG(gNativeKeyBindingsLog, LogLevel::Info, ("%p NativeKeyBindings::GetEditCommands", this));
+
+  // Recover the current event, which should always be the key down we are
+  // responding to.
+
+  NSEvent* cocoaEvent = reinterpret_cast<NSEvent*>(aEvent.mNativeKeyEvent);
+
+  if (!cocoaEvent || [cocoaEvent type] != NSEventTypeKeyDown) {
+    MOZ_LOG(gNativeKeyBindingsLog, LogLevel::Info,
+            ("%p NativeKeyBindings::GetEditCommands, no Cocoa key down event", this));
+
+    return;
+  }
+
+  if (aWritingMode.isSome() && aEvent.NeedsToRemapNavigationKey() &&
+      aWritingMode.ref().IsVertical()) {
+    NSEvent* originalEvent = cocoaEvent;
+
+    // TODO: Use KeyNameIndex rather than legacy keyCode.
+    uint32_t remappedGeckoKeyCode = aEvent.GetRemappedKeyCode(aWritingMode.ref());
+    uint32_t remappedCocoaKeyCode = 0;
+    switch (remappedGeckoKeyCode) {
+      case NS_VK_UP:
+        remappedCocoaKeyCode = kVK_UpArrow;
+        break;
+      case NS_VK_DOWN:
+        remappedCocoaKeyCode = kVK_DownArrow;
+        break;
+      case NS_VK_LEFT:
+        remappedCocoaKeyCode = kVK_LeftArrow;
+        break;
+      case NS_VK_RIGHT:
+        remappedCocoaKeyCode = kVK_RightArrow;
+        break;
+      default:
+        MOZ_ASSERT_UNREACHABLE("Add a case for the new remapped key");
+        return;
+    }
+    unichar ch = nsCocoaUtils::ConvertGeckoKeyCodeToMacCharCode(remappedGeckoKeyCode);
+    NSString* chars = [[[NSString alloc] initWithCharacters:&ch length:1] autorelease];
+    cocoaEvent = [NSEvent keyEventWithType:[originalEvent type]
+                                  location:[originalEvent locationInWindow]
+                             modifierFlags:[originalEvent modifierFlags]
+                                 timestamp:[originalEvent timestamp]
+                              windowNumber:[originalEvent windowNumber]
+                                   context:nil
+                                characters:chars
+               charactersIgnoringModifiers:chars
+                                 isARepeat:[originalEvent isARepeat]
+                                   keyCode:remappedCocoaKeyCode];
+  }
+
+  MOZ_LOG(gNativeKeyBindingsLog, LogLevel::Info,
+          ("%p NativeKeyBindings::GetEditCommands, interpreting", this));
+
+  AutoTArray<KeyBindingsCommand, 2> bindingCommands;
+  nsCocoaUtils::GetCommandsFromKeyEvent(cocoaEvent, bindingCommands);
+
+  MOZ_LOG(gNativeKeyBindingsLog, LogLevel::Info,
+          ("%p NativeKeyBindings::GetEditCommands, bindingCommands=%zu", this,
+           bindingCommands.Length()));
+
+  for (uint32_t i = 0; i < bindingCommands.Length(); i++) {
+    SEL selector = bindingCommands[i].selector;
+
+    if (MOZ_LOG_TEST(gNativeKeyBindingsLog, LogLevel::Info)) {
+      NSString* selectorString = NSStringFromSelector(selector);
+      nsAutoString nsSelectorString;
+      nsCocoaUtils::GetStringForNSString(selectorString, nsSelectorString);
+
+      MOZ_LOG(gNativeKeyBindingsLog, LogLevel::Info,
+              ("%p NativeKeyBindings::GetEditCommands, selector=%s", this,
+               NS_LossyConvertUTF16toASCII(nsSelectorString).get()));
+    }
+
+    AppendEditCommandsForSelector(ToObjcSelectorPtr(selector), aCommands);
+  }
+
+  LogEditCommands(aCommands, "NativeKeyBindings::GetEditCommands");
+}
+
+void NativeKeyBindings::AppendEditCommandsForSelector(objc_selector* aSelector,
+                                                      nsTArray<CommandInt>& aCommands) const {
+  // Try to find a simple mapping in the hashtable
+  Command geckoCommand = Command::DoNothing;
+  if (mSelectorToCommand.Get(aSelector, &geckoCommand) && geckoCommand != Command::DoNothing) {
+    aCommands.AppendElement(static_cast<CommandInt>(geckoCommand));
+  } else if (aSelector == ToObjcSelectorPtr(@selector(selectLine:))) {
+    // This is functional, but Cocoa's version is direction-less in that
+    // selection direction is not determined until some future directed action
+    // is taken. See bug 282097, comment 79 for more details.
+    aCommands.AppendElement(static_cast<CommandInt>(Command::BeginLine));
+    aCommands.AppendElement(static_cast<CommandInt>(Command::SelectEndLine));
+  } else if (aSelector == ToObjcSelectorPtr(@selector(selectWord:))) {
+    // This is functional, but Cocoa's version is direction-less in that
+    // selection direction is not determined until some future directed action
+    // is taken. See bug 282097, comment 79 for more details.
+    aCommands.AppendElement(static_cast<CommandInt>(Command::WordPrevious));
+    aCommands.AppendElement(static_cast<CommandInt>(Command::SelectWordNext));
+  }
+}
+
+void NativeKeyBindings::LogEditCommands(const nsTArray<CommandInt>& aCommands,
+                                        const char* aDescription) const {
+  if (!MOZ_LOG_TEST(gNativeKeyBindingsLog, LogLevel::Info)) {
+    return;
+  }
+
+  if (aCommands.IsEmpty()) {
+    MOZ_LOG(gNativeKeyBindingsLog, LogLevel::Info, ("%p %s, no edit commands", this, aDescription));
+    return;
+  }
+
+  for (CommandInt commandInt : aCommands) {
+    Command geckoCommand = static_cast<Command>(commandInt);
+    MOZ_LOG(gNativeKeyBindingsLog, LogLevel::Info,
+            ("%p %s, command=%s", this, aDescription,
+             WidgetKeyboardEvent::GetCommandStr(geckoCommand)));
+  }
+}
+
+// static
+void NativeKeyBindings::GetEditCommandsForTests(NativeKeyBindingsType aType,
+                                                const WidgetKeyboardEvent& aEvent,
+                                                const Maybe<WritingMode>& aWritingMode,
+                                                nsTArray<CommandInt>& aCommands) {
+  MOZ_DIAGNOSTIC_ASSERT(aEvent.IsTrusted());
+
+  // The following mapping is checked on Big Sur. Some of them are defined in:
+  // https://support.apple.com/en-us/HT201236#text
+  NativeKeyBindings* instance = NativeKeyBindings::GetInstance(aType);
+  if (NS_WARN_IF(!instance)) {
+    return;
+  }
+  switch (aWritingMode.isSome() ? aEvent.GetRemappedKeyNameIndex(aWritingMode.ref())
+                                : aEvent.mKeyNameIndex) {
+    case KEY_NAME_INDEX_USE_STRING:
+      if (!aEvent.IsControl() || aEvent.IsAlt() || aEvent.IsMeta()) {
+        break;
+      }
+      switch (aEvent.PseudoCharCode()) {
+        case 'a':
+        case 'A':
+          instance->AppendEditCommandsForSelector(
+              !aEvent.IsShift()
+                  ? ToObjcSelectorPtr(@selector(moveToBeginningOfParagraph:))
+                  : ToObjcSelectorPtr(@selector(moveToBeginningOfParagraphAndModifySelection:)),
+              aCommands);
+          break;
+        case 'b':
+        case 'B':
+          instance->AppendEditCommandsForSelector(
+              !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(moveBackward:))
+                                : ToObjcSelectorPtr(@selector(moveBackwardAndModifySelection:)),
+              aCommands);
+          break;
+        case 'd':
+        case 'D':
+          if (!aEvent.IsShift()) {
+            instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(deleteForward:)),
+                                                    aCommands);
+          }
+          break;
+        case 'e':
+        case 'E':
+          instance->AppendEditCommandsForSelector(
+              !aEvent.IsShift()
+                  ? ToObjcSelectorPtr(@selector(moveToEndOfParagraph:))
+                  : ToObjcSelectorPtr(@selector(moveToEndOfParagraphAndModifySelection:)),
+              aCommands);
+          break;
+        case 'f':
+        case 'F':
+          instance->AppendEditCommandsForSelector(
+              !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(moveForward:))
+                                : ToObjcSelectorPtr(@selector(moveForwardAndModifySelection:)),
+              aCommands);
+          break;
+        case 'h':
+        case 'H':
+          if (!aEvent.IsShift()) {
+            instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(deleteBackward:)),
+                                                    aCommands);
+          }
+          break;
+        case 'k':
+        case 'K':
+          if (!aEvent.IsShift()) {
+            instance->AppendEditCommandsForSelector(
+                ToObjcSelectorPtr(@selector(deleteToEndOfParagraph:)), aCommands);
+          }
+          break;
+        case 'n':
+        case 'N':
+          instance->AppendEditCommandsForSelector(
+              !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(moveDown:))
+                                : ToObjcSelectorPtr(@selector(moveDownAndModifySelection:)),
+              aCommands);
+          break;
+        case 'p':
+        case 'P':
+          instance->AppendEditCommandsForSelector(
+              !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(moveUp:))
+                                : ToObjcSelectorPtr(@selector(moveUpAndModifySelection:)),
+              aCommands);
+          break;
+        default:
+          break;
+      }
+      break;
+    case KEY_NAME_INDEX_Backspace:
+      if (aEvent.IsMeta()) {
+        if (aEvent.IsAlt() || aEvent.IsControl()) {
+          break;
+        }
+        // Shift is ignored.
+        instance->AppendEditCommandsForSelector(
+            ToObjcSelectorPtr(@selector(deleteToBeginningOfLine:)), aCommands);
+        break;
+      }
+      if (aEvent.IsAlt()) {
+        // Shift and Control are ignored.
+        instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(deleteWordBackward:)),
+                                                aCommands);
+        break;
+      }
+      if (aEvent.IsControl()) {
+        if (aEvent.IsShift()) {
+          instance->AppendEditCommandsForSelector(
+              ToObjcSelectorPtr(@selector(deleteBackwardByDecomposingPreviousCharacter:)),
+              aCommands);
+        }
+        break;
+      }
+      // Shift is ignored.
+      instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(deleteBackward:)),
+                                              aCommands);
+      break;
+    case KEY_NAME_INDEX_Delete:
+      if (aEvent.IsControl() || aEvent.IsMeta()) {
+        break;
+      }
+      if (aEvent.IsAlt()) {
+        // Shift is ignored.
+        instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(deleteWordForward:)),
+                                                aCommands);
+        break;
+      }
+      // Shift is ignored.
+      instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(deleteForward:)),
+                                              aCommands);
+      break;
+    case KEY_NAME_INDEX_PageDown:
+      if (aEvent.IsControl() || aEvent.IsMeta()) {
+        break;
+      }
+      if (aEvent.IsAlt()) {
+        // Shift is ignored.
+        instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(pageDown:)), aCommands);
+        break;
+      }
+      instance->AppendEditCommandsForSelector(
+          !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(scrollPageDown:))
+                            : ToObjcSelectorPtr(@selector(pageDownAndModifySelection:)),
+          aCommands);
+      break;
+    case KEY_NAME_INDEX_PageUp:
+      if (aEvent.IsControl() || aEvent.IsMeta()) {
+        break;
+      }
+      if (aEvent.IsAlt()) {
+        // Shift is ignored.
+        instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(pageUp:)), aCommands);
+        break;
+      }
+      instance->AppendEditCommandsForSelector(
+          !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(scrollPageUp:))
+                            : ToObjcSelectorPtr(@selector(pageUpAndModifySelection:)),
+          aCommands);
+      break;
+    case KEY_NAME_INDEX_Home:
+      if (aEvent.IsAlt() || aEvent.IsControl() || aEvent.IsMeta()) {
+        break;
+      }
+      instance->AppendEditCommandsForSelector(
+          !aEvent.IsShift()
+              ? ToObjcSelectorPtr(@selector(scrollToBeginningOfDocument:))
+              : ToObjcSelectorPtr(@selector(moveToBeginningOfDocumentAndModifySelection:)),
+          aCommands);
+      break;
+    case KEY_NAME_INDEX_End:
+      if (aEvent.IsAlt() || aEvent.IsControl() || aEvent.IsMeta()) {
+        break;
+      }
+      instance->AppendEditCommandsForSelector(
+          !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(scrollToEndOfDocument:))
+                            : ToObjcSelectorPtr(@selector(moveToEndOfDocumentAndModifySelection:)),
+          aCommands);
+      break;
+    case KEY_NAME_INDEX_ArrowLeft:
+      if (aEvent.IsAlt()) {
+        break;
+      }
+      if (aEvent.IsMeta() || (aEvent.IsControl() && aEvent.IsShift())) {
+        instance->AppendEditCommandsForSelector(
+            !aEvent.IsShift()
+                ? ToObjcSelectorPtr(@selector(moveToLeftEndOfLine:))
+                : ToObjcSelectorPtr(@selector(moveToLeftEndOfLineAndModifySelection:)),
+            aCommands);
+        break;
+      }
+      if (aEvent.IsControl()) {
+        break;
+      }
+      instance->AppendEditCommandsForSelector(
+          !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(moveLeft:))
+                            : ToObjcSelectorPtr(@selector(moveLeftAndModifySelection:)),
+          aCommands);
+      break;
+    case KEY_NAME_INDEX_ArrowRight:
+      if (aEvent.IsAlt()) {
+        break;
+      }
+      if (aEvent.IsMeta() || (aEvent.IsControl() && aEvent.IsShift())) {
+        instance->AppendEditCommandsForSelector(
+            !aEvent.IsShift()
+                ? ToObjcSelectorPtr(@selector(moveToRightEndOfLine:))
+                : ToObjcSelectorPtr(@selector(moveToRightEndOfLineAndModifySelection:)),
+            aCommands);
+        break;
+      }
+      if (aEvent.IsControl()) {
+        break;
+      }
+      instance->AppendEditCommandsForSelector(
+          !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(moveRight:))
+                            : ToObjcSelectorPtr(@selector(moveRightAndModifySelection:)),
+          aCommands);
+      break;
+    case KEY_NAME_INDEX_ArrowUp:
+      if (aEvent.IsControl()) {
+        break;
+      }
+      if (aEvent.IsMeta()) {
+        if (aEvent.IsAlt()) {
+          break;
+        }
+        instance->AppendEditCommandsForSelector(
+            !aEvent.IsShift()
+                ? ToObjcSelectorPtr(@selector(moveToBeginningOfDocument:))
+                : ToObjcSelectorPtr(@selector(moveToBegginingOfDocumentAndModifySelection:)),
+            aCommands);
+        break;
+      }
+      if (aEvent.IsAlt()) {
+        if (!aEvent.IsShift()) {
+          instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(moveBackward:)),
+                                                  aCommands);
+          instance->AppendEditCommandsForSelector(
+              ToObjcSelectorPtr(@selector(moveToBeginningOfParagraph:)), aCommands);
+          break;
+        }
+        instance->AppendEditCommandsForSelector(
+            ToObjcSelectorPtr(@selector(moveParagraphBackwardAndModifySelection:)), aCommands);
+        break;
+      }
+      instance->AppendEditCommandsForSelector(
+          !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(moveUp:))
+                            : ToObjcSelectorPtr(@selector(moveUpAndModifySelection:)),
+          aCommands);
+      break;
+    case KEY_NAME_INDEX_ArrowDown:
+      if (aEvent.IsControl()) {
+        break;
+      }
+      if (aEvent.IsMeta()) {
+        if (aEvent.IsAlt()) {
+          break;
+        }
+        instance->AppendEditCommandsForSelector(
+            !aEvent.IsShift()
+                ? ToObjcSelectorPtr(@selector(moveToEndOfDocument:))
+                : ToObjcSelectorPtr(@selector(moveToEndOfDocumentAndModifySelection:)),
+            aCommands);
+        break;
+      }
+      if (aEvent.IsAlt()) {
+        if (!aEvent.IsShift()) {
+          instance->AppendEditCommandsForSelector(ToObjcSelectorPtr(@selector(moveForward:)),
+                                                  aCommands);
+          instance->AppendEditCommandsForSelector(
+              ToObjcSelectorPtr(@selector(moveToEndOfParagraph:)), aCommands);
+          break;
+        }
+        instance->AppendEditCommandsForSelector(
+            ToObjcSelectorPtr(@selector(moveParagraphForwardAndModifySelection:)), aCommands);
+        break;
+      }
+      instance->AppendEditCommandsForSelector(
+          !aEvent.IsShift() ? ToObjcSelectorPtr(@selector(moveDown:))
+                            : ToObjcSelectorPtr(@selector(moveDownAndModifySelection:)),
+          aCommands);
+      break;
+    default:
+      break;
+  }
+
+  instance->LogEditCommands(aCommands, "NativeKeyBindings::GetEditCommandsForTests");
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/cocoa/NativeMenuMac.h b/widget/cocoa/NativeMenuMac.h
new file mode 100644
index 0000000000..f2f5d20033
--- /dev/null
+++ b/widget/cocoa/NativeMenuMac.h
@@ -0,0 +1,93 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NativeMenuMac_h
+#define NativeMenuMac_h
+
+#include "mozilla/widget/NativeMenu.h"
+
+#include "nsMenuItemIconX.h"
+#include "nsMenuX.h"
+
+class nsIContent;
+class nsMenuGroupOwnerX;
+
+namespace mozilla {
+
+namespace dom {
+class Element;
+}
+
+namespace widget {
+
+class NativeMenuMac : public NativeMenu,
+                      public nsMenuItemIconX::Listener,
+                      public nsMenuX::Observer {
+ public:
+  explicit NativeMenuMac(dom::Element* aElement);
+
+  // NativeMenu
+  void ShowAsContextMenu(nsIFrame* aClickedFrame, const CSSIntPoint& aPosition,
+                         bool aIsContextMenu) override;
+  bool Close() override;
+  void ActivateItem(dom::Element* aItemElement, Modifiers aModifiers, int16_t aButton,
+                    ErrorResult& aRv) override;
+  void OpenSubmenu(dom::Element* aMenuElement) override;
+  void CloseSubmenu(dom::Element* aMenuElement) override;
+  RefPtr<dom::Element> Element() override;
+  void AddObserver(NativeMenu::Observer* aObserver) override {
+    mObservers.AppendElement(aObserver);
+  }
+  void RemoveObserver(NativeMenu::Observer* aObserver) override {
+    mObservers.RemoveElement(aObserver);
+  }
+
+  // nsMenuItemIconX::Listener
+  void IconUpdated() override;
+
+  // nsMenuX::Observer
+  void OnMenuWillOpen(dom::Element* aPopupElement) override;
+  void OnMenuDidOpen(dom::Element* aPopupElement) override;
+  void OnMenuWillActivateItem(dom::Element* aPopupElement, dom::Element* aMenuItemElement) override;
+  void OnMenuClosed(dom::Element* aPopupElement) override;
+
+  NSMenu* NativeNSMenu() { return mMenu ? mMenu->NativeNSMenu() : nil; }
+  void MenuWillOpen();
+
+  // Returns whether a menu item was found at the specified path.
+  bool ActivateNativeMenuItemAt(const nsAString& aIndexString);
+
+  void ForceUpdateNativeMenuAt(const nsAString& aIndexString);
+  void Dump();
+
+  // If this menu is the menu of a system status bar item (NSStatusItem),
+  // let the menu know about the status item so that it can propagate
+  // any icon changes to the status item.
+  void SetContainerStatusBarItem(NSStatusItem* aItem);
+
+ protected:
+  virtual ~NativeMenuMac();
+
+  // Find the deepest nsMenuX which contains aElement, only descending into open
+  // menus.
+  // Returns nullptr if the element was not found or if the menus on the path
+  // were not all open.
+  RefPtr<nsMenuX> GetOpenMenuContainingElement(dom::Element* aElement);
+
+  RefPtr<dom::Element> mElement;
+  RefPtr<nsMenuGroupOwnerX> mMenuGroupOwner;
+  RefPtr<nsMenuX> mMenu;
+  nsTArray<NativeMenu::Observer*> mObservers;
+  NSStatusItem* mContainerStatusBarItem;
+
+  // Non-zero after a call to ShowAsContextMenu. Stores the handle from the
+  // MOZMenuOpeningCoordinator.
+  NSInteger mOpeningHandle = 0;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif
diff --git a/widget/cocoa/NativeMenuMac.mm b/widget/cocoa/NativeMenuMac.mm
new file mode 100644
index 0000000000..061d6c7ad9
--- /dev/null
+++ b/widget/cocoa/NativeMenuMac.mm
@@ -0,0 +1,394 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "NativeMenuMac.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/BasicEvents.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/Element.h"
+
+#include "MOZMenuOpeningCoordinator.h"
+#include "nsISupports.h"
+#include "nsGkAtoms.h"
+#include "nsMenuGroupOwnerX.h"
+#include "nsMenuItemX.h"
+#include "nsMenuUtilsX.h"
+#include "nsNativeThemeColors.h"
+#include "nsObjCExceptions.h"
+#include "nsThreadUtils.h"
+#include "PresShell.h"
+#include "nsCocoaUtils.h"
+#include "nsIFrame.h"
+#include "nsPresContext.h"
+#include "nsDeviceContext.h"
+#include "nsCocoaFeatures.h"
+
+namespace mozilla {
+
+using dom::Element;
+
+namespace widget {
+
+NativeMenuMac::NativeMenuMac(dom::Element* aElement)
+    : mElement(aElement), mContainerStatusBarItem(nil) {
+  MOZ_RELEASE_ASSERT(aElement->IsAnyOfXULElements(nsGkAtoms::menu, nsGkAtoms::menupopup));
+  mMenuGroupOwner = new nsMenuGroupOwnerX(aElement, nullptr);
+  mMenu = MakeRefPtr<nsMenuX>(nullptr, mMenuGroupOwner, aElement);
+  mMenu->SetObserver(this);
+  mMenu->SetIconListener(this);
+  mMenu->SetupIcon();
+}
+
+NativeMenuMac::~NativeMenuMac() {
+  mMenu->DetachFromGroupOwnerRecursive();
+  mMenu->ClearObserver();
+  mMenu->ClearIconListener();
+}
+
+static void UpdateMenu(nsMenuX* aMenu) {
+  aMenu->MenuOpened();
+  aMenu->MenuClosed();
+
+  uint32_t itemCount = aMenu->GetItemCount();
+  for (uint32_t i = 0; i < itemCount; i++) {
+    nsMenuX::MenuChild menuObject = *aMenu->GetItemAt(i);
+    if (menuObject.is<RefPtr<nsMenuX>>()) {
+      UpdateMenu(menuObject.as<RefPtr<nsMenuX>>());
+    }
+  }
+}
+
+void NativeMenuMac::MenuWillOpen() {
+  // Force an update on the mMenu by faking an open/close on all of
+  // its submenus.
+  UpdateMenu(mMenu.get());
+}
+
+bool NativeMenuMac::ActivateNativeMenuItemAt(const nsAString& aIndexString) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  NSMenu* menu = mMenu->NativeNSMenu();
+
+  nsMenuUtilsX::CheckNativeMenuConsistency(menu);
+
+  NSString* locationString =
+      [NSString stringWithCharacters:reinterpret_cast<const unichar*>(aIndexString.BeginReading())
+                              length:aIndexString.Length()];
+  NSMenuItem* item = nsMenuUtilsX::NativeMenuItemWithLocation(menu, locationString, false);
+
+  // We can't perform an action on an item with a submenu, that will raise
+  // an obj-c exception.
+  if (item && !item.hasSubmenu) {
+    NSMenu* parent = item.menu;
+    if (parent) {
+      // NSLog(@"Performing action for native menu item titled: %@\n",
+      //       [[currentSubmenu itemAtIndex:targetIndex] title]);
+      mozilla::AutoRestore<bool> autoRestore(
+          nsMenuUtilsX::gIsSynchronouslyActivatingNativeMenuItemDuringTest);
+      nsMenuUtilsX::gIsSynchronouslyActivatingNativeMenuItemDuringTest = true;
+      [parent performActionForItemAtIndex:[parent indexOfItem:item]];
+      return true;
+    }
+  }
+
+  return false;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void NativeMenuMac::ForceUpdateNativeMenuAt(const nsAString& aIndexString) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  NSString* locationString =
+      [NSString stringWithCharacters:reinterpret_cast<const unichar*>(aIndexString.BeginReading())
+                              length:aIndexString.Length()];
+  NSArray<NSString*>* indexes = [locationString componentsSeparatedByString:@"|"];
+  RefPtr<nsMenuX> currentMenu = mMenu.get();
+
+  // now find the correct submenu
+  unsigned int indexCount = indexes.count;
+  for (unsigned int i = 1; currentMenu && i < indexCount; i++) {
+    int targetIndex = [indexes objectAtIndex:i].intValue;
+    int visible = 0;
+    uint32_t length = currentMenu->GetItemCount();
+    for (unsigned int j = 0; j < length; j++) {
+      Maybe<nsMenuX::MenuChild> targetMenu = currentMenu->GetItemAt(j);
+      if (!targetMenu) {
+        return;
+      }
+      RefPtr<nsIContent> content = targetMenu->match(
+          [](const RefPtr<nsMenuX>& aMenu) { return aMenu->Content(); },
+          [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->Content(); });
+      if (!nsMenuUtilsX::NodeIsHiddenOrCollapsed(content)) {
+        visible++;
+        if (targetMenu->is<RefPtr<nsMenuX>>() && visible == (targetIndex + 1)) {
+          currentMenu = targetMenu->as<RefPtr<nsMenuX>>();
+          break;
+        }
+      }
+    }
+  }
+
+  // fake open/close to cause lazy update to happen
+  currentMenu->MenuOpened();
+  currentMenu->MenuClosed();
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void NativeMenuMac::IconUpdated() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (mContainerStatusBarItem) {
+    NSImage* menuImage = mMenu->NativeNSMenuItem().image;
+    if (menuImage) {
+      [menuImage setTemplate:YES];
+    }
+    mContainerStatusBarItem.button.image = menuImage;
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void NativeMenuMac::SetContainerStatusBarItem(NSStatusItem* aItem) {
+  mContainerStatusBarItem = aItem;
+  IconUpdated();
+}
+
+void NativeMenuMac::Dump() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  mMenu->Dump(0);
+  nsMenuUtilsX::DumpNativeMenu(mMenu->NativeNSMenu());
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void NativeMenuMac::OnMenuWillOpen(dom::Element* aPopupElement) {
+  if (aPopupElement == mElement) {
+    return;
+  }
+
+  // Our caller isn't keeping us alive, so make sure we stay alive throughout this function in case
+  // one of the observer notifications destroys us.
+  RefPtr<NativeMenuMac> kungFuDeathGrip(this);
+
+  for (NativeMenu::Observer* observer : mObservers.Clone()) {
+    observer->OnNativeSubMenuWillOpen(aPopupElement);
+  }
+}
+
+void NativeMenuMac::OnMenuDidOpen(dom::Element* aPopupElement) {
+  // Our caller isn't keeping us alive, so make sure we stay alive throughout this function in case
+  // one of the observer notifications destroys us.
+  RefPtr<NativeMenuMac> kungFuDeathGrip(this);
+
+  for (NativeMenu::Observer* observer : mObservers.Clone()) {
+    if (aPopupElement == mElement) {
+      observer->OnNativeMenuOpened();
+    } else {
+      observer->OnNativeSubMenuDidOpen(aPopupElement);
+    }
+  }
+}
+
+void NativeMenuMac::OnMenuWillActivateItem(dom::Element* aPopupElement,
+                                           dom::Element* aMenuItemElement) {
+  // Our caller isn't keeping us alive, so make sure we stay alive throughout this function in case
+  // one of the observer notifications destroys us.
+  RefPtr<NativeMenuMac> kungFuDeathGrip(this);
+
+  for (NativeMenu::Observer* observer : mObservers.Clone()) {
+    observer->OnNativeMenuWillActivateItem(aMenuItemElement);
+  }
+}
+
+void NativeMenuMac::OnMenuClosed(dom::Element* aPopupElement) {
+  // Our caller isn't keeping us alive, so make sure we stay alive throughout this function in case
+  // one of the observer notifications destroys us.
+  RefPtr<NativeMenuMac> kungFuDeathGrip(this);
+
+  for (NativeMenu::Observer* observer : mObservers.Clone()) {
+    if (aPopupElement == mElement) {
+      observer->OnNativeMenuClosed();
+    } else {
+      observer->OnNativeSubMenuClosed(aPopupElement);
+    }
+  }
+}
+
+static NSView* NativeViewForFrame(nsIFrame* aFrame) {
+  nsIWidget* widget = aFrame->GetNearestWidget();
+  return (NSView*)widget->GetNativeData(NS_NATIVE_WIDGET);
+}
+
+static NSAppearance* NativeAppearanceForContent(nsIContent* aContent) {
+  nsIFrame* f = aContent->GetPrimaryFrame();
+  if (!f) {
+    return nil;
+  }
+  return NSAppearanceForColorScheme(LookAndFeel::ColorSchemeForFrame(f));
+}
+
+void NativeMenuMac::ShowAsContextMenu(nsIFrame* aClickedFrame, const CSSIntPoint& aPosition,
+                                      bool aIsContextMenu) {
+  nsPresContext* pc = aClickedFrame->PresContext();
+  auto cssToDesktopScale =
+      pc->CSSToDevPixelScale() / pc->DeviceContext()->GetDesktopToDeviceScale();
+  const DesktopPoint desktopPoint = aPosition * cssToDesktopScale;
+
+  mMenu->PopupShowingEventWasSentAndApprovedExternally();
+
+  NSMenu* menu = mMenu->NativeNSMenu();
+  NSView* view = NativeViewForFrame(aClickedFrame);
+  NSAppearance* appearance = NativeAppearanceForContent(mMenu->Content());
+  NSPoint locationOnScreen = nsCocoaUtils::GeckoPointToCocoaPoint(desktopPoint);
+
+  // Let the MOZMenuOpeningCoordinator do the actual opening, so that this ShowAsContextMenu call
+  // does not spawn a nested event loop, which would be surprising to our callers.
+  mOpeningHandle = [MOZMenuOpeningCoordinator.sharedInstance asynchronouslyOpenMenu:menu
+                                                                   atScreenPosition:locationOnScreen
+                                                                            forView:view
+                                                                     withAppearance:appearance
+                                                                      asContextMenu:aIsContextMenu];
+}
+
+bool NativeMenuMac::Close() {
+  if (mOpeningHandle) {
+    // In case the menu was trying to open, but this Close() call interrupted it, cancel opening.
+    [MOZMenuOpeningCoordinator.sharedInstance cancelAsynchronousOpening:mOpeningHandle];
+  }
+  return mMenu->Close();
+}
+
+RefPtr<nsMenuX> NativeMenuMac::GetOpenMenuContainingElement(dom::Element* aElement) {
+  nsTArray<RefPtr<dom::Element>> submenuChain;
+  RefPtr<dom::Element> currentElement = aElement->GetParentElement();
+  while (currentElement && currentElement != mElement) {
+    if (currentElement->IsXULElement(nsGkAtoms::menu)) {
+      submenuChain.AppendElement(currentElement);
+    }
+    currentElement = currentElement->GetParentElement();
+  }
+  if (!currentElement) {
+    // aElement was not a descendent of mElement. Refuse to activate the item.
+    return nullptr;
+  }
+
+  // Traverse submenuChain from shallow to deep, to find the nsMenuX that contains aElement.
+  submenuChain.Reverse();
+  RefPtr<nsMenuX> menu = mMenu;
+  for (const auto& submenu : submenuChain) {
+    if (!menu->IsOpenForGecko()) {
+      // Refuse to descend into closed menus.
+      return nullptr;
+    }
+    Maybe<nsMenuX::MenuChild> menuChild = menu->GetItemForElement(submenu);
+    if (!menuChild || !menuChild->is<RefPtr<nsMenuX>>()) {
+      // Couldn't find submenu.
+      return nullptr;
+    }
+    menu = menuChild->as<RefPtr<nsMenuX>>();
+  }
+
+  if (!menu->IsOpenForGecko()) {
+    // Refuse to descend into closed menus.
+    return nullptr;
+  }
+  return menu;
+}
+
+static NSEventModifierFlags ConvertModifierFlags(Modifiers aModifiers) {
+  NSEventModifierFlags flags = 0;
+  if (aModifiers & MODIFIER_CONTROL) {
+    flags |= NSEventModifierFlagControl;
+  }
+  if (aModifiers & MODIFIER_ALT) {
+    flags |= NSEventModifierFlagOption;
+  }
+  if (aModifiers & MODIFIER_SHIFT) {
+    flags |= NSEventModifierFlagShift;
+  }
+  if (aModifiers & MODIFIER_META) {
+    flags |= NSEventModifierFlagCommand;
+  }
+  return flags;
+}
+
+void NativeMenuMac::ActivateItem(dom::Element* aItemElement, Modifiers aModifiers, int16_t aButton,
+                                 ErrorResult& aRv) {
+  RefPtr<nsMenuX> menu = GetOpenMenuContainingElement(aItemElement);
+  if (!menu) {
+    aRv.ThrowInvalidStateError("Menu containing menu item is not open");
+    return;
+  }
+  Maybe<nsMenuX::MenuChild> child = menu->GetItemForElement(aItemElement);
+  if (!child || !child->is<RefPtr<nsMenuItemX>>()) {
+    aRv.ThrowInvalidStateError("Could not find the supplied menu item");
+    return;
+  }
+
+  RefPtr<nsMenuItemX> item = std::move(child->as<RefPtr<nsMenuItemX>>());
+  if (!item->IsVisible()) {
+    aRv.ThrowInvalidStateError("Menu item is not visible");
+    return;
+  }
+
+  NSMenuItem* nativeItem = [item->NativeNSMenuItem() retain];
+
+  // First, initiate the closing of the NSMenu.
+  // This synchronously calls the menu delegate's menuDidClose handler. So menuDidClose is
+  // what runs first; this matches the order of events for user-initiated menu item activation.
+  // This call doesn't immediately hide the menu; the menu only hides once the stack unwinds
+  // from NSMenu's nested "tracking" event loop.
+  [mMenu->NativeNSMenu() cancelTrackingWithoutAnimation];
+
+  // Next, call OnWillActivateItem. This also matches the order of calls that happen when a user
+  // activates a menu item in the real world: -[MenuDelegate menu:willActivateItem:] runs after
+  // menuDidClose.
+  menu->OnWillActivateItem(nativeItem);
+
+  // Finally, call ActivateItemAfterClosing. This also mimics the order in the real world:
+  // menuItemHit is called after menu:willActivateItem:.
+  menu->ActivateItemAfterClosing(std::move(item), ConvertModifierFlags(aModifiers), aButton);
+
+  // Tell our native event loop that it should not process any more work before
+  // unwinding the stack, so that we can get out of the menu's nested event loop
+  // as fast as possible. This was needed to fix spurious failures in tests, where
+  // a call to cancelTrackingWithoutAnimation was ignored if more native events were
+  // processed before the event loop was exited. As a result, the menu stayed open
+  // forever and the test never finished.
+  MOZMenuOpeningCoordinator.needToUnwindForMenuClosing = YES;
+
+  [nativeItem release];
+}
+
+void NativeMenuMac::OpenSubmenu(dom::Element* aMenuElement) {
+  if (RefPtr<nsMenuX> menu = GetOpenMenuContainingElement(aMenuElement)) {
+    Maybe<nsMenuX::MenuChild> item = menu->GetItemForElement(aMenuElement);
+    if (item && item->is<RefPtr<nsMenuX>>()) {
+      item->as<RefPtr<nsMenuX>>()->MenuOpened();
+    }
+  }
+}
+
+void NativeMenuMac::CloseSubmenu(dom::Element* aMenuElement) {
+  if (RefPtr<nsMenuX> menu = GetOpenMenuContainingElement(aMenuElement)) {
+    Maybe<nsMenuX::MenuChild> item = menu->GetItemForElement(aMenuElement);
+    if (item && item->is<RefPtr<nsMenuX>>()) {
+      item->as<RefPtr<nsMenuX>>()->MenuClosed();
+    }
+  }
+}
+
+RefPtr<Element> NativeMenuMac::Element() { return mElement; }
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/cocoa/NativeMenuSupport.mm b/widget/cocoa/NativeMenuSupport.mm
new file mode 100644
index 0000000000..98f9fc045e
--- /dev/null
+++ b/widget/cocoa/NativeMenuSupport.mm
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/widget/NativeMenuSupport.h"
+
+#include "MainThreadUtils.h"
+#include "mozilla/StaticPrefs_browser.h"
+#include "mozilla/StaticPrefs_widget.h"
+#include "NativeMenuMac.h"
+#include "nsCocoaWindow.h"
+#include "nsMenuBarX.h"
+
+namespace mozilla::widget {
+
+void NativeMenuSupport::CreateNativeMenuBar(nsIWidget* aParent, dom::Element* aMenuBarElement) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread(), "Attempting to create native menu bar on wrong thread!");
+
+  // Create the menubar and give it to the parent window. The parent takes ownership.
+  static_cast<nsCocoaWindow*>(aParent)->SetMenuBar(MakeRefPtr<nsMenuBarX>(aMenuBarElement));
+}
+
+already_AddRefed<NativeMenu> NativeMenuSupport::CreateNativeContextMenu(dom::Element* aPopup) {
+  return MakeAndAddRef<NativeMenuMac>(aPopup);
+}
+
+bool NativeMenuSupport::ShouldUseNativeContextMenus() {
+  return StaticPrefs::widget_macos_native_context_menus();
+}
+
+}  // namespace mozilla::widget
diff --git a/widget/cocoa/OSXNotificationCenter.h b/widget/cocoa/OSXNotificationCenter.h
new file mode 100644
index 0000000000..9ff1ff62d8
--- /dev/null
+++ b/widget/cocoa/OSXNotificationCenter.h
@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef OSXNotificationCenter_h
+#define OSXNotificationCenter_h
+
+#import <Foundation/Foundation.h>
+#include "nsIAlertsService.h"
+#include "nsTArray.h"
+#include "mozilla/RefPtr.h"
+
+// mozNotificationCenterDelegate is used to access the macOS notification
+// center. It is not related to the DesktopNotificationCenter object, which was
+// removed in bug 952453. While there are no direct references to this class
+// elsewhere, removing this will cause push notifications on macOS to stop
+// working.
+@class mozNotificationCenterDelegate;
+
+namespace mozilla {
+
+class OSXNotificationInfo;
+
+class OSXNotificationCenter : public nsIAlertsService,
+                              public nsIAlertsIconData,
+                              public nsIAlertsDoNotDisturb,
+                              public nsIAlertNotificationImageListener {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIALERTSSERVICE
+  NS_DECL_NSIALERTSICONDATA
+  NS_DECL_NSIALERTSDONOTDISTURB
+  NS_DECL_NSIALERTNOTIFICATIONIMAGELISTENER
+
+  OSXNotificationCenter();
+
+  nsresult Init();
+  void CloseAlertCocoaString(NSString* aAlertName);
+  void OnActivate(NSString* aAlertName, NSUserNotificationActivationType aActivationType,
+                  unsigned long long aAdditionalActionIndex);
+  void ShowPendingNotification(OSXNotificationInfo* osxni);
+
+ protected:
+  virtual ~OSXNotificationCenter();
+
+ private:
+  mozNotificationCenterDelegate* mDelegate;
+  nsTArray<RefPtr<OSXNotificationInfo> > mActiveAlerts;
+  nsTArray<RefPtr<OSXNotificationInfo> > mPendingAlerts;
+  bool mSuppressForScreenSharing;
+};
+
+}  // namespace mozilla
+
+#endif  // OSXNotificationCenter_h
diff --git a/widget/cocoa/OSXNotificationCenter.mm b/widget/cocoa/OSXNotificationCenter.mm
new file mode 100644
index 0000000000..854bcadb13
--- /dev/null
+++ b/widget/cocoa/OSXNotificationCenter.mm
@@ -0,0 +1,556 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "OSXNotificationCenter.h"
+#import <AppKit/AppKit.h>
+#include "imgIRequest.h"
+#include "imgIContainer.h"
+#include "nsICancelable.h"
+#include "nsIStringBundle.h"
+#include "nsNetUtil.h"
+#import "nsCocoaUtils.h"
+#include "nsComponentManagerUtils.h"
+#include "nsContentUtils.h"
+#include "nsObjCExceptions.h"
+#include "nsString.h"
+#include "nsCOMPtr.h"
+#include "nsIObserver.h"
+
+using namespace mozilla;
+
+#define MAX_NOTIFICATION_NAME_LEN 5000
+
+@protocol FakeNSUserNotification <NSObject>
+@property(copy) NSString* title;
+@property(copy) NSString* subtitle;
+@property(copy) NSString* informativeText;
+@property(copy) NSString* actionButtonTitle;
+@property(copy) NSDictionary* userInfo;
+@property(copy) NSDate* deliveryDate;
+@property(copy) NSTimeZone* deliveryTimeZone;
+@property(copy) NSDateComponents* deliveryRepeatInterval;
+@property(readonly) NSDate* actualDeliveryDate;
+@property(readonly, getter=isPresented) BOOL presented;
+@property(readonly, getter=isRemote) BOOL remote;
+@property(copy) NSString* soundName;
+@property BOOL hasActionButton;
+@property(readonly) NSUserNotificationActivationType activationType;
+@property(copy) NSString* otherButtonTitle;
+@property(copy) NSImage* contentImage;
+@end
+
+@protocol FakeNSUserNotificationCenter <NSObject>
++ (id<FakeNSUserNotificationCenter>)defaultUserNotificationCenter;
+@property(assign) id<NSUserNotificationCenterDelegate> delegate;
+@property(copy) NSArray* scheduledNotifications;
+- (void)scheduleNotification:(id<FakeNSUserNotification>)notification;
+- (void)removeScheduledNotification:(id<FakeNSUserNotification>)notification;
+@property(readonly) NSArray* deliveredNotifications;
+- (void)deliverNotification:(id<FakeNSUserNotification>)notification;
+- (void)removeDeliveredNotification:(id<FakeNSUserNotification>)notification;
+- (void)removeAllDeliveredNotifications;
+- (void)_removeAllDisplayedNotifications;
+- (void)_removeDisplayedNotification:(id<FakeNSUserNotification>)notification;
+@end
+
+@interface mozNotificationCenterDelegate : NSObject <NSUserNotificationCenterDelegate> {
+  OSXNotificationCenter* mOSXNC;
+}
+- (id)initWithOSXNC:(OSXNotificationCenter*)osxnc;
+@end
+
+@implementation mozNotificationCenterDelegate
+
+- (id)initWithOSXNC:(OSXNotificationCenter*)osxnc {
+  [super init];
+  // We should *never* outlive this OSXNotificationCenter.
+  mOSXNC = osxnc;
+  return self;
+}
+
+- (void)userNotificationCenter:(id<FakeNSUserNotificationCenter>)center
+        didDeliverNotification:(id<FakeNSUserNotification>)notification {
+}
+
+- (void)userNotificationCenter:(id<FakeNSUserNotificationCenter>)center
+       didActivateNotification:(id<FakeNSUserNotification>)notification {
+  unsigned long long additionalActionIndex = ULLONG_MAX;
+  if ([notification respondsToSelector:@selector(_alternateActionIndex)]) {
+    NSNumber* alternateActionIndex = [(NSObject*)notification valueForKey:@"_alternateActionIndex"];
+    additionalActionIndex = [alternateActionIndex unsignedLongLongValue];
+  }
+  mOSXNC->OnActivate([[notification userInfo] valueForKey:@"name"], notification.activationType,
+                     additionalActionIndex);
+}
+
+- (BOOL)userNotificationCenter:(id<FakeNSUserNotificationCenter>)center
+     shouldPresentNotification:(id<FakeNSUserNotification>)notification {
+  return YES;
+}
+
+// This is an undocumented method that we need for parity with Safari.
+// Apple bug #15440664.
+- (void)userNotificationCenter:(id<FakeNSUserNotificationCenter>)center
+    didRemoveDeliveredNotifications:(NSArray*)notifications {
+  for (id<FakeNSUserNotification> notification in notifications) {
+    NSString* name = [[notification userInfo] valueForKey:@"name"];
+    mOSXNC->CloseAlertCocoaString(name);
+  }
+}
+
+// This is an undocumented method that we need to be notified if a user clicks the close button.
+- (void)userNotificationCenter:(id<FakeNSUserNotificationCenter>)center
+               didDismissAlert:(id<FakeNSUserNotification>)notification {
+  NSString* name = [[notification userInfo] valueForKey:@"name"];
+  mOSXNC->CloseAlertCocoaString(name);
+}
+
+@end
+
+namespace mozilla {
+
+enum {
+  OSXNotificationActionDisable = 0,
+  OSXNotificationActionSettings = 1,
+};
+
+class OSXNotificationInfo final : public nsISupports {
+ private:
+  virtual ~OSXNotificationInfo();
+
+ public:
+  NS_DECL_ISUPPORTS
+  OSXNotificationInfo(NSString* name, nsIObserver* observer, const nsAString& alertCookie);
+
+  NSString* mName;
+  nsCOMPtr<nsIObserver> mObserver;
+  nsString mCookie;
+  RefPtr<nsICancelable> mIconRequest;
+  id<FakeNSUserNotification> mPendingNotification;
+};
+
+NS_IMPL_ISUPPORTS0(OSXNotificationInfo)
+
+OSXNotificationInfo::OSXNotificationInfo(NSString* name, nsIObserver* observer,
+                                         const nsAString& alertCookie) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NS_ASSERTION(name, "Cannot create OSXNotificationInfo without a name!");
+  mName = [name retain];
+  mObserver = observer;
+  mCookie = alertCookie;
+  mPendingNotification = nil;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+OSXNotificationInfo::~OSXNotificationInfo() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mName release];
+  [mPendingNotification release];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static id<FakeNSUserNotificationCenter> GetNotificationCenter() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  Class c = NSClassFromString(@"NSUserNotificationCenter");
+  return [c performSelector:@selector(defaultUserNotificationCenter)];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+OSXNotificationCenter::OSXNotificationCenter() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  mDelegate = [[mozNotificationCenterDelegate alloc] initWithOSXNC:this];
+  GetNotificationCenter().delegate = mDelegate;
+  mSuppressForScreenSharing = false;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+OSXNotificationCenter::~OSXNotificationCenter() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [GetNotificationCenter() removeAllDeliveredNotifications];
+  [mDelegate release];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+NS_IMPL_ISUPPORTS(OSXNotificationCenter, nsIAlertsService, nsIAlertsIconData, nsIAlertsDoNotDisturb,
+                  nsIAlertNotificationImageListener)
+
+nsresult OSXNotificationCenter::Init() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return (!!NSClassFromString(@"NSUserNotification")) ? NS_OK : NS_ERROR_FAILURE;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+OSXNotificationCenter::ShowAlertNotification(
+    const nsAString& aImageUrl, const nsAString& aAlertTitle, const nsAString& aAlertText,
+    bool aAlertTextClickable, const nsAString& aAlertCookie, nsIObserver* aAlertListener,
+    const nsAString& aAlertName, const nsAString& aBidi, const nsAString& aLang,
+    const nsAString& aData, nsIPrincipal* aPrincipal, bool aInPrivateBrowsing,
+    bool aRequireInteraction) {
+  nsCOMPtr<nsIAlertNotification> alert = do_CreateInstance(ALERT_NOTIFICATION_CONTRACTID);
+  NS_ENSURE_TRUE(alert, NS_ERROR_FAILURE);
+  // vibrate is unused for now
+  nsTArray<uint32_t> vibrate;
+  nsresult rv = alert->Init(aAlertName, aImageUrl, aAlertTitle, aAlertText, aAlertTextClickable,
+                            aAlertCookie, aBidi, aLang, aData, aPrincipal, aInPrivateBrowsing,
+                            aRequireInteraction, false, vibrate);
+  NS_ENSURE_SUCCESS(rv, rv);
+  return ShowAlert(alert, aAlertListener);
+}
+
+NS_IMETHODIMP
+OSXNotificationCenter::ShowPersistentNotification(const nsAString& aPersistentData,
+                                                  nsIAlertNotification* aAlert,
+                                                  nsIObserver* aAlertListener) {
+  return ShowAlert(aAlert, aAlertListener);
+}
+
+NS_IMETHODIMP
+OSXNotificationCenter::ShowAlert(nsIAlertNotification* aAlert, nsIObserver* aAlertListener) {
+  return ShowAlertWithIconData(aAlert, aAlertListener, 0, nullptr);
+}
+
+NS_IMETHODIMP
+OSXNotificationCenter::ShowAlertWithIconData(nsIAlertNotification* aAlert,
+                                             nsIObserver* aAlertListener, uint32_t aIconSize,
+                                             const uint8_t* aIconData) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NS_ENSURE_ARG(aAlert);
+
+  if (mSuppressForScreenSharing) {
+    return NS_OK;
+  }
+
+  Class unClass = NSClassFromString(@"NSUserNotification");
+  id<FakeNSUserNotification> notification = [[unClass alloc] init];
+
+  nsAutoString title;
+  nsresult rv = aAlert->GetTitle(title);
+  NS_ENSURE_SUCCESS(rv, rv);
+  notification.title = nsCocoaUtils::ToNSString(title);
+
+  nsAutoString hostPort;
+  rv = aAlert->GetSource(hostPort);
+  NS_ENSURE_SUCCESS(rv, rv);
+  nsCOMPtr<nsIStringBundle> bundle;
+  nsCOMPtr<nsIStringBundleService> sbs = do_GetService(NS_STRINGBUNDLE_CONTRACTID);
+  sbs->CreateBundle("chrome://alerts/locale/alert.properties", getter_AddRefs(bundle));
+
+  if (!hostPort.IsEmpty() && bundle) {
+    AutoTArray<nsString, 1> formatStrings = {hostPort};
+    nsAutoString notificationSource;
+    bundle->FormatStringFromName("source.label", formatStrings, notificationSource);
+    notification.subtitle = nsCocoaUtils::ToNSString(notificationSource);
+  }
+
+  nsAutoString text;
+  rv = aAlert->GetText(text);
+  NS_ENSURE_SUCCESS(rv, rv);
+  notification.informativeText = nsCocoaUtils::ToNSString(text);
+
+  bool isSilent;
+  aAlert->GetSilent(&isSilent);
+  notification.soundName = isSilent ? nil : NSUserNotificationDefaultSoundName;
+  notification.hasActionButton = NO;
+
+  // If this is not an application/extension alert, show additional actions dealing with
+  // permissions.
+  bool isActionable;
+  if (bundle && NS_SUCCEEDED(aAlert->GetActionable(&isActionable)) && isActionable) {
+    nsAutoString closeButtonTitle, actionButtonTitle, disableButtonTitle, settingsButtonTitle;
+    bundle->GetStringFromName("closeButton.title", closeButtonTitle);
+    bundle->GetStringFromName("actionButton.label", actionButtonTitle);
+    if (!hostPort.IsEmpty()) {
+      AutoTArray<nsString, 1> formatStrings = {hostPort};
+      bundle->FormatStringFromName("webActions.disableForOrigin.label", formatStrings,
+                                   disableButtonTitle);
+    }
+    bundle->GetStringFromName("webActions.settings.label", settingsButtonTitle);
+
+    notification.otherButtonTitle = nsCocoaUtils::ToNSString(closeButtonTitle);
+
+    // OS X 10.8 only shows action buttons if the "Alerts" style is set in
+    // Notification Center preferences, and doesn't support the alternate
+    // action menu.
+    if ([notification respondsToSelector:@selector(set_showsButtons:)] &&
+        [notification respondsToSelector:@selector(set_alwaysShowAlternateActionMenu:)] &&
+        [notification respondsToSelector:@selector(set_alternateActionButtonTitles:)]) {
+      notification.hasActionButton = YES;
+      notification.actionButtonTitle = nsCocoaUtils::ToNSString(actionButtonTitle);
+
+      [(NSObject*)notification setValue:@(YES) forKey:@"_showsButtons"];
+      [(NSObject*)notification setValue:@(YES) forKey:@"_alwaysShowAlternateActionMenu"];
+      [(NSObject*)notification setValue:@[
+        nsCocoaUtils::ToNSString(disableButtonTitle), nsCocoaUtils::ToNSString(settingsButtonTitle)
+      ]
+                                 forKey:@"_alternateActionButtonTitles"];
+    }
+  }
+  nsAutoString name;
+  rv = aAlert->GetName(name);
+  // Don't let an alert name be more than MAX_NOTIFICATION_NAME_LEN characters.
+  // More than that shouldn't be necessary and userInfo (assigned to below) has
+  // a length limit of 16k on OS X 10.11. Exception thrown if limit exceeded.
+  if (name.Length() > MAX_NOTIFICATION_NAME_LEN) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NS_ENSURE_SUCCESS(rv, rv);
+  NSString* alertName = nsCocoaUtils::ToNSString(name);
+  if (!alertName) {
+    return NS_ERROR_FAILURE;
+  }
+  notification.userInfo =
+      [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:alertName, nil]
+                                  forKeys:[NSArray arrayWithObjects:@"name", nil]];
+
+  nsAutoString cookie;
+  rv = aAlert->GetCookie(cookie);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  OSXNotificationInfo* osxni = new OSXNotificationInfo(alertName, aAlertListener, cookie);
+
+  // Show the favicon if supported on this version of OS X.
+  if (aIconSize > 0 && [notification respondsToSelector:@selector(set_identityImage:)] &&
+      [notification respondsToSelector:@selector(set_identityImageHasBorder:)]) {
+    NSData* iconData = [NSData dataWithBytes:aIconData length:aIconSize];
+    NSImage* icon = [[[NSImage alloc] initWithData:iconData] autorelease];
+
+    [(NSObject*)notification setValue:icon forKey:@"_identityImage"];
+    [(NSObject*)notification setValue:@(NO) forKey:@"_identityImageHasBorder"];
+  }
+
+  bool inPrivateBrowsing;
+  rv = aAlert->GetInPrivateBrowsing(&inPrivateBrowsing);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Show the notification without waiting for an image if there is no icon URL or
+  // notification icons are not supported on this version of OS X.
+  if (![unClass instancesRespondToSelector:@selector(setContentImage:)]) {
+    CloseAlertCocoaString(alertName);
+    mActiveAlerts.AppendElement(osxni);
+    [GetNotificationCenter() deliverNotification:notification];
+    [notification release];
+    if (aAlertListener) {
+      aAlertListener->Observe(nullptr, "alertshow", cookie.get());
+    }
+  } else {
+    mPendingAlerts.AppendElement(osxni);
+    osxni->mPendingNotification = notification;
+    // Wait six seconds for the image to load.
+    rv = aAlert->LoadImage(6000, this, osxni, getter_AddRefs(osxni->mIconRequest));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      ShowPendingNotification(osxni);
+    }
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+OSXNotificationCenter::CloseAlert(const nsAString& aAlertName, bool aContextClosed) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSString* alertName = nsCocoaUtils::ToNSString(aAlertName);
+  CloseAlertCocoaString(alertName);
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void OSXNotificationCenter::CloseAlertCocoaString(NSString* aAlertName) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!aAlertName) {
+    return;  // Can't do anything without a name
+  }
+
+  NSArray* notifications = [GetNotificationCenter() deliveredNotifications];
+  for (id<FakeNSUserNotification> notification in notifications) {
+    NSString* name = [[notification userInfo] valueForKey:@"name"];
+    if ([name isEqualToString:aAlertName]) {
+      [GetNotificationCenter() removeDeliveredNotification:notification];
+      [GetNotificationCenter() _removeDisplayedNotification:notification];
+      break;
+    }
+  }
+
+  for (unsigned int i = 0; i < mActiveAlerts.Length(); i++) {
+    OSXNotificationInfo* osxni = mActiveAlerts[i];
+    if ([aAlertName isEqualToString:osxni->mName]) {
+      if (osxni->mObserver) {
+        osxni->mObserver->Observe(nullptr, "alertfinished", osxni->mCookie.get());
+      }
+      if (osxni->mIconRequest) {
+        osxni->mIconRequest->Cancel(NS_BINDING_ABORTED);
+        osxni->mIconRequest = nullptr;
+      }
+      mActiveAlerts.RemoveElementAt(i);
+      break;
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void OSXNotificationCenter::OnActivate(NSString* aAlertName,
+                                       NSUserNotificationActivationType aActivationType,
+                                       unsigned long long aAdditionalActionIndex) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!aAlertName) {
+    return;  // Can't do anything without a name
+  }
+
+  for (unsigned int i = 0; i < mActiveAlerts.Length(); i++) {
+    OSXNotificationInfo* osxni = mActiveAlerts[i];
+    if ([aAlertName isEqualToString:osxni->mName]) {
+      if (osxni->mObserver) {
+        switch ((int)aActivationType) {
+          case NSUserNotificationActivationTypeAdditionalActionClicked:
+          case NSUserNotificationActivationTypeActionButtonClicked:
+            switch (aAdditionalActionIndex) {
+              case OSXNotificationActionDisable:
+                osxni->mObserver->Observe(nullptr, "alertdisablecallback", osxni->mCookie.get());
+                break;
+              case OSXNotificationActionSettings:
+                osxni->mObserver->Observe(nullptr, "alertsettingscallback", osxni->mCookie.get());
+                break;
+              default:
+                NS_WARNING("Unknown NSUserNotification additional action clicked");
+                break;
+            }
+            break;
+          default:
+            osxni->mObserver->Observe(nullptr, "alertclickcallback", osxni->mCookie.get());
+            break;
+        }
+      }
+      return;
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void OSXNotificationCenter::ShowPendingNotification(OSXNotificationInfo* osxni) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (osxni->mIconRequest) {
+    osxni->mIconRequest->Cancel(NS_BINDING_ABORTED);
+    osxni->mIconRequest = nullptr;
+  }
+
+  CloseAlertCocoaString(osxni->mName);
+
+  for (unsigned int i = 0; i < mPendingAlerts.Length(); i++) {
+    if (mPendingAlerts[i] == osxni) {
+      mActiveAlerts.AppendElement(osxni);
+      mPendingAlerts.RemoveElementAt(i);
+      break;
+    }
+  }
+
+  [GetNotificationCenter() deliverNotification:osxni->mPendingNotification];
+
+  if (osxni->mObserver) {
+    osxni->mObserver->Observe(nullptr, "alertshow", osxni->mCookie.get());
+  }
+
+  [osxni->mPendingNotification release];
+  osxni->mPendingNotification = nil;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+NS_IMETHODIMP
+OSXNotificationCenter::OnImageMissing(nsISupports* aUserData) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  OSXNotificationInfo* osxni = static_cast<OSXNotificationInfo*>(aUserData);
+  if (osxni->mPendingNotification) {
+    // If there was an error getting the image, or the request timed out, show
+    // the notification without a content image.
+    ShowPendingNotification(osxni);
+  }
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+OSXNotificationCenter::OnImageReady(nsISupports* aUserData, imgIRequest* aRequest) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsCOMPtr<imgIContainer> image;
+  nsresult rv = aRequest->GetImage(getter_AddRefs(image));
+  if (NS_WARN_IF(NS_FAILED(rv) || !image)) {
+    return rv;
+  }
+
+  OSXNotificationInfo* osxni = static_cast<OSXNotificationInfo*>(aUserData);
+  if (!osxni->mPendingNotification) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSImage* cocoaImage = nil;
+  // TODO: Pass pres context / ComputedStyle here to support context paint properties
+  nsCocoaUtils::CreateDualRepresentationNSImageFromImageContainer(image, imgIContainer::FRAME_FIRST,
+                                                                  nullptr, nullptr, &cocoaImage);
+  (osxni->mPendingNotification).contentImage = cocoaImage;
+  [cocoaImage release];
+  ShowPendingNotification(osxni);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+// nsIAlertsDoNotDisturb
+NS_IMETHODIMP
+OSXNotificationCenter::GetManualDoNotDisturb(bool* aRetVal) { return NS_ERROR_NOT_IMPLEMENTED; }
+
+NS_IMETHODIMP
+OSXNotificationCenter::SetManualDoNotDisturb(bool aDoNotDisturb) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+OSXNotificationCenter::GetSuppressForScreenSharing(bool* aRetVal) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN
+
+  NS_ENSURE_ARG(aRetVal);
+  *aRetVal = mSuppressForScreenSharing;
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE)
+}
+
+NS_IMETHODIMP
+OSXNotificationCenter::SetSuppressForScreenSharing(bool aSuppress) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN
+
+  mSuppressForScreenSharing = aSuppress;
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE)
+}
+
+}  // namespace mozilla
diff --git a/widget/cocoa/SDKDeclarations.h b/widget/cocoa/SDKDeclarations.h
new file mode 100644
index 0000000000..b064093582
--- /dev/null
+++ b/widget/cocoa/SDKDeclarations.h
@@ -0,0 +1,133 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef SDKDefines_h
+#define SDKDefines_h
+
+#import <Cocoa/Cocoa.h>
+
+/**
+ * This file contains header declarations from SDKs more recent than the minimum macOS SDK which we
+ * require for building Firefox, which is currently the macOS 10.12 SDK.
+ */
+
+#if !defined(MAC_OS_X_VERSION_10_12_2) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_12_2
+
+@interface NSView (NSView10_12_2)
+- (NSTouchBar*)makeTouchBar;
+@end
+
+#endif
+
+#if !defined(MAC_OS_X_VERSION_10_13) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_13
+
+using NSAppearanceName = NSString*;
+
+@interface NSColor (NSColor10_13)
+// "Available in 10.10", but not present in any SDK less than 10.13
+@property(class, strong, readonly) NSColor* systemPurpleColor NS_AVAILABLE_MAC(10_10);
+@end
+
+@interface NSTask (NSTask10_13)
+@property(copy) NSURL* executableURL NS_AVAILABLE_MAC(10_13);
+@property(copy) NSArray<NSString*>* arguments;
+- (BOOL)launchAndReturnError:(NSError**)error NS_AVAILABLE_MAC(10_13);
+@end
+
+enum : OSType {
+  kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange = 'x420',
+  kCVPixelFormatType_420YpCbCr10BiPlanarFullRange = 'xf20',
+};
+
+#endif
+
+#if !defined(MAC_OS_X_VERSION_10_14) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_14
+
+const NSAppearanceName NSAppearanceNameDarkAqua = @"NSAppearanceNameDarkAqua";
+
+@interface NSWindow (NSWindow10_14)
+@property(weak) NSObject<NSAppearanceCustomization>* appearanceSource NS_AVAILABLE_MAC(10_14);
+@end
+
+@interface NSApplication (NSApplication10_14)
+@property(strong) NSAppearance* appearance NS_AVAILABLE_MAC(10_14);
+@property(readonly, strong) NSAppearance* effectiveAppearance NS_AVAILABLE_MAC(10_14);
+@end
+
+@interface NSAppearance (NSAppearance10_14)
+- (NSAppearanceName)bestMatchFromAppearancesWithNames:(NSArray<NSAppearanceName>*)appearances
+    NS_AVAILABLE_MAC(10_14);
+@end
+
+@interface NSColor (NSColor10_14)
+// Available in 10.10, but retroactively made public in 10.14.
+@property(class, strong, readonly) NSColor* linkColor NS_AVAILABLE_MAC(10_10);
+@end
+
+enum {
+  NSVisualEffectMaterialToolTip NS_ENUM_AVAILABLE_MAC(10_14) = 17,
+};
+
+#endif
+
+#if !defined(MAC_OS_VERSION_11_0) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_11_0
+// The declarations below do not have NS_AVAILABLE_MAC(11_0) on them because we're building with a
+// pre-macOS 11 SDK, so macOS 11 identifies itself as 10.16, and @available(macOS 11.0, *) checks
+// won't work. You'll need to use an annoying double-whammy check for these:
+//
+// #if !defined(MAC_OS_VERSION_11_0) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_11_0
+//   if (nsCocoaFeatures::OnBigSurOrLater()) {
+// #else
+//   if (@available(macOS 11.0, *)) {
+// #endif
+//     ...
+//   }
+//
+
+typedef NS_ENUM(NSInteger, NSTitlebarSeparatorStyle) {
+  NSTitlebarSeparatorStyleAutomatic,
+  NSTitlebarSeparatorStyleNone,
+  NSTitlebarSeparatorStyleLine,
+  NSTitlebarSeparatorStyleShadow
+};
+
+@interface NSWindow (NSWindow11_0)
+@property NSTitlebarSeparatorStyle titlebarSeparatorStyle;
+@end
+
+@interface NSMenu (NSMenu11_0)
+// In reality, NSMenu implements the NSAppearanceCustomization protocol, and picks up the appearance
+// property from that protocol. But we can't tack on protocol implementations, so we just declare
+// the property setter here.
+- (void)setAppearance:(NSAppearance*)appearance;
+@end
+
+#endif
+
+#if !defined(MAC_OS_VERSION_12_0) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_12_0
+
+typedef CFTypeRef AXTextMarkerRef;
+typedef CFTypeRef AXTextMarkerRangeRef;
+
+extern "C" {
+CFTypeID AXTextMarkerGetTypeID();
+AXTextMarkerRef AXTextMarkerCreate(CFAllocatorRef allocator, const UInt8* bytes, CFIndex length);
+const UInt8* AXTextMarkerGetBytePtr(AXTextMarkerRef text_marker);
+CFIndex AXTextMarkerGetLength(AXTextMarkerRef text_marker);
+CFTypeID AXTextMarkerRangeGetTypeID();
+AXTextMarkerRangeRef AXTextMarkerRangeCreate(CFAllocatorRef allocator, AXTextMarkerRef start_marker,
+                                             AXTextMarkerRef end_marker);
+AXTextMarkerRef AXTextMarkerRangeCopyStartMarker(AXTextMarkerRangeRef text_marker_range);
+AXTextMarkerRef AXTextMarkerRangeCopyEndMarker(AXTextMarkerRangeRef text_marker_range);
+}
+
+@interface NSScreen (NSScreen12_0)
+// https://developer.apple.com/documentation/appkit/nsscreen/3882821-safeareainsets?language=objc&changes=latest_major
+@property(readonly) NSEdgeInsets safeAreaInsets;
+@end
+
+#endif
+
+#endif  // SDKDefines_h
diff --git a/widget/cocoa/ScreenHelperCocoa.h b/widget/cocoa/ScreenHelperCocoa.h
new file mode 100644
index 0000000000..91f4a19677
--- /dev/null
+++ b/widget/cocoa/ScreenHelperCocoa.h
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_widget_cocoa_ScreenHelperCocoa_h
+#define mozilla_widget_cocoa_ScreenHelperCocoa_h
+
+#include "mozilla/widget/ScreenManager.h"
+
+@class ScreenHelperDelegate;
+@class NSScreen;
+
+namespace mozilla {
+namespace widget {
+
+class ScreenHelperCocoa final : public ScreenManager::Helper {
+ public:
+  ScreenHelperCocoa();
+  ~ScreenHelperCocoa() override;
+
+  void RefreshScreens();
+
+  static NSScreen* CocoaScreenForScreen(nsIScreen* aScreen);
+
+ private:
+  ScreenHelperDelegate* mDelegate;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_gtk_ScreenHelperGtk_h
diff --git a/widget/cocoa/ScreenHelperCocoa.mm b/widget/cocoa/ScreenHelperCocoa.mm
new file mode 100644
index 0000000000..27c18bbfdf
--- /dev/null
+++ b/widget/cocoa/ScreenHelperCocoa.mm
@@ -0,0 +1,178 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ScreenHelperCocoa.h"
+
+#import <Cocoa/Cocoa.h>
+
+#include "mozilla/Logging.h"
+#include "nsCocoaUtils.h"
+#include "nsObjCExceptions.h"
+
+using namespace mozilla;
+
+static LazyLogModule sScreenLog("WidgetScreen");
+
+@interface ScreenHelperDelegate : NSObject {
+ @private
+  mozilla::widget::ScreenHelperCocoa* mHelper;
+}
+
+- (id)initWithScreenHelper:(mozilla::widget::ScreenHelperCocoa*)aScreenHelper;
+- (void)didChangeScreenParameters:(NSNotification*)aNotification;
+@end
+
+@implementation ScreenHelperDelegate
+- (id)initWithScreenHelper:(mozilla::widget::ScreenHelperCocoa*)aScreenHelper {
+  if ((self = [self init])) {
+    mHelper = aScreenHelper;
+
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(didChangeScreenParameters:)
+               name:NSApplicationDidChangeScreenParametersNotification
+             object:nil];
+  }
+
+  return self;
+}
+
+- (void)dealloc {
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+  [super dealloc];
+}
+
+- (void)didChangeScreenParameters:(NSNotification*)aNotification {
+  MOZ_LOG(sScreenLog, LogLevel::Debug,
+          ("Received NSApplicationDidChangeScreenParametersNotification"));
+
+  mHelper->RefreshScreens();
+}
+@end
+
+namespace mozilla {
+namespace widget {
+
+ScreenHelperCocoa::ScreenHelperCocoa() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_LOG(sScreenLog, LogLevel::Debug, ("ScreenHelperCocoa created"));
+
+  mDelegate = [[ScreenHelperDelegate alloc] initWithScreenHelper:this];
+
+  RefreshScreens();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+ScreenHelperCocoa::~ScreenHelperCocoa() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mDelegate release];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static already_AddRefed<Screen> MakeScreen(NSScreen* aScreen) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  DesktopToLayoutDeviceScale contentsScaleFactor(nsCocoaUtils::GetBackingScaleFactor(aScreen));
+  CSSToLayoutDeviceScale defaultCssScaleFactor(contentsScaleFactor.scale);
+  NSRect frame = [aScreen frame];
+  LayoutDeviceIntRect rect =
+      nsCocoaUtils::CocoaRectToGeckoRectDevPix(frame, contentsScaleFactor.scale);
+  frame = [aScreen visibleFrame];
+  LayoutDeviceIntRect availRect =
+      nsCocoaUtils::CocoaRectToGeckoRectDevPix(frame, contentsScaleFactor.scale);
+
+  // aScreen may be capable of displaying multiple pixel depths, for example by
+  // transitioning to an HDR-capable depth when required by a window displayed on
+  // the screen. We want to note the maximum capabilities of the screen, so we use
+  // the largest depth it offers.
+  uint32_t pixelDepth = 0;
+  const NSWindowDepth* depths = [aScreen supportedWindowDepths];
+  for (size_t d = 0; NSWindowDepth depth = depths[d]; d++) {
+    uint32_t bpp = NSBitsPerPixelFromDepth(depth);
+    if (bpp > pixelDepth) {
+      pixelDepth = bpp;
+    }
+  }
+
+  // But it confuses content if we return too-high a value here. Cap depth with
+  // a value that matches what Chrome returns for high bpp screens.
+  static const uint32_t MAX_REPORTED_PIXEL_DEPTH = 30;
+  if (pixelDepth > MAX_REPORTED_PIXEL_DEPTH) {
+    pixelDepth = MAX_REPORTED_PIXEL_DEPTH;
+  }
+
+  float dpi = 96.0f;
+  CGDirectDisplayID displayID =
+      [[[aScreen deviceDescription] objectForKey:@"NSScreenNumber"] intValue];
+  CGFloat heightMM = ::CGDisplayScreenSize(displayID).height;
+  if (heightMM > 0) {
+    dpi = rect.height / (heightMM / MM_PER_INCH_FLOAT);
+  }
+  MOZ_LOG(sScreenLog, LogLevel::Debug,
+          ("New screen [%d %d %d %d (%d %d %d %d) %d %f %f %f]", rect.x, rect.y, rect.width,
+           rect.height, availRect.x, availRect.y, availRect.width, availRect.height, pixelDepth,
+           contentsScaleFactor.scale, defaultCssScaleFactor.scale, dpi));
+
+  // Getting the refresh rate is a little hard on OS X. We could use
+  // CVDisplayLinkGetNominalOutputVideoRefreshPeriod, but that's a little
+  // involved. Ideally we could query it from vsync. For now, we leave it out.
+  RefPtr<Screen> screen =
+      new Screen(rect, availRect, pixelDepth, pixelDepth, 0, contentsScaleFactor,
+                 defaultCssScaleFactor, dpi, Screen::IsPseudoDisplay::No);
+  return screen.forget();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nullptr);
+}
+
+void ScreenHelperCocoa::RefreshScreens() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_LOG(sScreenLog, LogLevel::Debug, ("Refreshing screens"));
+
+  AutoTArray<RefPtr<Screen>, 4> screens;
+
+  for (NSScreen* screen in [NSScreen screens]) {
+    NSDictionary* desc = [screen deviceDescription];
+    if ([desc objectForKey:NSDeviceIsScreen] == nil) {
+      continue;
+    }
+    screens.AppendElement(MakeScreen(screen));
+  }
+
+  ScreenManager::Refresh(std::move(screens));
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+NSScreen* ScreenHelperCocoa::CocoaScreenForScreen(nsIScreen* aScreen) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  for (NSScreen* screen in [NSScreen screens]) {
+    NSDictionary* desc = [screen deviceDescription];
+    if ([desc objectForKey:NSDeviceIsScreen] == nil) {
+      continue;
+    }
+    LayoutDeviceIntRect rect;
+    double scale;
+    aScreen->GetRect(&rect.x, &rect.y, &rect.width, &rect.height);
+    aScreen->GetContentsScaleFactor(&scale);
+    NSRect frame = [screen frame];
+    LayoutDeviceIntRect frameRect = nsCocoaUtils::CocoaRectToGeckoRectDevPix(frame, scale);
+    if (rect == frameRect) {
+      return screen;
+    }
+  }
+  return [NSScreen mainScreen];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/cocoa/TextInputHandler.h b/widget/cocoa/TextInputHandler.h
new file mode 100644
index 0000000000..91ca29a901
--- /dev/null
+++ b/widget/cocoa/TextInputHandler.h
@@ -0,0 +1,1283 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sw=2 et tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef TextInputHandler_h_
+#define TextInputHandler_h_
+
+#include "nsCocoaUtils.h"
+
+#import <Carbon/Carbon.h>
+#import <Cocoa/Cocoa.h>
+#include "mozView.h"
+#include "nsString.h"
+#include "nsCOMPtr.h"
+#include "nsITimer.h"
+#include "nsTArray.h"
+#include "mozilla/BasicEvents.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/TextEventDispatcherListener.h"
+#include "WritingModes.h"
+
+class nsChildView;
+
+namespace mozilla {
+namespace widget {
+
+// Key code constants
+enum {
+  kVK_PC_PrintScreen = kVK_F13,
+  kVK_PC_ScrollLock = kVK_F14,
+  kVK_PC_Pause = kVK_F15,
+
+  kVK_PC_Insert = kVK_Help,
+  kVK_PC_Backspace = kVK_Delete,
+  kVK_PC_Delete = kVK_ForwardDelete,
+
+  kVK_PC_ContextMenu = 0x6E,
+
+  kVK_Powerbook_KeypadEnter = 0x34  // Enter on Powerbook's keyboard is different
+};
+
+/**
+ * TISInputSourceWrapper is a wrapper for the TISInputSourceRef.  If we get the
+ * TISInputSourceRef from InputSourceID, we need to release the CFArray instance
+ * which is returned by TISCreateInputSourceList.  However, when we release the
+ * list, we cannot access the TISInputSourceRef.  So, it's not usable, and it
+ * may cause the memory leak bugs.  nsTISInputSource automatically releases the
+ * list when the instance is destroyed.
+ */
+class TISInputSourceWrapper {
+ public:
+  static TISInputSourceWrapper& CurrentInputSource();
+  /**
+   * Shutdown() should be called when nobody doesn't need to use this class.
+   */
+  static void Shutdown();
+
+  TISInputSourceWrapper()
+      : mInputSource{nullptr},
+        mKeyboardLayout{nullptr},
+        mUCKeyboardLayout{nullptr},
+        mIsRTL{0},
+        mOverrideKeyboard{false} {
+    mInputSourceList = nullptr;
+    Clear();
+  }
+
+  explicit TISInputSourceWrapper(const char* aID)
+      : mInputSource{nullptr},
+        mKeyboardLayout{nullptr},
+        mUCKeyboardLayout{nullptr},
+        mIsRTL{0},
+        mOverrideKeyboard{false} {
+    mInputSourceList = nullptr;
+    InitByInputSourceID(aID);
+  }
+
+  explicit TISInputSourceWrapper(SInt32 aLayoutID)
+      : mInputSource{nullptr},
+        mKeyboardLayout{nullptr},
+        mUCKeyboardLayout{nullptr},
+        mIsRTL{0},
+        mOverrideKeyboard{false} {
+    mInputSourceList = nullptr;
+    InitByLayoutID(aLayoutID);
+  }
+
+  explicit TISInputSourceWrapper(TISInputSourceRef aInputSource)
+      : mInputSource{nullptr},
+        mKeyboardLayout{nullptr},
+        mUCKeyboardLayout{nullptr},
+        mIsRTL{0},
+        mOverrideKeyboard{false} {
+    mInputSourceList = nullptr;
+    InitByTISInputSourceRef(aInputSource);
+  }
+
+  ~TISInputSourceWrapper() { Clear(); }
+
+  void InitByInputSourceID(const char* aID);
+  void InitByInputSourceID(const nsString& aID);
+  void InitByInputSourceID(const CFStringRef aID);
+  /**
+   * InitByLayoutID() initializes the keyboard layout by the layout ID.
+   *
+   * @param aLayoutID             An ID of keyboard layout.
+   *                                0: US
+   *                                1: Greek
+   *                                2: German
+   *                                3: Swedish-Pro
+   *                                4: Dvorak-Qwerty Cmd
+   *                                5: Thai
+   *                                6: Arabic
+   *                                7: French
+   *                                8: Hebrew
+   *                                9: Lithuanian
+   *                               10: Norwegian
+   *                               11: Spanish
+   * @param aOverrideKeyboard     When testing set to TRUE, otherwise, set to
+   *                              FALSE.  When TRUE, we use an ANSI keyboard
+   *                              instead of the actual keyboard.
+   */
+  void InitByLayoutID(SInt32 aLayoutID, bool aOverrideKeyboard = false);
+  void InitByCurrentInputSource();
+  void InitByCurrentKeyboardLayout();
+  void InitByCurrentASCIICapableInputSource();
+  void InitByCurrentASCIICapableKeyboardLayout();
+  void InitByCurrentInputMethodKeyboardLayoutOverride();
+  void InitByTISInputSourceRef(TISInputSourceRef aInputSource);
+  void InitByLanguage(CFStringRef aLanguage);
+
+  /**
+   * If the instance is initialized with a keyboard layout input source,
+   * returns it.
+   * If the instance is initialized with an IME mode input source, the result
+   * references the keyboard layout for the IME mode.  However, this can be
+   * initialized only when the IME mode is actually selected.  I.e, if IME mode
+   * input source is initialized with LayoutID or SourceID, this returns null.
+   */
+  TISInputSourceRef GetKeyboardLayoutInputSource() const { return mKeyboardLayout; }
+  const UCKeyboardLayout* GetUCKeyboardLayout();
+
+  bool IsOpenedIMEMode();
+  bool IsIMEMode();
+  bool IsKeyboardLayout();
+
+  bool IsASCIICapable() {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetBoolProperty(kTISPropertyInputSourceIsASCIICapable);
+  }
+
+  bool IsEnabled() {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetBoolProperty(kTISPropertyInputSourceIsEnabled);
+  }
+
+  bool GetLanguageList(CFArrayRef& aLanguageList);
+  bool GetPrimaryLanguage(CFStringRef& aPrimaryLanguage);
+  bool GetPrimaryLanguage(nsAString& aPrimaryLanguage);
+
+  bool GetLocalizedName(CFStringRef& aName) {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetStringProperty(kTISPropertyLocalizedName, aName);
+  }
+
+  bool GetLocalizedName(nsAString& aName) {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetStringProperty(kTISPropertyLocalizedName, aName);
+  }
+
+  bool GetInputSourceID(CFStringRef& aID) {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetStringProperty(kTISPropertyInputSourceID, aID);
+  }
+
+  bool GetInputSourceID(nsAString& aID) {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetStringProperty(kTISPropertyInputSourceID, aID);
+  }
+
+  bool GetBundleID(CFStringRef& aBundleID) {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetStringProperty(kTISPropertyBundleID, aBundleID);
+  }
+
+  bool GetBundleID(nsAString& aBundleID) {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetStringProperty(kTISPropertyBundleID, aBundleID);
+  }
+
+  bool GetInputSourceType(CFStringRef& aType) {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetStringProperty(kTISPropertyInputSourceType, aType);
+  }
+
+  bool GetInputSourceType(nsAString& aType) {
+    NS_ENSURE_TRUE(mInputSource, false);
+    return GetStringProperty(kTISPropertyInputSourceType, aType);
+  }
+
+  bool IsForRTLLanguage();
+  bool IsForJapaneseLanguage();
+  bool IsInitializedByCurrentInputSource();
+
+  enum {
+    // 40 is an actual result of the ::LMGetKbdType() when we connect an
+    // unknown keyboard and set the keyboard type to ANSI manually on the
+    // set up dialog.
+    eKbdType_ANSI = 40
+  };
+
+  void Select();
+  void Clear();
+
+  /**
+   * InitKeyEvent() initializes aKeyEvent for aNativeKeyEvent.
+   *
+   * @param aNativeKeyEvent       A native key event for which you want to
+   *                              dispatch a Gecko key event.
+   * @param aKeyEvent             The result -- a Gecko key event initialized
+   *                              from the native key event.
+   * @param aIsProcessedByIME     true if aNativeKeyEvent has been handled
+   *                              by IME (but except if the composition was
+   *                              started with dead key).
+   * @param aInsertString         If caller expects that the event will cause
+   *                              a character to be input (say in an editor),
+   *                              the caller should set this.  Otherwise,
+   *                              if caller sets null to this, this method will
+   *                              compute the character to be input from
+   *                              characters of aNativeKeyEvent.
+   */
+  void InitKeyEvent(NSEvent* aNativeKeyEvent, WidgetKeyboardEvent& aKeyEvent,
+                    bool aIsProcessedByIME, const nsAString* aInsertString = nullptr);
+
+  /**
+   * WillDispatchKeyboardEvent() computes aKeyEvent.mAlternativeCharCodes and
+   * recompute aKeyEvent.mCharCode if it's necessary.
+   *
+   * @param aNativeKeyEvent       A native key event for which you want to
+   *                              dispatch a Gecko key event.
+   * @param aInsertString         If caller expects that the event will cause
+   *                              a character to be input (say in an editor),
+   *                              the caller should set this.  Otherwise,
+   *                              if caller sets null to this, this method will
+   *                              compute the character to be input from
+   *                              characters of aNativeKeyEvent.
+   * @param aIndexOfKeypress      Index of the eKeyPress event.  If a key
+   *                              inputs 2 or more characters, eKeyPress events
+   *                              are dispatched for each character.  This is
+   *                              0 for the first eKeyPress event.
+   * @param aKeyEvent             The result -- a Gecko key event initialized
+   *                              from the native key event.  This must be
+   *                              eKeyPress event.
+   */
+  void WillDispatchKeyboardEvent(NSEvent* aNativeKeyEvent, const nsAString* aInsertString,
+                                 uint32_t aIndexOfKeypress, WidgetKeyboardEvent& aKeyEvent);
+
+  /**
+   * ComputeGeckoKeyCode() returns Gecko keycode for aNativeKeyCode on current
+   * keyboard layout.
+   *
+   * @param aNativeKeyCode        A native keycode.
+   * @param aKbType               A native Keyboard Type value.  Typically,
+   *                              this is a result of ::LMGetKbdType().
+   * @param aCmdIsPressed         TRUE if Cmd key is pressed.  Otherwise, FALSE.
+   * @return                      The computed Gecko keycode.
+   */
+  uint32_t ComputeGeckoKeyCode(UInt32 aNativeKeyCode, UInt32 aKbType, bool aCmdIsPressed);
+
+  /**
+   * ComputeGeckoKeyNameIndex() returns Gecko key name index for the key.
+   *
+   * @param aNativeKeyCode        A native keycode.
+   */
+  static KeyNameIndex ComputeGeckoKeyNameIndex(UInt32 aNativeKeyCode);
+
+  /**
+   * ComputeGeckoCodeNameIndex() returns Gecko code name index for the key.
+   *
+   * @param aNativeKeyCode        A native keycode.
+   * @param aKbType               A native Keyboard Type value.  Typically,
+   *                              this is a result of ::LMGetKbdType().
+   */
+  static CodeNameIndex ComputeGeckoCodeNameIndex(UInt32 aNativeKeyCode, UInt32 aKbType);
+
+  /**
+   * TranslateToChar() checks if aNativeKeyEvent is a dead key.
+   *
+   * @param aNativeKeyEvent       A native key event.
+   * @return                      Returns true if the key event is a dead key
+   *                              event.  Otherwise, false.
+   */
+  bool IsDeadKey(NSEvent* aNativeKeyEvent);
+
+ protected:
+  /**
+   * TranslateToString() computes the inputted text from the native keyCode,
+   * modifier flags and keyboard type.
+   *
+   * @param aKeyCode              A native keyCode.
+   * @param aModifiers            Combination of native modifier flags.
+   * @param aKbType               A native Keyboard Type value.  Typically,
+   *                              this is a result of ::LMGetKbdType().
+   * @param aStr                  Result, i.e., inputted text.
+   *                              The result can be two or more characters.
+   * @return                      If succeeded, TRUE.  Otherwise, FALSE.
+   *                              Even if TRUE, aStr can be empty string.
+   */
+  bool TranslateToString(UInt32 aKeyCode, UInt32 aModifiers, UInt32 aKbType, nsAString& aStr);
+
+  /**
+   * TranslateToChar() computes the inputted character from the native keyCode,
+   * modifier flags and keyboard type.  If two or more characters would be
+   * input, this returns 0.
+   *
+   * @param aKeyCode              A native keyCode.
+   * @param aModifiers            Combination of native modifier flags.
+   * @param aKbType               A native Keyboard Type value.  Typically,
+   *                              this is a result of ::LMGetKbdType().
+   * @return                      If succeeded and the result is one character,
+   *                              returns the charCode of it.  Otherwise,
+   *                              returns 0.
+   */
+  uint32_t TranslateToChar(UInt32 aKeyCode, UInt32 aModifiers, UInt32 aKbType);
+
+  /**
+   * TranslateToChar() checks if aKeyCode with aModifiers is a dead key.
+   *
+   * @param aKeyCode              A native keyCode.
+   * @param aModifiers            Combination of native modifier flags.
+   * @param aKbType               A native Keyboard Type value.  Typically,
+   *                              this is a result of ::LMGetKbdType().
+   * @return                      Returns true if the key with specified
+   *                              modifier state is a dead key.  Otherwise,
+   *                              false.
+   */
+  bool IsDeadKey(UInt32 aKeyCode, UInt32 aModifiers, UInt32 aKbType);
+
+  /**
+   * ComputeInsertString() computes string to be inserted with the key event.
+   *
+   * @param aNativeKeyEvent     The native key event which causes our keyboard
+   *                            event(s).
+   * @param aKeyEvent           A Gecko key event which was partially
+   *                            initialized with aNativeKeyEvent.
+   * @param aInsertString       The string to be inputting by aNativeKeyEvent.
+   *                            This should be specified by InsertText().
+   *                            In other words, if the key event doesn't cause
+   *                            a call of InsertText(), this can be nullptr.
+   * @param aResult             The string which should be set to charCode of
+   *                            keypress event(s).
+   */
+  void ComputeInsertStringForCharCode(NSEvent* aNativeKeyEvent,
+                                      const WidgetKeyboardEvent& aKeyEvent,
+                                      const nsAString* aInsertString, nsAString& aResult);
+
+  /**
+   * IsPrintableKeyEvent() returns true if aNativeKeyEvent is caused by
+   * a printable key.  Otherwise, returns false.
+   */
+  bool IsPrintableKeyEvent(NSEvent* aNativeKeyEvent) const;
+
+  /**
+   * GetKbdType() returns physical keyboard type.
+   */
+  UInt32 GetKbdType() const;
+
+  bool GetBoolProperty(const CFStringRef aKey);
+  bool GetStringProperty(const CFStringRef aKey, CFStringRef& aStr);
+  bool GetStringProperty(const CFStringRef aKey, nsAString& aStr);
+
+  TISInputSourceRef mInputSource;
+  TISInputSourceRef mKeyboardLayout;
+  CFArrayRef mInputSourceList;
+  const UCKeyboardLayout* mUCKeyboardLayout;
+  int8_t mIsRTL;
+
+  bool mOverrideKeyboard;
+
+  static TISInputSourceWrapper* sCurrentInputSource;
+};
+
+/**
+ * TextInputHandlerBase is a base class of IMEInputHandler and TextInputHandler.
+ * Utility methods should be implemented this level.
+ */
+
+class TextInputHandlerBase : public TextEventDispatcherListener {
+ public:
+  /**
+   * Other TextEventDispatcherListener methods should be implemented in
+   * IMEInputHandler.
+   */
+  NS_DECL_ISUPPORTS
+
+  /**
+   * DispatchEvent() dispatches aEvent on mWidget.
+   *
+   * @param aEvent                An event which you want to dispatch.
+   * @return                      TRUE if the event is consumed by web contents
+   *                              or chrome contents.  Otherwise, FALSE.
+   */
+  bool DispatchEvent(WidgetGUIEvent& aEvent);
+
+  /**
+   * SetSelection() dispatches eSetSelection event for the aRange.
+   *
+   * @param aRange                The range which will be selected.
+   * @return                      TRUE if setting selection is succeeded and
+   *                              the widget hasn't been destroyed.
+   *                              Otherwise, FALSE.
+   */
+  bool SetSelection(NSRange& aRange);
+
+  /**
+   * InitKeyEvent() initializes aKeyEvent for aNativeKeyEvent.
+   *
+   * @param aNativeKeyEvent       A native key event for which you want to
+   *                              dispatch a Gecko key event.
+   * @param aKeyEvent             The result -- a Gecko key event initialized
+   *                              from the native key event.
+   * @param aIsProcessedByIME     true if aNativeKeyEvent has been handled
+   *                              by IME (but except if the composition was
+   *                              started with dead key).
+   * @param aInsertString         If caller expects that the event will cause
+   *                              a character to be input (say in an editor),
+   *                              the caller should set this.  Otherwise,
+   *                              if caller sets null to this, this method will
+   *                              compute the character to be input from
+   *                              characters of aNativeKeyEvent.
+   */
+  void InitKeyEvent(NSEvent* aNativeKeyEvent, WidgetKeyboardEvent& aKeyEvent,
+                    bool aIsProcessedByIME, const nsAString* aInsertString = nullptr);
+
+  /**
+   * SynthesizeNativeKeyEvent() is an implementation of
+   * nsIWidget::SynthesizeNativeKeyEvent().  See the document in nsIWidget.h
+   * for the detail.
+   */
+  nsresult SynthesizeNativeKeyEvent(int32_t aNativeKeyboardLayout, int32_t aNativeKeyCode,
+                                    uint32_t aModifierFlags, const nsAString& aCharacters,
+                                    const nsAString& aUnmodifiedCharacters);
+
+  /**
+   * Utility method intended for testing. Attempts to construct a native key
+   * event that would have been generated during an actual key press. This
+   * *does not dispatch* the native event. Instead, it is attached to the
+   * |mNativeKeyEvent| field of the Gecko event that is passed in.
+   * @param aKeyEvent  Gecko key event to attach the native event to
+   */
+  NS_IMETHOD AttachNativeKeyEvent(WidgetKeyboardEvent& aKeyEvent);
+
+  /**
+   * GetWindowLevel() returns the window level of current focused (in Gecko)
+   * window.  E.g., if an <input> element in XUL panel has focus, this returns
+   * the XUL panel's window level.
+   */
+  NSInteger GetWindowLevel();
+
+  /**
+   * IsSpecialGeckoKey() checks whether aNativeKeyCode is mapped to a special
+   * Gecko keyCode.  A key is "special" if it isn't used for text input.
+   *
+   * @param aNativeKeyCode        A native keycode.
+   * @return                      If the keycode is mapped to a special key,
+   *                              TRUE.  Otherwise, FALSE.
+   */
+  static bool IsSpecialGeckoKey(UInt32 aNativeKeyCode);
+
+  /**
+   * EnableSecureEventInput() and DisableSecureEventInput() wrap the Carbon
+   * Event Manager APIs with the same names.  In addition they keep track of
+   * how many times we've called them (in the same process) -- unlike the
+   * Carbon Event Manager APIs, which only keep track of how many times they've
+   * been called from any and all processes.
+   *
+   * The Carbon Event Manager's IsSecureEventInputEnabled() returns whether
+   * secure event input mode is enabled (in any process).  This class's
+   * IsSecureEventInputEnabled() returns whether we've made any calls to
+   * EnableSecureEventInput() that are not (yet) offset by the calls we've
+   * made to DisableSecureEventInput().
+   */
+  static void EnableSecureEventInput();
+  static void DisableSecureEventInput();
+  static bool IsSecureEventInputEnabled();
+
+  /**
+   * EnsureSecureEventInputDisabled() calls DisableSecureEventInput() until
+   * our call count becomes 0.
+   */
+  static void EnsureSecureEventInputDisabled();
+
+ public:
+  /**
+   * mWidget must not be destroyed without OnDestroyWidget being called.
+   *
+   * @param aDestroyingWidget     Destroying widget.  This might not be mWidget.
+   * @return                      This result doesn't have any meaning for
+   *                              callers.  When aDstroyingWidget isn't the same
+   *                              as mWidget, FALSE.  Then, inherited methods in
+   *                              sub classes should return from this method
+   *                              without cleaning up.
+   */
+  virtual bool OnDestroyWidget(nsChildView* aDestroyingWidget);
+
+ protected:
+  // The creator of this instance, client and its text event dispatcher.
+  // These members must not be nullptr after initialized until
+  // OnDestroyWidget() is called.
+  nsChildView* mWidget;  // [WEAK]
+  RefPtr<TextEventDispatcher> mDispatcher;
+
+  // The native view for mWidget.
+  // This view handles the actual text inputting.
+  NSView<mozView>* mView;  // [STRONG]
+
+  TextInputHandlerBase(nsChildView* aWidget, NSView<mozView>* aNativeView);
+  virtual ~TextInputHandlerBase();
+
+  bool Destroyed() { return !mWidget; }
+
+  /**
+   * mCurrentKeyEvent indicates what key event we are handling.  While
+   * handling a native keydown event, we need to store the event for insertText,
+   * doCommandBySelector and various action message handlers of NSResponder
+   * such as [NSResponder insertNewline:sender].
+   */
+  struct KeyEventState {
+    // Handling native key event
+    NSEvent* mKeyEvent;
+    // String specified by InsertText().  This is not null only during a
+    // call of InsertText().
+    nsAString* mInsertString;
+    // String which are included in [mKeyEvent characters] and already handled
+    // by InsertText() call(s).
+    nsString mInsertedString;
+    // Unique id associated with a keydown / keypress event. It's ok if this
+    // wraps over long periods.
+    uint32_t mUniqueId;
+    // Whether keydown event was dispatched for mKeyEvent.
+    bool mKeyDownDispatched;
+    // Whether keydown event was consumed by web contents or chrome contents.
+    bool mKeyDownHandled;
+    // Whether keypress event was dispatched for mKeyEvent.
+    bool mKeyPressDispatched;
+    // Whether keypress event was consumed by web contents or chrome contents.
+    bool mKeyPressHandled;
+    // Whether the key event causes other key events via IME or something.
+    bool mCausedOtherKeyEvents;
+    // Whether the key event causes composition change or committing
+    // composition.  So, even if InsertText() is called, this may be false
+    // if it dispatches keypress event.
+    bool mCompositionDispatched;
+
+    KeyEventState() : mKeyEvent(nullptr), mUniqueId(0) { Clear(); }
+
+    explicit KeyEventState(NSEvent* aNativeKeyEvent, uint32_t aUniqueId = 0)
+        : mKeyEvent(nullptr), mUniqueId(0) {
+      Clear();
+      Set(aNativeKeyEvent, aUniqueId);
+    }
+
+    KeyEventState(const KeyEventState& aOther) = delete;
+
+    ~KeyEventState() { Clear(); }
+
+    void Set(NSEvent* aNativeKeyEvent, uint32_t aUniqueId = 0) {
+      MOZ_ASSERT(aNativeKeyEvent, "aNativeKeyEvent must not be NULL");
+      Clear();
+      mKeyEvent = [aNativeKeyEvent retain];
+      mUniqueId = aUniqueId;
+    }
+
+    void Clear() {
+      if (mKeyEvent) {
+        [mKeyEvent release];
+        mKeyEvent = nullptr;
+        mUniqueId = 0;
+      }
+      mInsertString = nullptr;
+      mInsertedString.Truncate();
+      mKeyDownDispatched = false;
+      mKeyDownHandled = false;
+      mKeyPressDispatched = false;
+      mKeyPressHandled = false;
+      mCausedOtherKeyEvents = false;
+      mCompositionDispatched = false;
+    }
+
+    bool IsDefaultPrevented() const {
+      return mKeyDownHandled || mKeyPressHandled || mCausedOtherKeyEvents || mCompositionDispatched;
+    }
+
+    bool CanDispatchKeyDownEvent() const { return !mKeyDownDispatched; }
+
+    bool CanDispatchKeyPressEvent() const { return !mKeyPressDispatched && !IsDefaultPrevented(); }
+
+    bool CanHandleCommand() const { return !mKeyDownHandled && !mKeyPressHandled; }
+
+    bool IsProperKeyEvent(Command aCommand) const {
+      if (NS_WARN_IF(!mKeyEvent)) {
+        return false;
+      }
+      KeyNameIndex keyNameIndex =
+          TISInputSourceWrapper::ComputeGeckoKeyNameIndex([mKeyEvent keyCode]);
+      Modifiers modifiers = nsCocoaUtils::ModifiersForEvent(mKeyEvent) &
+                            (MODIFIER_SHIFT | MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+      switch (aCommand) {
+        case Command::InsertLineBreak:
+          return keyNameIndex == KEY_NAME_INDEX_Enter && modifiers == MODIFIER_CONTROL;
+        case Command::InsertParagraph:
+          return keyNameIndex == KEY_NAME_INDEX_Enter && modifiers == MODIFIER_NONE;
+        case Command::DeleteCharBackward:
+          return keyNameIndex == KEY_NAME_INDEX_Backspace && modifiers == MODIFIER_NONE;
+        case Command::DeleteToBeginningOfLine:
+          return keyNameIndex == KEY_NAME_INDEX_Backspace && modifiers == MODIFIER_META;
+        case Command::DeleteWordBackward:
+          return keyNameIndex == KEY_NAME_INDEX_Backspace && modifiers == MODIFIER_ALT;
+        case Command::DeleteCharForward:
+          return keyNameIndex == KEY_NAME_INDEX_Delete && modifiers == MODIFIER_NONE;
+        case Command::DeleteWordForward:
+          return keyNameIndex == KEY_NAME_INDEX_Delete && modifiers == MODIFIER_ALT;
+        case Command::InsertTab:
+          return keyNameIndex == KEY_NAME_INDEX_Tab && modifiers == MODIFIER_NONE;
+        case Command::InsertBacktab:
+          return keyNameIndex == KEY_NAME_INDEX_Tab && modifiers == MODIFIER_SHIFT;
+        case Command::CharNext:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowRight && modifiers == MODIFIER_NONE;
+        case Command::SelectCharNext:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowRight && modifiers == MODIFIER_SHIFT;
+        case Command::WordNext:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowRight && modifiers == MODIFIER_ALT;
+        case Command::SelectWordNext:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowRight &&
+                 modifiers == (MODIFIER_ALT | MODIFIER_SHIFT);
+        case Command::EndLine:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowRight && modifiers == MODIFIER_META;
+        case Command::SelectEndLine:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowRight &&
+                 modifiers == (MODIFIER_META | MODIFIER_SHIFT);
+        case Command::CharPrevious:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowLeft && modifiers == MODIFIER_NONE;
+        case Command::SelectCharPrevious:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowLeft && modifiers == MODIFIER_SHIFT;
+        case Command::WordPrevious:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowLeft && modifiers == MODIFIER_ALT;
+        case Command::SelectWordPrevious:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowLeft &&
+                 modifiers == (MODIFIER_ALT | MODIFIER_SHIFT);
+        case Command::BeginLine:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowLeft && modifiers == MODIFIER_META;
+        case Command::SelectBeginLine:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowLeft &&
+                 modifiers == (MODIFIER_META | MODIFIER_SHIFT);
+        case Command::LinePrevious:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowUp && modifiers == MODIFIER_NONE;
+        case Command::SelectLinePrevious:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowUp && modifiers == MODIFIER_SHIFT;
+        case Command::MoveTop:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowUp && modifiers == MODIFIER_META;
+        case Command::SelectTop:
+          return (keyNameIndex == KEY_NAME_INDEX_ArrowUp &&
+                  modifiers == (MODIFIER_META | MODIFIER_SHIFT)) ||
+                 (keyNameIndex == KEY_NAME_INDEX_Home && modifiers == MODIFIER_SHIFT);
+        case Command::LineNext:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowDown && modifiers == MODIFIER_NONE;
+        case Command::SelectLineNext:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowDown && modifiers == MODIFIER_SHIFT;
+        case Command::MoveBottom:
+          return keyNameIndex == KEY_NAME_INDEX_ArrowDown && modifiers == MODIFIER_META;
+        case Command::SelectBottom:
+          return (keyNameIndex == KEY_NAME_INDEX_ArrowDown &&
+                  modifiers == (MODIFIER_META | MODIFIER_SHIFT)) ||
+                 (keyNameIndex == KEY_NAME_INDEX_End && modifiers == MODIFIER_SHIFT);
+        case Command::ScrollPageUp:
+          return keyNameIndex == KEY_NAME_INDEX_PageUp && modifiers == MODIFIER_NONE;
+        case Command::SelectPageUp:
+          return keyNameIndex == KEY_NAME_INDEX_PageUp && modifiers == MODIFIER_SHIFT;
+        case Command::ScrollPageDown:
+          return keyNameIndex == KEY_NAME_INDEX_PageDown && modifiers == MODIFIER_NONE;
+        case Command::SelectPageDown:
+          return keyNameIndex == KEY_NAME_INDEX_PageDown && modifiers == MODIFIER_SHIFT;
+        case Command::ScrollBottom:
+          return keyNameIndex == KEY_NAME_INDEX_End && modifiers == MODIFIER_NONE;
+        case Command::ScrollTop:
+          return keyNameIndex == KEY_NAME_INDEX_Home && modifiers == MODIFIER_NONE;
+        case Command::CancelOperation:
+          return (keyNameIndex == KEY_NAME_INDEX_Escape &&
+                  (modifiers == MODIFIER_NONE || modifiers == MODIFIER_SHIFT)) ||
+                 ([mKeyEvent keyCode] == kVK_ANSI_Period && modifiers == MODIFIER_META);
+        case Command::Complete:
+          return keyNameIndex == KEY_NAME_INDEX_Escape &&
+                 (modifiers == MODIFIER_ALT || modifiers == (MODIFIER_ALT | MODIFIER_SHIFT));
+        default:
+          return false;
+      }
+    }
+
+    void InitKeyEvent(TextInputHandlerBase* aHandler, WidgetKeyboardEvent& aKeyEvent,
+                      bool aIsProcessedByIME);
+
+    /**
+     * GetUnhandledString() returns characters of the event which have not been
+     * handled with InsertText() yet. For example, if there is a composition
+     * caused by a dead key press like '`' and it's committed by some key
+     * combinations like |Cmd+v|, then, the |v|'s KeyDown event's |characters|
+     * is |`v|.  Then, after |`| is committed with a call of InsertString(),
+     * this returns only 'v'.
+     */
+    void GetUnhandledString(nsAString& aUnhandledString) const;
+  };
+
+  /**
+   * Helper classes for guaranteeing cleaning mCurrentKeyEvent
+   */
+  class AutoKeyEventStateCleaner {
+   public:
+    explicit AutoKeyEventStateCleaner(TextInputHandlerBase* aHandler) : mHandler(aHandler) {}
+
+    ~AutoKeyEventStateCleaner() { mHandler->RemoveCurrentKeyEvent(); }
+
+   private:
+    RefPtr<TextInputHandlerBase> mHandler;
+  };
+
+  class MOZ_STACK_CLASS AutoInsertStringClearer {
+   public:
+    explicit AutoInsertStringClearer(KeyEventState* aState) : mState(aState) {}
+    ~AutoInsertStringClearer();
+
+   private:
+    KeyEventState* mState;
+  };
+
+  /**
+   * mCurrentKeyEvents stores all key events which are being processed.
+   * When we call interpretKeyEvents, IME may generate other key events.
+   * mCurrentKeyEvents[0] is the latest key event.
+   */
+  nsTArray<KeyEventState*> mCurrentKeyEvents;
+
+  /**
+   * mFirstKeyEvent must be used for first key event.  This member prevents
+   * memory fragmentation for most key events.
+   */
+  KeyEventState mFirstKeyEvent;
+
+  /**
+   * PushKeyEvent() adds the current key event to mCurrentKeyEvents.
+   */
+  KeyEventState* PushKeyEvent(NSEvent* aNativeKeyEvent, uint32_t aUniqueId = 0) {
+    uint32_t nestCount = mCurrentKeyEvents.Length();
+    for (uint32_t i = 0; i < nestCount; i++) {
+      // When the key event is caused by another key event, all key events
+      // which are being handled should be marked as "consumed".
+      mCurrentKeyEvents[i]->mCausedOtherKeyEvents = true;
+    }
+
+    KeyEventState* keyEvent = nullptr;
+    if (nestCount == 0) {
+      mFirstKeyEvent.Set(aNativeKeyEvent, aUniqueId);
+      keyEvent = &mFirstKeyEvent;
+    } else {
+      keyEvent = new KeyEventState(aNativeKeyEvent, aUniqueId);
+    }
+    return *mCurrentKeyEvents.AppendElement(keyEvent);
+  }
+
+  /**
+   * RemoveCurrentKeyEvent() removes the current key event from
+   * mCurrentKeyEvents.
+   */
+  void RemoveCurrentKeyEvent() {
+    NS_ASSERTION(mCurrentKeyEvents.Length() > 0, "RemoveCurrentKeyEvent() is called unexpectedly");
+    KeyEventState* keyEvent = mCurrentKeyEvents.PopLastElement();
+    if (keyEvent == &mFirstKeyEvent) {
+      keyEvent->Clear();
+    } else {
+      delete keyEvent;
+    }
+  }
+
+  /**
+   * GetCurrentKeyEvent() returns current processing key event.
+   */
+  KeyEventState* GetCurrentKeyEvent() {
+    if (mCurrentKeyEvents.Length() == 0) {
+      return nullptr;
+    }
+    return mCurrentKeyEvents[mCurrentKeyEvents.Length() - 1];
+  }
+
+  struct KeyboardLayoutOverride final {
+    int32_t mKeyboardLayout;
+    bool mOverrideEnabled;
+
+    KeyboardLayoutOverride() : mKeyboardLayout(0), mOverrideEnabled(false) {}
+  };
+
+  const KeyboardLayoutOverride& KeyboardLayoutOverrideRef() const { return mKeyboardOverride; }
+
+  /**
+   * IsPrintableChar() checks whether the unicode character is
+   * a non-printable ASCII character or not.  Note that this returns
+   * TRUE even if aChar is a non-printable UNICODE character.
+   *
+   * @param aChar                 A unicode character.
+   * @return                      TRUE if aChar is a printable ASCII character
+   *                              or a unicode character.  Otherwise, i.e,
+   *                              if aChar is a non-printable ASCII character,
+   *                              FALSE.
+   */
+  static bool IsPrintableChar(char16_t aChar);
+
+  /**
+   * IsNormalCharInputtingEvent() checks whether aNativeEvent causes text input.
+   *
+   * @param aNativeEvent          A key event.
+   * @return                      TRUE if the key event causes text input.
+   *                              Otherwise, FALSE.
+   */
+  static bool IsNormalCharInputtingEvent(NSEvent* aNativeEvent);
+
+  /**
+   * IsModifierKey() checks whether the native keyCode is for a modifier key.
+   *
+   * @param aNativeKeyCode        A native keyCode.
+   * @return                      TRUE if aNativeKeyCode is for a modifier key.
+   *                              Otherwise, FALSE.
+   */
+  static bool IsModifierKey(UInt32 aNativeKeyCode);
+
+ private:
+  KeyboardLayoutOverride mKeyboardOverride;
+
+  static int32_t sSecureEventInputCount;
+};
+
+/**
+ * IMEInputHandler manages:
+ *   1. The IME/keyboard layout statement of nsChildView.
+ *   2. The IME composition statement of nsChildView.
+ * And also provides the methods which controls the current IME transaction of
+ * the instance.
+ *
+ * Note that an nsChildView handles one or more NSView's events.  E.g., even if
+ * a text editor on XUL panel element, the input events handled on the parent
+ * (or its ancestor) widget handles it (the native focus is set to it).  The
+ * actual focused view is notified by OnFocusChangeInGecko.
+ */
+
+class IMEInputHandler : public TextInputHandlerBase {
+ public:
+  // TextEventDispatcherListener methods
+  NS_IMETHOD NotifyIME(TextEventDispatcher* aTextEventDispatcher,
+                       const IMENotification& aNotification) override;
+  NS_IMETHOD_(IMENotificationRequests) GetIMENotificationRequests() override;
+  NS_IMETHOD_(void) OnRemovedFrom(TextEventDispatcher* aTextEventDispatcher) override;
+  NS_IMETHOD_(void)
+  WillDispatchKeyboardEvent(TextEventDispatcher* aTextEventDispatcher,
+                            WidgetKeyboardEvent& aKeyboardEvent, uint32_t aIndexOfKeypress,
+                            void* aData) override;
+
+ public:
+  virtual bool OnDestroyWidget(nsChildView* aDestroyingWidget) override;
+
+  virtual void OnFocusChangeInGecko(bool aFocus);
+
+  void OnSelectionChange(const IMENotification& aIMENotification);
+  void OnLayoutChange();
+
+  /**
+   * Call [NSTextInputContext handleEvent] for mouse event support of IME
+   */
+  bool OnHandleEvent(NSEvent* aEvent);
+
+  /**
+   * SetMarkedText() is a handler of setMarkedText of NSTextInput.
+   *
+   * @param aAttrString           This mut be an instance of NSAttributedString.
+   *                              If the aString parameter to
+   *                              [ChildView setMarkedText:setSelectedRange:]
+   *                              isn't an instance of NSAttributedString,
+   *                              create an NSAttributedString from it and pass
+   *                              that instead.
+   * @param aSelectedRange        Current selected range (or caret position).
+   * @param aReplacementRange     The range which will be replaced with the
+   *                              aAttrString instead of current marked range.
+   */
+  void SetMarkedText(NSAttributedString* aAttrString, NSRange& aSelectedRange,
+                     NSRange* aReplacementRange = nullptr);
+
+  /**
+   * GetAttributedSubstringFromRange() returns an NSAttributedString instance
+   * which is allocated as autorelease for aRange.
+   *
+   * @param aRange                The range of string which you want.
+   * @param aActualRange          The actual range of the result.
+   * @return                      The string in aRange.  If the string is empty,
+   *                              this returns nil.  If succeeded, this returns
+   *                              an instance which is allocated as autorelease.
+   *                              If this has some troubles, returns nil.
+   */
+  NSAttributedString* GetAttributedSubstringFromRange(NSRange& aRange,
+                                                      NSRange* aActualRange = nullptr);
+
+  /**
+   * SelectedRange() returns current selected range.
+   *
+   * @return                      If an editor has focus, this returns selection
+   *                              range in the editor.  Otherwise, this returns
+   *                              selection range  in the focused document.
+   */
+  NSRange SelectedRange();
+
+  /**
+   * DrawsVerticallyForCharacterAtIndex() returns whether the character at
+   * the given index is being rendered vertically.
+   *
+   * @param aCharIndex            The character offset to query.
+   *
+   * @return                      True if writing-mode is vertical at the given
+   *                              character offset; otherwise false.
+   */
+  bool DrawsVerticallyForCharacterAtIndex(uint32_t aCharIndex);
+
+  /**
+   * FirstRectForCharacterRange() returns first *character* rect in the range.
+   * Cocoa needs the first line rect in the range, but we cannot compute it
+   * on current implementation.
+   *
+   * @param aRange                A range of text to examine.  Its position is
+   *                              an offset from the beginning of the focused
+   *                              editor or document.
+   * @param aActualRange          If this is not null, this returns the actual
+   *                              range used for computing the result.
+   * @return                      An NSRect containing the first character in
+   *                              aRange, in screen coordinates.
+   *                              If the length of aRange is 0, the width will
+   *                              be 0.
+   */
+  NSRect FirstRectForCharacterRange(NSRange& aRange, NSRange* aActualRange = nullptr);
+
+  /**
+   * CharacterIndexForPoint() returns an offset of a character at aPoint.
+   * XXX This isn't implemented, always returns 0.
+   *
+   * @param                       The point in screen coordinates.
+   * @return                      The offset of the character at aPoint from
+   *                              the beginning of the focused editor or
+   *                              document.
+   */
+  NSUInteger CharacterIndexForPoint(NSPoint& aPoint);
+
+  /**
+   * GetValidAttributesForMarkedText() returns attributes which we support.
+   *
+   * @return                      Always empty array for now.
+   */
+  NSArray* GetValidAttributesForMarkedText();
+
+  bool HasMarkedText();
+  NSRange MarkedRange();
+
+  bool IsIMEComposing() { return mIsIMEComposing; }
+  bool IsDeadKeyComposing() { return mIsDeadKeyComposing; }
+  bool IsIMEOpened();
+  bool IsIMEEnabled() { return mIsIMEEnabled; }
+  bool IsASCIICapableOnly() { return mIsASCIICapableOnly; }
+  bool IsEditableContent() const { return mIsIMEEnabled || mIsASCIICapableOnly; }
+  bool IgnoreIMECommit() { return mIgnoreIMECommit; }
+
+  void CommitIMEComposition();
+  void CancelIMEComposition();
+
+  void EnableIME(bool aEnableIME);
+  void SetIMEOpenState(bool aOpen);
+  void SetASCIICapableOnly(bool aASCIICapableOnly);
+
+  /**
+   * True if OSX believes that our view has keyboard focus.
+   */
+  bool IsFocused();
+
+  static CFArrayRef CreateAllIMEModeList();
+  static void DebugPrintAllIMEModes();
+
+  // Don't use ::TSMGetActiveDocument() API directly, the document may not
+  // be what you want.
+  static TSMDocumentID GetCurrentTSMDocumentID();
+
+ protected:
+  // We cannot do some jobs in the given stack by some reasons.
+  // Following flags and the timer provide the execution pending mechanism,
+  // See the comment in nsCocoaTextInputHandler.mm.
+  nsCOMPtr<nsITimer> mTimer;
+  enum { kNotifyIMEOfFocusChangeInGecko = 1, kSyncASCIICapableOnly = 2 };
+  uint32_t mPendingMethods;
+
+  IMEInputHandler(nsChildView* aWidget, NSView<mozView>* aNativeView);
+  virtual ~IMEInputHandler();
+
+  void ResetTimer();
+
+  virtual void ExecutePendingMethods();
+
+  /**
+   * InsertTextAsCommittingComposition() commits current composition.  If there
+   * is no composition, this starts a composition and commits it immediately.
+   *
+   * @param aAttrString           A string which is committed.
+   * @param aReplacementRange     The range which will be replaced with the
+   *                              aAttrString instead of current selection.
+   */
+  void InsertTextAsCommittingComposition(NSAttributedString* aAttrString,
+                                         NSRange* aReplacementRange);
+
+  /**
+   * MaybeDispatchCurrentKeydownEvent() dispatches eKeyDown event for current
+   * key event.  If eKeyDown for current key event has already been dispatched,
+   * this does nothing.
+   *
+   * @param aIsProcessedByIME   true if current key event is handled by IME.
+   * @return                    true if the caller can continue to handle
+   *                            current key event.  Otherwise, false.  E.g.,
+   *                            focus is moved, the widget has been destroyed
+   *                            or something.
+   */
+  bool MaybeDispatchCurrentKeydownEvent(bool aIsProcessedByIME);
+
+ private:
+  // If mIsIMEComposing is true, the composition string is stored here.
+  NSString* mIMECompositionString;
+  // If mIsIMEComposing is true, the start offset of the composition string.
+  uint32_t mIMECompositionStart;
+
+  NSRange mMarkedRange;
+  NSRange mSelectedRange;
+
+  NSRange mRangeForWritingMode;  // range within which mWritingMode applies
+  mozilla::WritingMode mWritingMode;
+
+  bool mIsIMEComposing;
+  // If the composition started with dead key, mIsDeadKeyComposing is set to
+  // true.
+  bool mIsDeadKeyComposing;
+  bool mIsIMEEnabled;
+  bool mIsASCIICapableOnly;
+  bool mIgnoreIMECommit;
+  bool mIMEHasFocus;
+
+  void KillIMEComposition();
+  void SendCommittedText(NSString* aString);
+  void OpenSystemPreferredLanguageIME();
+
+  // Pending methods
+  void NotifyIMEOfFocusChangeInGecko();
+  void SyncASCIICapableOnly();
+
+  static bool sStaticMembersInitialized;
+  static CFStringRef sLatestIMEOpenedModeInputSourceID;
+  static void InitStaticMembers();
+  static void OnCurrentTextInputSourceChange(CFNotificationCenterRef aCenter, void* aObserver,
+                                             CFStringRef aName, const void* aObject,
+                                             CFDictionaryRef aUserInfo);
+
+  static void FlushPendingMethods(nsITimer* aTimer, void* aClosure);
+
+  /**
+   * ConvertToTextRangeStyle converts the given native underline style to
+   * our defined text range type.
+   *
+   * @param aUnderlineStyle       NSUnderlineStyleSingle or
+   *                              NSUnderlineStyleThick.
+   * @param aSelectedRange        Current selected range (or caret position).
+   * @return                      NS_TEXTRANGE_*.
+   */
+  TextRangeType ConvertToTextRangeType(uint32_t aUnderlineStyle, NSRange& aSelectedRange);
+
+  /**
+   * GetRangeCount() computes the range count of aAttrString.
+   *
+   * @param aAttrString           An NSAttributedString instance whose number of
+   *                              NSUnderlineStyleAttributeName ranges you with
+   *                              to know.
+   * @return                      The count of NSUnderlineStyleAttributeName
+   *                              ranges in aAttrString.
+   */
+  uint32_t GetRangeCount(NSAttributedString* aString);
+
+  /**
+   * CreateTextRangeArray() returns text ranges for clauses and/or caret.
+   *
+   * @param aAttrString           An NSAttributedString instance which indicates
+   *                              current composition string.
+   * @param aSelectedRange        Current selected range (or caret position).
+   * @return                      The result is set to the
+   *                              NSUnderlineStyleAttributeName ranges in
+   *                              aAttrString.
+   */
+  already_AddRefed<mozilla::TextRangeArray> CreateTextRangeArray(NSAttributedString* aAttrString,
+                                                                 NSRange& aSelectedRange);
+
+  /**
+   * DispatchCompositionStartEvent() dispatches a compositionstart event and
+   * initializes the members indicating composition state.
+   *
+   * @return                      true if it can continues handling composition.
+   *                              Otherwise, e.g., canceled by the web page,
+   *                              this returns false.
+   */
+  bool DispatchCompositionStartEvent();
+
+  /**
+   * DispatchCompositionChangeEvent() dispatches a compositionchange event on
+   * mWidget and modifies the members indicating composition state.
+   *
+   * @param aText                 User text input.
+   * @param aAttrString           An NSAttributedString instance which indicates
+   *                              current composition string.
+   * @param aSelectedRange        Current selected range (or caret position).
+   *
+   * @return                      true if it can continues handling composition.
+   *                              Otherwise, e.g., canceled by the web page,
+   *                              this returns false.
+   */
+  bool DispatchCompositionChangeEvent(const nsString& aText, NSAttributedString* aAttrString,
+                                      NSRange& aSelectedRange);
+
+  /**
+   * DispatchCompositionCommitEvent() dispatches a compositioncommit event or
+   * compositioncommitasis event.  If aCommitString is null, dispatches
+   * compositioncommitasis event.  I.e., if aCommitString is null, this
+   * commits the composition with the last data.  Otherwise, commits the
+   * composition with aCommitString value.
+   *
+   * @return                      true if the widget isn't destroyed.
+   *                              Otherwise, false.
+   */
+  bool DispatchCompositionCommitEvent(const nsAString* aCommitString = nullptr);
+
+  // The focused IME handler.  Please note that the handler might lost the
+  // actual focus by deactivating the application.  If we are active, this
+  // must have the actual focused handle.
+  // We cannot access to the NSInputManager during we aren't active, so, the
+  // focused handler can have an IME transaction even if we are deactive.
+  static IMEInputHandler* sFocusedIMEHandler;
+
+  static bool sCachedIsForRTLLangage;
+};
+
+/**
+ * TextInputHandler implements the NSTextInput protocol.
+ */
+class TextInputHandler : public IMEInputHandler {
+ public:
+  static NSUInteger sLastModifierState;
+
+  static CFArrayRef CreateAllKeyboardLayoutList();
+  static void DebugPrintAllKeyboardLayouts();
+
+  TextInputHandler(nsChildView* aWidget, NSView<mozView>* aNativeView);
+  virtual ~TextInputHandler();
+
+  /**
+   * KeyDown event handler.
+   *
+   * @param aNativeEvent          A native NSEventTypeKeyDown event.
+   * @param aUniqueId             A unique ID for the event.
+   * @return                      TRUE if the event is dispatched to web
+   *                              contents or chrome contents. Otherwise, FALSE.
+   */
+  bool HandleKeyDownEvent(NSEvent* aNativeEvent, uint32_t aUniqueId);
+
+  /**
+   * KeyUp event handler.
+   *
+   * @param aNativeEvent          A native NSEventTypeKeyUp event.
+   */
+  void HandleKeyUpEvent(NSEvent* aNativeEvent);
+
+  /**
+   * FlagsChanged event handler.
+   *
+   * @param aNativeEvent          A native NSEventTypeFlagsChanged event.
+   */
+  void HandleFlagsChanged(NSEvent* aNativeEvent);
+
+  /**
+   * Insert the string to content.  I.e., this is a text input event handler.
+   * If this is called during keydown event handling, this may dispatch a
+   * eKeyPress event.  If this is called during composition, this commits
+   * the composition by the aAttrString.
+   *
+   * @param aAttrString           An inserted string.
+   * @param aReplacementRange     The range which will be replaced with the
+   *                              aAttrString instead of current selection.
+   */
+  void InsertText(NSAttributedString* aAttrString, NSRange* aReplacementRange = nullptr);
+
+  /**
+   * Handles aCommand.  This may cause dispatching an eKeyPress event.
+   *
+   * @param aCommand    The command which receives from Cocoa.
+   * @return            true if this handles the command even if it does
+   *                    nothing actually.  Otherwise, false.
+   */
+  bool HandleCommand(Command aCommand);
+
+  /**
+   * doCommandBySelector event handler.
+   *
+   * @param aSelector             A selector of the command.
+   * @return                      TRUE if the command is consumed.  Otherwise,
+   *                              FALSE.
+   */
+  bool DoCommandBySelector(const char* aSelector);
+
+  /**
+   * KeyPressWasHandled() checks whether keypress event was handled or not.
+   *
+   * @return                      TRUE if keypress event for latest native key
+   *                              event was handled.  Otherwise, FALSE.
+   *                              If this handler isn't handling any key events,
+   *                              always returns FALSE.
+   */
+  bool KeyPressWasHandled() {
+    KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
+    return currentKeyEvent && currentKeyEvent->mKeyPressHandled;
+  }
+
+ protected:
+  // Stores the association of device dependent modifier flags with a modifier
+  // keyCode.  Being device dependent, this association may differ from one kind
+  // of hardware to the next.
+  struct ModifierKey {
+    NSUInteger flags;
+    unsigned short keyCode;
+
+    ModifierKey(NSUInteger aFlags, unsigned short aKeyCode) : flags(aFlags), keyCode(aKeyCode) {}
+
+    NSUInteger GetDeviceDependentFlags() const {
+      return (flags & ~NSEventModifierFlagDeviceIndependentFlagsMask);
+    }
+
+    NSUInteger GetDeviceIndependentFlags() const {
+      return (flags & NSEventModifierFlagDeviceIndependentFlagsMask);
+    }
+  };
+  typedef nsTArray<ModifierKey> ModifierKeyArray;
+  ModifierKeyArray mModifierKeys;
+
+  /**
+   * GetModifierKeyForNativeKeyCode() returns the stored ModifierKey for
+   * the key.
+   */
+  const ModifierKey* GetModifierKeyForNativeKeyCode(unsigned short aKeyCode) const;
+
+  /**
+   * GetModifierKeyForDeviceDependentFlags() returns the stored ModifierKey for
+   * the device dependent flags.
+   */
+  const ModifierKey* GetModifierKeyForDeviceDependentFlags(NSUInteger aFlags) const;
+
+  /**
+   * DispatchKeyEventForFlagsChanged() dispatches keydown event or keyup event
+   * for the aNativeEvent.
+   *
+   * @param aNativeEvent          A native flagschanged event which you want to
+   *                              dispatch our key event for.
+   * @param aDispatchKeyDown      TRUE if you want to dispatch a keydown event.
+   *                              Otherwise, i.e., to dispatch keyup event,
+   *                              FALSE.
+   */
+  void DispatchKeyEventForFlagsChanged(NSEvent* aNativeEvent, bool aDispatchKeyDown);
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // TextInputHandler_h_
diff --git a/widget/cocoa/TextInputHandler.mm b/widget/cocoa/TextInputHandler.mm
new file mode 100644
index 0000000000..a6d9dd3c02
--- /dev/null
+++ b/widget/cocoa/TextInputHandler.mm
@@ -0,0 +1,5073 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sw=2 et tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "TextInputHandler.h"
+
+#include "mozilla/Logging.h"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/MiscEvents.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/StaticPrefs_intl.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/TextEventDispatcher.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/ToString.h"
+
+#include "nsChildView.h"
+#include "nsCocoaFeatures.h"
+#include "nsObjCExceptions.h"
+#include "nsBidiUtils.h"
+#include "nsToolkit.h"
+#include "nsCocoaUtils.h"
+#include "WidgetUtils.h"
+#include "nsPrintfCString.h"
+
+using namespace mozilla;
+using namespace mozilla::widget;
+
+// For collecting other people's log, tell them `MOZ_LOG=IMEHandler:4,sync`
+// rather than `MOZ_LOG=IMEHandler:5,sync` since using `5` may create too
+// big file.
+// Therefore you shouldn't use `LogLevel::Verbose` for logging usual behavior.
+mozilla::LazyLogModule gIMELog("IMEHandler");
+
+// For collecting other people's log, tell them `MOZ_LOG=KeyboardHandler:4,sync`
+// rather than `MOZ_LOG=KeyboardHandler:5,sync` since using `5` may create too
+// big file.
+// Therefore you shouldn't use `LogLevel::Verbose` for logging usual behavior.
+mozilla::LazyLogModule gKeyLog("KeyboardHandler");
+
+// The behavior of `TextInputHandler` class is important both for logging
+// keyboard handler and IME handler.  Therefore, the behavior is logged when
+// either `IMEHandler` or `KeyboardHandler` is set to `MOZ_LOG`.  Therefore,
+// you may not need to tell people `MOZ_LOG=IMEHandler:4,KeyboardHandler:4,sync`.
+#define MOZ_LOG_KEY_OR_IME(aLogLevel, aArgs) \
+  MOZ_LOG(MOZ_LOG_TEST(gIMELog, aLogLevel) ? gIMELog : gKeyLog, aLogLevel, aArgs)
+
+static const char* OnOrOff(bool aBool) { return aBool ? "ON" : "off"; }
+
+static const char* TrueOrFalse(bool aBool) { return aBool ? "TRUE" : "FALSE"; }
+
+static const char* GetKeyNameForNativeKeyCode(unsigned short aNativeKeyCode) {
+  switch (aNativeKeyCode) {
+    case kVK_Escape:
+      return "Escape";
+    case kVK_RightCommand:
+      return "Right-Command";
+    case kVK_Command:
+      return "Command";
+    case kVK_Shift:
+      return "Shift";
+    case kVK_CapsLock:
+      return "CapsLock";
+    case kVK_Option:
+      return "Option";
+    case kVK_Control:
+      return "Control";
+    case kVK_RightShift:
+      return "Right-Shift";
+    case kVK_RightOption:
+      return "Right-Option";
+    case kVK_RightControl:
+      return "Right-Control";
+    case kVK_ANSI_KeypadClear:
+      return "Clear";
+
+    case kVK_F1:
+      return "F1";
+    case kVK_F2:
+      return "F2";
+    case kVK_F3:
+      return "F3";
+    case kVK_F4:
+      return "F4";
+    case kVK_F5:
+      return "F5";
+    case kVK_F6:
+      return "F6";
+    case kVK_F7:
+      return "F7";
+    case kVK_F8:
+      return "F8";
+    case kVK_F9:
+      return "F9";
+    case kVK_F10:
+      return "F10";
+    case kVK_F11:
+      return "F11";
+    case kVK_F12:
+      return "F12";
+    case kVK_F13:
+      return "F13/PrintScreen";
+    case kVK_F14:
+      return "F14/ScrollLock";
+    case kVK_F15:
+      return "F15/Pause";
+
+    case kVK_ANSI_Keypad0:
+      return "NumPad-0";
+    case kVK_ANSI_Keypad1:
+      return "NumPad-1";
+    case kVK_ANSI_Keypad2:
+      return "NumPad-2";
+    case kVK_ANSI_Keypad3:
+      return "NumPad-3";
+    case kVK_ANSI_Keypad4:
+      return "NumPad-4";
+    case kVK_ANSI_Keypad5:
+      return "NumPad-5";
+    case kVK_ANSI_Keypad6:
+      return "NumPad-6";
+    case kVK_ANSI_Keypad7:
+      return "NumPad-7";
+    case kVK_ANSI_Keypad8:
+      return "NumPad-8";
+    case kVK_ANSI_Keypad9:
+      return "NumPad-9";
+
+    case kVK_ANSI_KeypadMultiply:
+      return "NumPad-*";
+    case kVK_ANSI_KeypadPlus:
+      return "NumPad-+";
+    case kVK_ANSI_KeypadMinus:
+      return "NumPad--";
+    case kVK_ANSI_KeypadDecimal:
+      return "NumPad-.";
+    case kVK_ANSI_KeypadDivide:
+      return "NumPad-/";
+    case kVK_ANSI_KeypadEquals:
+      return "NumPad-=";
+    case kVK_ANSI_KeypadEnter:
+      return "NumPad-Enter";
+    case kVK_Return:
+      return "Return";
+    case kVK_Powerbook_KeypadEnter:
+      return "NumPad-EnterOnPowerBook";
+
+    case kVK_PC_Insert:
+      return "Insert/Help";
+    case kVK_PC_Delete:
+      return "Delete";
+    case kVK_Tab:
+      return "Tab";
+    case kVK_PC_Backspace:
+      return "Backspace";
+    case kVK_Home:
+      return "Home";
+    case kVK_End:
+      return "End";
+    case kVK_PageUp:
+      return "PageUp";
+    case kVK_PageDown:
+      return "PageDown";
+    case kVK_LeftArrow:
+      return "LeftArrow";
+    case kVK_RightArrow:
+      return "RightArrow";
+    case kVK_UpArrow:
+      return "UpArrow";
+    case kVK_DownArrow:
+      return "DownArrow";
+    case kVK_PC_ContextMenu:
+      return "ContextMenu";
+
+    case kVK_Function:
+      return "Function";
+    case kVK_VolumeUp:
+      return "VolumeUp";
+    case kVK_VolumeDown:
+      return "VolumeDown";
+    case kVK_Mute:
+      return "Mute";
+
+    case kVK_ISO_Section:
+      return "ISO_Section";
+
+    case kVK_JIS_Yen:
+      return "JIS_Yen";
+    case kVK_JIS_Underscore:
+      return "JIS_Underscore";
+    case kVK_JIS_KeypadComma:
+      return "JIS_KeypadComma";
+    case kVK_JIS_Eisu:
+      return "JIS_Eisu";
+    case kVK_JIS_Kana:
+      return "JIS_Kana";
+
+    case kVK_ANSI_A:
+      return "A";
+    case kVK_ANSI_B:
+      return "B";
+    case kVK_ANSI_C:
+      return "C";
+    case kVK_ANSI_D:
+      return "D";
+    case kVK_ANSI_E:
+      return "E";
+    case kVK_ANSI_F:
+      return "F";
+    case kVK_ANSI_G:
+      return "G";
+    case kVK_ANSI_H:
+      return "H";
+    case kVK_ANSI_I:
+      return "I";
+    case kVK_ANSI_J:
+      return "J";
+    case kVK_ANSI_K:
+      return "K";
+    case kVK_ANSI_L:
+      return "L";
+    case kVK_ANSI_M:
+      return "M";
+    case kVK_ANSI_N:
+      return "N";
+    case kVK_ANSI_O:
+      return "O";
+    case kVK_ANSI_P:
+      return "P";
+    case kVK_ANSI_Q:
+      return "Q";
+    case kVK_ANSI_R:
+      return "R";
+    case kVK_ANSI_S:
+      return "S";
+    case kVK_ANSI_T:
+      return "T";
+    case kVK_ANSI_U:
+      return "U";
+    case kVK_ANSI_V:
+      return "V";
+    case kVK_ANSI_W:
+      return "W";
+    case kVK_ANSI_X:
+      return "X";
+    case kVK_ANSI_Y:
+      return "Y";
+    case kVK_ANSI_Z:
+      return "Z";
+
+    case kVK_ANSI_1:
+      return "1";
+    case kVK_ANSI_2:
+      return "2";
+    case kVK_ANSI_3:
+      return "3";
+    case kVK_ANSI_4:
+      return "4";
+    case kVK_ANSI_5:
+      return "5";
+    case kVK_ANSI_6:
+      return "6";
+    case kVK_ANSI_7:
+      return "7";
+    case kVK_ANSI_8:
+      return "8";
+    case kVK_ANSI_9:
+      return "9";
+    case kVK_ANSI_0:
+      return "0";
+    case kVK_ANSI_Equal:
+      return "Equal";
+    case kVK_ANSI_Minus:
+      return "Minus";
+    case kVK_ANSI_RightBracket:
+      return "RightBracket";
+    case kVK_ANSI_LeftBracket:
+      return "LeftBracket";
+    case kVK_ANSI_Quote:
+      return "Quote";
+    case kVK_ANSI_Semicolon:
+      return "Semicolon";
+    case kVK_ANSI_Backslash:
+      return "Backslash";
+    case kVK_ANSI_Comma:
+      return "Comma";
+    case kVK_ANSI_Slash:
+      return "Slash";
+    case kVK_ANSI_Period:
+      return "Period";
+    case kVK_ANSI_Grave:
+      return "Grave";
+
+    default:
+      return "undefined";
+  }
+}
+
+static const char* GetCharacters(const nsAString& aString) {
+  if (aString.IsEmpty()) {
+    return "";
+  }
+  nsAutoString escapedStr;
+  for (uint32_t i = 0; i < aString.Length(); i++) {
+    char16_t ch = aString.CharAt(i);
+    if (ch < 0x20) {
+      nsPrintfCString utf8str("(U+%04X)", ch);
+      escapedStr += NS_ConvertUTF8toUTF16(utf8str);
+    } else if (ch <= 0x7E) {
+      escapedStr += ch;
+    } else {
+      nsPrintfCString utf8str("(U+%04X)", ch);
+      escapedStr += ch;
+      escapedStr += NS_ConvertUTF8toUTF16(utf8str);
+    }
+  }
+
+  // the result will be freed automatically by cocoa.
+  NSString* result = nsCocoaUtils::ToNSString(escapedStr);
+  return [result UTF8String];
+}
+
+static const char* GetCharacters(const NSString* aString) {
+  nsAutoString str;
+  nsCocoaUtils::GetStringForNSString(aString, str);
+  return GetCharacters(str);
+}
+
+static const char* GetCharacters(const CFStringRef aString) {
+  const NSString* str = reinterpret_cast<const NSString*>(aString);
+  return GetCharacters(str);
+}
+
+static const char* GetNativeKeyEventType(NSEvent* aNativeEvent) {
+  switch ([aNativeEvent type]) {
+    case NSEventTypeKeyDown:
+      return "NSEventTypeKeyDown";
+    case NSEventTypeKeyUp:
+      return "NSEventTypeKeyUp";
+    case NSEventTypeFlagsChanged:
+      return "NSEventTypeFlagsChanged";
+    default:
+      return "not key event";
+  }
+}
+
+static const char* GetGeckoKeyEventType(const WidgetEvent& aEvent) {
+  switch (aEvent.mMessage) {
+    case eKeyDown:
+      return "eKeyDown";
+    case eKeyUp:
+      return "eKeyUp";
+    case eKeyPress:
+      return "eKeyPress";
+    default:
+      return "not key event";
+  }
+}
+
+static const char* GetWindowLevelName(NSInteger aWindowLevel) {
+  switch (aWindowLevel) {
+    case kCGBaseWindowLevelKey:
+      return "kCGBaseWindowLevelKey (NSNormalWindowLevel)";
+    case kCGMinimumWindowLevelKey:
+      return "kCGMinimumWindowLevelKey";
+    case kCGDesktopWindowLevelKey:
+      return "kCGDesktopWindowLevelKey";
+    case kCGBackstopMenuLevelKey:
+      return "kCGBackstopMenuLevelKey";
+    case kCGNormalWindowLevelKey:
+      return "kCGNormalWindowLevelKey";
+    case kCGFloatingWindowLevelKey:
+      return "kCGFloatingWindowLevelKey (NSFloatingWindowLevel)";
+    case kCGTornOffMenuWindowLevelKey:
+      return "kCGTornOffMenuWindowLevelKey (NSSubmenuWindowLevel, NSTornOffMenuWindowLevel)";
+    case kCGDockWindowLevelKey:
+      return "kCGDockWindowLevelKey (NSDockWindowLevel)";
+    case kCGMainMenuWindowLevelKey:
+      return "kCGMainMenuWindowLevelKey (NSMainMenuWindowLevel)";
+    case kCGStatusWindowLevelKey:
+      return "kCGStatusWindowLevelKey (NSStatusWindowLevel)";
+    case kCGModalPanelWindowLevelKey:
+      return "kCGModalPanelWindowLevelKey (NSModalPanelWindowLevel)";
+    case kCGPopUpMenuWindowLevelKey:
+      return "kCGPopUpMenuWindowLevelKey (NSPopUpMenuWindowLevel)";
+    case kCGDraggingWindowLevelKey:
+      return "kCGDraggingWindowLevelKey";
+    case kCGScreenSaverWindowLevelKey:
+      return "kCGScreenSaverWindowLevelKey (NSScreenSaverWindowLevel)";
+    case kCGMaximumWindowLevelKey:
+      return "kCGMaximumWindowLevelKey";
+    case kCGOverlayWindowLevelKey:
+      return "kCGOverlayWindowLevelKey";
+    case kCGHelpWindowLevelKey:
+      return "kCGHelpWindowLevelKey";
+    case kCGUtilityWindowLevelKey:
+      return "kCGUtilityWindowLevelKey";
+    case kCGDesktopIconWindowLevelKey:
+      return "kCGDesktopIconWindowLevelKey";
+    case kCGCursorWindowLevelKey:
+      return "kCGCursorWindowLevelKey";
+    case kCGNumberOfWindowLevelKeys:
+      return "kCGNumberOfWindowLevelKeys";
+    default:
+      return "unknown window level";
+  }
+}
+
+static bool IsControlChar(uint32_t aCharCode) { return aCharCode < ' ' || aCharCode == 0x7F; }
+
+static uint32_t gHandlerInstanceCount = 0;
+
+static void EnsureToLogAllKeyboardLayoutsAndIMEs() {
+  static bool sDone = false;
+  if (!sDone) {
+    sDone = true;
+    TextInputHandler::DebugPrintAllKeyboardLayouts();
+    IMEInputHandler::DebugPrintAllIMEModes();
+  }
+}
+
+inline NSRange MakeNSRangeFrom(const Maybe<OffsetAndData<uint32_t>>& aOffsetAndData) {
+  if (aOffsetAndData.isNothing()) {
+    return NSMakeRange(NSNotFound, 0);
+  }
+  return NSMakeRange(aOffsetAndData->StartOffset(), aOffsetAndData->Length());
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ *  TISInputSourceWrapper implementation
+ *
+ ******************************************************************************/
+
+TISInputSourceWrapper* TISInputSourceWrapper::sCurrentInputSource = nullptr;
+
+// static
+TISInputSourceWrapper& TISInputSourceWrapper::CurrentInputSource() {
+  if (!sCurrentInputSource) {
+    sCurrentInputSource = new TISInputSourceWrapper();
+  }
+  if (!sCurrentInputSource->IsInitializedByCurrentInputSource()) {
+    sCurrentInputSource->InitByCurrentInputSource();
+  }
+  return *sCurrentInputSource;
+}
+
+// static
+void TISInputSourceWrapper::Shutdown() {
+  if (!sCurrentInputSource) {
+    return;
+  }
+  sCurrentInputSource->Clear();
+  delete sCurrentInputSource;
+  sCurrentInputSource = nullptr;
+}
+
+bool TISInputSourceWrapper::TranslateToString(UInt32 aKeyCode, UInt32 aModifiers, UInt32 aKbType,
+                                              nsAString& aStr) {
+  aStr.Truncate();
+
+  const UCKeyboardLayout* UCKey = GetUCKeyboardLayout();
+
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p TISInputSourceWrapper::TranslateToString, aKeyCode=0x%X, "
+           "aModifiers=0x%X, aKbType=0x%X UCKey=%p\n    "
+           "Shift: %s, Ctrl: %s, Opt: %s, Cmd: %s, CapsLock: %s, NumLock: %s",
+           this, static_cast<unsigned int>(aKeyCode), static_cast<unsigned int>(aModifiers),
+           static_cast<unsigned int>(aKbType), UCKey, OnOrOff(aModifiers & shiftKey),
+           OnOrOff(aModifiers & controlKey), OnOrOff(aModifiers & optionKey),
+           OnOrOff(aModifiers & cmdKey), OnOrOff(aModifiers & alphaLock),
+           OnOrOff(aModifiers & kEventKeyModifierNumLockMask)));
+
+  NS_ENSURE_TRUE(UCKey, false);
+
+  UInt32 deadKeyState = 0;
+  UniCharCount len;
+  UniChar chars[5];
+  OSStatus err = ::UCKeyTranslate(UCKey, aKeyCode, kUCKeyActionDown, aModifiers >> 8, aKbType,
+                                  kUCKeyTranslateNoDeadKeysMask, &deadKeyState, 5, &len, chars);
+
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p   TISInputSourceWrapper::TranslateToString, err=0x%X, len=%zu", this,
+           static_cast<int>(err), len));
+
+  NS_ENSURE_TRUE(err == noErr, false);
+  if (len == 0) {
+    return true;
+  }
+  if (!aStr.SetLength(len, fallible)) {
+    return false;
+  }
+  NS_ASSERTION(sizeof(char16_t) == sizeof(UniChar),
+               "size of char16_t and size of UniChar are different");
+  memcpy(aStr.BeginWriting(), chars, len * sizeof(char16_t));
+
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p   TISInputSourceWrapper::TranslateToString, aStr=\"%s\"", this,
+           NS_ConvertUTF16toUTF8(aStr).get()));
+
+  return true;
+}
+
+uint32_t TISInputSourceWrapper::TranslateToChar(UInt32 aKeyCode, UInt32 aModifiers,
+                                                UInt32 aKbType) {
+  nsAutoString str;
+  if (!TranslateToString(aKeyCode, aModifiers, aKbType, str) || str.Length() != 1) {
+    return 0;
+  }
+  return static_cast<uint32_t>(str.CharAt(0));
+}
+
+bool TISInputSourceWrapper::IsDeadKey(NSEvent* aNativeKeyEvent) {
+  if ([[aNativeKeyEvent characters] length]) {
+    return false;
+  }
+
+  // Assmue that if control key or command key is pressed, it's not a dead key.
+  NSUInteger cocoaState = [aNativeKeyEvent modifierFlags];
+  if (cocoaState & (NSEventModifierFlagControl | NSEventModifierFlagCommand)) {
+    return false;
+  }
+
+  UInt32 nativeKeyCode = [aNativeKeyEvent keyCode];
+  switch (nativeKeyCode) {
+    case kVK_ANSI_A:
+    case kVK_ANSI_B:
+    case kVK_ANSI_C:
+    case kVK_ANSI_D:
+    case kVK_ANSI_E:
+    case kVK_ANSI_F:
+    case kVK_ANSI_G:
+    case kVK_ANSI_H:
+    case kVK_ANSI_I:
+    case kVK_ANSI_J:
+    case kVK_ANSI_K:
+    case kVK_ANSI_L:
+    case kVK_ANSI_M:
+    case kVK_ANSI_N:
+    case kVK_ANSI_O:
+    case kVK_ANSI_P:
+    case kVK_ANSI_Q:
+    case kVK_ANSI_R:
+    case kVK_ANSI_S:
+    case kVK_ANSI_T:
+    case kVK_ANSI_U:
+    case kVK_ANSI_V:
+    case kVK_ANSI_W:
+    case kVK_ANSI_X:
+    case kVK_ANSI_Y:
+    case kVK_ANSI_Z:
+    case kVK_ANSI_1:
+    case kVK_ANSI_2:
+    case kVK_ANSI_3:
+    case kVK_ANSI_4:
+    case kVK_ANSI_5:
+    case kVK_ANSI_6:
+    case kVK_ANSI_7:
+    case kVK_ANSI_8:
+    case kVK_ANSI_9:
+    case kVK_ANSI_0:
+    case kVK_ANSI_Equal:
+    case kVK_ANSI_Minus:
+    case kVK_ANSI_RightBracket:
+    case kVK_ANSI_LeftBracket:
+    case kVK_ANSI_Quote:
+    case kVK_ANSI_Semicolon:
+    case kVK_ANSI_Backslash:
+    case kVK_ANSI_Comma:
+    case kVK_ANSI_Slash:
+    case kVK_ANSI_Period:
+    case kVK_ANSI_Grave:
+    case kVK_JIS_Yen:
+    case kVK_JIS_Underscore:
+      break;
+    default:
+      // Let's assume that dead key can be only a printable key in standard
+      // position.
+      return false;
+  }
+
+  // If TranslateToChar() returns non-zero value, that means that
+  // the key may input a character with different dead key state.
+  UInt32 kbType = GetKbdType();
+  UInt32 carbonState = nsCocoaUtils::ConvertToCarbonModifier(cocoaState);
+  return IsDeadKey(nativeKeyCode, carbonState, kbType);
+}
+
+bool TISInputSourceWrapper::IsDeadKey(UInt32 aKeyCode, UInt32 aModifiers, UInt32 aKbType) {
+  const UCKeyboardLayout* UCKey = GetUCKeyboardLayout();
+
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p TISInputSourceWrapper::IsDeadKey, aKeyCode=0x%X, "
+           "aModifiers=0x%X, aKbType=0x%X UCKey=%p\n    "
+           "Shift: %s, Ctrl: %s, Opt: %s, Cmd: %s, CapsLock: %s, NumLock: %s",
+           this, static_cast<unsigned int>(aKeyCode), static_cast<unsigned int>(aModifiers),
+           static_cast<unsigned int>(aKbType), UCKey, OnOrOff(aModifiers & shiftKey),
+           OnOrOff(aModifiers & controlKey), OnOrOff(aModifiers & optionKey),
+           OnOrOff(aModifiers & cmdKey), OnOrOff(aModifiers & alphaLock),
+           OnOrOff(aModifiers & kEventKeyModifierNumLockMask)));
+
+  if (NS_WARN_IF(!UCKey)) {
+    return false;
+  }
+
+  UInt32 deadKeyState = 0;
+  UniCharCount len;
+  UniChar chars[5];
+  OSStatus err = ::UCKeyTranslate(UCKey, aKeyCode, kUCKeyActionDown, aModifiers >> 8, aKbType, 0,
+                                  &deadKeyState, 5, &len, chars);
+
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p   TISInputSourceWrapper::IsDeadKey, err=0x%X, "
+           "len=%zu, deadKeyState=%u",
+           this, static_cast<int>(err), len, deadKeyState));
+
+  if (NS_WARN_IF(err != noErr)) {
+    return false;
+  }
+
+  return deadKeyState != 0;
+}
+
+void TISInputSourceWrapper::InitByInputSourceID(const char* aID) {
+  Clear();
+  if (!aID) return;
+
+  CFStringRef idstr = ::CFStringCreateWithCString(kCFAllocatorDefault, aID, kCFStringEncodingASCII);
+  InitByInputSourceID(idstr);
+  ::CFRelease(idstr);
+}
+
+void TISInputSourceWrapper::InitByInputSourceID(const nsString& aID) {
+  Clear();
+  if (aID.IsEmpty()) return;
+  CFStringRef idstr = ::CFStringCreateWithCharacters(
+      kCFAllocatorDefault, reinterpret_cast<const UniChar*>(aID.get()), aID.Length());
+  InitByInputSourceID(idstr);
+  ::CFRelease(idstr);
+}
+
+void TISInputSourceWrapper::InitByInputSourceID(const CFStringRef aID) {
+  Clear();
+  if (!aID) return;
+  const void* keys[] = {kTISPropertyInputSourceID};
+  const void* values[] = {aID};
+  CFDictionaryRef filter = ::CFDictionaryCreate(kCFAllocatorDefault, keys, values, 1, NULL, NULL);
+  NS_ASSERTION(filter, "failed to create the filter");
+  mInputSourceList = ::TISCreateInputSourceList(filter, true);
+  ::CFRelease(filter);
+  if (::CFArrayGetCount(mInputSourceList) > 0) {
+    mInputSource = static_cast<TISInputSourceRef>(
+        const_cast<void*>(::CFArrayGetValueAtIndex(mInputSourceList, 0)));
+    if (IsKeyboardLayout()) {
+      mKeyboardLayout = mInputSource;
+    }
+  }
+}
+
+void TISInputSourceWrapper::InitByLayoutID(SInt32 aLayoutID, bool aOverrideKeyboard) {
+  // NOTE: Doument new layout IDs in TextInputHandler.h when you add ones.
+  switch (aLayoutID) {
+    case 0:
+      InitByInputSourceID("com.apple.keylayout.US");
+      break;
+    case 1:
+      InitByInputSourceID("com.apple.keylayout.Greek");
+      break;
+    case 2:
+      InitByInputSourceID("com.apple.keylayout.German");
+      break;
+    case 3:
+      InitByInputSourceID("com.apple.keylayout.Swedish-Pro");
+      break;
+    case 4:
+      InitByInputSourceID("com.apple.keylayout.DVORAK-QWERTYCMD");
+      break;
+    case 5:
+      InitByInputSourceID("com.apple.keylayout.Thai");
+      break;
+    case 6:
+      InitByInputSourceID("com.apple.keylayout.Arabic");
+      break;
+    case 7:
+      InitByInputSourceID("com.apple.keylayout.ArabicPC");
+      break;
+    case 8:
+      InitByInputSourceID("com.apple.keylayout.French");
+      break;
+    case 9:
+      InitByInputSourceID("com.apple.keylayout.Hebrew");
+      break;
+    case 10:
+      InitByInputSourceID("com.apple.keylayout.Lithuanian");
+      break;
+    case 11:
+      InitByInputSourceID("com.apple.keylayout.Norwegian");
+      break;
+    case 12:
+      InitByInputSourceID("com.apple.keylayout.Spanish");
+      break;
+    default:
+      Clear();
+      break;
+  }
+  mOverrideKeyboard = aOverrideKeyboard;
+}
+
+void TISInputSourceWrapper::InitByCurrentInputSource() {
+  Clear();
+  mInputSource = ::TISCopyCurrentKeyboardInputSource();
+  mKeyboardLayout = ::TISCopyInputMethodKeyboardLayoutOverride();
+  if (!mKeyboardLayout) {
+    mKeyboardLayout = ::TISCopyCurrentKeyboardLayoutInputSource();
+  }
+  // If this causes composition, the current keyboard layout may input non-ASCII
+  // characters such as Japanese Kana characters or Hangul characters.
+  // However, we need to set ASCII characters to DOM key events for consistency
+  // with other platforms.
+  if (IsOpenedIMEMode()) {
+    TISInputSourceWrapper tis(mKeyboardLayout);
+    if (!tis.IsASCIICapable()) {
+      mKeyboardLayout = ::TISCopyCurrentASCIICapableKeyboardLayoutInputSource();
+    }
+  }
+}
+
+void TISInputSourceWrapper::InitByCurrentKeyboardLayout() {
+  Clear();
+  mInputSource = ::TISCopyCurrentKeyboardLayoutInputSource();
+  mKeyboardLayout = mInputSource;
+}
+
+void TISInputSourceWrapper::InitByCurrentASCIICapableInputSource() {
+  Clear();
+  mInputSource = ::TISCopyCurrentASCIICapableKeyboardInputSource();
+  mKeyboardLayout = ::TISCopyInputMethodKeyboardLayoutOverride();
+  if (mKeyboardLayout) {
+    TISInputSourceWrapper tis(mKeyboardLayout);
+    if (!tis.IsASCIICapable()) {
+      mKeyboardLayout = nullptr;
+    }
+  }
+  if (!mKeyboardLayout) {
+    mKeyboardLayout = ::TISCopyCurrentASCIICapableKeyboardLayoutInputSource();
+  }
+}
+
+void TISInputSourceWrapper::InitByCurrentASCIICapableKeyboardLayout() {
+  Clear();
+  mInputSource = ::TISCopyCurrentASCIICapableKeyboardLayoutInputSource();
+  mKeyboardLayout = mInputSource;
+}
+
+void TISInputSourceWrapper::InitByCurrentInputMethodKeyboardLayoutOverride() {
+  Clear();
+  mInputSource = ::TISCopyInputMethodKeyboardLayoutOverride();
+  mKeyboardLayout = mInputSource;
+}
+
+void TISInputSourceWrapper::InitByTISInputSourceRef(TISInputSourceRef aInputSource) {
+  Clear();
+  mInputSource = aInputSource;
+  if (IsKeyboardLayout()) {
+    mKeyboardLayout = mInputSource;
+  }
+}
+
+void TISInputSourceWrapper::InitByLanguage(CFStringRef aLanguage) {
+  Clear();
+  mInputSource = ::TISCopyInputSourceForLanguage(aLanguage);
+  if (IsKeyboardLayout()) {
+    mKeyboardLayout = mInputSource;
+  }
+}
+
+const UCKeyboardLayout* TISInputSourceWrapper::GetUCKeyboardLayout() {
+  NS_ENSURE_TRUE(mKeyboardLayout, nullptr);
+  if (mUCKeyboardLayout) {
+    return mUCKeyboardLayout;
+  }
+  CFDataRef uchr = static_cast<CFDataRef>(
+      ::TISGetInputSourceProperty(mKeyboardLayout, kTISPropertyUnicodeKeyLayoutData));
+
+  // We should be always able to get the layout here.
+  NS_ENSURE_TRUE(uchr, nullptr);
+  mUCKeyboardLayout = reinterpret_cast<const UCKeyboardLayout*>(CFDataGetBytePtr(uchr));
+  return mUCKeyboardLayout;
+}
+
+bool TISInputSourceWrapper::GetBoolProperty(const CFStringRef aKey) {
+  CFBooleanRef ret = static_cast<CFBooleanRef>(::TISGetInputSourceProperty(mInputSource, aKey));
+  return ::CFBooleanGetValue(ret);
+}
+
+bool TISInputSourceWrapper::GetStringProperty(const CFStringRef aKey, CFStringRef& aStr) {
+  aStr = static_cast<CFStringRef>(::TISGetInputSourceProperty(mInputSource, aKey));
+  return aStr != nullptr;
+}
+
+bool TISInputSourceWrapper::GetStringProperty(const CFStringRef aKey, nsAString& aStr) {
+  CFStringRef str;
+  GetStringProperty(aKey, str);
+  nsCocoaUtils::GetStringForNSString((const NSString*)str, aStr);
+  return !aStr.IsEmpty();
+}
+
+bool TISInputSourceWrapper::IsOpenedIMEMode() {
+  NS_ENSURE_TRUE(mInputSource, false);
+  if (!IsIMEMode()) return false;
+  return !IsASCIICapable();
+}
+
+bool TISInputSourceWrapper::IsIMEMode() {
+  NS_ENSURE_TRUE(mInputSource, false);
+  CFStringRef str;
+  GetInputSourceType(str);
+  NS_ENSURE_TRUE(str, false);
+  return ::CFStringCompare(kTISTypeKeyboardInputMode, str, 0) == kCFCompareEqualTo;
+}
+
+bool TISInputSourceWrapper::IsKeyboardLayout() {
+  NS_ENSURE_TRUE(mInputSource, false);
+  CFStringRef str;
+  GetInputSourceType(str);
+  NS_ENSURE_TRUE(str, false);
+  return ::CFStringCompare(kTISTypeKeyboardLayout, str, 0) == kCFCompareEqualTo;
+}
+
+bool TISInputSourceWrapper::GetLanguageList(CFArrayRef& aLanguageList) {
+  NS_ENSURE_TRUE(mInputSource, false);
+  aLanguageList = static_cast<CFArrayRef>(
+      ::TISGetInputSourceProperty(mInputSource, kTISPropertyInputSourceLanguages));
+  return aLanguageList != nullptr;
+}
+
+bool TISInputSourceWrapper::GetPrimaryLanguage(CFStringRef& aPrimaryLanguage) {
+  NS_ENSURE_TRUE(mInputSource, false);
+  CFArrayRef langList;
+  NS_ENSURE_TRUE(GetLanguageList(langList), false);
+  if (::CFArrayGetCount(langList) == 0) return false;
+  aPrimaryLanguage = static_cast<CFStringRef>(::CFArrayGetValueAtIndex(langList, 0));
+  return aPrimaryLanguage != nullptr;
+}
+
+bool TISInputSourceWrapper::GetPrimaryLanguage(nsAString& aPrimaryLanguage) {
+  NS_ENSURE_TRUE(mInputSource, false);
+  CFStringRef primaryLanguage;
+  NS_ENSURE_TRUE(GetPrimaryLanguage(primaryLanguage), false);
+  nsCocoaUtils::GetStringForNSString((const NSString*)primaryLanguage, aPrimaryLanguage);
+  return !aPrimaryLanguage.IsEmpty();
+}
+
+bool TISInputSourceWrapper::IsForRTLLanguage() {
+  if (mIsRTL < 0) {
+    // Get the input character of the 'A' key of ANSI keyboard layout.
+    nsAutoString str;
+    bool ret = TranslateToString(kVK_ANSI_A, 0, eKbdType_ANSI, str);
+    NS_ENSURE_TRUE(ret, ret);
+    char16_t ch = str.IsEmpty() ? char16_t(0) : str.CharAt(0);
+    mIsRTL = UTF16_CODE_UNIT_IS_BIDI(ch);
+  }
+  return mIsRTL != 0;
+}
+
+bool TISInputSourceWrapper::IsForJapaneseLanguage() {
+  nsAutoString lang;
+  GetPrimaryLanguage(lang);
+  return lang.EqualsLiteral("ja");
+}
+
+bool TISInputSourceWrapper::IsInitializedByCurrentInputSource() {
+  return mInputSource == ::TISCopyCurrentKeyboardInputSource();
+}
+
+void TISInputSourceWrapper::Select() {
+  if (!mInputSource) return;
+  ::TISSelectInputSource(mInputSource);
+}
+
+void TISInputSourceWrapper::Clear() {
+  // Clear() is always called when TISInputSourceWrappper is created.
+  EnsureToLogAllKeyboardLayoutsAndIMEs();
+
+  if (mInputSourceList) {
+    ::CFRelease(mInputSourceList);
+  }
+  mInputSourceList = nullptr;
+  mInputSource = nullptr;
+  mKeyboardLayout = nullptr;
+  mIsRTL = -1;
+  mUCKeyboardLayout = nullptr;
+  mOverrideKeyboard = false;
+}
+
+bool TISInputSourceWrapper::IsPrintableKeyEvent(NSEvent* aNativeKeyEvent) const {
+  UInt32 nativeKeyCode = [aNativeKeyEvent keyCode];
+
+  bool isPrintableKey = !TextInputHandler::IsSpecialGeckoKey(nativeKeyCode);
+  if (isPrintableKey && [aNativeKeyEvent type] != NSEventTypeKeyDown &&
+      [aNativeKeyEvent type] != NSEventTypeKeyUp) {
+    NS_WARNING("Why would a printable key not be an NSEventTypeKeyDown or NSEventTypeKeyUp event?");
+    isPrintableKey = false;
+  }
+  return isPrintableKey;
+}
+
+UInt32 TISInputSourceWrapper::GetKbdType() const {
+  // If a keyboard layout override is set, we also need to force the keyboard
+  // type to something ANSI to avoid test failures on machines with JIS
+  // keyboards (since the pair of keyboard layout and physical keyboard type
+  // form the actual key layout).  This assumes that the test setting the
+  // override was written assuming an ANSI keyboard.
+  return mOverrideKeyboard ? eKbdType_ANSI : ::LMGetKbdType();
+}
+
+void TISInputSourceWrapper::ComputeInsertStringForCharCode(NSEvent* aNativeKeyEvent,
+                                                           const WidgetKeyboardEvent& aKeyEvent,
+                                                           const nsAString* aInsertString,
+                                                           nsAString& aResult) {
+  if (aInsertString) {
+    // If the caller expects that the aInsertString will be input, we shouldn't
+    // change it.
+    aResult = *aInsertString;
+  } else if (IsPrintableKeyEvent(aNativeKeyEvent)) {
+    // If IME is open, [aNativeKeyEvent characters] may be a character
+    // which will be appended to the composition string.  However, especially,
+    // while IME is disabled, most users and developers expect the key event
+    // works as IME closed.  So, we should compute the aResult with
+    // the ASCII capable keyboard layout.
+    // NOTE: Such keyboard layouts typically change the layout to its ASCII
+    //       capable layout when Command key is pressed.  And we don't worry
+    //       when Control key is pressed too because it causes inputting
+    //       control characters.
+    // Additionally, if the key event doesn't input any text, the event may be
+    // dead key event.  In this case, the charCode value should be the dead
+    // character.
+    UInt32 nativeKeyCode = [aNativeKeyEvent keyCode];
+    if ((!aKeyEvent.IsMeta() && !aKeyEvent.IsControl() && IsOpenedIMEMode()) ||
+        ![[aNativeKeyEvent characters] length]) {
+      UInt32 state = nsCocoaUtils::ConvertToCarbonModifier([aNativeKeyEvent modifierFlags]);
+      uint32_t ch = TranslateToChar(nativeKeyCode, state, GetKbdType());
+      if (ch) {
+        aResult = ch;
+      }
+    } else {
+      // If the caller isn't sure what string will be input, let's use
+      // characters of NSEvent.
+      nsCocoaUtils::GetStringForNSString([aNativeKeyEvent characters], aResult);
+    }
+
+    // If control key is pressed and the eventChars is a non-printable control
+    // character, we should convert it to ASCII alphabet.
+    if (aKeyEvent.IsControl() && !aResult.IsEmpty() && aResult[0] <= char16_t(26)) {
+      aResult = (aKeyEvent.IsShift() ^ aKeyEvent.IsCapsLocked())
+                    ? static_cast<char16_t>(aResult[0] + ('A' - 1))
+                    : static_cast<char16_t>(aResult[0] + ('a' - 1));
+    }
+    // If Meta key is pressed, it may cause to switch the keyboard layout like
+    // Arabic, Russian, Hebrew, Greek and Dvorak-QWERTY.
+    else if (aKeyEvent.IsMeta() && !(aKeyEvent.IsControl() || aKeyEvent.IsAlt())) {
+      UInt32 kbType = GetKbdType();
+      UInt32 numLockState = aKeyEvent.IsNumLocked() ? kEventKeyModifierNumLockMask : 0;
+      UInt32 capsLockState = aKeyEvent.IsCapsLocked() ? alphaLock : 0;
+      UInt32 shiftState = aKeyEvent.IsShift() ? shiftKey : 0;
+      uint32_t uncmdedChar = TranslateToChar(nativeKeyCode, numLockState, kbType);
+      uint32_t cmdedChar = TranslateToChar(nativeKeyCode, cmdKey | numLockState, kbType);
+      // If we can make a good guess at the characters that the user would
+      // expect this key combination to produce (with and without Shift) then
+      // use those characters.  This also corrects for CapsLock.
+      uint32_t ch = 0;
+      if (uncmdedChar == cmdedChar) {
+        // The characters produced with Command seem similar to those without
+        // Command.
+        ch = TranslateToChar(nativeKeyCode, shiftState | capsLockState | numLockState, kbType);
+      } else {
+        TISInputSourceWrapper USLayout("com.apple.keylayout.US");
+        uint32_t uncmdedUSChar = USLayout.TranslateToChar(nativeKeyCode, numLockState, kbType);
+        // If it looks like characters from US keyboard layout when Command key
+        // is pressed, we should compute a character in the layout.
+        if (uncmdedUSChar == cmdedChar) {
+          ch = USLayout.TranslateToChar(nativeKeyCode, shiftState | capsLockState | numLockState,
+                                        kbType);
+        }
+      }
+
+      // If there is a more preferred character for the commanded key event,
+      // we should use it.
+      if (ch) {
+        aResult = ch;
+      }
+    }
+  }
+
+  // Remove control characters which shouldn't be inputted on editor.
+  // XXX Currently, we don't find any cases inserting control characters with
+  //     printable character.  So, just checking first character is enough.
+  if (!aResult.IsEmpty() && IsControlChar(aResult[0])) {
+    aResult.Truncate();
+  }
+}
+
+void TISInputSourceWrapper::InitKeyEvent(NSEvent* aNativeKeyEvent, WidgetKeyboardEvent& aKeyEvent,
+                                         bool aIsProcessedByIME, const nsAString* aInsertString) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_ASSERT(!aIsProcessedByIME || aKeyEvent.mMessage != eKeyPress,
+             "eKeyPress event should not be marked as proccessed by IME");
+
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p TISInputSourceWrapper::InitKeyEvent, aNativeKeyEvent=%p, "
+           "aKeyEvent.mMessage=%s, aProcessedByIME=%s, aInsertString=%p, "
+           "IsOpenedIMEMode()=%s",
+           this, aNativeKeyEvent, GetGeckoKeyEventType(aKeyEvent), TrueOrFalse(aIsProcessedByIME),
+           aInsertString, TrueOrFalse(IsOpenedIMEMode())));
+
+  if (NS_WARN_IF(!aNativeKeyEvent)) {
+    return;
+  }
+
+  nsCocoaUtils::InitInputEvent(aKeyEvent, aNativeKeyEvent);
+
+  // This is used only while dispatching the event (which is a synchronous
+  // call), so there is no need to retain and release this data.
+  aKeyEvent.mNativeKeyEvent = aNativeKeyEvent;
+
+  aKeyEvent.mRefPoint = LayoutDeviceIntPoint(0, 0);
+
+  UInt32 kbType = GetKbdType();
+  UInt32 nativeKeyCode = [aNativeKeyEvent keyCode];
+
+  // macOS handles dead key as IME.  If the key is first key press of dead
+  // key, we should use KEY_NAME_INDEX_Dead for first (dead) key event.
+  // So, if aIsProcessedByIME is true, it may be dead key.  Let's check
+  // if current key event is a dead key's keydown event.
+  bool isProcessedByIME =
+      aIsProcessedByIME && !TISInputSourceWrapper::CurrentInputSource().IsDeadKey(aNativeKeyEvent);
+
+  aKeyEvent.mKeyCode = isProcessedByIME
+                           ? NS_VK_PROCESSKEY
+                           : ComputeGeckoKeyCode(nativeKeyCode, kbType, aKeyEvent.IsMeta());
+
+  switch (nativeKeyCode) {
+    case kVK_Command:
+    case kVK_Shift:
+    case kVK_Option:
+    case kVK_Control:
+      aKeyEvent.mLocation = eKeyLocationLeft;
+      break;
+
+    case kVK_RightCommand:
+    case kVK_RightShift:
+    case kVK_RightOption:
+    case kVK_RightControl:
+      aKeyEvent.mLocation = eKeyLocationRight;
+      break;
+
+    case kVK_ANSI_Keypad0:
+    case kVK_ANSI_Keypad1:
+    case kVK_ANSI_Keypad2:
+    case kVK_ANSI_Keypad3:
+    case kVK_ANSI_Keypad4:
+    case kVK_ANSI_Keypad5:
+    case kVK_ANSI_Keypad6:
+    case kVK_ANSI_Keypad7:
+    case kVK_ANSI_Keypad8:
+    case kVK_ANSI_Keypad9:
+    case kVK_ANSI_KeypadMultiply:
+    case kVK_ANSI_KeypadPlus:
+    case kVK_ANSI_KeypadMinus:
+    case kVK_ANSI_KeypadDecimal:
+    case kVK_ANSI_KeypadDivide:
+    case kVK_ANSI_KeypadEquals:
+    case kVK_ANSI_KeypadEnter:
+    case kVK_JIS_KeypadComma:
+    case kVK_Powerbook_KeypadEnter:
+      aKeyEvent.mLocation = eKeyLocationNumpad;
+      break;
+
+    default:
+      aKeyEvent.mLocation = eKeyLocationStandard;
+      break;
+  }
+
+  aKeyEvent.mIsRepeat =
+      ([aNativeKeyEvent type] == NSEventTypeKeyDown) ? [aNativeKeyEvent isARepeat] : false;
+
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p   TISInputSourceWrapper::InitKeyEvent, "
+           "shift=%s, ctrl=%s, alt=%s, meta=%s",
+           this, OnOrOff(aKeyEvent.IsShift()), OnOrOff(aKeyEvent.IsControl()),
+           OnOrOff(aKeyEvent.IsAlt()), OnOrOff(aKeyEvent.IsMeta())));
+
+  if (isProcessedByIME) {
+    aKeyEvent.mKeyNameIndex = KEY_NAME_INDEX_Process;
+  } else if (IsPrintableKeyEvent(aNativeKeyEvent)) {
+    aKeyEvent.mKeyNameIndex = KEY_NAME_INDEX_USE_STRING;
+    // If insertText calls this method, let's use the string.
+    if (aInsertString && !aInsertString->IsEmpty() && !IsControlChar((*aInsertString)[0])) {
+      aKeyEvent.mKeyValue = *aInsertString;
+    }
+    // If meta key is pressed, the printable key layout may be switched from
+    // non-ASCII capable layout to ASCII capable, or from Dvorak to QWERTY.
+    // KeyboardEvent.key value should be the switched layout's character.
+    else if (aKeyEvent.IsMeta()) {
+      nsCocoaUtils::GetStringForNSString([aNativeKeyEvent characters], aKeyEvent.mKeyValue);
+    }
+    // If control key is pressed, some keys may produce printable character via
+    // [aNativeKeyEvent characters].  Otherwise, translate input character of
+    // the key without control key.
+    else if (aKeyEvent.IsControl()) {
+      NSUInteger cocoaState = [aNativeKeyEvent modifierFlags] & ~NSEventModifierFlagControl;
+      UInt32 carbonState = nsCocoaUtils::ConvertToCarbonModifier(cocoaState);
+      if (IsDeadKey(nativeKeyCode, carbonState, kbType)) {
+        aKeyEvent.mKeyNameIndex = KEY_NAME_INDEX_Dead;
+      } else {
+        aKeyEvent.mKeyValue = TranslateToChar(nativeKeyCode, carbonState, kbType);
+        if (!aKeyEvent.mKeyValue.IsEmpty() && IsControlChar(aKeyEvent.mKeyValue[0])) {
+          // Don't expose control character to the web.
+          aKeyEvent.mKeyValue.Truncate();
+        }
+      }
+    }
+    // Otherwise, KeyboardEvent.key expose
+    // [aNativeKeyEvent characters] value.  However, if IME is open and the
+    // keyboard layout isn't ASCII capable, exposing the non-ASCII character
+    // doesn't match with other platform's behavior.  For the compatibility
+    // with other platform's Gecko, we need to set a translated character.
+    else if (IsOpenedIMEMode()) {
+      UInt32 state = nsCocoaUtils::ConvertToCarbonModifier([aNativeKeyEvent modifierFlags]);
+      aKeyEvent.mKeyValue = TranslateToChar(nativeKeyCode, state, kbType);
+    } else {
+      nsCocoaUtils::GetStringForNSString([aNativeKeyEvent characters], aKeyEvent.mKeyValue);
+      // If the key value is empty, the event may be a dead key event.
+      // If TranslateToChar() returns non-zero value, that means that
+      // the key may input a character with different dead key state.
+      if (aKeyEvent.mKeyValue.IsEmpty()) {
+        NSUInteger cocoaState = [aNativeKeyEvent modifierFlags];
+        UInt32 carbonState = nsCocoaUtils::ConvertToCarbonModifier(cocoaState);
+        if (TranslateToChar(nativeKeyCode, carbonState, kbType)) {
+          aKeyEvent.mKeyNameIndex = KEY_NAME_INDEX_Dead;
+        }
+      }
+    }
+
+    // Last resort.  If .key value becomes empty string, we should use
+    // charactersIgnoringModifiers, if it's available.
+    if (aKeyEvent.mKeyNameIndex == KEY_NAME_INDEX_USE_STRING &&
+        (aKeyEvent.mKeyValue.IsEmpty() || IsControlChar(aKeyEvent.mKeyValue[0]))) {
+      nsCocoaUtils::GetStringForNSString([aNativeKeyEvent charactersIgnoringModifiers],
+                                         aKeyEvent.mKeyValue);
+      // But don't expose it if it's a control character.
+      if (!aKeyEvent.mKeyValue.IsEmpty() && IsControlChar(aKeyEvent.mKeyValue[0])) {
+        aKeyEvent.mKeyValue.Truncate();
+      }
+    }
+  } else {
+    // Compute the key for non-printable keys and some special printable keys.
+    aKeyEvent.mKeyNameIndex = ComputeGeckoKeyNameIndex(nativeKeyCode);
+  }
+
+  aKeyEvent.mCodeNameIndex = ComputeGeckoCodeNameIndex(nativeKeyCode, kbType);
+  MOZ_ASSERT(aKeyEvent.mCodeNameIndex != CODE_NAME_INDEX_USE_STRING);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK
+}
+
+void TISInputSourceWrapper::WillDispatchKeyboardEvent(NSEvent* aNativeKeyEvent,
+                                                      const nsAString* aInsertString,
+                                                      uint32_t aIndexOfKeypress,
+                                                      WidgetKeyboardEvent& aKeyEvent) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Nothing to do here if the native key event is neither NSEventTypeKeyDown nor
+  // NSEventTypeKeyUp because accessing [aNativeKeyEvent characters] causes throwing
+  // an exception.
+  if ([aNativeKeyEvent type] != NSEventTypeKeyDown && [aNativeKeyEvent type] != NSEventTypeKeyUp) {
+    return;
+  }
+
+  UInt32 kbType = GetKbdType();
+
+  if (MOZ_LOG_TEST(gKeyLog, LogLevel::Info)) {
+    nsAutoString chars;
+    nsCocoaUtils::GetStringForNSString([aNativeKeyEvent characters], chars);
+    NS_ConvertUTF16toUTF8 utf8Chars(chars);
+    char16_t uniChar = static_cast<char16_t>(aKeyEvent.mCharCode);
+    MOZ_LOG(gKeyLog, LogLevel::Info,
+            ("%p TISInputSourceWrapper::WillDispatchKeyboardEvent, "
+             "aNativeKeyEvent=%p, aInsertString=%p (\"%s\"), "
+             "aIndexOfKeypress=%u, [aNativeKeyEvent characters]=\"%s\", "
+             "aKeyEvent={ mMessage=%s, mCharCode=0x%X(%s) }, kbType=0x%X, "
+             "IsOpenedIMEMode()=%s",
+             this, aNativeKeyEvent, aInsertString,
+             aInsertString ? GetCharacters(*aInsertString) : "", aIndexOfKeypress,
+             GetCharacters([aNativeKeyEvent characters]), GetGeckoKeyEventType(aKeyEvent),
+             aKeyEvent.mCharCode, uniChar ? NS_ConvertUTF16toUTF8(&uniChar, 1).get() : "",
+             static_cast<unsigned int>(kbType), TrueOrFalse(IsOpenedIMEMode())));
+  }
+
+  nsAutoString insertStringForCharCode;
+  ComputeInsertStringForCharCode(aNativeKeyEvent, aKeyEvent, aInsertString,
+                                 insertStringForCharCode);
+
+  // The mCharCode was set from mKeyValue. However, for example, when Ctrl key
+  // is pressed, its value should indicate an ASCII character for backward
+  // compatibility rather than inputting character without the modifiers.
+  // Therefore, we need to modify mCharCode value here.
+  uint32_t charCode = 0;
+  if (aIndexOfKeypress < insertStringForCharCode.Length()) {
+    charCode = insertStringForCharCode[aIndexOfKeypress];
+  }
+  aKeyEvent.SetCharCode(charCode);
+
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p   TISInputSourceWrapper::WillDispatchKeyboardEvent, "
+           "aKeyEvent.mKeyCode=0x%X, aKeyEvent.mCharCode=0x%X",
+           this, aKeyEvent.mKeyCode, aKeyEvent.mCharCode));
+
+  // If aInsertString is not nullptr (it means InsertText() is called)
+  // and it acutally inputs a character, we don't need to append alternative
+  // charCode values since such keyboard event shouldn't be handled as
+  // a shortcut key.
+  if (aInsertString && charCode) {
+    return;
+  }
+
+  TISInputSourceWrapper USLayout("com.apple.keylayout.US");
+  bool isRomanKeyboardLayout = IsASCIICapable();
+
+  UInt32 key = [aNativeKeyEvent keyCode];
+
+  // Caps lock and num lock modifier state:
+  UInt32 lockState = 0;
+  if ([aNativeKeyEvent modifierFlags] & NSEventModifierFlagCapsLock) {
+    lockState |= alphaLock;
+  }
+  if ([aNativeKeyEvent modifierFlags] & NSEventModifierFlagNumericPad) {
+    lockState |= kEventKeyModifierNumLockMask;
+  }
+
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p   TISInputSourceWrapper::WillDispatchKeyboardEvent, "
+           "isRomanKeyboardLayout=%s, kbType=0x%X, key=0x%X",
+           this, TrueOrFalse(isRomanKeyboardLayout), static_cast<unsigned int>(kbType),
+           static_cast<unsigned int>(key)));
+
+  nsString str;
+
+  // normal chars
+  uint32_t unshiftedChar = TranslateToChar(key, lockState, kbType);
+  UInt32 shiftLockMod = shiftKey | lockState;
+  uint32_t shiftedChar = TranslateToChar(key, shiftLockMod, kbType);
+
+  // characters generated with Cmd key
+  // XXX we should remove CapsLock state, which changes characters from
+  //     Latin to Cyrillic with Russian layout on 10.4 only when Cmd key
+  //     is pressed.
+  UInt32 numState = (lockState & ~alphaLock);  // only num lock state
+  uint32_t uncmdedChar = TranslateToChar(key, numState, kbType);
+  UInt32 shiftNumMod = numState | shiftKey;
+  uint32_t uncmdedShiftChar = TranslateToChar(key, shiftNumMod, kbType);
+  uint32_t uncmdedUSChar = USLayout.TranslateToChar(key, numState, kbType);
+  UInt32 cmdNumMod = cmdKey | numState;
+  uint32_t cmdedChar = TranslateToChar(key, cmdNumMod, kbType);
+  UInt32 cmdShiftNumMod = shiftKey | cmdNumMod;
+  uint32_t cmdedShiftChar = TranslateToChar(key, cmdShiftNumMod, kbType);
+
+  // Is the keyboard layout changed by Cmd key?
+  // E.g., Arabic, Russian, Hebrew, Greek and Dvorak-QWERTY.
+  bool isCmdSwitchLayout = uncmdedChar != cmdedChar;
+  // Is the keyboard layout for Latin, but Cmd key switches the layout?
+  // I.e., Dvorak-QWERTY
+  bool isDvorakQWERTY = isCmdSwitchLayout && isRomanKeyboardLayout;
+
+  // If the current keyboard is not Dvorak-QWERTY or Cmd is not pressed,
+  // we should append unshiftedChar and shiftedChar for handling the
+  // normal characters.  These are the characters that the user is most
+  // likely to associate with this key.
+  if ((unshiftedChar || shiftedChar) && (!aKeyEvent.IsMeta() || !isDvorakQWERTY)) {
+    AlternativeCharCode altCharCodes(unshiftedChar, shiftedChar);
+    aKeyEvent.mAlternativeCharCodes.AppendElement(altCharCodes);
+  }
+  MOZ_LOG(
+      gKeyLog, LogLevel::Info,
+      ("%p   TISInputSourceWrapper::WillDispatchKeyboardEvent, "
+       "aKeyEvent.isMeta=%s, isDvorakQWERTY=%s, "
+       "unshiftedChar=U+%X, shiftedChar=U+%X",
+       this, OnOrOff(aKeyEvent.IsMeta()), TrueOrFalse(isDvorakQWERTY), unshiftedChar, shiftedChar));
+
+  // Most keyboard layouts provide the same characters in the NSEvents
+  // with Command+Shift as with Command.  However, with Command+Shift we
+  // want the character on the second level.  e.g. With a US QWERTY
+  // layout, we want "?" when the "/","?" key is pressed with
+  // Command+Shift.
+
+  // On a German layout, the OS gives us '/' with Cmd+Shift+SS(eszett)
+  // even though Cmd+SS is 'SS' and Shift+'SS' is '?'.  This '/' seems
+  // like a hack to make the Cmd+"?" event look the same as the Cmd+"?"
+  // event on a US keyboard.  The user thinks they are typing Cmd+"?", so
+  // we'll prefer the "?" character, replacing mCharCode with shiftedChar
+  // when Shift is pressed.  However, in case there is a layout where the
+  // character unique to Cmd+Shift is the character that the user expects,
+  // we'll send it as an alternative char.
+  bool hasCmdShiftOnlyChar = cmdedChar != cmdedShiftChar && uncmdedShiftChar != cmdedShiftChar;
+  uint32_t originalCmdedShiftChar = cmdedShiftChar;
+
+  // If we can make a good guess at the characters that the user would
+  // expect this key combination to produce (with and without Shift) then
+  // use those characters.  This also corrects for CapsLock, which was
+  // ignored above.
+  if (!isCmdSwitchLayout) {
+    // The characters produced with Command seem similar to those without
+    // Command.
+    if (unshiftedChar) {
+      cmdedChar = unshiftedChar;
+    }
+    if (shiftedChar) {
+      cmdedShiftChar = shiftedChar;
+    }
+  } else if (uncmdedUSChar == cmdedChar) {
+    // It looks like characters from a US layout are provided when Command
+    // is down.
+    uint32_t ch = USLayout.TranslateToChar(key, lockState, kbType);
+    if (ch) {
+      cmdedChar = ch;
+    }
+    ch = USLayout.TranslateToChar(key, shiftLockMod, kbType);
+    if (ch) {
+      cmdedShiftChar = ch;
+    }
+  }
+
+  // If the current keyboard layout is switched by the Cmd key,
+  // we should append cmdedChar and shiftedCmdChar that are
+  // Latin char for the key.
+  // If the keyboard layout is Dvorak-QWERTY, we should append them only when
+  // command key is pressed because when command key isn't pressed, uncmded
+  // chars have been appended already.
+  if ((cmdedChar || cmdedShiftChar) && isCmdSwitchLayout &&
+      (aKeyEvent.IsMeta() || !isDvorakQWERTY)) {
+    AlternativeCharCode altCharCodes(cmdedChar, cmdedShiftChar);
+    aKeyEvent.mAlternativeCharCodes.AppendElement(altCharCodes);
+  }
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p   TISInputSourceWrapper::WillDispatchKeyboardEvent, "
+           "hasCmdShiftOnlyChar=%s, isCmdSwitchLayout=%s, isDvorakQWERTY=%s, "
+           "cmdedChar=U+%X, cmdedShiftChar=U+%X",
+           this, TrueOrFalse(hasCmdShiftOnlyChar), TrueOrFalse(isDvorakQWERTY),
+           TrueOrFalse(isDvorakQWERTY), cmdedChar, cmdedShiftChar));
+  // Special case for 'SS' key of German layout. See the comment of
+  // hasCmdShiftOnlyChar definition for the detail.
+  if (hasCmdShiftOnlyChar && originalCmdedShiftChar) {
+    AlternativeCharCode altCharCodes(0, originalCmdedShiftChar);
+    aKeyEvent.mAlternativeCharCodes.AppendElement(altCharCodes);
+  }
+  MOZ_LOG(gKeyLog, LogLevel::Info,
+          ("%p   TISInputSourceWrapper::WillDispatchKeyboardEvent, "
+           "hasCmdShiftOnlyChar=%s, originalCmdedShiftChar=U+%X",
+           this, TrueOrFalse(hasCmdShiftOnlyChar), originalCmdedShiftChar));
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK
+}
+
+uint32_t TISInputSourceWrapper::ComputeGeckoKeyCode(UInt32 aNativeKeyCode, UInt32 aKbType,
+                                                    bool aCmdIsPressed) {
+  MOZ_LOG(
+      gKeyLog, LogLevel::Info,
+      ("%p TISInputSourceWrapper::ComputeGeckoKeyCode, aNativeKeyCode=0x%X, "
+       "aKbType=0x%X, aCmdIsPressed=%s, IsOpenedIMEMode()=%s, "
+       "IsASCIICapable()=%s",
+       this, static_cast<unsigned int>(aNativeKeyCode), static_cast<unsigned int>(aKbType),
+       TrueOrFalse(aCmdIsPressed), TrueOrFalse(IsOpenedIMEMode()), TrueOrFalse(IsASCIICapable())));
+
+  switch (aNativeKeyCode) {
+    case kVK_Space:
+      return NS_VK_SPACE;
+    case kVK_Escape:
+      return NS_VK_ESCAPE;
+
+    // modifiers
+    case kVK_RightCommand:
+    case kVK_Command:
+      return NS_VK_META;
+    case kVK_RightShift:
+    case kVK_Shift:
+      return NS_VK_SHIFT;
+    case kVK_CapsLock:
+      return NS_VK_CAPS_LOCK;
+    case kVK_RightControl:
+    case kVK_Control:
+      return NS_VK_CONTROL;
+    case kVK_RightOption:
+    case kVK_Option:
+      return NS_VK_ALT;
+
+    case kVK_ANSI_KeypadClear:
+      return NS_VK_CLEAR;
+
+    // function keys
+    case kVK_F1:
+      return NS_VK_F1;
+    case kVK_F2:
+      return NS_VK_F2;
+    case kVK_F3:
+      return NS_VK_F3;
+    case kVK_F4:
+      return NS_VK_F4;
+    case kVK_F5:
+      return NS_VK_F5;
+    case kVK_F6:
+      return NS_VK_F6;
+    case kVK_F7:
+      return NS_VK_F7;
+    case kVK_F8:
+      return NS_VK_F8;
+    case kVK_F9:
+      return NS_VK_F9;
+    case kVK_F10:
+      return NS_VK_F10;
+    case kVK_F11:
+      return NS_VK_F11;
+    case kVK_F12:
+      return NS_VK_F12;
+    // case kVK_F13:               return NS_VK_F13;  // clash with the 3 below
+    // case kVK_F14:               return NS_VK_F14;
+    // case kVK_F15:               return NS_VK_F15;
+    case kVK_F16:
+      return NS_VK_F16;
+    case kVK_F17:
+      return NS_VK_F17;
+    case kVK_F18:
+      return NS_VK_F18;
+    case kVK_F19:
+      return NS_VK_F19;
+
+    case kVK_PC_Pause:
+      return NS_VK_PAUSE;
+    case kVK_PC_ScrollLock:
+      return NS_VK_SCROLL_LOCK;
+    case kVK_PC_PrintScreen:
+      return NS_VK_PRINTSCREEN;
+
+    // keypad
+    case kVK_ANSI_Keypad0:
+      return NS_VK_NUMPAD0;
+    case kVK_ANSI_Keypad1:
+      return NS_VK_NUMPAD1;
+    case kVK_ANSI_Keypad2:
+      return NS_VK_NUMPAD2;
+    case kVK_ANSI_Keypad3:
+      return NS_VK_NUMPAD3;
+    case kVK_ANSI_Keypad4:
+      return NS_VK_NUMPAD4;
+    case kVK_ANSI_Keypad5:
+      return NS_VK_NUMPAD5;
+    case kVK_ANSI_Keypad6:
+      return NS_VK_NUMPAD6;
+    case kVK_ANSI_Keypad7:
+      return NS_VK_NUMPAD7;
+    case kVK_ANSI_Keypad8:
+      return NS_VK_NUMPAD8;
+    case kVK_ANSI_Keypad9:
+      return NS_VK_NUMPAD9;
+
+    case kVK_ANSI_KeypadMultiply:
+      return NS_VK_MULTIPLY;
+    case kVK_ANSI_KeypadPlus:
+      return NS_VK_ADD;
+    case kVK_ANSI_KeypadMinus:
+      return NS_VK_SUBTRACT;
+    case kVK_ANSI_KeypadDecimal:
+      return NS_VK_DECIMAL;
+    case kVK_ANSI_KeypadDivide:
+      return NS_VK_DIVIDE;
+
+    case kVK_JIS_KeypadComma:
+      return NS_VK_SEPARATOR;
+
+    // IME keys
+    case kVK_JIS_Eisu:
+      return NS_VK_EISU;
+    case kVK_JIS_Kana:
+      return NS_VK_KANA;
+
+    // these may clash with forward delete and help
+    case kVK_PC_Insert:
+      return NS_VK_INSERT;
+    case kVK_PC_Delete:
+      return NS_VK_DELETE;
+
+    case kVK_PC_Backspace:
+      return NS_VK_BACK;
+    case kVK_Tab:
+      return NS_VK_TAB;
+
+    case kVK_Home:
+      return NS_VK_HOME;
+    case kVK_End:
+      return NS_VK_END;
+
+    case kVK_PageUp:
+      return NS_VK_PAGE_UP;
+    case kVK_PageDown:
+      return NS_VK_PAGE_DOWN;
+
+    case kVK_LeftArrow:
+      return NS_VK_LEFT;
+    case kVK_RightArrow:
+      return NS_VK_RIGHT;
+    case kVK_UpArrow:
+      return NS_VK_UP;
+    case kVK_DownArrow:
+      return NS_VK_DOWN;
+
+    case kVK_PC_ContextMenu:
+      return NS_VK_CONTEXT_MENU;
+
+    case kVK_ANSI_1:
+      return NS_VK_1;
+    case kVK_ANSI_2:
+      return NS_VK_2;
+    case kVK_ANSI_3:
+      return NS_VK_3;
+    case kVK_ANSI_4:
+      return NS_VK_4;
+    case kVK_ANSI_5:
+      return NS_VK_5;
+    case kVK_ANSI_6:
+      return NS_VK_6;
+    case kVK_ANSI_7:
+      return NS_VK_7;
+    case kVK_ANSI_8:
+      return NS_VK_8;
+    case kVK_ANSI_9:
+      return NS_VK_9;
+    case kVK_ANSI_0:
+      return NS_VK_0;
+
+    case kVK_ANSI_KeypadEnter:
+    case kVK_Return:
+    case kVK_Powerbook_KeypadEnter:
+      return NS_VK_RETURN;
+  }
+
+  // If Cmd key is pressed, that causes switching keyboard layout temporarily.
+  // E.g., Dvorak-QWERTY.  Therefore, if Cmd key is pressed, we should honor it.
+  UInt32 modifiers = aCmdIsPressed ? cmdKey : 0;
+
+  uint32_t charCode = TranslateToChar(aNativeKeyCode, modifiers, aKbType);
+
+  // Special case for Mac.  Mac inputs Yen sign (U+00A5) directly instead of
+  // Back slash (U+005C).  We should return NS_VK_BACK_SLASH for compatibility
+  // with other platforms.
+  // XXX How about Won sign (U+20A9) which has same problem as Yen sign?
+  if (charCode == 0x00A5) {
+    return NS_VK_BACK_SLASH;
+  }
+
+  uint32_t keyCode = WidgetUtils::ComputeKeyCodeFromChar(charCode);
+  if (keyCode) {
+    return keyCode;
+  }
+
+  // If the unshifed char isn't an ASCII character, use shifted char.
+  charCode = TranslateToChar(aNativeKeyCode, modifiers | shiftKey, aKbType);
+  keyCode = WidgetUtils::ComputeKeyCodeFromChar(charCode);
+  if (keyCode) {
+    return keyCode;
+  }
+
+  if (!IsASCIICapable()) {
+    // Retry with ASCII capable keyboard layout.
+    TISInputSourceWrapper currentKeyboardLayout;
+    currentKeyboardLayout.InitByCurrentASCIICapableKeyboardLayout();
+    NS_ENSURE_TRUE(mInputSource != currentKeyboardLayout.mInputSource, 0);
+    keyCode = currentKeyboardLayout.ComputeGeckoKeyCode(aNativeKeyCode, aKbType, aCmdIsPressed);
+    // We've returned 0 for long time if keyCode isn't for an alphabet keys or
+    // a numeric key even in alternative ASCII capable keyboard layout because
+    // we decided that we should avoid setting same keyCode value to 2 or
+    // more keys since active keyboard layout may have a key to input the
+    // punctuation with different key.  However, setting keyCode to 0 makes
+    // some web applications which are aware of neither KeyboardEvent.key nor
+    // KeyboardEvent.code not work with Firefox when user selects non-ASCII
+    // capable keyboard layout such as Russian and Thai.  So, if alternative
+    // ASCII capable keyboard layout has keyCode value for the key, we should
+    // use it.  In other words, this behavior does that non-ASCII capable
+    // keyboard layout overrides some keys' keyCode value only if the key
+    // produces ASCII character by itself or with Shift key.
+    if (keyCode) {
+      return keyCode;
+    }
+  }
+
+  // Otherwise, let's decide keyCode value from the native virtual keycode
+  // value on major keyboard layout.
+  CodeNameIndex code = ComputeGeckoCodeNameIndex(aNativeKeyCode, aKbType);
+  return WidgetKeyboardEvent::GetFallbackKeyCodeOfPunctuationKey(code);
+}
+
+// static
+KeyNameIndex TISInputSourceWrapper::ComputeGeckoKeyNameIndex(UInt32 aNativeKeyCode) {
+  // NOTE:
+  //   When unsupported keys like Convert, Nonconvert of Japanese keyboard is
+  //   pressed:
+  //     on 10.6.x, 'A' key event is fired (and also actually 'a' is inserted).
+  //     on 10.7.x, Nothing happens.
+  //     on 10.8.x, Nothing happens.
+  //     on 10.9.x, FlagsChanged event is fired with keyCode 0xFF.
+  switch (aNativeKeyCode) {
+#define NS_NATIVE_KEY_TO_DOM_KEY_NAME_INDEX(aNativeKey, aKeyNameIndex) \
+  case aNativeKey:                                                     \
+    return aKeyNameIndex;
+
+#include "NativeKeyToDOMKeyName.h"
+
+#undef NS_NATIVE_KEY_TO_DOM_KEY_NAME_INDEX
+
+    default:
+      return KEY_NAME_INDEX_Unidentified;
+  }
+}
+
+// static
+CodeNameIndex TISInputSourceWrapper::ComputeGeckoCodeNameIndex(UInt32 aNativeKeyCode,
+                                                               UInt32 aKbType) {
+  // macOS swaps native key code between Backquote key and IntlBackslash key
+  // only when the keyboard type is ISO.  Let's treat the key code after
+  // swapping them here because Chromium does so only when computing .code
+  // value.
+  if (::KBGetLayoutType(aKbType) == kKeyboardISO) {
+    if (aNativeKeyCode == kVK_ISO_Section) {
+      aNativeKeyCode = kVK_ANSI_Grave;
+    } else if (aNativeKeyCode == kVK_ANSI_Grave) {
+      aNativeKeyCode = kVK_ISO_Section;
+    }
+  }
+
+  switch (aNativeKeyCode) {
+#define NS_NATIVE_KEY_TO_DOM_CODE_NAME_INDEX(aNativeKey, aCodeNameIndex) \
+  case aNativeKey:                                                       \
+    return aCodeNameIndex;
+
+#include "NativeKeyToDOMCodeName.h"
+
+#undef NS_NATIVE_KEY_TO_DOM_CODE_NAME_INDEX
+
+    default:
+      return CODE_NAME_INDEX_UNKNOWN;
+  }
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ *  TextInputHandler implementation (static methods)
+ *
+ ******************************************************************************/
+
+NSUInteger TextInputHandler::sLastModifierState = 0;
+
+// static
+CFArrayRef TextInputHandler::CreateAllKeyboardLayoutList() {
+  const void* keys[] = {kTISPropertyInputSourceType};
+  const void* values[] = {kTISTypeKeyboardLayout};
+  CFDictionaryRef filter = ::CFDictionaryCreate(kCFAllocatorDefault, keys, values, 1, NULL, NULL);
+  NS_ASSERTION(filter, "failed to create the filter");
+  CFArrayRef list = ::TISCreateInputSourceList(filter, true);
+  ::CFRelease(filter);
+  return list;
+}
+
+// static
+void TextInputHandler::DebugPrintAllKeyboardLayouts() {
+  if (MOZ_LOG_TEST(gKeyLog, LogLevel::Info)) {
+    CFArrayRef list = CreateAllKeyboardLayoutList();
+    MOZ_LOG(gKeyLog, LogLevel::Info, ("Keyboard layout configuration:"));
+    CFIndex idx = ::CFArrayGetCount(list);
+    TISInputSourceWrapper tis;
+    for (CFIndex i = 0; i < idx; ++i) {
+      TISInputSourceRef inputSource =
+          static_cast<TISInputSourceRef>(const_cast<void*>(::CFArrayGetValueAtIndex(list, i)));
+      tis.InitByTISInputSourceRef(inputSource);
+      nsAutoString name, isid;
+      tis.GetLocalizedName(name);
+      tis.GetInputSourceID(isid);
+      MOZ_LOG(
+          gKeyLog, LogLevel::Info,
+          ("  %s\t<%s>%s%s\n", NS_ConvertUTF16toUTF8(name).get(), NS_ConvertUTF16toUTF8(isid).get(),
+           tis.IsASCIICapable() ? "" : "\t(Isn't ASCII capable)",
+           tis.IsKeyboardLayout() && tis.GetUCKeyboardLayout() ? "" : "\t(uchr is NOT AVAILABLE)"));
+    }
+    ::CFRelease(list);
+  }
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ *  TextInputHandler implementation
+ *
+ ******************************************************************************/
+
+TextInputHandler::TextInputHandler(nsChildView* aWidget, NSView<mozView>* aNativeView)
+    : IMEInputHandler(aWidget, aNativeView) {
+  EnsureToLogAllKeyboardLayoutsAndIMEs();
+  [mView installTextInputHandler:this];
+}
+
+TextInputHandler::~TextInputHandler() { [mView uninstallTextInputHandler]; }
+
+bool TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent, uint32_t aUniqueId) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (Destroyed()) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info, ("%p TextInputHandler::HandleKeyDownEvent, "
+                                        "widget has been already destroyed",
+                                        this));
+    return false;
+  }
+
+  // Insert empty line to the log for easier to read.
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info, (""));
+  MOZ_LOG_KEY_OR_IME(
+      LogLevel::Info,
+      ("%p TextInputHandler::HandleKeyDownEvent, aNativeEvent=%p, "
+       "type=%s, keyCode=%u (0x%X), modifierFlags=0x%lX, characters=\"%s\", "
+       "charactersIgnoringModifiers=\"%s\"",
+       this, aNativeEvent, GetNativeKeyEventType(aNativeEvent), [aNativeEvent keyCode],
+       [aNativeEvent keyCode], static_cast<unsigned long>([aNativeEvent modifierFlags]),
+       GetCharacters([aNativeEvent characters]),
+       GetCharacters([aNativeEvent charactersIgnoringModifiers])));
+
+  // Except when Command key is pressed, we should hide mouse cursor until
+  // next mousemove.  Handling here means that:
+  // - Don't hide mouse cursor at pressing modifier key
+  // - Hide mouse cursor even if the key event will be handled by IME (i.e.,
+  //   even without dispatching eKeyPress events)
+  // - Hide mouse cursor even when a plugin has focus
+  if (!([aNativeEvent modifierFlags] & NSEventModifierFlagCommand)) {
+    [NSCursor setHiddenUntilMouseMoves:YES];
+  }
+
+  RefPtr<nsChildView> widget(mWidget);
+
+  KeyEventState* currentKeyEvent = PushKeyEvent(aNativeEvent, aUniqueId);
+  AutoKeyEventStateCleaner remover(this);
+
+  RefPtr<TextInputHandler> kungFuDeathGrip(this);
+
+  // When we're already in a composition, we need always to mark the eKeyDown
+  // event as "processed by IME".  So, let's dispatch eKeyDown event here in
+  // such case.
+  if (IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(true)) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                       ("%p   TextInputHandler::HandleKeyDownEvent, eKeyDown caused focus move or "
+                        "something and canceling the composition",
+                        this));
+    return false;
+  }
+
+  // Let Cocoa interpret the key events, caching IsIMEComposing first.
+  bool wasComposing = IsIMEComposing();
+  bool interpretKeyEventsCalled = false;
+  // Don't call interpretKeyEvents when a plugin has focus.  If we call it,
+  // for example, a character is inputted twice during a composition in e10s
+  // mode.
+  if (IsIMEEnabled() || IsASCIICapableOnly()) {
+    MOZ_LOG_KEY_OR_IME(
+        LogLevel::Info,
+        ("%p   TextInputHandler::HandleKeyDownEvent, calling interpretKeyEvents", this));
+    [mView interpretKeyEvents:[NSArray arrayWithObject:aNativeEvent]];
+    interpretKeyEventsCalled = true;
+    MOZ_LOG_KEY_OR_IME(
+        LogLevel::Info,
+        ("%p   TextInputHandler::HandleKeyDownEvent, called interpretKeyEvents", this));
+  }
+
+  if (Destroyed()) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                       ("%p   TextInputHandler::HandleKeyDownEvent, widget was destroyed", this));
+    return currentKeyEvent->IsDefaultPrevented();
+  }
+
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                     ("%p   TextInputHandler::HandleKeyDownEvent, wasComposing=%s, "
+                      "IsIMEComposing()=%s",
+                      this, TrueOrFalse(wasComposing), TrueOrFalse(IsIMEComposing())));
+
+  if (currentKeyEvent->CanDispatchKeyDownEvent()) {
+    // Dispatch eKeyDown event if nobody has dispatched it yet.
+    // NOTE: Although reaching here means that the native keydown event may
+    //       not be handled by IME.  However, we cannot know if it is.
+    //       For example, Japanese IME of Apple shows candidate window for
+    //       typing window.  They, you can switch the sort order with Tab key.
+    //       However, when you choose "Symbol" of the sort order, there may
+    //       be no candiate words.  In this case, IME handles the Tab key
+    //       actually, but we cannot know it because composition string is
+    //       not updated.  So, let's mark eKeyDown event as "processed by IME"
+    //       when there is composition string.  This is same as Chrome.
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                       ("%p   TextInputHandler::HandleKeyDownEvent, trying to dispatch eKeyDown "
+                        "event since it's not yet dispatched",
+                        this));
+    if (!MaybeDispatchCurrentKeydownEvent(IsIMEComposing())) {
+      return true;  // treat the eKeydDown event as consumed.
+    }
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                       ("%p   TextInputHandler::HandleKeyDownEvent, eKeyDown event has been "
+                        "dispatched",
+                        this));
+  }
+
+  if (currentKeyEvent->CanDispatchKeyPressEvent() && !wasComposing && !IsIMEComposing()) {
+    nsresult rv = mDispatcher->BeginNativeInputTransaction();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      MOZ_LOG_KEY_OR_IME(LogLevel::Error, ("%p   TextInputHandler::HandleKeyDownEvent, "
+                                           "FAILED, due to BeginNativeInputTransaction() failure "
+                                           "at dispatching keypress",
+                                           this));
+      return false;
+    }
+
+    WidgetKeyboardEvent keypressEvent(true, eKeyPress, widget);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
+
+    // If we called interpretKeyEvents and this isn't normal character input
+    // then IME probably ate the event for some reason. We do not want to
+    // send a key press event in that case.
+    // TODO:
+    // There are some other cases which IME eats the current event.
+    // 1. If key events were nested during calling interpretKeyEvents, it means
+    //    that IME did something.  Then, we should do nothing.
+    // 2. If one or more commands are called like "deleteBackward", we should
+    //    dispatch keypress event at that time.  Note that the command may have
+    //    been a converted or generated action by IME.  Then, we shouldn't do
+    //    our default action for this key.
+    if (!(interpretKeyEventsCalled && IsNormalCharInputtingEvent(aNativeEvent))) {
+      MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                         ("%p   TextInputHandler::HandleKeyDownEvent, trying to dispatch "
+                          "eKeyPress event since it's not yet dispatched",
+                          this));
+      nsEventStatus status = nsEventStatus_eIgnore;
+      currentKeyEvent->mKeyPressDispatched =
+          mDispatcher->MaybeDispatchKeypressEvents(keypressEvent, status, currentKeyEvent);
+      currentKeyEvent->mKeyPressHandled = (status == nsEventStatus_eConsumeNoDefault);
+      currentKeyEvent->mKeyPressDispatched = true;
+      MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                         ("%p TextInputHandler::HandleKeyDownEvent, eKeyPress event has been "
+                          "dispatched",
+                          this));
+    }
+  }
+
+  // Note: mWidget might have become null here. Don't count on it from here on.
+
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                     ("%p   TextInputHandler::HandleKeyDownEvent, "
+                      "keydown handled=%s, keypress handled=%s, causedOtherKeyEvents=%s, "
+                      "compositionDispatched=%s",
+                      this, TrueOrFalse(currentKeyEvent->mKeyDownHandled),
+                      TrueOrFalse(currentKeyEvent->mKeyPressHandled),
+                      TrueOrFalse(currentKeyEvent->mCausedOtherKeyEvents),
+                      TrueOrFalse(currentKeyEvent->mCompositionDispatched)));
+  // Insert empty line to the log for easier to read.
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info, (""));
+  return currentKeyEvent->IsDefaultPrevented();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+void TextInputHandler::HandleKeyUpEvent(NSEvent* aNativeEvent) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_LOG_KEY_OR_IME(
+      LogLevel::Info,
+      ("%p   TextInputHandler::HandleKeyUpEvent, aNativeEvent=%p, "
+       "type=%s, keyCode=%u (0x%X), modifierFlags=0x%lX, characters=\"%s\", "
+       "charactersIgnoringModifiers=\"%s\", "
+       "IsIMEComposing()=%s",
+       this, aNativeEvent, GetNativeKeyEventType(aNativeEvent), [aNativeEvent keyCode],
+       [aNativeEvent keyCode], static_cast<unsigned long>([aNativeEvent modifierFlags]),
+       GetCharacters([aNativeEvent characters]),
+       GetCharacters([aNativeEvent charactersIgnoringModifiers]), TrueOrFalse(IsIMEComposing())));
+
+  if (Destroyed()) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info, ("%p TextInputHandler::HandleKeyUpEvent, "
+                                        "widget has been already destroyed",
+                                        this));
+    return;
+  }
+
+  nsresult rv = mDispatcher->BeginNativeInputTransaction();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Error, ("%p   TextInputHandler::HandleKeyUpEvent, "
+                                         "FAILED, due to BeginNativeInputTransaction() failure",
+                                         this));
+    return;
+  }
+
+  // Neither Chrome for macOS nor Safari marks "keyup" event as "processed by
+  // IME" even during composition.  So, let's follow this behavior.
+  WidgetKeyboardEvent keyupEvent(true, eKeyUp, mWidget);
+  InitKeyEvent(aNativeEvent, keyupEvent, false);
+
+  KeyEventState currentKeyEvent(aNativeEvent);
+  nsEventStatus status = nsEventStatus_eIgnore;
+  mDispatcher->DispatchKeyboardEvent(eKeyUp, keyupEvent, status, &currentKeyEvent);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void TextInputHandler::HandleFlagsChanged(NSEvent* aNativeEvent) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (Destroyed()) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info, ("%p TextInputHandler::HandleFlagsChanged, "
+                                        "widget has been already destroyed",
+                                        this));
+    return;
+  }
+
+  RefPtr<nsChildView> kungFuDeathGrip(mWidget);
+  mozilla::Unused << kungFuDeathGrip;  // Not referenced within this function
+
+  MOZ_LOG_KEY_OR_IME(
+      LogLevel::Info,
+      ("%p TextInputHandler::HandleFlagsChanged, aNativeEvent=%p, "
+       "type=%s, keyCode=%s (0x%X), modifierFlags=0x%08lX, "
+       "sLastModifierState=0x%08lX, IsIMEComposing()=%s",
+       this, aNativeEvent, GetNativeKeyEventType(aNativeEvent),
+       GetKeyNameForNativeKeyCode([aNativeEvent keyCode]), [aNativeEvent keyCode],
+       static_cast<unsigned long>([aNativeEvent modifierFlags]),
+       static_cast<unsigned long>(sLastModifierState), TrueOrFalse(IsIMEComposing())));
+
+  MOZ_ASSERT([aNativeEvent type] == NSEventTypeFlagsChanged);
+
+  NSUInteger diff = [aNativeEvent modifierFlags] ^ sLastModifierState;
+  // Device dependent flags for left-control key, both shift keys, both command
+  // keys and both option keys have been defined in Next's SDK.  But we
+  // shouldn't use it directly as far as possible since Cocoa SDK doesn't
+  // define them.  Fortunately, we need them only when we dispatch keyup
+  // events.  So, we can usually know the actual relation between keyCode and
+  // device dependent flags.  However, we need to remove following flags first
+  // since the differences don't indicate modifier key state.
+  // NX_STYLUSPROXIMITYMASK: Probably used for pen like device.
+  // kCGEventFlagMaskNonCoalesced (= NX_NONCOALSESCEDMASK): See the document for
+  // Quartz Event Services.
+  diff &= ~(NX_STYLUSPROXIMITYMASK | kCGEventFlagMaskNonCoalesced);
+
+  switch ([aNativeEvent keyCode]) {
+    // CapsLock state and other modifier states are different:
+    // CapsLock state does not revert when the CapsLock key goes up, as the
+    // modifier state does for other modifier keys on key up.
+    case kVK_CapsLock: {
+      // Fire key down event for caps lock.
+      DispatchKeyEventForFlagsChanged(aNativeEvent, true);
+      // XXX should we fire keyup event too? The keyup event for CapsLock key
+      // is never dispatched on Gecko.
+      // XXX WebKit dispatches keydown event when CapsLock is locked, otherwise,
+      // keyup event.  If we do so, we cannot keep the consistency with other
+      // platform's behavior...
+      break;
+    }
+
+    // If the event is caused by pressing or releasing a modifier key, just
+    // dispatch the key's event.
+    case kVK_Shift:
+    case kVK_RightShift:
+    case kVK_Command:
+    case kVK_RightCommand:
+    case kVK_Control:
+    case kVK_RightControl:
+    case kVK_Option:
+    case kVK_RightOption:
+    case kVK_Help: {
+      // We assume that at most one modifier is changed per event if the event
+      // is caused by pressing or releasing a modifier key.
+      bool isKeyDown = ([aNativeEvent modifierFlags] & diff) != 0;
+      DispatchKeyEventForFlagsChanged(aNativeEvent, isKeyDown);
+      // XXX Some applications might send the event with incorrect device-
+      //     dependent flags.
+      if (isKeyDown && ((diff & ~NSEventModifierFlagDeviceIndependentFlagsMask) != 0)) {
+        unsigned short keyCode = [aNativeEvent keyCode];
+        const ModifierKey* modifierKey = GetModifierKeyForDeviceDependentFlags(diff);
+        if (modifierKey && modifierKey->keyCode != keyCode) {
+          // Although, we're not sure the actual cause of this case, the stored
+          // modifier information and the latest key event information may be
+          // mismatched. Then, let's reset the stored information.
+          // NOTE: If this happens, it may fail to handle NSEventTypeFlagsChanged event
+          // in the default case (below). However, it's the rare case handler
+          // and this case occurs rarely. So, we can ignore the edge case bug.
+          NS_WARNING("Resetting stored modifier key information");
+          mModifierKeys.Clear();
+          modifierKey = nullptr;
+        }
+        if (!modifierKey) {
+          mModifierKeys.AppendElement(ModifierKey(diff, keyCode));
+        }
+      }
+      break;
+    }
+
+    // Currently we don't support Fn key since other browsers don't dispatch
+    // events for it and we don't have keyCode for this key.
+    // It should be supported when we implement .key and .char.
+    case kVK_Function:
+      break;
+
+    // If the event is caused by something else than pressing or releasing a
+    // single modifier key (for example by the app having been deactivated
+    // using command-tab), use the modifiers themselves to determine which
+    // key's event to dispatch, and whether it's a keyup or keydown event.
+    // In all cases we assume one or more modifiers are being deactivated
+    // (never activated) -- otherwise we'd have received one or more events
+    // corresponding to a single modifier key being pressed.
+    default: {
+      NSUInteger modifiers = sLastModifierState;
+      AutoTArray<unsigned short, 10> dispatchedKeyCodes;
+      for (int32_t bit = 0; bit < 32; ++bit) {
+        NSUInteger flag = 1 << bit;
+        if (!(diff & flag)) {
+          continue;
+        }
+
+        // Given correct information from the application, a flag change here
+        // will normally be a deactivation (except for some lockable modifiers
+        // such as CapsLock).  But some applications (like VNC) can send an
+        // activating event with a zero keyCode.  So we need to check for that
+        // here.
+        bool dispatchKeyDown = ((flag & [aNativeEvent modifierFlags]) != 0);
+
+        unsigned short keyCode = 0;
+        if (flag & NSEventModifierFlagDeviceIndependentFlagsMask) {
+          switch (flag) {
+            case NSEventModifierFlagCapsLock:
+              keyCode = kVK_CapsLock;
+              dispatchKeyDown = true;
+              break;
+
+            case NSEventModifierFlagNumericPad:
+              // NSEventModifierFlagNumericPad is fired by VNC a lot. But not all of
+              // these events can really be Clear key events, so we just ignore
+              // them.
+              continue;
+
+            case NSEventModifierFlagHelp:
+              keyCode = kVK_Help;
+              break;
+
+            case NSEventModifierFlagFunction:
+              // An NSEventModifierFlagFunction change here will normally be a
+              // deactivation.  But sometimes it will be an activation send (by
+              // VNC for example) with a zero keyCode.
+              continue;
+
+            // These cases (NSEventModifierFlagShift, NSEventModifierFlagControl,
+            // NSEventModifierFlagOption and NSEventModifierFlagCommand) should be handled by the
+            // other branch of the if statement, below (which handles device dependent flags).
+            // However, some applications (like VNC) can send key events without
+            // any device dependent flags, so we handle them here instead.
+            case NSEventModifierFlagShift:
+              keyCode = (modifiers & 0x0004) ? kVK_RightShift : kVK_Shift;
+              break;
+            case NSEventModifierFlagControl:
+              keyCode = (modifiers & 0x2000) ? kVK_RightControl : kVK_Control;
+              break;
+            case NSEventModifierFlagOption:
+              keyCode = (modifiers & 0x0040) ? kVK_RightOption : kVK_Option;
+              break;
+            case NSEventModifierFlagCommand:
+              keyCode = (modifiers & 0x0010) ? kVK_RightCommand : kVK_Command;
+              break;
+
+            default:
+              continue;
+          }
+        } else {
+          const ModifierKey* modifierKey = GetModifierKeyForDeviceDependentFlags(flag);
+          if (!modifierKey) {
+            // See the note above (in the other branch of the if statement)
+            // about the NSEventModifierFlagShift, NSEventModifierFlagControl,
+            // NSEventModifierFlagOption and NSEventModifierFlagCommand cases.
+            continue;
+          }
+          keyCode = modifierKey->keyCode;
+        }
+
+        // Remove flags
+        modifiers &= ~flag;
+        switch (keyCode) {
+          case kVK_Shift: {
+            const ModifierKey* modifierKey = GetModifierKeyForNativeKeyCode(kVK_RightShift);
+            if (!modifierKey || !(modifiers & modifierKey->GetDeviceDependentFlags())) {
+              modifiers &= ~NSEventModifierFlagShift;
+            }
+            break;
+          }
+          case kVK_RightShift: {
+            const ModifierKey* modifierKey = GetModifierKeyForNativeKeyCode(kVK_Shift);
+            if (!modifierKey || !(modifiers & modifierKey->GetDeviceDependentFlags())) {
+              modifiers &= ~NSEventModifierFlagShift;
+            }
+            break;
+          }
+          case kVK_Command: {
+            const ModifierKey* modifierKey = GetModifierKeyForNativeKeyCode(kVK_RightCommand);
+            if (!modifierKey || !(modifiers & modifierKey->GetDeviceDependentFlags())) {
+              modifiers &= ~NSEventModifierFlagCommand;
+            }
+            break;
+          }
+          case kVK_RightCommand: {
+            const ModifierKey* modifierKey = GetModifierKeyForNativeKeyCode(kVK_Command);
+            if (!modifierKey || !(modifiers & modifierKey->GetDeviceDependentFlags())) {
+              modifiers &= ~NSEventModifierFlagCommand;
+            }
+            break;
+          }
+          case kVK_Control: {
+            const ModifierKey* modifierKey = GetModifierKeyForNativeKeyCode(kVK_RightControl);
+            if (!modifierKey || !(modifiers & modifierKey->GetDeviceDependentFlags())) {
+              modifiers &= ~NSEventModifierFlagControl;
+            }
+            break;
+          }
+          case kVK_RightControl: {
+            const ModifierKey* modifierKey = GetModifierKeyForNativeKeyCode(kVK_Control);
+            if (!modifierKey || !(modifiers & modifierKey->GetDeviceDependentFlags())) {
+              modifiers &= ~NSEventModifierFlagControl;
+            }
+            break;
+          }
+          case kVK_Option: {
+            const ModifierKey* modifierKey = GetModifierKeyForNativeKeyCode(kVK_RightOption);
+            if (!modifierKey || !(modifiers & modifierKey->GetDeviceDependentFlags())) {
+              modifiers &= ~NSEventModifierFlagOption;
+            }
+            break;
+          }
+          case kVK_RightOption: {
+            const ModifierKey* modifierKey = GetModifierKeyForNativeKeyCode(kVK_Option);
+            if (!modifierKey || !(modifiers & modifierKey->GetDeviceDependentFlags())) {
+              modifiers &= ~NSEventModifierFlagOption;
+            }
+            break;
+          }
+          case kVK_Help:
+            modifiers &= ~NSEventModifierFlagHelp;
+            break;
+          default:
+            break;
+        }
+
+        // Avoid dispatching same keydown/keyup events twice or more.
+        // We must be able to assume that there is no case to dispatch
+        // both keydown and keyup events with same key code value here.
+        if (dispatchedKeyCodes.Contains(keyCode)) {
+          continue;
+        }
+        dispatchedKeyCodes.AppendElement(keyCode);
+
+        NSEvent* event = [NSEvent keyEventWithType:NSEventTypeFlagsChanged
+                                          location:[aNativeEvent locationInWindow]
+                                     modifierFlags:modifiers
+                                         timestamp:[aNativeEvent timestamp]
+                                      windowNumber:[aNativeEvent windowNumber]
+                                           context:nil
+                                        characters:@""
+                       charactersIgnoringModifiers:@""
+                                         isARepeat:NO
+                                           keyCode:keyCode];
+        DispatchKeyEventForFlagsChanged(event, dispatchKeyDown);
+        if (Destroyed()) {
+          break;
+        }
+
+        // Stop if focus has changed.
+        // Check to see if mView is still the first responder.
+        if (![mView isFirstResponder]) {
+          break;
+        }
+      }
+      break;
+    }
+  }
+
+  // Be aware, the widget may have been destroyed.
+  sLastModifierState = [aNativeEvent modifierFlags];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+const TextInputHandler::ModifierKey* TextInputHandler::GetModifierKeyForNativeKeyCode(
+    unsigned short aKeyCode) const {
+  for (ModifierKeyArray::index_type i = 0; i < mModifierKeys.Length(); ++i) {
+    if (mModifierKeys[i].keyCode == aKeyCode) {
+      return &((ModifierKey&)mModifierKeys[i]);
+    }
+  }
+  return nullptr;
+}
+
+const TextInputHandler::ModifierKey* TextInputHandler::GetModifierKeyForDeviceDependentFlags(
+    NSUInteger aFlags) const {
+  for (ModifierKeyArray::index_type i = 0; i < mModifierKeys.Length(); ++i) {
+    if (mModifierKeys[i].GetDeviceDependentFlags() ==
+        (aFlags & ~NSEventModifierFlagDeviceIndependentFlagsMask)) {
+      return &((ModifierKey&)mModifierKeys[i]);
+    }
+  }
+  return nullptr;
+}
+
+void TextInputHandler::DispatchKeyEventForFlagsChanged(NSEvent* aNativeEvent,
+                                                       bool aDispatchKeyDown) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (Destroyed()) {
+    return;
+  }
+
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                     ("%p TextInputHandler::DispatchKeyEventForFlagsChanged, aNativeEvent=%p, "
+                      "type=%s, keyCode=%s (0x%X), aDispatchKeyDown=%s, IsIMEComposing()=%s",
+                      this, aNativeEvent, GetNativeKeyEventType(aNativeEvent),
+                      GetKeyNameForNativeKeyCode([aNativeEvent keyCode]), [aNativeEvent keyCode],
+                      TrueOrFalse(aDispatchKeyDown), TrueOrFalse(IsIMEComposing())));
+
+  if ([aNativeEvent type] != NSEventTypeFlagsChanged) {
+    return;
+  }
+
+  nsresult rv = mDispatcher->BeginNativeInputTransaction();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Error, ("%p   TextInputHandler::DispatchKeyEventForFlagsChanged, "
+                                         "FAILED, due to BeginNativeInputTransaction() failure",
+                                         this));
+    return;
+  }
+
+  EventMessage message = aDispatchKeyDown ? eKeyDown : eKeyUp;
+
+  // Fire a key event for the modifier key.  Note that even if modifier key
+  // is pressed during composition, we shouldn't mark the keyboard event as
+  // "processed by IME" since neither Chrome for macOS nor Safari does it.
+  WidgetKeyboardEvent keyEvent(true, message, mWidget);
+  InitKeyEvent(aNativeEvent, keyEvent, false);
+
+  KeyEventState currentKeyEvent(aNativeEvent);
+  nsEventStatus status = nsEventStatus_eIgnore;
+  mDispatcher->DispatchKeyboardEvent(message, keyEvent, status, &currentKeyEvent);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void TextInputHandler::InsertText(NSAttributedString* aAttrString, NSRange* aReplacementRange) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (Destroyed()) {
+    return;
+  }
+
+  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
+
+  MOZ_LOG_KEY_OR_IME(
+      LogLevel::Info,
+      ("%p TextInputHandler::InsertText, aAttrString=\"%s\", "
+       "aReplacementRange=%p { location=%lu, length=%lu }, "
+       "IsIMEComposing()=%s, "
+       "keyevent=%p, keydownDispatched=%s, "
+       "keydownHandled=%s, keypressDispatched=%s, "
+       "causedOtherKeyEvents=%s, compositionDispatched=%s",
+       this, GetCharacters([aAttrString string]), aReplacementRange,
+       static_cast<unsigned long>(aReplacementRange ? aReplacementRange->location : 0),
+       static_cast<unsigned long>(aReplacementRange ? aReplacementRange->length : 0),
+       TrueOrFalse(IsIMEComposing()), currentKeyEvent ? currentKeyEvent->mKeyEvent : nullptr,
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyDownDispatched) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyPressDispatched) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mCausedOtherKeyEvents) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mCompositionDispatched) : "N/A"));
+
+  InputContext context = mWidget->GetInputContext();
+  bool isEditable = (context.mIMEState.mEnabled == IMEEnabled::Enabled ||
+                     context.mIMEState.mEnabled == IMEEnabled::Password);
+  NSRange selectedRange = SelectedRange();
+
+  nsAutoString str;
+  nsCocoaUtils::GetStringForNSString([aAttrString string], str);
+
+  AutoInsertStringClearer clearer(currentKeyEvent);
+  if (currentKeyEvent) {
+    currentKeyEvent->mInsertString = &str;
+  }
+
+  if (!IsIMEComposing() && str.IsEmpty()) {
+    // nothing to do if there is no content which can be removed.
+    if (!isEditable) {
+      return;
+    }
+    // If replacement range is specified, we need to remove the range.
+    // Otherwise, we need to remove the selected range if it's not collapsed.
+    if (aReplacementRange && aReplacementRange->location != NSNotFound) {
+      // nothing to do since the range is collapsed.
+      if (aReplacementRange->length == 0) {
+        return;
+      }
+      // If the replacement range is different from current selected range,
+      // select the range.
+      if (!NSEqualRanges(selectedRange, *aReplacementRange)) {
+        NS_ENSURE_TRUE_VOID(SetSelection(*aReplacementRange));
+      }
+      selectedRange = SelectedRange();
+    }
+    NS_ENSURE_TRUE_VOID(selectedRange.location != NSNotFound);
+    if (selectedRange.length == 0) {
+      return;  // nothing to do
+    }
+    // If this is caused by a key input, the keypress event which will be
+    // dispatched later should cause the delete.  Therefore, nothing to do here.
+    // Although, we're not sure if such case is actually possible.
+    if (!currentKeyEvent) {
+      return;
+    }
+
+    // When current keydown event causes this empty text input, let's
+    // dispatch eKeyDown event before any other events.  Note that if we're
+    // in a composition, we've already dispatched eKeyDown event from
+    // TextInputHandler::HandleKeyDownEvent().
+    // XXX Should we mark this eKeyDown event as "processed by IME"?
+    RefPtr<TextInputHandler> kungFuDeathGrip(this);
+    if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
+      MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                         ("%p   TextInputHandler::InsertText, eKeyDown caused focus move or "
+                          "something and canceling the composition",
+                          this));
+      return;
+    }
+
+    // Delete the selected range.
+    WidgetContentCommandEvent deleteCommandEvent(true, eContentCommandDelete, mWidget);
+    DispatchEvent(deleteCommandEvent);
+    NS_ENSURE_TRUE_VOID(deleteCommandEvent.mSucceeded);
+    // Be aware! The widget might be destroyed here.
+    return;
+  }
+
+  bool isReplacingSpecifiedRange = isEditable && aReplacementRange &&
+                                   aReplacementRange->location != NSNotFound &&
+                                   !NSEqualRanges(selectedRange, *aReplacementRange);
+
+  // If this is not caused by pressing a key, there is a composition or
+  // replacing a range which is different from current selection, let's
+  // insert the text as committing a composition.
+  // If InsertText() is called two or more times, we should insert all
+  // text with composition events.
+  // XXX When InsertText() is called multiple times, Chromium dispatches
+  //     only one composition event.  So, we need to store InsertText()
+  //     calls and flush later.
+  if (!currentKeyEvent || currentKeyEvent->mCompositionDispatched || IsIMEComposing() ||
+      isReplacingSpecifiedRange) {
+    InsertTextAsCommittingComposition(aAttrString, aReplacementRange);
+    if (currentKeyEvent) {
+      currentKeyEvent->mCompositionDispatched = true;
+    }
+    return;
+  }
+
+  // Don't let the same event be fired twice when hitting
+  // enter/return for Bug 420502.  However, Korean IME (or some other
+  // simple IME) may work without marked text.  For example, composing
+  // character may be inserted as committed text and it's modified with
+  // aReplacementRange.  When a keydown starts new composition with
+  // committing previous character, InsertText() may be called twice,
+  // one is for committing previous character and then, inserting new
+  // composing character as committed character.  In the latter case,
+  // |CanDispatchKeyPressEvent()| returns true but we need to dispatch
+  // keypress event for the new character.  So, when IME tries to insert
+  // printable characters, we should ignore current key event state even
+  // after the keydown has already caused dispatching composition event.
+  // XXX Anyway, we should sort out around this at fixing bug 1338460.
+  if (currentKeyEvent && !currentKeyEvent->CanDispatchKeyPressEvent() &&
+      (str.IsEmpty() || (str.Length() == 1 && !IsPrintableChar(str[0])))) {
+    return;
+  }
+
+  // This is the normal path to input a character when you press a key.
+  // Let's dispatch eKeyDown event now.
+  RefPtr<TextInputHandler> kungFuDeathGrip(this);
+  if (!MaybeDispatchCurrentKeydownEvent(false)) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                       ("%p   TextInputHandler::InsertText, eKeyDown caused focus move or "
+                        "something and canceling the composition",
+                        this));
+    return;
+  }
+
+  // XXX Shouldn't we hold mDispatcher instead of mWidget?
+  RefPtr<nsChildView> widget(mWidget);
+  nsresult rv = mDispatcher->BeginNativeInputTransaction();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Error, ("%p   TextInputHandler::InsertText, "
+                                         "FAILED, due to BeginNativeInputTransaction() failure",
+                                         this));
+    return;
+  }
+
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                     ("%p   TextInputHandler::InsertText, "
+                      "maybe dispatches eKeyPress event without control, alt and meta modifiers",
+                      this));
+
+  // Dispatch keypress event with char instead of compositionchange event
+  WidgetKeyboardEvent keypressEvent(true, eKeyPress, widget);
+  // XXX Why do we need to dispatch keypress event for not inputting any
+  //     string?  If it wants to delete the specified range, should we
+  //     dispatch an eContentCommandDelete event instead?  Because this
+  //     must not be caused by a key operation, a part of IME's processing.
+
+  // Don't set other modifiers from the current event, because here in
+  // -insertText: they've already been taken into account in creating
+  // the input string.
+
+  if (currentKeyEvent) {
+    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
+  } else {
+    nsCocoaUtils::InitInputEvent(keypressEvent, static_cast<NSEvent*>(nullptr));
+    keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_USE_STRING;
+    keypressEvent.mKeyValue = str;
+    // FYI: TextEventDispatcher will set mKeyCode to 0 for printable key's
+    //      keypress events even if they don't cause inputting non-empty string.
+  }
+
+  // TODO:
+  // If mCurrentKeyEvent.mKeyEvent is null, the text should be inputted as
+  // composition events.
+  nsEventStatus status = nsEventStatus_eIgnore;
+  bool keyPressDispatched =
+      mDispatcher->MaybeDispatchKeypressEvents(keypressEvent, status, currentKeyEvent);
+  bool keyPressHandled = (status == nsEventStatus_eConsumeNoDefault);
+
+  // Note: mWidget might have become null here. Don't count on it from here on.
+
+  if (currentKeyEvent) {
+    currentKeyEvent->mKeyPressHandled = keyPressHandled;
+    currentKeyEvent->mKeyPressDispatched = keyPressDispatched;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+bool TextInputHandler::HandleCommand(Command aCommand) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (Destroyed()) {
+    return false;
+  }
+
+  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
+
+  MOZ_LOG_KEY_OR_IME(
+      LogLevel::Info,
+      ("%p TextInputHandler::HandleCommand, "
+       "aCommand=%s, IsIMEComposing()=%s, "
+       "keyevent=%p, keydownHandled=%s, keypressDispatched=%s, "
+       "causedOtherKeyEvents=%s, compositionDispatched=%s",
+       this, ToChar(aCommand), TrueOrFalse(IsIMEComposing()),
+       currentKeyEvent ? currentKeyEvent->mKeyEvent : nullptr,
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyPressDispatched) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mCausedOtherKeyEvents) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mCompositionDispatched) : "N/A"));
+
+  // The command shouldn't be handled, let's ignore it.
+  if (currentKeyEvent && !currentKeyEvent->CanHandleCommand()) {
+    return false;
+  }
+
+  // When current keydown event causes this command, let's dispatch
+  // eKeyDown event before any other events.  Note that if we're in a
+  // composition, we've already dispatched eKeyDown event from
+  // TextInputHandler::HandleKeyDownEvent().
+  RefPtr<TextInputHandler> kungFuDeathGrip(this);
+  if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                       ("%p   TextInputHandler::SetMarkedText, eKeyDown caused focus move or "
+                        "something and canceling the composition",
+                        this));
+    return false;
+  }
+
+  // If it's in composition, we cannot dispatch keypress event.
+  // Therefore, we should use different approach or give up to handle
+  // the command.
+  if (IsIMEComposing()) {
+    switch (aCommand) {
+      case Command::InsertLineBreak:
+      case Command::InsertParagraph: {
+        // Insert '\n' as committing composition.
+        // Otherwise, we need to dispatch keypress event because HTMLEditor
+        // doesn't treat "\n" in composition string as a line break unless
+        // the whitespace is treated as pre (see bug 1350541).  In strictly
+        // speaking, we should dispatch keypress event as-is if it's handling
+        // NSEventTypeKeyDown event or should insert it with committing composition.
+        NSAttributedString* lineBreaker = [[NSAttributedString alloc] initWithString:@"\n"];
+        InsertTextAsCommittingComposition(lineBreaker, nullptr);
+        if (currentKeyEvent) {
+          currentKeyEvent->mCompositionDispatched = true;
+        }
+        [lineBreaker release];
+        return true;
+      }
+      case Command::DeleteCharBackward:
+      case Command::DeleteCharForward:
+      case Command::DeleteToBeginningOfLine:
+      case Command::DeleteWordBackward:
+      case Command::DeleteWordForward:
+        // Don't remove any contents during composition.
+        return false;
+      case Command::InsertTab:
+      case Command::InsertBacktab:
+        // Don't move focus during composition.
+        return false;
+      case Command::CharNext:
+      case Command::SelectCharNext:
+      case Command::WordNext:
+      case Command::SelectWordNext:
+      case Command::EndLine:
+      case Command::SelectEndLine:
+      case Command::CharPrevious:
+      case Command::SelectCharPrevious:
+      case Command::WordPrevious:
+      case Command::SelectWordPrevious:
+      case Command::BeginLine:
+      case Command::SelectBeginLine:
+      case Command::LinePrevious:
+      case Command::SelectLinePrevious:
+      case Command::MoveTop:
+      case Command::LineNext:
+      case Command::SelectLineNext:
+      case Command::MoveBottom:
+      case Command::SelectBottom:
+      case Command::SelectPageUp:
+      case Command::SelectPageDown:
+      case Command::ScrollBottom:
+      case Command::ScrollTop:
+        // Don't move selection during composition.
+        return false;
+      case Command::CancelOperation:
+      case Command::Complete:
+        // Don't handle Escape key by ourselves during composition.
+        return false;
+      case Command::ScrollPageUp:
+      case Command::ScrollPageDown:
+        // Allow to scroll.
+        break;
+      default:
+        break;
+    }
+  }
+
+  RefPtr<nsChildView> widget(mWidget);
+  nsresult rv = mDispatcher->BeginNativeInputTransaction();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Error, ("%p,   TextInputHandler::HandleCommand, "
+                                         "FAILED, due to BeginNativeInputTransaction() failure",
+                                         this));
+    return false;
+  }
+
+  // TODO: If it's not appropriate keypress but user customized the OS
+  //       settings to do the command with other key, we should just set
+  //       command to the keypress event and it should be handled as
+  //       the key press in editor.
+
+  // If it's handling actual key event and hasn't cause any composition
+  // events nor other key events, we should expose actual modifier state.
+  // Otherwise, we should adjust Control, Option and Command state since
+  // editor may behave differently if some of them are active.
+  bool dispatchFakeKeyPress = !(currentKeyEvent && currentKeyEvent->IsProperKeyEvent(aCommand));
+
+  WidgetKeyboardEvent keydownEvent(true, eKeyDown, widget);
+  WidgetKeyboardEvent keypressEvent(true, eKeyPress, widget);
+  if (!dispatchFakeKeyPress) {
+    // If we're acutally handling a key press, we should dispatch
+    // the keypress event as-is.
+    currentKeyEvent->InitKeyEvent(this, keydownEvent, false);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
+  } else {
+    // Otherwise, we should dispatch "fake" keypress event.
+    // However, for making it possible to compute edit commands, we need to
+    // set current native key event to the fake keyboard event even if it's
+    // not same as what we expect since the native keyboard event caused
+    // this command.
+    NSEvent* keyEvent = currentKeyEvent ? currentKeyEvent->mKeyEvent : nullptr;
+    keydownEvent.mNativeKeyEvent = keypressEvent.mNativeKeyEvent = keyEvent;
+    NS_WARNING_ASSERTION(keypressEvent.mNativeKeyEvent,
+                         "Without native key event, NativeKeyBindings cannot compute aCommand");
+    switch (aCommand) {
+      case Command::InsertLineBreak:
+      case Command::InsertParagraph: {
+        // Although, Shift+Enter and Enter are work differently in HTML
+        // editor, we should expose actual Shift state if it's caused by
+        // Enter key for compatibility with Chromium.  Chromium breaks
+        // line in HTML editor with default pargraph separator when Enter
+        // is pressed, with <br> element when Shift+Enter.  Safari breaks
+        // line in HTML editor with default paragraph separator when
+        // Enter, Shift+Enter or Option+Enter.  So, we should not change
+        // Shift+Enter meaning when there was composition string or not.
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_RETURN;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_Enter;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::InsertLineBreak) {
+          // In default settings, Ctrl + Enter causes insertLineBreak command.
+          // So, let's make Ctrl state active of the keypress event.
+          keypressEvent.mModifiers |= MODIFIER_CONTROL;
+        }
+        break;
+      }
+      case Command::InsertTab:
+      case Command::InsertBacktab:
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_TAB;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_Tab;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::InsertBacktab) {
+          keypressEvent.mModifiers |= MODIFIER_SHIFT;
+        }
+        break;
+      case Command::DeleteCharBackward:
+      case Command::DeleteToBeginningOfLine:
+      case Command::DeleteWordBackward: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_BACK;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_Backspace;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::DeleteToBeginningOfLine) {
+          keypressEvent.mModifiers |= MODIFIER_META;
+        } else if (aCommand == Command::DeleteWordBackward) {
+          keypressEvent.mModifiers |= MODIFIER_ALT;
+        }
+        break;
+      }
+      case Command::DeleteCharForward:
+      case Command::DeleteWordForward: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_DELETE;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_Delete;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::DeleteWordForward) {
+          keypressEvent.mModifiers |= MODIFIER_ALT;
+        }
+        break;
+      }
+      case Command::CharNext:
+      case Command::SelectCharNext:
+      case Command::WordNext:
+      case Command::SelectWordNext:
+      case Command::EndLine:
+      case Command::SelectEndLine: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_RIGHT;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_ArrowRight;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::SelectCharNext || aCommand == Command::SelectWordNext ||
+            aCommand == Command::SelectEndLine) {
+          keypressEvent.mModifiers |= MODIFIER_SHIFT;
+        }
+        if (aCommand == Command::WordNext || aCommand == Command::SelectWordNext) {
+          keypressEvent.mModifiers |= MODIFIER_ALT;
+        }
+        if (aCommand == Command::EndLine || aCommand == Command::SelectEndLine) {
+          keypressEvent.mModifiers |= MODIFIER_META;
+        }
+        break;
+      }
+      case Command::CharPrevious:
+      case Command::SelectCharPrevious:
+      case Command::WordPrevious:
+      case Command::SelectWordPrevious:
+      case Command::BeginLine:
+      case Command::SelectBeginLine: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_LEFT;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_ArrowLeft;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::SelectCharPrevious || aCommand == Command::SelectWordPrevious ||
+            aCommand == Command::SelectBeginLine) {
+          keypressEvent.mModifiers |= MODIFIER_SHIFT;
+        }
+        if (aCommand == Command::WordPrevious || aCommand == Command::SelectWordPrevious) {
+          keypressEvent.mModifiers |= MODIFIER_ALT;
+        }
+        if (aCommand == Command::BeginLine || aCommand == Command::SelectBeginLine) {
+          keypressEvent.mModifiers |= MODIFIER_META;
+        }
+        break;
+      }
+      case Command::LinePrevious:
+      case Command::SelectLinePrevious:
+      case Command::MoveTop:
+      case Command::SelectTop: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_UP;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_ArrowUp;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::SelectLinePrevious || aCommand == Command::SelectTop) {
+          keypressEvent.mModifiers |= MODIFIER_SHIFT;
+        }
+        if (aCommand == Command::MoveTop || aCommand == Command::SelectTop) {
+          keypressEvent.mModifiers |= MODIFIER_META;
+        }
+        break;
+      }
+      case Command::LineNext:
+      case Command::SelectLineNext:
+      case Command::MoveBottom:
+      case Command::SelectBottom: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_DOWN;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_ArrowDown;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::SelectLineNext || aCommand == Command::SelectBottom) {
+          keypressEvent.mModifiers |= MODIFIER_SHIFT;
+        }
+        if (aCommand == Command::MoveBottom || aCommand == Command::SelectBottom) {
+          keypressEvent.mModifiers |= MODIFIER_META;
+        }
+        break;
+      }
+      case Command::ScrollPageUp:
+      case Command::SelectPageUp: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_PAGE_UP;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_PageUp;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::SelectPageUp) {
+          keypressEvent.mModifiers |= MODIFIER_SHIFT;
+        }
+        break;
+      }
+      case Command::ScrollPageDown:
+      case Command::SelectPageDown: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_PAGE_DOWN;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_PageDown;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::SelectPageDown) {
+          keypressEvent.mModifiers |= MODIFIER_SHIFT;
+        }
+        break;
+      }
+      case Command::ScrollBottom:
+      case Command::ScrollTop: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        if (aCommand == Command::ScrollBottom) {
+          keypressEvent.mKeyCode = NS_VK_END;
+          keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_End;
+        } else {
+          keypressEvent.mKeyCode = NS_VK_HOME;
+          keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_Home;
+        }
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        break;
+      }
+      case Command::CancelOperation:
+      case Command::Complete: {
+        nsCocoaUtils::InitInputEvent(keypressEvent, keyEvent);
+        keypressEvent.mKeyCode = NS_VK_ESCAPE;
+        keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_Escape;
+        keypressEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+        if (aCommand == Command::Complete) {
+          keypressEvent.mModifiers |= MODIFIER_ALT;
+        }
+        break;
+      }
+      default:
+        return false;
+    }
+
+    nsCocoaUtils::InitInputEvent(keydownEvent, keyEvent);
+    keydownEvent.mKeyCode = keypressEvent.mKeyCode;
+    keydownEvent.mKeyNameIndex = keypressEvent.mKeyNameIndex;
+    keydownEvent.mModifiers = keypressEvent.mModifiers;
+  }
+
+  // We've stopped dispatching "keypress" events of non-printable keys on
+  // the web.  Therefore, we need to dispatch eKeyDown event here for web
+  // apps.  This is non-standard behavior if we've already dispatched a
+  // "keydown" event.  However, Chrome also dispatches such fake "keydown"
+  // (and "keypress") event for making same behavior as Safari.
+  nsEventStatus status = nsEventStatus_eIgnore;
+  if (mDispatcher->DispatchKeyboardEvent(eKeyDown, keydownEvent, status, nullptr)) {
+    bool keydownHandled = status == nsEventStatus_eConsumeNoDefault;
+    if (currentKeyEvent) {
+      currentKeyEvent->mKeyDownDispatched = true;
+      currentKeyEvent->mKeyDownHandled |= keydownHandled;
+    }
+    if (keydownHandled) {
+      // Don't dispatch eKeyPress event if preceding eKeyDown event is
+      // consumed for conforming to UI Events.
+      // XXX Perhaps, we should ignore previous eKeyDown event result
+      //     even if we've already dispatched because it may notify web apps
+      //     of different key information, e.g., it's handled by IME, but
+      //     web apps want to handle only this key.
+      return true;
+    }
+  }
+
+  bool keyPressDispatched =
+      mDispatcher->MaybeDispatchKeypressEvents(keypressEvent, status, currentKeyEvent);
+  bool keyPressHandled = (status == nsEventStatus_eConsumeNoDefault);
+
+  // NOTE: mWidget might have become null here.
+
+  if (keyPressDispatched) {
+    // Record the keypress event state only when it dispatched actual Enter
+    // keypress event because in other cases, the keypress event just a
+    // messenger.  E.g., if it's caused by different key, keypress event for
+    // the actual key should be dispatched.
+    if (!dispatchFakeKeyPress && currentKeyEvent) {
+      currentKeyEvent->mKeyPressHandled = keyPressHandled;
+      currentKeyEvent->mKeyPressDispatched = keyPressDispatched;
+    }
+    return true;
+  }
+
+  // If keypress event isn't dispatched as expected, we should fallback to
+  // using composition events.
+  if (aCommand == Command::InsertLineBreak || aCommand == Command::InsertParagraph) {
+    NSAttributedString* lineBreaker = [[NSAttributedString alloc] initWithString:@"\n"];
+    InsertTextAsCommittingComposition(lineBreaker, nullptr);
+    if (currentKeyEvent) {
+      currentKeyEvent->mCompositionDispatched = true;
+    }
+    [lineBreaker release];
+    return true;
+  }
+
+  return false;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+bool TextInputHandler::DoCommandBySelector(const char* aSelector) {
+  RefPtr<nsChildView> widget(mWidget);
+
+  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
+
+  MOZ_LOG_KEY_OR_IME(
+      LogLevel::Info,
+      ("%p TextInputHandler::DoCommandBySelector, aSelector=\"%s\", "
+       "Destroyed()=%s, keydownDispatched=%s, keydownHandled=%s, "
+       "keypressDispatched=%s, keypressHandled=%s, causedOtherKeyEvents=%s",
+       this, aSelector ? aSelector : "", TrueOrFalse(Destroyed()),
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyDownDispatched) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyPressDispatched) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyPressHandled) : "N/A",
+       currentKeyEvent ? TrueOrFalse(currentKeyEvent->mCausedOtherKeyEvents) : "N/A"));
+
+  // If the command isn't caused by key operation, the command should
+  // be handled in the super class of the caller.
+  if (!currentKeyEvent) {
+    return Destroyed();
+  }
+
+  // When current keydown event causes this command, let's dispatch
+  // eKeyDown event before any other events.  Note that if we're in a
+  // composition, we've already dispatched eKeyDown event from
+  // TextInputHandler::HandleKeyDownEvent().
+  RefPtr<TextInputHandler> kungFuDeathGrip(this);
+  if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
+    MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                       ("%p   TextInputHandler::SetMarkedText, eKeyDown caused focus move or "
+                        "something and canceling the composition",
+                        this));
+    return true;
+  }
+
+  // If the key operation causes this command, should dispatch a keypress
+  // event.
+  // XXX This must be worng.  Even if this command is caused by the key
+  //     operation, its our default action can be different from the
+  //     command.  So, in this case, we should dispatch a keypress event
+  //     which have the command and editor should handle it.
+  if (currentKeyEvent->CanDispatchKeyPressEvent()) {
+    nsresult rv = mDispatcher->BeginNativeInputTransaction();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      MOZ_LOG_KEY_OR_IME(LogLevel::Error, ("%p   TextInputHandler::DoCommandBySelector, "
+                                           "FAILED, due to BeginNativeInputTransaction() failure "
+                                           "at dispatching keypress",
+                                           this));
+      return Destroyed();
+    }
+
+    WidgetKeyboardEvent keypressEvent(true, eKeyPress, widget);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
+
+    nsEventStatus status = nsEventStatus_eIgnore;
+    currentKeyEvent->mKeyPressDispatched =
+        mDispatcher->MaybeDispatchKeypressEvents(keypressEvent, status, currentKeyEvent);
+    currentKeyEvent->mKeyPressHandled = (status == nsEventStatus_eConsumeNoDefault);
+    MOZ_LOG_KEY_OR_IME(
+        LogLevel::Info,
+        ("%p   TextInputHandler::DoCommandBySelector, keypress event "
+         "dispatched, Destroyed()=%s, keypressHandled=%s",
+         this, TrueOrFalse(Destroyed()), TrueOrFalse(currentKeyEvent->mKeyPressHandled)));
+    // This command is now dispatched with keypress event.
+    // So, this shouldn't be handled by nobody anymore.
+    return true;
+  }
+
+  // If the key operation didn't cause keypress event or caused keypress event
+  // but not prevented its default, we need to honor the command.  For example,
+  // Korean IME sends "insertNewline:" when committing existing composition
+  // with Enter key press.  In such case, the key operation has been consumed
+  // by the committing composition but we still need to handle the command.
+  if (Destroyed() || !currentKeyEvent->CanHandleCommand()) {
+    return true;
+  }
+
+  // cancelOperation: command is fired after Escape or Command + Period.
+  // However, if ChildView implements cancelOperation:, calling
+  // [[ChildView super] doCommandBySelector:aSelector] when Command + Period
+  // causes only a call of [ChildView cancelOperation:sender].  I.e.,
+  // [ChildView keyDown:theEvent] becomes to be never called.  For avoiding
+  // this odd behavior, we need to handle the command before super class of
+  // ChildView only when current key event is proper event to fire Escape
+  // keypress event.
+  if (!strcmp(aSelector, "cancelOperation:") && currentKeyEvent &&
+      currentKeyEvent->IsProperKeyEvent(Command::CancelOperation)) {
+    return HandleCommand(Command::CancelOperation);
+  }
+
+  // Otherwise, we've not handled the command yet.  Propagate the command
+  // to the super class of ChildView.
+  return false;
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ *  IMEInputHandler implementation (static methods)
+ *
+ ******************************************************************************/
+
+bool IMEInputHandler::sStaticMembersInitialized = false;
+bool IMEInputHandler::sCachedIsForRTLLangage = false;
+CFStringRef IMEInputHandler::sLatestIMEOpenedModeInputSourceID = nullptr;
+IMEInputHandler* IMEInputHandler::sFocusedIMEHandler = nullptr;
+
+// static
+void IMEInputHandler::InitStaticMembers() {
+  if (sStaticMembersInitialized) return;
+  sStaticMembersInitialized = true;
+  // We need to check the keyboard layout changes on all applications.
+  CFNotificationCenterRef center = ::CFNotificationCenterGetDistributedCenter();
+  // XXX Don't we need to remove the observer at shut down?
+  // Mac Dev Center's document doesn't say how to remove the observer if
+  // the second parameter is NULL.
+  ::CFNotificationCenterAddObserver(center, NULL, OnCurrentTextInputSourceChange,
+                                    kTISNotifySelectedKeyboardInputSourceChanged, NULL,
+                                    CFNotificationSuspensionBehaviorDeliverImmediately);
+  // Initiailize with the current keyboard layout
+  OnCurrentTextInputSourceChange(NULL, NULL, kTISNotifySelectedKeyboardInputSourceChanged, NULL,
+                                 NULL);
+}
+
+// static
+void IMEInputHandler::OnCurrentTextInputSourceChange(CFNotificationCenterRef aCenter,
+                                                     void* aObserver, CFStringRef aName,
+                                                     const void* aObject,
+                                                     CFDictionaryRef aUserInfo) {
+  // Cache the latest IME opened mode to sLatestIMEOpenedModeInputSourceID.
+  TISInputSourceWrapper tis;
+  tis.InitByCurrentInputSource();
+  if (tis.IsOpenedIMEMode()) {
+    tis.GetInputSourceID(sLatestIMEOpenedModeInputSourceID);
+    // Collect Input Source ID which includes input mode in most cases.
+    // However, if it's Japanese IME, collecting input mode (e.g.,
+    // "HiraganaKotei") does not make sense because in most languages,
+    // input mode changes "how to input", but Japanese IME changes
+    // "which type of characters to input".  I.e., only Japanese IME
+    // users may use multiple input modes.  If we'd collect each type of
+    // input mode of Japanese IMEs, it'd be difficult to count actual
+    // users of each IME from the result.  So, only when active IME is
+    // a Japanese IME, we should use Bundle ID which does not contain
+    // input mode instead.
+    nsAutoString key;
+    if (tis.IsForJapaneseLanguage()) {
+      tis.GetBundleID(key);
+    } else {
+      tis.GetInputSourceID(key);
+    }
+    // 72 is kMaximumKeyStringLength in TelemetryScalar.cpp
+    if (key.Length() > 72) {
+      if (NS_IS_SURROGATE_PAIR(key[72 - 2], key[72 - 1])) {
+        key.Truncate(72 - 2);
+      } else {
+        key.Truncate(72 - 1);
+      }
+      // U+2026 is "..."
+      key.Append(char16_t(0x2026));
+    }
+    Telemetry::ScalarSet(Telemetry::ScalarID::WIDGET_IME_NAME_ON_MAC, key, true);
+  }
+
+  if (MOZ_LOG_TEST(gIMELog, LogLevel::Info)) {
+    static CFStringRef sLastTIS = nullptr;
+    CFStringRef newTIS;
+    tis.GetInputSourceID(newTIS);
+    if (!sLastTIS || ::CFStringCompare(sLastTIS, newTIS, 0) != kCFCompareEqualTo) {
+      TISInputSourceWrapper tis1, tis2, tis3, tis4, tis5;
+      tis1.InitByCurrentKeyboardLayout();
+      tis2.InitByCurrentASCIICapableInputSource();
+      tis3.InitByCurrentASCIICapableKeyboardLayout();
+      tis4.InitByCurrentInputMethodKeyboardLayoutOverride();
+      tis5.InitByTISInputSourceRef(tis.GetKeyboardLayoutInputSource());
+      CFStringRef is0 = nullptr, is1 = nullptr, is2 = nullptr, is3 = nullptr, is4 = nullptr,
+                  is5 = nullptr, type0 = nullptr, lang0 = nullptr, bundleID0 = nullptr;
+      tis.GetInputSourceID(is0);
+      tis1.GetInputSourceID(is1);
+      tis2.GetInputSourceID(is2);
+      tis3.GetInputSourceID(is3);
+      tis4.GetInputSourceID(is4);
+      tis5.GetInputSourceID(is5);
+      tis.GetInputSourceType(type0);
+      tis.GetPrimaryLanguage(lang0);
+      tis.GetBundleID(bundleID0);
+
+      MOZ_LOG(gIMELog, LogLevel::Info,
+              ("IMEInputHandler::OnCurrentTextInputSourceChange,\n"
+               "  Current Input Source is changed to:\n"
+               "    currentInputContext=%p\n"
+               "    %s\n"
+               "      type=%s %s\n"
+               "      overridden keyboard layout=%s\n"
+               "      used keyboard layout for translation=%s\n"
+               "    primary language=%s\n"
+               "    bundle ID=%s\n"
+               "    current ASCII capable Input Source=%s\n"
+               "    current Keyboard Layout=%s\n"
+               "    current ASCII capable Keyboard Layout=%s",
+               [NSTextInputContext currentInputContext], GetCharacters(is0), GetCharacters(type0),
+               tis.IsASCIICapable() ? "- ASCII capable " : "", GetCharacters(is4),
+               GetCharacters(is5), GetCharacters(lang0), GetCharacters(bundleID0),
+               GetCharacters(is2), GetCharacters(is1), GetCharacters(is3)));
+    }
+    sLastTIS = newTIS;
+  }
+
+  /**
+   * When the direction is changed, all the children are notified.
+   * No need to treat the initial case separately because it is covered
+   * by the general case (sCachedIsForRTLLangage is initially false)
+   */
+  if (sCachedIsForRTLLangage != tis.IsForRTLLanguage()) {
+    WidgetUtils::SendBidiKeyboardInfoToContent();
+    sCachedIsForRTLLangage = tis.IsForRTLLanguage();
+  }
+}
+
+// static
+void IMEInputHandler::FlushPendingMethods(nsITimer* aTimer, void* aClosure) {
+  NS_ASSERTION(aClosure, "aClosure is null");
+  static_cast<IMEInputHandler*>(aClosure)->ExecutePendingMethods();
+}
+
+// static
+CFArrayRef IMEInputHandler::CreateAllIMEModeList() {
+  const void* keys[] = {kTISPropertyInputSourceType};
+  const void* values[] = {kTISTypeKeyboardInputMode};
+  CFDictionaryRef filter = ::CFDictionaryCreate(kCFAllocatorDefault, keys, values, 1, NULL, NULL);
+  NS_ASSERTION(filter, "failed to create the filter");
+  CFArrayRef list = ::TISCreateInputSourceList(filter, true);
+  ::CFRelease(filter);
+  return list;
+}
+
+// static
+void IMEInputHandler::DebugPrintAllIMEModes() {
+  if (MOZ_LOG_TEST(gIMELog, LogLevel::Info)) {
+    CFArrayRef list = CreateAllIMEModeList();
+    MOZ_LOG(gIMELog, LogLevel::Info, ("IME mode configuration:"));
+    CFIndex idx = ::CFArrayGetCount(list);
+    TISInputSourceWrapper tis;
+    for (CFIndex i = 0; i < idx; ++i) {
+      TISInputSourceRef inputSource =
+          static_cast<TISInputSourceRef>(const_cast<void*>(::CFArrayGetValueAtIndex(list, i)));
+      tis.InitByTISInputSourceRef(inputSource);
+      nsAutoString name, isid, bundleID;
+      tis.GetLocalizedName(name);
+      tis.GetInputSourceID(isid);
+      tis.GetBundleID(bundleID);
+      MOZ_LOG(gIMELog, LogLevel::Info,
+              ("  %s\t<%s>%s%s\n"
+               "    bundled in <%s>\n",
+               NS_ConvertUTF16toUTF8(name).get(), NS_ConvertUTF16toUTF8(isid).get(),
+               tis.IsASCIICapable() ? "" : "\t(Isn't ASCII capable)",
+               tis.IsEnabled() ? "" : "\t(Isn't Enabled)", NS_ConvertUTF16toUTF8(bundleID).get()));
+    }
+    ::CFRelease(list);
+  }
+}
+
+// static
+TSMDocumentID IMEInputHandler::GetCurrentTSMDocumentID() {
+  // At least on Mac OS X 10.6.x and 10.7.x, ::TSMGetActiveDocument() has a bug.
+  // The result of ::TSMGetActiveDocument() isn't modified for new active text
+  // input context until [NSTextInputContext currentInputContext] is called.
+  // Therefore, we need to call it here.
+  [NSTextInputContext currentInputContext];
+  return ::TSMGetActiveDocument();
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ *  IMEInputHandler implementation #1
+ *    The methods are releated to the pending methods.  Some jobs should be
+ *    run after the stack is finished, e.g, some methods cannot run the jobs
+ *    during processing the focus event.  And also some other jobs should be
+ *    run at the next focus event is processed.
+ *    The pending methods are recorded in mPendingMethods.  They are executed
+ *    by ExecutePendingMethods via FlushPendingMethods.
+ *
+ ******************************************************************************/
+
+nsresult IMEInputHandler::NotifyIME(TextEventDispatcher* aTextEventDispatcher,
+                                    const IMENotification& aNotification) {
+  switch (aNotification.mMessage) {
+    case REQUEST_TO_COMMIT_COMPOSITION:
+      CommitIMEComposition();
+      return NS_OK;
+    case REQUEST_TO_CANCEL_COMPOSITION:
+      CancelIMEComposition();
+      return NS_OK;
+    case NOTIFY_IME_OF_FOCUS:
+      if (IsFocused()) {
+        nsIWidget* widget = aTextEventDispatcher->GetWidget();
+        if (widget && widget->GetInputContext().IsPasswordEditor()) {
+          EnableSecureEventInput();
+        } else {
+          EnsureSecureEventInputDisabled();
+        }
+      }
+      OnFocusChangeInGecko(true);
+      return NS_OK;
+    case NOTIFY_IME_OF_BLUR:
+      OnFocusChangeInGecko(false);
+      return NS_OK;
+    case NOTIFY_IME_OF_SELECTION_CHANGE:
+      OnSelectionChange(aNotification);
+      return NS_OK;
+    case NOTIFY_IME_OF_POSITION_CHANGE:
+      OnLayoutChange();
+      return NS_OK;
+    default:
+      return NS_ERROR_NOT_IMPLEMENTED;
+  }
+}
+
+NS_IMETHODIMP_(IMENotificationRequests)
+IMEInputHandler::GetIMENotificationRequests() {
+  // XXX Shouldn't we move floating window which shows composition string
+  //     when plugin has focus and its parent is scrolled or the window is
+  //     moved?
+  return IMENotificationRequests();
+}
+
+NS_IMETHODIMP_(void)
+IMEInputHandler::OnRemovedFrom(TextEventDispatcher* aTextEventDispatcher) {
+  // XXX When input transaction is being stolen by add-on, what should we do?
+}
+
+NS_IMETHODIMP_(void)
+IMEInputHandler::WillDispatchKeyboardEvent(TextEventDispatcher* aTextEventDispatcher,
+                                           WidgetKeyboardEvent& aKeyboardEvent,
+                                           uint32_t aIndexOfKeypress, void* aData) {
+  // If the keyboard event is not caused by a native key event, we can do
+  // nothing here.
+  if (!aData) {
+    return;
+  }
+
+  KeyEventState* currentKeyEvent = static_cast<KeyEventState*>(aData);
+  NSEvent* nativeEvent = currentKeyEvent->mKeyEvent;
+  nsAString* insertString = currentKeyEvent->mInsertString;
+  if (aKeyboardEvent.mMessage == eKeyPress && aIndexOfKeypress == 0 &&
+      (!insertString || insertString->IsEmpty())) {
+    // Inform the child process that this is an event that we want a reply
+    // from.
+    // XXX This should be called only when the target is a remote process.
+    //     However, it's difficult to check it under widget/.
+    //     So, let's do this here for now, then,
+    //     EventStateManager::PreHandleEvent() will reset the flags if
+    //     the event target isn't in remote process.
+    aKeyboardEvent.MarkAsWaitingReplyFromRemoteProcess();
+  }
+  if (KeyboardLayoutOverrideRef().mOverrideEnabled) {
+    TISInputSourceWrapper tis;
+    tis.InitByLayoutID(KeyboardLayoutOverrideRef().mKeyboardLayout, true);
+    tis.WillDispatchKeyboardEvent(nativeEvent, insertString, aIndexOfKeypress, aKeyboardEvent);
+  } else {
+    TISInputSourceWrapper::CurrentInputSource().WillDispatchKeyboardEvent(
+        nativeEvent, insertString, aIndexOfKeypress, aKeyboardEvent);
+  }
+
+  // Remove basic modifiers from keypress event because if they are included
+  // but this causes inputting text, since TextEditor won't handle eKeyPress
+  // events whose ctrlKey, altKey or metaKey is true as text input.
+  // Note that this hack should be used only when an editor has focus because
+  // this is a hack for TextEditor and modifier key information may be
+  // important for current web app.
+  if (IsEditableContent() && insertString && aKeyboardEvent.mMessage == eKeyPress &&
+      aKeyboardEvent.mCharCode) {
+    aKeyboardEvent.mModifiers &= ~(MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META);
+  }
+}
+
+void IMEInputHandler::NotifyIMEOfFocusChangeInGecko() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::NotifyIMEOfFocusChangeInGecko, "
+           "Destroyed()=%s, IsFocused()=%s, inputContext=%p",
+           this, TrueOrFalse(Destroyed()), TrueOrFalse(IsFocused()),
+           mView ? [mView inputContext] : nullptr));
+
+  if (Destroyed()) {
+    return;
+  }
+
+  if (!IsFocused()) {
+    // retry at next focus event
+    mPendingMethods |= kNotifyIMEOfFocusChangeInGecko;
+    return;
+  }
+
+  MOZ_ASSERT(mView);
+  NSTextInputContext* inputContext = [mView inputContext];
+  NS_ENSURE_TRUE_VOID(inputContext);
+
+  // When an <input> element on a XUL <panel> element gets focus from an <input>
+  // element on the opener window of the <panel> element, the owner window
+  // still has native focus.  Therefore, IMEs may store the opener window's
+  // level at this time because they don't know the actual focus is moved to
+  // different window.  If IMEs try to get the newest window level after the
+  // focus change, we return the window level of the XUL <panel>'s widget.
+  // Therefore, let's emulate the native focus change.  Then, IMEs can refresh
+  // the stored window level.
+  [inputContext deactivate];
+  [inputContext activate];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void IMEInputHandler::SyncASCIICapableOnly() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::SyncASCIICapableOnly, "
+           "Destroyed()=%s, IsFocused()=%s, mIsASCIICapableOnly=%s, "
+           "GetCurrentTSMDocumentID()=%p",
+           this, TrueOrFalse(Destroyed()), TrueOrFalse(IsFocused()),
+           TrueOrFalse(mIsASCIICapableOnly), GetCurrentTSMDocumentID()));
+
+  if (Destroyed()) {
+    return;
+  }
+
+  if (!IsFocused()) {
+    // retry at next focus event
+    mPendingMethods |= kSyncASCIICapableOnly;
+    return;
+  }
+
+  TSMDocumentID doc = GetCurrentTSMDocumentID();
+  if (!doc) {
+    // retry
+    mPendingMethods |= kSyncASCIICapableOnly;
+    NS_WARNING("Application is active but there is no active document");
+    ResetTimer();
+    return;
+  }
+
+  if (mIsASCIICapableOnly) {
+    CFArrayRef ASCIICapableTISList = ::TISCreateASCIICapableInputSourceList();
+    ::TSMSetDocumentProperty(doc, kTSMDocumentEnabledInputSourcesPropertyTag, sizeof(CFArrayRef),
+                             &ASCIICapableTISList);
+    ::CFRelease(ASCIICapableTISList);
+  } else {
+    ::TSMRemoveDocumentProperty(doc, kTSMDocumentEnabledInputSourcesPropertyTag);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void IMEInputHandler::ResetTimer() {
+  NS_ASSERTION(mPendingMethods != 0, "There are not pending methods, why this is called?");
+  if (mTimer) {
+    mTimer->Cancel();
+  } else {
+    mTimer = NS_NewTimer();
+    NS_ENSURE_TRUE(mTimer, );
+  }
+  mTimer->InitWithNamedFuncCallback(FlushPendingMethods, this, 0, nsITimer::TYPE_ONE_SHOT,
+                                    "IMEInputHandler::FlushPendingMethods");
+}
+
+void IMEInputHandler::ExecutePendingMethods() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mTimer) {
+    mTimer->Cancel();
+    mTimer = nullptr;
+  }
+
+  if (![[NSApplication sharedApplication] isActive]) {
+    // If we're not active, we should retry at focus event
+    return;
+  }
+
+  uint32_t pendingMethods = mPendingMethods;
+  // First, reset the pending method flags because if each methods cannot
+  // run now, they can reentry to the pending flags by theirselves.
+  mPendingMethods = 0;
+
+  if (pendingMethods & kSyncASCIICapableOnly) SyncASCIICapableOnly();
+  if (pendingMethods & kNotifyIMEOfFocusChangeInGecko) {
+    NotifyIMEOfFocusChangeInGecko();
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ * IMEInputHandler implementation (native event handlers)
+ *
+ ******************************************************************************/
+
+TextRangeType IMEInputHandler::ConvertToTextRangeType(uint32_t aUnderlineStyle,
+                                                      NSRange& aSelectedRange) {
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::ConvertToTextRangeType, "
+           "aUnderlineStyle=%u, aSelectedRange.length=%lu,",
+           this, aUnderlineStyle, static_cast<unsigned long>(aSelectedRange.length)));
+
+  // We assume that aUnderlineStyle is NSUnderlineStyleSingle or
+  // NSUnderlineStyleThick.  NSUnderlineStyleThick should indicate a selected
+  // clause.  Otherwise, should indicate non-selected clause.
+
+  if (aSelectedRange.length == 0) {
+    switch (aUnderlineStyle) {
+      case NSUnderlineStyleSingle:
+        return TextRangeType::eRawClause;
+      case NSUnderlineStyleThick:
+        return TextRangeType::eSelectedRawClause;
+      default:
+        NS_WARNING("Unexpected line style");
+        return TextRangeType::eSelectedRawClause;
+    }
+  }
+
+  switch (aUnderlineStyle) {
+    case NSUnderlineStyleSingle:
+      return TextRangeType::eConvertedClause;
+    case NSUnderlineStyleThick:
+      return TextRangeType::eSelectedClause;
+    default:
+      NS_WARNING("Unexpected line style");
+      return TextRangeType::eSelectedClause;
+  }
+}
+
+uint32_t IMEInputHandler::GetRangeCount(NSAttributedString* aAttrString) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // Iterate through aAttrString for the NSUnderlineStyleAttributeName and
+  // count the different segments adjusting limitRange as we go.
+  uint32_t count = 0;
+  NSRange effectiveRange;
+  NSRange limitRange = NSMakeRange(0, [aAttrString length]);
+  while (limitRange.length > 0) {
+    [aAttrString attribute:NSUnderlineStyleAttributeName
+                      atIndex:limitRange.location
+        longestEffectiveRange:&effectiveRange
+                      inRange:limitRange];
+    limitRange = NSMakeRange(NSMaxRange(effectiveRange),
+                             NSMaxRange(limitRange) - NSMaxRange(effectiveRange));
+    count++;
+  }
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::GetRangeCount, aAttrString=\"%s\", count=%u", this,
+           GetCharacters([aAttrString string]), count));
+
+  return count;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(0);
+}
+
+already_AddRefed<mozilla::TextRangeArray> IMEInputHandler::CreateTextRangeArray(
+    NSAttributedString* aAttrString, NSRange& aSelectedRange) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  RefPtr<mozilla::TextRangeArray> textRangeArray = new mozilla::TextRangeArray();
+
+  // Note that we shouldn't append ranges when composition string
+  // is empty because it may cause TextComposition confused.
+  if (![aAttrString length]) {
+    return textRangeArray.forget();
+  }
+
+  // Convert the Cocoa range into the TextRange Array used in Gecko.
+  // Iterate through the attributed string and map the underline attribute to
+  // Gecko IME textrange attributes.  We may need to change the code here if
+  // we change the implementation of validAttributesForMarkedText.
+  NSRange limitRange = NSMakeRange(0, [aAttrString length]);
+  uint32_t rangeCount = GetRangeCount(aAttrString);
+  for (uint32_t i = 0; i < rangeCount && limitRange.length > 0; i++) {
+    NSRange effectiveRange;
+    id attributeValue = [aAttrString attribute:NSUnderlineStyleAttributeName
+                                       atIndex:limitRange.location
+                         longestEffectiveRange:&effectiveRange
+                                       inRange:limitRange];
+
+    TextRange range;
+    range.mStartOffset = effectiveRange.location;
+    range.mEndOffset = NSMaxRange(effectiveRange);
+    range.mRangeType = ConvertToTextRangeType([attributeValue intValue], aSelectedRange);
+    textRangeArray->AppendElement(range);
+
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::CreateTextRangeArray, "
+             "range={ mStartOffset=%u, mEndOffset=%u, mRangeType=%s }",
+             this, range.mStartOffset, range.mEndOffset, ToChar(range.mRangeType)));
+
+    limitRange = NSMakeRange(NSMaxRange(effectiveRange),
+                             NSMaxRange(limitRange) - NSMaxRange(effectiveRange));
+  }
+
+  // Get current caret position.
+  TextRange range;
+  range.mStartOffset = aSelectedRange.location + aSelectedRange.length;
+  range.mEndOffset = range.mStartOffset;
+  range.mRangeType = TextRangeType::eCaret;
+  textRangeArray->AppendElement(range);
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::CreateTextRangeArray, "
+           "range={ mStartOffset=%u, mEndOffset=%u, mRangeType=%s }",
+           this, range.mStartOffset, range.mEndOffset, ToChar(range.mRangeType)));
+
+  return textRangeArray.forget();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nullptr);
+}
+
+bool IMEInputHandler::DispatchCompositionStartEvent() {
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::DispatchCompositionStartEvent, "
+           "mSelectedRange={ location=%lu, length=%lu }, Destroyed()=%s, "
+           "mView=%p, mWidget=%p, inputContext=%p, mIsIMEComposing=%s",
+           this, static_cast<unsigned long>(SelectedRange().location),
+           static_cast<unsigned long>(mSelectedRange.length), TrueOrFalse(Destroyed()), mView,
+           mWidget, mView ? [mView inputContext] : nullptr, TrueOrFalse(mIsIMEComposing)));
+
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
+  nsresult rv = mDispatcher->BeginNativeInputTransaction();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG(gIMELog, LogLevel::Error,
+            ("%p   IMEInputHandler::DispatchCompositionStartEvent, "
+             "FAILED, due to BeginNativeInputTransaction() failure",
+             this));
+    return false;
+  }
+
+  NS_ASSERTION(!mIsIMEComposing, "There is a composition already");
+  mIsIMEComposing = true;
+  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
+  mIsDeadKeyComposing =
+      currentKeyEvent && currentKeyEvent->mKeyEvent &&
+      TISInputSourceWrapper::CurrentInputSource().IsDeadKey(currentKeyEvent->mKeyEvent);
+
+  nsEventStatus status;
+  rv = mDispatcher->StartComposition(status);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG(gIMELog, LogLevel::Error,
+            ("%p   IMEInputHandler::DispatchCompositionStartEvent, "
+             "FAILED, due to StartComposition() failure",
+             this));
+    return false;
+  }
+
+  if (Destroyed()) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::DispatchCompositionStartEvent, "
+             "destroyed by compositionstart event",
+             this));
+    return false;
+  }
+
+  // FYI: compositionstart may cause committing composition by the webapp.
+  if (!mIsIMEComposing) {
+    return false;
+  }
+
+  // FYI: The selection range might have been modified by a compositionstart
+  //      event handler.
+  mIMECompositionStart = SelectedRange().location;
+  return true;
+}
+
+bool IMEInputHandler::DispatchCompositionChangeEvent(const nsString& aText,
+                                                     NSAttributedString* aAttrString,
+                                                     NSRange& aSelectedRange) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::DispatchCompositionChangeEvent, "
+           "aText=\"%s\", aAttrString=\"%s\", "
+           "aSelectedRange={ location=%lu, length=%lu }, Destroyed()=%s, mView=%p, "
+           "mWidget=%p, inputContext=%p, mIsIMEComposing=%s",
+           this, NS_ConvertUTF16toUTF8(aText).get(), GetCharacters([aAttrString string]),
+           static_cast<unsigned long>(aSelectedRange.location),
+           static_cast<unsigned long>(aSelectedRange.length), TrueOrFalse(Destroyed()), mView,
+           mWidget, mView ? [mView inputContext] : nullptr, TrueOrFalse(mIsIMEComposing)));
+
+  NS_ENSURE_TRUE(!Destroyed(), false);
+
+  NS_ASSERTION(mIsIMEComposing, "We're not in composition");
+
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
+  nsresult rv = mDispatcher->BeginNativeInputTransaction();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG(gIMELog, LogLevel::Error,
+            ("%p   IMEInputHandler::DispatchCompositionChangeEvent, "
+             "FAILED, due to BeginNativeInputTransaction() failure",
+             this));
+    return false;
+  }
+
+  RefPtr<TextRangeArray> rangeArray = CreateTextRangeArray(aAttrString, aSelectedRange);
+
+  rv = mDispatcher->SetPendingComposition(aText, rangeArray);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG(gIMELog, LogLevel::Error,
+            ("%p   IMEInputHandler::DispatchCompositionChangeEvent, "
+             "FAILED, due to SetPendingComposition() failure",
+             this));
+    return false;
+  }
+
+  mSelectedRange.location = mIMECompositionStart + aSelectedRange.location;
+  mSelectedRange.length = aSelectedRange.length;
+
+  if (mIMECompositionString) {
+    [mIMECompositionString release];
+  }
+  mIMECompositionString = [[aAttrString string] retain];
+
+  nsEventStatus status;
+  rv = mDispatcher->FlushPendingComposition(status);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG(gIMELog, LogLevel::Error,
+            ("%p   IMEInputHandler::DispatchCompositionChangeEvent, "
+             "FAILED, due to FlushPendingComposition() failure",
+             this));
+    return false;
+  }
+
+  if (Destroyed()) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::DispatchCompositionChangeEvent, "
+             "destroyed by compositionchange event",
+             this));
+    return false;
+  }
+
+  // FYI: compositionstart may cause committing composition by the webapp.
+  return mIsIMEComposing;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+bool IMEInputHandler::DispatchCompositionCommitEvent(const nsAString* aCommitString) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::DispatchCompositionCommitEvent, "
+           "aCommitString=0x%p (\"%s\"), Destroyed()=%s, mView=%p, mWidget=%p, "
+           "inputContext=%p, mIsIMEComposing=%s",
+           this, aCommitString, aCommitString ? NS_ConvertUTF16toUTF8(*aCommitString).get() : "",
+           TrueOrFalse(Destroyed()), mView, mWidget, mView ? [mView inputContext] : nullptr,
+           TrueOrFalse(mIsIMEComposing)));
+
+  NS_ASSERTION(mIsIMEComposing, "We're not in composition");
+
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
+  if (!Destroyed()) {
+    // IME may query selection immediately after this, however, in e10s mode,
+    // OnSelectionChange() will be called asynchronously.  Until then, we
+    // should emulate expected selection range if the webapp does nothing.
+    mSelectedRange.location = mIMECompositionStart;
+    if (aCommitString) {
+      mSelectedRange.location += aCommitString->Length();
+    } else if (mIMECompositionString) {
+      nsAutoString commitString;
+      nsCocoaUtils::GetStringForNSString(mIMECompositionString, commitString);
+      mSelectedRange.location += commitString.Length();
+    }
+    mSelectedRange.length = 0;
+
+    nsresult rv = mDispatcher->BeginNativeInputTransaction();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      MOZ_LOG(gIMELog, LogLevel::Error,
+              ("%p   IMEInputHandler::DispatchCompositionCommitEvent, "
+               "FAILED, due to BeginNativeInputTransaction() failure",
+               this));
+    } else {
+      nsEventStatus status;
+      rv = mDispatcher->CommitComposition(status, aCommitString);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        MOZ_LOG(gIMELog, LogLevel::Error,
+                ("%p   IMEInputHandler::DispatchCompositionCommitEvent, "
+                 "FAILED, due to BeginNativeInputTransaction() failure",
+                 this));
+      }
+    }
+  }
+
+  mIsIMEComposing = mIsDeadKeyComposing = false;
+  mIMECompositionStart = UINT32_MAX;
+  if (mIMECompositionString) {
+    [mIMECompositionString release];
+    mIMECompositionString = nullptr;
+  }
+
+  if (Destroyed()) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::DispatchCompositionCommitEvent, "
+             "destroyed by compositioncommit event",
+             this));
+    return false;
+  }
+
+  return true;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+bool IMEInputHandler::MaybeDispatchCurrentKeydownEvent(bool aIsProcessedByIME) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (Destroyed()) {
+    return false;
+  }
+  MOZ_ASSERT(mWidget);
+
+  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
+  if (!currentKeyEvent || !currentKeyEvent->CanDispatchKeyDownEvent()) {
+    return true;
+  }
+
+  NSEvent* nativeEvent = currentKeyEvent->mKeyEvent;
+  if (NS_WARN_IF(!nativeEvent) || [nativeEvent type] != NSEventTypeKeyDown) {
+    return true;
+  }
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::MaybeDispatchKeydownEvent, aIsProcessedByIME=%s "
+           "currentKeyEvent={ mKeyEvent(%p)={ type=%s, keyCode=%s (0x%X) } }, "
+           "aIsProcessedBy=%s, IsDeadKeyComposing()=%s",
+           this, TrueOrFalse(aIsProcessedByIME), nativeEvent, GetNativeKeyEventType(nativeEvent),
+           GetKeyNameForNativeKeyCode([nativeEvent keyCode]), [nativeEvent keyCode],
+           TrueOrFalse(IsIMEComposing()), TrueOrFalse(IsDeadKeyComposing())));
+
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+  RefPtr<TextEventDispatcher> dispatcher(mDispatcher);
+  nsresult rv = dispatcher->BeginNativeInputTransaction();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG(gIMELog, LogLevel::Error,
+            ("%p   IMEInputHandler::DispatchKeyEventForFlagsChanged, "
+             "FAILED, due to BeginNativeInputTransaction() failure",
+             this));
+    return false;
+  }
+
+  NSResponder* firstResponder = [[mView window] firstResponder];
+
+  // Mark currentKeyEvent as "dispatched eKeyDown event" and actually do it.
+  currentKeyEvent->mKeyDownDispatched = true;
+
+  RefPtr<nsChildView> widget(mWidget);
+
+  WidgetKeyboardEvent keydownEvent(true, eKeyDown, widget);
+  // Don't mark the eKeyDown event as "processed by IME" if the composition
+  // is started with dead key.
+  currentKeyEvent->InitKeyEvent(this, keydownEvent, aIsProcessedByIME && !IsDeadKeyComposing());
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  dispatcher->DispatchKeyboardEvent(eKeyDown, keydownEvent, status, currentKeyEvent);
+  currentKeyEvent->mKeyDownHandled = (status == nsEventStatus_eConsumeNoDefault);
+
+  if (Destroyed()) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::MaybeDispatchKeydownEvent, "
+             "widget was destroyed by keydown event",
+             this));
+    return false;
+  }
+
+  // The key down event may have shifted the focus, in which case, we should
+  // not continue to handle current key sequence and let's commit current
+  // composition.
+  if (firstResponder != [[mView window] firstResponder]) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::MaybeDispatchKeydownEvent, "
+             "view lost focus by keydown event",
+             this));
+    CommitIMEComposition();
+    return false;
+  }
+
+  return true;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+void IMEInputHandler::InsertTextAsCommittingComposition(NSAttributedString* aAttrString,
+                                                        NSRange* aReplacementRange) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::InsertTextAsCommittingComposition, "
+           "aAttrString=\"%s\", aReplacementRange=%p { location=%lu, length=%lu }, "
+           "Destroyed()=%s, IsIMEComposing()=%s, "
+           "mMarkedRange={ location=%lu, length=%lu }",
+           this, GetCharacters([aAttrString string]), aReplacementRange,
+           static_cast<unsigned long>(aReplacementRange ? aReplacementRange->location : 0),
+           static_cast<unsigned long>(aReplacementRange ? aReplacementRange->length : 0),
+           TrueOrFalse(Destroyed()), TrueOrFalse(IsIMEComposing()),
+           static_cast<unsigned long>(mMarkedRange.location),
+           static_cast<unsigned long>(mMarkedRange.length)));
+
+  if (IgnoreIMECommit()) {
+    MOZ_CRASH("IMEInputHandler::InsertTextAsCommittingComposition() must not"
+              "be called while canceling the composition");
+  }
+
+  if (Destroyed()) {
+    return;
+  }
+
+  // When current keydown event causes this text input, let's dispatch
+  // eKeyDown event before any other events.  Note that if we're in a
+  // composition, we've already dispatched eKeyDown event from
+  // TextInputHandler::HandleKeyDownEvent().
+  // XXX Should we mark the eKeyDown event as "processed by IME"?
+  //     However, if the key causes two or more Unicode characters as
+  //     UTF-16 string, this is used.  So, perhaps, we need to improve
+  //     HandleKeyDownEvent() before do that.
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+  if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::InsertTextAsCommittingComposition, eKeyDown "
+             "caused focus move or something and canceling the composition",
+             this));
+    return;
+  }
+
+  // First, commit current composition with the latest composition string if the
+  // replacement range is different from marked range.
+  if (IsIMEComposing() && aReplacementRange && aReplacementRange->location != NSNotFound &&
+      !NSEqualRanges(MarkedRange(), *aReplacementRange)) {
+    if (!DispatchCompositionCommitEvent()) {
+      MOZ_LOG(gIMELog, LogLevel::Info,
+              ("%p   IMEInputHandler::InsertTextAsCommittingComposition, "
+               "destroyed by commiting composition for setting replacement range",
+               this));
+      return;
+    }
+  }
+
+  nsString str;
+  nsCocoaUtils::GetStringForNSString([aAttrString string], str);
+
+  if (!IsIMEComposing()) {
+    MOZ_DIAGNOSTIC_ASSERT(!str.IsEmpty());
+
+    // If there is no selection and replacement range is specified, set the
+    // range as selection.
+    if (aReplacementRange && aReplacementRange->location != NSNotFound &&
+        !NSEqualRanges(SelectedRange(), *aReplacementRange)) {
+      NS_ENSURE_TRUE_VOID(SetSelection(*aReplacementRange));
+    }
+
+    if (!StaticPrefs::intl_ime_use_composition_events_for_insert_text()) {
+      // In the default settings, we should not use composition events for
+      // inserting text without key press nor IME composition because the
+      // other browsers do so.   This will cause only a cancelable `beforeinput`
+      // event whose `inputType` is `insertText`.
+      WidgetContentCommandEvent insertTextEvent(true, eContentCommandInsertText, mWidget);
+      insertTextEvent.mString = Some(str);
+      DispatchEvent(insertTextEvent);
+      return;
+    }
+
+    // Otherise, emulate an IME composition.  This is our traditional behavior,
+    // but `beforeinput` events are not cancelable since they should be so for
+    // native IME limitation.  So, this is now seriously imcompatible with the
+    // other browsers.
+    if (!DispatchCompositionStartEvent()) {
+      MOZ_LOG(gIMELog, LogLevel::Info,
+              ("%p   IMEInputHandler::InsertTextAsCommittingComposition, "
+               "cannot continue handling composition after compositionstart",
+               this));
+      return;
+    }
+  }
+
+  if (!DispatchCompositionCommitEvent(&str)) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::InsertTextAsCommittingComposition, "
+             "destroyed by compositioncommit event",
+             this));
+    return;
+  }
+
+  mMarkedRange = NSMakeRange(NSNotFound, 0);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void IMEInputHandler::SetMarkedText(NSAttributedString* aAttrString, NSRange& aSelectedRange,
+                                    NSRange* aReplacementRange) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::SetMarkedText, "
+           "aAttrString=\"%s\", aSelectedRange={ location=%lu, length=%lu }, "
+           "aReplacementRange=%p { location=%lu, length=%lu }, "
+           "Destroyed()=%s, IsIMEComposing()=%s, "
+           "mMarkedRange={ location=%lu, length=%lu }, keyevent=%p, "
+           "keydownDispatched=%s, keydownHandled=%s, "
+           "keypressDispatched=%s, causedOtherKeyEvents=%s, "
+           "compositionDispatched=%s",
+           this, GetCharacters([aAttrString string]),
+           static_cast<unsigned long>(aSelectedRange.location),
+           static_cast<unsigned long>(aSelectedRange.length), aReplacementRange,
+           static_cast<unsigned long>(aReplacementRange ? aReplacementRange->location : 0),
+           static_cast<unsigned long>(aReplacementRange ? aReplacementRange->length : 0),
+           TrueOrFalse(Destroyed()), TrueOrFalse(IsIMEComposing()),
+           static_cast<unsigned long>(mMarkedRange.location),
+           static_cast<unsigned long>(mMarkedRange.length),
+           currentKeyEvent ? currentKeyEvent->mKeyEvent : nullptr,
+           currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyDownDispatched) : "N/A",
+           currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
+           currentKeyEvent ? TrueOrFalse(currentKeyEvent->mKeyPressDispatched) : "N/A",
+           currentKeyEvent ? TrueOrFalse(currentKeyEvent->mCausedOtherKeyEvents) : "N/A",
+           currentKeyEvent ? TrueOrFalse(currentKeyEvent->mCompositionDispatched) : "N/A"));
+
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
+  // If SetMarkedText() is called during handling a key press, that means that
+  // the key event caused this composition.  So, keypress event shouldn't
+  // be dispatched later, let's mark the key event causing composition event.
+  if (currentKeyEvent) {
+    currentKeyEvent->mCompositionDispatched = true;
+
+    // When current keydown event causes this text input, let's dispatch
+    // eKeyDown event before any other events.  Note that if we're in a
+    // composition, we've already dispatched eKeyDown event from
+    // TextInputHandler::HandleKeyDownEvent().  On the other hand, if we're
+    // not in composition, the key event starts new composition.  So, we
+    // need to mark the eKeyDown event as "processed by IME".
+    if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(true)) {
+      MOZ_LOG(gIMELog, LogLevel::Info,
+              ("%p   IMEInputHandler::SetMarkedText, eKeyDown caused focus move or "
+               "something and canceling the composition",
+               this));
+      return;
+    }
+  }
+
+  if (Destroyed()) {
+    return;
+  }
+
+  // First, commit current composition with the latest composition string if the
+  // replacement range is different from marked range.
+  if (IsIMEComposing() && aReplacementRange && aReplacementRange->location != NSNotFound &&
+      !NSEqualRanges(MarkedRange(), *aReplacementRange)) {
+    AutoRestore<bool> ignoreIMECommit(mIgnoreIMECommit);
+    mIgnoreIMECommit = false;
+    if (!DispatchCompositionCommitEvent()) {
+      MOZ_LOG(gIMELog, LogLevel::Info,
+              ("%p   IMEInputHandler::SetMarkedText, "
+               "destroyed by commiting composition for setting replacement range",
+               this));
+      return;
+    }
+  }
+
+  nsString str;
+  nsCocoaUtils::GetStringForNSString([aAttrString string], str);
+
+  mMarkedRange.length = str.Length();
+
+  if (!IsIMEComposing() && !str.IsEmpty()) {
+    // If there is no selection and replacement range is specified, set the
+    // range as selection.
+    if (aReplacementRange && aReplacementRange->location != NSNotFound &&
+        !NSEqualRanges(SelectedRange(), *aReplacementRange)) {
+      // Set temporary selection range since OnSelectionChange is async.
+      mSelectedRange = *aReplacementRange;
+      if (NS_WARN_IF(!SetSelection(*aReplacementRange))) {
+        mSelectedRange.location = NSNotFound;  // Marking dirty
+        return;
+      }
+    }
+
+    mMarkedRange.location = SelectedRange().location;
+
+    if (!DispatchCompositionStartEvent()) {
+      MOZ_LOG(gIMELog, LogLevel::Info,
+              ("%p   IMEInputHandler::SetMarkedText, cannot continue handling "
+               "composition after dispatching compositionstart",
+               this));
+      return;
+    }
+  }
+
+  if (!str.IsEmpty()) {
+    if (!DispatchCompositionChangeEvent(str, aAttrString, aSelectedRange)) {
+      MOZ_LOG(gIMELog, LogLevel::Info,
+              ("%p   IMEInputHandler::SetMarkedText, cannot continue handling "
+               "composition after dispatching compositionchange",
+               this));
+    }
+    return;
+  }
+
+  // If the composition string becomes empty string, we should commit
+  // current composition.
+  if (!DispatchCompositionCommitEvent(&EmptyString())) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::SetMarkedText, "
+             "destroyed by compositioncommit event",
+             this));
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+NSAttributedString* IMEInputHandler::GetAttributedSubstringFromRange(NSRange& aRange,
+                                                                     NSRange* aActualRange) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p   IMEInputHandler::GetAttributedSubstringFromRange, "
+           "aRange={ location=%lu, length=%lu }, aActualRange=%p, Destroyed()=%s",
+           this, static_cast<unsigned long>(aRange.location),
+           static_cast<unsigned long>(aRange.length), aActualRange, TrueOrFalse(Destroyed())));
+
+  if (aActualRange) {
+    *aActualRange = NSMakeRange(NSNotFound, 0);
+  }
+
+  if (Destroyed() || aRange.location == NSNotFound || aRange.length == 0) {
+    return nil;
+  }
+
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
+  // If we're in composing, the queried range may be in the composition string.
+  // In such case, we should use mIMECompositionString since if the composition
+  // string is handled by a remote process, the content cache may be out of
+  // date.
+  // XXX Should we set composition string attributes?  Although, Blink claims
+  //     that some attributes of marked text are supported, but they return
+  //     just marked string without any style.  So, let's keep current behavior
+  //     at least for now.
+  NSUInteger compositionLength = mIMECompositionString ? [mIMECompositionString length] : 0;
+  if (mIMECompositionStart != UINT32_MAX && aRange.location >= mIMECompositionStart &&
+      aRange.location + aRange.length <= mIMECompositionStart + compositionLength) {
+    NSRange range = NSMakeRange(aRange.location - mIMECompositionStart, aRange.length);
+    NSString* nsstr = [mIMECompositionString substringWithRange:range];
+    NSMutableAttributedString* result =
+        [[[NSMutableAttributedString alloc] initWithString:nsstr attributes:nil] autorelease];
+    // XXX We cannot return font information in this case.  However, this
+    //     case must occur only when IME tries to confirm if composing string
+    //     is handled as expected.
+    if (aActualRange) {
+      *aActualRange = aRange;
+    }
+
+    if (MOZ_LOG_TEST(gIMELog, LogLevel::Info)) {
+      nsAutoString str;
+      nsCocoaUtils::GetStringForNSString(nsstr, str);
+      MOZ_LOG(gIMELog, LogLevel::Info,
+              ("%p   IMEInputHandler::GetAttributedSubstringFromRange, "
+               "computed with mIMECompositionString (result string=\"%s\")",
+               this, NS_ConvertUTF16toUTF8(str).get()));
+    }
+    return result;
+  }
+
+  nsAutoString str;
+  WidgetQueryContentEvent queryTextContentEvent(true, eQueryTextContent, mWidget);
+  WidgetQueryContentEvent::Options options;
+  int64_t startOffset = aRange.location;
+  if (IsIMEComposing()) {
+    // The composition may be at different offset from the selection start
+    // offset at dispatching compositionstart because start of composition
+    // is fixed when composition string becomes non-empty in the editor.
+    // Therefore, we need to use query event which is relative to insertion
+    // point.
+    options.mRelativeToInsertionPoint = true;
+    startOffset -= mIMECompositionStart;
+  }
+  queryTextContentEvent.InitForQueryTextContent(startOffset, aRange.length, options);
+  queryTextContentEvent.RequestFontRanges();
+  DispatchEvent(queryTextContentEvent);
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p   IMEInputHandler::GetAttributedSubstringFromRange, "
+           "queryTextContentEvent={ mReply=%s }",
+           this, ToString(queryTextContentEvent.mReply).c_str()));
+
+  if (queryTextContentEvent.Failed()) {
+    return nil;
+  }
+
+  // We don't set vertical information at this point.  If required,
+  // OS will calls drawsVerticallyForCharacterAtIndex.
+  NSMutableAttributedString* result = nsCocoaUtils::GetNSMutableAttributedString(
+      queryTextContentEvent.mReply->DataRef(), queryTextContentEvent.mReply->mFontRanges, false,
+      mWidget->BackingScaleFactor());
+  if (aActualRange) {
+    *aActualRange = MakeNSRangeFrom(queryTextContentEvent.mReply->mOffsetAndData);
+  }
+  return result;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+bool IMEInputHandler::HasMarkedText() {
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p   IMEInputHandler::HasMarkedText, "
+           "mMarkedRange={ location=%lu, length=%lu }",
+           this, static_cast<unsigned long>(mMarkedRange.location),
+           static_cast<unsigned long>(mMarkedRange.length)));
+
+  return (mMarkedRange.location != NSNotFound) && (mMarkedRange.length != 0);
+}
+
+NSRange IMEInputHandler::MarkedRange() {
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p   IMEInputHandler::MarkedRange, "
+           "mMarkedRange={ location=%lu, length=%lu }",
+           this, static_cast<unsigned long>(mMarkedRange.location),
+           static_cast<unsigned long>(mMarkedRange.length)));
+
+  if (!HasMarkedText()) {
+    return NSMakeRange(NSNotFound, 0);
+  }
+  return mMarkedRange;
+}
+
+NSRange IMEInputHandler::SelectedRange() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p   IMEInputHandler::SelectedRange, Destroyed()=%s, mSelectedRange={ "
+           "location=%lu, length=%lu }",
+           this, TrueOrFalse(Destroyed()), static_cast<unsigned long>(mSelectedRange.location),
+           static_cast<unsigned long>(mSelectedRange.length)));
+
+  if (Destroyed()) {
+    return mSelectedRange;
+  }
+
+  if (mSelectedRange.location != NSNotFound) {
+    MOZ_ASSERT(mIMEHasFocus);
+    return mSelectedRange;
+  }
+
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
+  WidgetQueryContentEvent querySelectedTextEvent(true, eQuerySelectedText, mWidget);
+  DispatchEvent(querySelectedTextEvent);
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p   IMEInputHandler::SelectedRange, querySelectedTextEvent={ mReply=%s }", this,
+           ToString(querySelectedTextEvent.mReply).c_str()));
+
+  if (querySelectedTextEvent.Failed()) {
+    return mSelectedRange;
+  }
+
+  mWritingMode = querySelectedTextEvent.mReply->WritingModeRef();
+  mRangeForWritingMode = MakeNSRangeFrom(querySelectedTextEvent.mReply->mOffsetAndData);
+
+  if (mIMEHasFocus) {
+    mSelectedRange = mRangeForWritingMode;
+  }
+
+  return mRangeForWritingMode;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(mSelectedRange);
+}
+
+bool IMEInputHandler::DrawsVerticallyForCharacterAtIndex(uint32_t aCharIndex) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (Destroyed()) {
+    return false;
+  }
+
+  if (mRangeForWritingMode.location == NSNotFound) {
+    // Update cached writing-mode value for the current selection.
+    SelectedRange();
+  }
+
+  if (aCharIndex < mRangeForWritingMode.location ||
+      aCharIndex > mRangeForWritingMode.location + mRangeForWritingMode.length) {
+    // It's not clear to me whether this ever happens in practice, but if an
+    // IME ever wants to query writing mode at an offset outside the current
+    // selection, the writing-mode value may not be correct for the index.
+    // In that case, use FirstRectForCharacterRange to get a fresh value.
+    // This does more work than strictly necessary (we don't need the rect here),
+    // but should be a rare case.
+    NS_WARNING("DrawsVerticallyForCharacterAtIndex not using cached writing mode");
+    NSRange range = NSMakeRange(aCharIndex, 1);
+    NSRange actualRange;
+    FirstRectForCharacterRange(range, &actualRange);
+  }
+
+  return mWritingMode.IsVertical();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+NSRect IMEInputHandler::FirstRectForCharacterRange(NSRange& aRange, NSRange* aActualRange) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::FirstRectForCharacterRange, Destroyed()=%s, "
+           "aRange={ location=%lu, length=%lu }, aActualRange=%p }",
+           this, TrueOrFalse(Destroyed()), static_cast<unsigned long>(aRange.location),
+           static_cast<unsigned long>(aRange.length), aActualRange));
+
+  // XXX this returns first character rect or caret rect, it is limitation of
+  // now. We need more work for returns first line rect. But current
+  // implementation is enough for IMEs.
+
+  NSRect rect = NSMakeRect(0.0, 0.0, 0.0, 0.0);
+  NSRange actualRange = NSMakeRange(NSNotFound, 0);
+  if (aActualRange) {
+    *aActualRange = actualRange;
+  }
+  if (Destroyed() || aRange.location == NSNotFound) {
+    return rect;
+  }
+
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
+  LayoutDeviceIntRect r;
+  bool useCaretRect = (aRange.length == 0);
+  if (!useCaretRect) {
+    WidgetQueryContentEvent queryTextRectEvent(true, eQueryTextRect, mWidget);
+    WidgetQueryContentEvent::Options options;
+    int64_t startOffset = aRange.location;
+    if (IsIMEComposing()) {
+      // The composition may be at different offset from the selection start
+      // offset at dispatching compositionstart because start of composition
+      // is fixed when composition string becomes non-empty in the editor.
+      // Therefore, we need to use query event which is relative to insertion
+      // point.
+      options.mRelativeToInsertionPoint = true;
+      startOffset -= mIMECompositionStart;
+    }
+    queryTextRectEvent.InitForQueryTextRect(startOffset, 1, options);
+    DispatchEvent(queryTextRectEvent);
+    if (queryTextRectEvent.Succeeded()) {
+      r = queryTextRectEvent.mReply->mRect;
+      actualRange = MakeNSRangeFrom(queryTextRectEvent.mReply->mOffsetAndData);
+      mWritingMode = queryTextRectEvent.mReply->WritingModeRef();
+      mRangeForWritingMode = actualRange;
+    } else {
+      useCaretRect = true;
+    }
+  }
+
+  if (useCaretRect) {
+    WidgetQueryContentEvent queryCaretRectEvent(true, eQueryCaretRect, mWidget);
+    WidgetQueryContentEvent::Options options;
+    int64_t startOffset = aRange.location;
+    if (IsIMEComposing()) {
+      // The composition may be at different offset from the selection start
+      // offset at dispatching compositionstart because start of composition
+      // is fixed when composition string becomes non-empty in the editor.
+      // Therefore, we need to use query event which is relative to insertion
+      // point.
+      options.mRelativeToInsertionPoint = true;
+      startOffset -= mIMECompositionStart;
+    }
+    queryCaretRectEvent.InitForQueryCaretRect(startOffset, options);
+    DispatchEvent(queryCaretRectEvent);
+    if (queryCaretRectEvent.Failed()) {
+      return rect;
+    }
+    r = queryCaretRectEvent.mReply->mRect;
+    r.width = 0;
+    actualRange.location = queryCaretRectEvent.mReply->StartOffset();
+    actualRange.length = 0;
+  }
+
+  nsIWidget* rootWidget = mWidget->GetTopLevelWidget();
+  NSWindow* rootWindow = static_cast<NSWindow*>(rootWidget->GetNativeData(NS_NATIVE_WINDOW));
+  NSView* rootView = static_cast<NSView*>(rootWidget->GetNativeData(NS_NATIVE_WIDGET));
+  if (!rootWindow || !rootView) {
+    return rect;
+  }
+  rect = nsCocoaUtils::DevPixelsToCocoaPoints(r, mWidget->BackingScaleFactor());
+  rect = [rootView convertRect:rect toView:nil];
+  rect.origin = nsCocoaUtils::ConvertPointToScreen(rootWindow, rect.origin);
+
+  if (aActualRange) {
+    *aActualRange = actualRange;
+  }
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p   IMEInputHandler::FirstRectForCharacterRange, "
+           "useCaretRect=%s rect={ x=%f, y=%f, width=%f, height=%f }, "
+           "actualRange={ location=%lu, length=%lu }",
+           this, TrueOrFalse(useCaretRect), rect.origin.x, rect.origin.y, rect.size.width,
+           rect.size.height, static_cast<unsigned long>(actualRange.location),
+           static_cast<unsigned long>(actualRange.length)));
+
+  return rect;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSMakeRect(0.0, 0.0, 0.0, 0.0));
+}
+
+NSUInteger IMEInputHandler::CharacterIndexForPoint(NSPoint& aPoint) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::CharacterIndexForPoint, aPoint={ x=%f, y=%f }", this, aPoint.x,
+           aPoint.y));
+
+  NSWindow* mainWindow = [NSApp mainWindow];
+  if (!mWidget || !mainWindow) {
+    return NSNotFound;
+  }
+
+  WidgetQueryContentEvent queryCharAtPointEvent(true, eQueryCharacterAtPoint, mWidget);
+  NSPoint ptInWindow = nsCocoaUtils::ConvertPointFromScreen(mainWindow, aPoint);
+  NSPoint ptInView = [mView convertPoint:ptInWindow fromView:nil];
+  queryCharAtPointEvent.mRefPoint.x =
+      static_cast<int32_t>(ptInView.x) * mWidget->BackingScaleFactor();
+  queryCharAtPointEvent.mRefPoint.y =
+      static_cast<int32_t>(ptInView.y) * mWidget->BackingScaleFactor();
+  mWidget->DispatchWindowEvent(queryCharAtPointEvent);
+  if (queryCharAtPointEvent.Failed() || queryCharAtPointEvent.DidNotFindChar() ||
+      queryCharAtPointEvent.mReply->StartOffset() >= static_cast<uint32_t>(NSNotFound)) {
+    return NSNotFound;
+  }
+
+  return queryCharAtPointEvent.mReply->StartOffset();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSNotFound);
+}
+
+extern "C" {
+extern NSString* NSTextInputReplacementRangeAttributeName;
+}
+
+NSArray* IMEInputHandler::GetValidAttributesForMarkedText() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_LOG(gIMELog, LogLevel::Info, ("%p IMEInputHandler::GetValidAttributesForMarkedText", this));
+
+  // Return same attributes as Chromium (see render_widget_host_view_mac.mm)
+  // because most IMEs must be tested with Safari (OS default) and Chrome
+  // (having most market share).  Therefore, we need to follow their behavior.
+  // XXX It might be better to reuse an array instance for this result because
+  //     this may be called a lot.  Note that Chromium does so.
+  return [NSArray arrayWithObjects:NSUnderlineStyleAttributeName, NSUnderlineColorAttributeName,
+                                   NSMarkedClauseSegmentAttributeName,
+                                   NSTextInputReplacementRangeAttributeName, nil];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ *  IMEInputHandler implementation #2
+ *
+ ******************************************************************************/
+
+IMEInputHandler::IMEInputHandler(nsChildView* aWidget, NSView<mozView>* aNativeView)
+    : TextInputHandlerBase(aWidget, aNativeView),
+      mPendingMethods(0),
+      mIMECompositionString(nullptr),
+      mIMECompositionStart(UINT32_MAX),
+      mRangeForWritingMode(),
+      mIsIMEComposing(false),
+      mIsDeadKeyComposing(false),
+      mIsIMEEnabled(true),
+      mIsASCIICapableOnly(false),
+      mIgnoreIMECommit(false),
+      mIMEHasFocus(false) {
+  InitStaticMembers();
+
+  mMarkedRange.location = NSNotFound;
+  mMarkedRange.length = 0;
+  mSelectedRange.location = NSNotFound;
+  mSelectedRange.length = 0;
+}
+
+IMEInputHandler::~IMEInputHandler() {
+  if (mTimer) {
+    mTimer->Cancel();
+    mTimer = nullptr;
+  }
+  if (sFocusedIMEHandler == this) {
+    sFocusedIMEHandler = nullptr;
+  }
+  if (mIMECompositionString) {
+    [mIMECompositionString release];
+    mIMECompositionString = nullptr;
+  }
+}
+
+void IMEInputHandler::OnFocusChangeInGecko(bool aFocus) {
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::OnFocusChangeInGecko, aFocus=%s, Destroyed()=%s, "
+           "sFocusedIMEHandler=%p",
+           this, TrueOrFalse(aFocus), TrueOrFalse(Destroyed()), sFocusedIMEHandler));
+
+  mSelectedRange.location = NSNotFound;  // Marking dirty
+  mIMEHasFocus = aFocus;
+
+  // This is called when the native focus is changed and when the native focus
+  // isn't changed but the focus is changed in Gecko.
+  if (!aFocus) {
+    if (sFocusedIMEHandler == this) sFocusedIMEHandler = nullptr;
+    return;
+  }
+
+  sFocusedIMEHandler = this;
+
+  // We need to notify IME of focus change in Gecko as native focus change
+  // because the window level of the focused element in Gecko may be changed.
+  mPendingMethods |= kNotifyIMEOfFocusChangeInGecko;
+  ResetTimer();
+}
+
+bool IMEInputHandler::OnDestroyWidget(nsChildView* aDestroyingWidget) {
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::OnDestroyWidget, aDestroyingWidget=%p, "
+           "sFocusedIMEHandler=%p, IsIMEComposing()=%s",
+           this, aDestroyingWidget, sFocusedIMEHandler, TrueOrFalse(IsIMEComposing())));
+
+  // If we're not focused, the focused IMEInputHandler may have been
+  // created by another widget/nsChildView.
+  if (sFocusedIMEHandler && sFocusedIMEHandler != this) {
+    sFocusedIMEHandler->OnDestroyWidget(aDestroyingWidget);
+  }
+
+  if (!TextInputHandlerBase::OnDestroyWidget(aDestroyingWidget)) {
+    return false;
+  }
+
+  if (IsIMEComposing()) {
+    // If our view is in the composition, we should clean up it.
+    CancelIMEComposition();
+  }
+
+  mSelectedRange.location = NSNotFound;  // Marking dirty
+  mIMEHasFocus = false;
+
+  return true;
+}
+
+void IMEInputHandler::SendCommittedText(NSString* aString) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_LOG(
+      gIMELog, LogLevel::Info,
+      ("%p IMEInputHandler::SendCommittedText, mView=%p, mWidget=%p, "
+       "inputContext=%p, mIsIMEComposing=%s",
+       this, mView, mWidget, mView ? [mView inputContext] : nullptr, TrueOrFalse(mIsIMEComposing)));
+
+  NS_ENSURE_TRUE(mWidget, );
+  // XXX We should send the string without mView.
+  if (!mView) {
+    return;
+  }
+
+  NSAttributedString* attrStr = [[NSAttributedString alloc] initWithString:aString];
+  if ([mView conformsToProtocol:@protocol(NSTextInputClient)]) {
+    NSObject<NSTextInputClient>* textInputClient = static_cast<NSObject<NSTextInputClient>*>(mView);
+    [textInputClient insertText:attrStr replacementRange:NSMakeRange(NSNotFound, 0)];
+  }
+
+  // Last resort.  If we cannot retrieve NSTextInputProtocol from mView
+  // or blocking to call our InsertText(), we should call InsertText()
+  // directly to commit composition forcibly.
+  if (mIsIMEComposing) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::SendCommittedText, trying to insert text directly "
+             "due to IME not calling our InsertText()",
+             this));
+    static_cast<TextInputHandler*>(this)->InsertText(attrStr);
+    MOZ_ASSERT(!mIsIMEComposing);
+  }
+
+  [attrStr release];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void IMEInputHandler::KillIMEComposition() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::KillIMEComposition, mView=%p, mWidget=%p, "
+           "inputContext=%p, mIsIMEComposing=%s, "
+           "Destroyed()=%s, IsFocused()=%s",
+           this, mView, mWidget, mView ? [mView inputContext] : nullptr,
+           TrueOrFalse(mIsIMEComposing), TrueOrFalse(Destroyed()), TrueOrFalse(IsFocused())));
+
+  if (Destroyed() || NS_WARN_IF(!mView)) {
+    return;
+  }
+
+  NSTextInputContext* inputContext = [mView inputContext];
+  if (NS_WARN_IF(!inputContext)) {
+    return;
+  }
+  [inputContext discardMarkedText];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void IMEInputHandler::CommitIMEComposition() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::CommitIMEComposition, mIMECompositionString=%s", this,
+           GetCharacters(mIMECompositionString)));
+
+  // If this is called before dispatching eCompositionStart, IsIMEComposing()
+  // returns false.  Even in such case, we need to commit composition *in*
+  // IME if this is called by preceding eKeyDown event of eCompositionStart.
+  // So, we need to call KillIMEComposition() even when IsIMEComposing()
+  // returns false.
+  KillIMEComposition();
+
+  if (!IsIMEComposing()) return;
+
+  // If the composition is still there, KillIMEComposition only kills the
+  // composition in TSM.  We also need to finish the our composition too.
+  SendCommittedText(mIMECompositionString);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void IMEInputHandler::CancelIMEComposition() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!IsIMEComposing()) return;
+
+  MOZ_LOG(gIMELog, LogLevel::Info,
+          ("%p IMEInputHandler::CancelIMEComposition, mIMECompositionString=%s", this,
+           GetCharacters(mIMECompositionString)));
+
+  // For canceling the current composing, we need to ignore the param of
+  // insertText.  But this code is ugly...
+  mIgnoreIMECommit = true;
+  KillIMEComposition();
+  mIgnoreIMECommit = false;
+
+  if (!IsIMEComposing()) return;
+
+  // If the composition is still there, KillIMEComposition only kills the
+  // composition in TSM.  We also need to kill the our composition too.
+  SendCommittedText(@"");
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+bool IMEInputHandler::IsFocused() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NS_ENSURE_TRUE(!Destroyed(), false);
+  NSWindow* window = [mView window];
+  NS_ENSURE_TRUE(window, false);
+  return [window firstResponder] == mView && [window isKeyWindow] &&
+         [[NSApplication sharedApplication] isActive];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+bool IMEInputHandler::IsIMEOpened() {
+  TISInputSourceWrapper tis;
+  tis.InitByCurrentInputSource();
+  return tis.IsOpenedIMEMode();
+}
+
+void IMEInputHandler::SetASCIICapableOnly(bool aASCIICapableOnly) {
+  if (aASCIICapableOnly == mIsASCIICapableOnly) return;
+
+  CommitIMEComposition();
+  mIsASCIICapableOnly = aASCIICapableOnly;
+  SyncASCIICapableOnly();
+}
+
+void IMEInputHandler::EnableIME(bool aEnableIME) {
+  if (aEnableIME == mIsIMEEnabled) return;
+
+  CommitIMEComposition();
+  mIsIMEEnabled = aEnableIME;
+}
+
+void IMEInputHandler::SetIMEOpenState(bool aOpenIME) {
+  if (!IsFocused() || IsIMEOpened() == aOpenIME) return;
+
+  if (!aOpenIME) {
+    TISInputSourceWrapper tis;
+    tis.InitByCurrentASCIICapableInputSource();
+    tis.Select();
+    return;
+  }
+
+  // If we know the latest IME opened mode, we should select it.
+  if (sLatestIMEOpenedModeInputSourceID) {
+    TISInputSourceWrapper tis;
+    tis.InitByInputSourceID(sLatestIMEOpenedModeInputSourceID);
+    tis.Select();
+    return;
+  }
+
+  // XXX If the current input source is a mode of IME, we should turn on it,
+  // but we haven't found such way...
+
+  // Finally, we should refer the system locale but this is a little expensive,
+  // we shouldn't retry this (if it was succeeded, we already set
+  // sLatestIMEOpenedModeInputSourceID at that time).
+  static bool sIsPrefferredIMESearched = false;
+  if (sIsPrefferredIMESearched) return;
+  sIsPrefferredIMESearched = true;
+  OpenSystemPreferredLanguageIME();
+}
+
+void IMEInputHandler::OpenSystemPreferredLanguageIME() {
+  MOZ_LOG(gIMELog, LogLevel::Info, ("%p IMEInputHandler::OpenSystemPreferredLanguageIME", this));
+
+  CFArrayRef langList = ::CFLocaleCopyPreferredLanguages();
+  if (!langList) {
+    MOZ_LOG(gIMELog, LogLevel::Info,
+            ("%p   IMEInputHandler::OpenSystemPreferredLanguageIME, langList is NULL", this));
+    return;
+  }
+  CFIndex count = ::CFArrayGetCount(langList);
+  for (CFIndex i = 0; i < count; i++) {
+    CFLocaleRef locale = ::CFLocaleCreate(
+        kCFAllocatorDefault, static_cast<CFStringRef>(::CFArrayGetValueAtIndex(langList, i)));
+    if (!locale) {
+      continue;
+    }
+
+    bool changed = false;
+    CFStringRef lang = static_cast<CFStringRef>(::CFLocaleGetValue(locale, kCFLocaleLanguageCode));
+    NS_ASSERTION(lang, "lang is null");
+    if (lang) {
+      TISInputSourceWrapper tis;
+      tis.InitByLanguage(lang);
+      if (tis.IsOpenedIMEMode()) {
+        if (MOZ_LOG_TEST(gIMELog, LogLevel::Info)) {
+          CFStringRef foundTIS;
+          tis.GetInputSourceID(foundTIS);
+          MOZ_LOG(gIMELog, LogLevel::Info,
+                  ("%p   IMEInputHandler::OpenSystemPreferredLanguageIME, "
+                   "foundTIS=%s, lang=%s",
+                   this, GetCharacters(foundTIS), GetCharacters(lang)));
+        }
+        tis.Select();
+        changed = true;
+      }
+    }
+    ::CFRelease(locale);
+    if (changed) {
+      break;
+    }
+  }
+  ::CFRelease(langList);
+}
+
+void IMEInputHandler::OnSelectionChange(const IMENotification& aIMENotification) {
+  MOZ_ASSERT(aIMENotification.mSelectionChangeData.IsInitialized());
+  MOZ_LOG(gIMELog, LogLevel::Info, ("%p IMEInputHandler::OnSelectionChange", this));
+
+  if (!aIMENotification.mSelectionChangeData.HasRange()) {
+    mSelectedRange.location = NSNotFound;
+    mSelectedRange.length = 0;
+    mRangeForWritingMode.location = NSNotFound;
+    mRangeForWritingMode.length = 0;
+    return;
+  }
+
+  mWritingMode = aIMENotification.mSelectionChangeData.GetWritingMode();
+  mRangeForWritingMode = NSMakeRange(aIMENotification.mSelectionChangeData.mOffset,
+                                     aIMENotification.mSelectionChangeData.Length());
+  if (mIMEHasFocus) {
+    mSelectedRange = mRangeForWritingMode;
+  }
+}
+
+void IMEInputHandler::OnLayoutChange() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!IsFocused()) {
+    return;
+  }
+  NSTextInputContext* inputContext = [mView inputContext];
+  [inputContext invalidateCharacterCoordinates];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+bool IMEInputHandler::OnHandleEvent(NSEvent* aEvent) {
+  if (!IsFocused()) {
+    return false;
+  }
+
+  bool allowConsumeEvent = true;
+  if (nsCocoaFeatures::OnCatalinaOrLater() && !IsIMEComposing()) {
+    // Hack for bug of Korean IMEs on Catalina (10.15).
+    // If we are inactivated during composition, active Korean IME keeps
+    // consuming all mousedown events of any mouse buttons.  So, we should
+    // allow Korean IMEs to handle mousedown events only when there is
+    // composition string.
+    // List of ID of Korean IME:
+    // * com.apple.inputmethod.Korean.2SetKorean
+    // * com.apple.inputmethod.Korean.3SetKorean
+    // * com.apple.inputmethod.Korean.390Sebulshik
+    // * com.apple.inputmethod.Korean.GongjinCheongRomaja
+    // * com.apple.inputmethod.Korean.HNCRomaja
+    TISInputSourceWrapper tis;
+    tis.InitByCurrentInputSource();
+    nsAutoString inputSourceID;
+    tis.GetInputSourceID(inputSourceID);
+    allowConsumeEvent = !StringBeginsWith(inputSourceID, u"com.apple.inputmethod.Korean."_ns);
+  }
+  NSTextInputContext* inputContext = [mView inputContext];
+  return [inputContext handleEvent:aEvent] && allowConsumeEvent;
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ *  TextInputHandlerBase implementation
+ *
+ ******************************************************************************/
+
+int32_t TextInputHandlerBase::sSecureEventInputCount = 0;
+
+NS_IMPL_ISUPPORTS(TextInputHandlerBase, TextEventDispatcherListener, nsISupportsWeakReference)
+
+TextInputHandlerBase::TextInputHandlerBase(nsChildView* aWidget, NSView<mozView>* aNativeView)
+    : mWidget(aWidget), mDispatcher(aWidget->GetTextEventDispatcher()) {
+  gHandlerInstanceCount++;
+  mView = [aNativeView retain];
+}
+
+TextInputHandlerBase::~TextInputHandlerBase() {
+  [mView release];
+  if (--gHandlerInstanceCount == 0) {
+    TISInputSourceWrapper::Shutdown();
+  }
+}
+
+bool TextInputHandlerBase::OnDestroyWidget(nsChildView* aDestroyingWidget) {
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info, ("%p TextInputHandlerBase::OnDestroyWidget, "
+                                      "aDestroyingWidget=%p, mWidget=%p",
+                                      this, aDestroyingWidget, mWidget));
+
+  if (aDestroyingWidget != mWidget) {
+    return false;
+  }
+
+  mWidget = nullptr;
+  mDispatcher = nullptr;
+  return true;
+}
+
+bool TextInputHandlerBase::DispatchEvent(WidgetGUIEvent& aEvent) {
+  return mWidget->DispatchWindowEvent(aEvent);
+}
+
+void TextInputHandlerBase::InitKeyEvent(NSEvent* aNativeKeyEvent, WidgetKeyboardEvent& aKeyEvent,
+                                        bool aIsProcessedByIME, const nsAString* aInsertString) {
+  NS_ASSERTION(aNativeKeyEvent, "aNativeKeyEvent must not be NULL");
+
+  if (mKeyboardOverride.mOverrideEnabled) {
+    TISInputSourceWrapper tis;
+    tis.InitByLayoutID(mKeyboardOverride.mKeyboardLayout, true);
+    tis.InitKeyEvent(aNativeKeyEvent, aKeyEvent, aIsProcessedByIME, aInsertString);
+    return;
+  }
+  TISInputSourceWrapper::CurrentInputSource().InitKeyEvent(aNativeKeyEvent, aKeyEvent,
+                                                           aIsProcessedByIME, aInsertString);
+}
+
+nsresult TextInputHandlerBase::SynthesizeNativeKeyEvent(int32_t aNativeKeyboardLayout,
+                                                        int32_t aNativeKeyCode,
+                                                        uint32_t aModifierFlags,
+                                                        const nsAString& aCharacters,
+                                                        const nsAString& aUnmodifiedCharacters) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  uint32_t modifierFlags = nsCocoaUtils::ConvertWidgetModifiersToMacModifierFlags(
+      static_cast<nsIWidget::Modifiers>(aModifierFlags));
+  NSInteger windowNumber = [[mView window] windowNumber];
+  bool sendFlagsChangedEvent = IsModifierKey(aNativeKeyCode);
+  NSEventType eventType = sendFlagsChangedEvent ? NSEventTypeFlagsChanged : NSEventTypeKeyDown;
+  NSEvent* downEvent = [NSEvent keyEventWithType:eventType
+                                        location:NSMakePoint(0, 0)
+                                   modifierFlags:modifierFlags
+                                       timestamp:0
+                                    windowNumber:windowNumber
+                                         context:nil
+                                      characters:nsCocoaUtils::ToNSString(aCharacters)
+                     charactersIgnoringModifiers:nsCocoaUtils::ToNSString(aUnmodifiedCharacters)
+                                       isARepeat:NO
+                                         keyCode:aNativeKeyCode];
+
+  NSEvent* upEvent = sendFlagsChangedEvent
+                         ? nil
+                         : nsCocoaUtils::MakeNewCocoaEventWithType(NSEventTypeKeyUp, downEvent);
+
+  if (downEvent && (sendFlagsChangedEvent || upEvent)) {
+    KeyboardLayoutOverride currentLayout = mKeyboardOverride;
+    mKeyboardOverride.mKeyboardLayout = aNativeKeyboardLayout;
+    mKeyboardOverride.mOverrideEnabled = true;
+    [NSApp sendEvent:downEvent];
+    if (upEvent) {
+      [NSApp sendEvent:upEvent];
+    }
+    // processKeyDownEvent and keyUp block exceptions so we're sure to
+    // reach here to restore mKeyboardOverride
+    mKeyboardOverride = currentLayout;
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NSInteger TextInputHandlerBase::GetWindowLevel() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info, ("%p TextInputHandlerBase::GetWindowLevel, Destryoed()=%s",
+                                      this, TrueOrFalse(Destroyed())));
+
+  if (Destroyed()) {
+    return NSNormalWindowLevel;
+  }
+
+  // When an <input> element on a XUL <panel> is focused, the actual focused view
+  // is the panel's parent view (mView). But the editor is displayed on the
+  // popped-up widget's view (editorView).  We want the latter's window level.
+  NSView<mozView>* editorView = mWidget->GetEditorView();
+  NS_ENSURE_TRUE(editorView, NSNormalWindowLevel);
+  NSInteger windowLevel = [[editorView window] level];
+
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                     ("%p TextInputHandlerBase::GetWindowLevel, windowLevel=%s (%lX)", this,
+                      GetWindowLevelName(windowLevel), static_cast<unsigned long>(windowLevel)));
+
+  return windowLevel;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSNormalWindowLevel);
+}
+
+NS_IMETHODIMP
+TextInputHandlerBase::AttachNativeKeyEvent(WidgetKeyboardEvent& aKeyEvent) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // Don't try to replace a native event if one already exists.
+  // OS X doesn't have an OS modifier, can't make a native event.
+  if (aKeyEvent.mNativeKeyEvent || aKeyEvent.mModifiers & MODIFIER_OS) {
+    return NS_OK;
+  }
+
+  MOZ_LOG_KEY_OR_IME(LogLevel::Info,
+                     ("%p TextInputHandlerBase::AttachNativeKeyEvent, key=0x%X, char=0x%X, "
+                      "mod=0x%X",
+                      this, aKeyEvent.mKeyCode, aKeyEvent.mCharCode, aKeyEvent.mModifiers));
+
+  NSInteger windowNumber = [[mView window] windowNumber];
+  NSGraphicsContext* context = [NSGraphicsContext currentContext];
+  aKeyEvent.mNativeKeyEvent =
+      nsCocoaUtils::MakeNewCococaEventFromWidgetEvent(aKeyEvent, windowNumber, context);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+bool TextInputHandlerBase::SetSelection(NSRange& aRange) {
+  MOZ_ASSERT(!Destroyed());
+
+  RefPtr<TextInputHandlerBase> kungFuDeathGrip(this);
+  WidgetSelectionEvent selectionEvent(true, eSetSelection, mWidget);
+  selectionEvent.mOffset = aRange.location;
+  selectionEvent.mLength = aRange.length;
+  selectionEvent.mReversed = false;
+  selectionEvent.mExpandToClusterBoundary = false;
+  DispatchEvent(selectionEvent);
+  NS_ENSURE_TRUE(selectionEvent.mSucceeded, false);
+  return !Destroyed();
+}
+
+/* static */ bool TextInputHandlerBase::IsPrintableChar(char16_t aChar) {
+  return (aChar >= 0x20 && aChar <= 0x7E) || aChar >= 0xA0;
+}
+
+/* static */ bool TextInputHandlerBase::IsSpecialGeckoKey(UInt32 aNativeKeyCode) {
+  // this table is used to determine which keys are special and should not
+  // generate a charCode
+  switch (aNativeKeyCode) {
+    // modifiers - we don't get separate events for these yet
+    case kVK_Escape:
+    case kVK_Shift:
+    case kVK_RightShift:
+    case kVK_Command:
+    case kVK_RightCommand:
+    case kVK_CapsLock:
+    case kVK_Control:
+    case kVK_RightControl:
+    case kVK_Option:
+    case kVK_RightOption:
+    case kVK_ANSI_KeypadClear:
+    case kVK_Function:
+
+    // function keys
+    case kVK_F1:
+    case kVK_F2:
+    case kVK_F3:
+    case kVK_F4:
+    case kVK_F5:
+    case kVK_F6:
+    case kVK_F7:
+    case kVK_F8:
+    case kVK_F9:
+    case kVK_F10:
+    case kVK_F11:
+    case kVK_F12:
+    case kVK_PC_Pause:
+    case kVK_PC_ScrollLock:
+    case kVK_PC_PrintScreen:
+    case kVK_F16:
+    case kVK_F17:
+    case kVK_F18:
+    case kVK_F19:
+
+    case kVK_PC_Insert:
+    case kVK_PC_Delete:
+    case kVK_Tab:
+    case kVK_PC_Backspace:
+    case kVK_PC_ContextMenu:
+
+    case kVK_JIS_Eisu:
+    case kVK_JIS_Kana:
+
+    case kVK_Home:
+    case kVK_End:
+    case kVK_PageUp:
+    case kVK_PageDown:
+    case kVK_LeftArrow:
+    case kVK_RightArrow:
+    case kVK_UpArrow:
+    case kVK_DownArrow:
+    case kVK_Return:
+    case kVK_ANSI_KeypadEnter:
+    case kVK_Powerbook_KeypadEnter:
+      return true;
+  }
+  return false;
+}
+
+/* static */ bool TextInputHandlerBase::IsNormalCharInputtingEvent(NSEvent* aNativeEvent) {
+  if ([aNativeEvent type] != NSEventTypeKeyDown && [aNativeEvent type] != NSEventTypeKeyUp) {
+    return false;
+  }
+  nsAutoString nativeChars;
+  nsCocoaUtils::GetStringForNSString([aNativeEvent characters], nativeChars);
+
+  // this is not character inputting event, simply.
+  if (nativeChars.IsEmpty() || ([aNativeEvent modifierFlags] & NSEventModifierFlagCommand)) {
+    return false;
+  }
+  return !IsControlChar(nativeChars[0]);
+}
+
+/* static */ bool TextInputHandlerBase::IsModifierKey(UInt32 aNativeKeyCode) {
+  switch (aNativeKeyCode) {
+    case kVK_CapsLock:
+    case kVK_RightCommand:
+    case kVK_Command:
+    case kVK_Shift:
+    case kVK_Option:
+    case kVK_Control:
+    case kVK_RightShift:
+    case kVK_RightOption:
+    case kVK_RightControl:
+    case kVK_Function:
+      return true;
+  }
+  return false;
+}
+
+/* static */ void TextInputHandlerBase::EnableSecureEventInput() {
+  sSecureEventInputCount++;
+  ::EnableSecureEventInput();
+}
+
+/* static */ void TextInputHandlerBase::DisableSecureEventInput() {
+  if (!sSecureEventInputCount) {
+    return;
+  }
+  sSecureEventInputCount--;
+  ::DisableSecureEventInput();
+}
+
+/* static */ bool TextInputHandlerBase::IsSecureEventInputEnabled() {
+  // sSecureEventInputCount is our mechanism to track when Secure Event Input
+  //   is enabled. Non-zero indicates we have enabled Secure Input. But
+  //   zero does not mean that Secure Input is _disabled_ because another
+  //   application may have enabled it.  If the OS reports Secure Event
+  //   Input is disabled though, a non-zero sSecureEventInputCount is an error.
+  NS_ASSERTION(
+      ::IsSecureEventInputEnabled() || 0 == sSecureEventInputCount,
+      "sSecureEventInputCount is not zero when the OS thinks SecureEventInput is disabled.");
+  return !!sSecureEventInputCount;
+}
+
+/* static */ void TextInputHandlerBase::EnsureSecureEventInputDisabled() {
+  while (sSecureEventInputCount) {
+    TextInputHandlerBase::DisableSecureEventInput();
+  }
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ *  TextInputHandlerBase::KeyEventState implementation
+ *
+ ******************************************************************************/
+
+void TextInputHandlerBase::KeyEventState::InitKeyEvent(TextInputHandlerBase* aHandler,
+                                                       WidgetKeyboardEvent& aKeyEvent,
+                                                       bool aIsProcessedByIME) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_ASSERT(aHandler);
+  MOZ_RELEASE_ASSERT(mKeyEvent);
+
+  NSEvent* nativeEvent = mKeyEvent;
+  if (!mInsertedString.IsEmpty()) {
+    nsAutoString unhandledString;
+    GetUnhandledString(unhandledString);
+    NSString* unhandledNSString = nsCocoaUtils::ToNSString(unhandledString);
+    // If the key event's some characters were already handled by
+    // InsertString() calls, we need to create a dummy event which doesn't
+    // include the handled characters.
+    nativeEvent = [NSEvent keyEventWithType:[mKeyEvent type]
+                                   location:[mKeyEvent locationInWindow]
+                              modifierFlags:[mKeyEvent modifierFlags]
+                                  timestamp:[mKeyEvent timestamp]
+                               windowNumber:[mKeyEvent windowNumber]
+                                    context:nil
+                                 characters:unhandledNSString
+                charactersIgnoringModifiers:[mKeyEvent charactersIgnoringModifiers]
+                                  isARepeat:[mKeyEvent isARepeat]
+                                    keyCode:[mKeyEvent keyCode]];
+  }
+
+  aKeyEvent.mUniqueId = mUniqueId;
+  aHandler->InitKeyEvent(nativeEvent, aKeyEvent, aIsProcessedByIME, mInsertString);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void TextInputHandlerBase::KeyEventState::GetUnhandledString(nsAString& aUnhandledString) const {
+  aUnhandledString.Truncate();
+  if (NS_WARN_IF(!mKeyEvent)) {
+    return;
+  }
+  nsAutoString characters;
+  nsCocoaUtils::GetStringForNSString([mKeyEvent characters], characters);
+  if (characters.IsEmpty()) {
+    return;
+  }
+  if (mInsertedString.IsEmpty()) {
+    aUnhandledString = characters;
+    return;
+  }
+
+  // The insertes string must match with the start of characters.
+  MOZ_ASSERT(StringBeginsWith(characters, mInsertedString));
+
+  aUnhandledString = nsDependentSubstring(characters, mInsertedString.Length());
+}
+
+#pragma mark -
+
+/******************************************************************************
+ *
+ *  TextInputHandlerBase::AutoInsertStringClearer implementation
+ *
+ ******************************************************************************/
+
+TextInputHandlerBase::AutoInsertStringClearer::~AutoInsertStringClearer() {
+  if (mState && mState->mInsertString) {
+    // If inserting string is a part of characters of the event,
+    // we should record it as inserted string.
+    nsAutoString characters;
+    nsCocoaUtils::GetStringForNSString([mState->mKeyEvent characters], characters);
+    nsAutoString insertedString(mState->mInsertedString);
+    insertedString += *mState->mInsertString;
+    if (StringBeginsWith(characters, insertedString)) {
+      mState->mInsertedString = insertedString;
+    }
+  }
+  if (mState) {
+    mState->mInsertString = nullptr;
+  }
+}
+
+#undef MOZ_LOG_KEY_OR_IME
diff --git a/widget/cocoa/TextRecognition.mm b/widget/cocoa/TextRecognition.mm
new file mode 100644
index 0000000000..1c962a2c05
--- /dev/null
+++ b/widget/cocoa/TextRecognition.mm
@@ -0,0 +1,109 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Vision/Vision.h>
+
+#include "mozilla/dom/Promise.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/ErrorResult.h"
+#include "ErrorList.h"
+#include "nsClipboard.h"
+#include "nsCocoaUtils.h"
+#include "mozilla/MacStringHelpers.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/widget/TextRecognition.h"
+#include "mozilla/dom/PContent.h"
+
+namespace mozilla::widget {
+
+auto TextRecognition::DoFindText(gfx::DataSourceSurface& aSurface,
+                                 const nsTArray<nsCString>& aLanguages) -> RefPtr<NativePromise> {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK
+  if (@available(macOS 10.15, *)) {
+    // TODO - Is this the most efficient path? Maybe we can write a new
+    // CreateCGImageFromXXX that enables more efficient marshalling of the data.
+    CGImageRef imageRef = NULL;
+    nsresult rv = nsCocoaUtils::CreateCGImageFromSurface(&aSurface, &imageRef);
+    if (NS_FAILED(rv) || !imageRef) {
+      return NativePromise::CreateAndReject("Failed to create CGImage"_ns, __func__);
+    }
+
+    auto promise = MakeRefPtr<NativePromise::Private>(__func__);
+
+    NSMutableArray* recognitionLanguages = [[NSMutableArray alloc] init];
+    for (const auto& locale : aLanguages) {
+      [recognitionLanguages addObject:nsCocoaUtils::ToNSString(locale)];
+    }
+
+    NS_DispatchBackgroundTask(
+        NS_NewRunnableFunction(
+            __func__,
+            [promise, imageRef, recognitionLanguages] {
+              auto unrefImage = MakeScopeExit([&] {
+                ::CGImageRelease(imageRef);
+                [recognitionLanguages release];
+              });
+
+              dom::TextRecognitionResult result;
+              dom::TextRecognitionResult* pResult = &result;
+
+              // Define the request to use, which also handles the result. It will be run below
+              // directly in this thread. After creating this request.
+              VNRecognizeTextRequest* textRecognitionRequest = [[VNRecognizeTextRequest alloc]
+                  initWithCompletionHandler:^(VNRequest* _Nonnull request,
+                                              NSError* _Nullable error) {
+                    NSArray<VNRecognizedTextObservation*>* observations = request.results;
+
+                    [observations
+                        enumerateObjectsUsingBlock:^(VNRecognizedTextObservation* _Nonnull obj,
+                                                     NSUInteger idx, BOOL* _Nonnull stop) {
+                          // Requests the n top candidates for a recognized text string.
+                          VNRecognizedText* recognizedText = [obj topCandidates:1].firstObject;
+
+                          // https://developer.apple.com/documentation/vision/vnrecognizedtext?language=objc
+                          auto& quad = *pResult->quads().AppendElement();
+                          CopyCocoaStringToXPCOMString(recognizedText.string, quad.string());
+                          quad.confidence() = recognizedText.confidence;
+
+                          auto ToImagePoint = [](CGPoint aPoint) -> ImagePoint {
+                            return {static_cast<float>(aPoint.x), static_cast<float>(aPoint.y)};
+                          };
+                          *quad.points().AppendElement() = ToImagePoint(obj.bottomLeft);
+                          *quad.points().AppendElement() = ToImagePoint(obj.topLeft);
+                          *quad.points().AppendElement() = ToImagePoint(obj.topRight);
+                          *quad.points().AppendElement() = ToImagePoint(obj.bottomRight);
+                        }];
+                  }];
+
+              textRecognitionRequest.recognitionLevel = VNRequestTextRecognitionLevelAccurate;
+              textRecognitionRequest.recognitionLanguages = recognitionLanguages;
+              textRecognitionRequest.usesLanguageCorrection = true;
+
+              // Send out the request. This blocks execution of this thread with an expensive
+              // CPU call.
+              NSError* error = nil;
+              VNImageRequestHandler* requestHandler =
+                  [[[VNImageRequestHandler alloc] initWithCGImage:imageRef
+                                                          options:@{}] autorelease];
+
+              [requestHandler performRequests:@[ textRecognitionRequest ] error:&error];
+              if (error != nil) {
+                promise->Reject(
+                    nsPrintfCString("Failed to perform text recognition request (%ld)\n",
+                                    error.code),
+                    __func__);
+              } else {
+                promise->Resolve(std::move(result), __func__);
+              }
+            }),
+        NS_DISPATCH_EVENT_MAY_BLOCK);
+    return promise;
+  } else {
+    return NativePromise::CreateAndReject("Text recognition is not available"_ns, __func__);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK
+}
+
+}  // namespace mozilla::widget
diff --git a/widget/cocoa/VibrancyManager.h b/widget/cocoa/VibrancyManager.h
new file mode 100644
index 0000000000..b85b8b1e80
--- /dev/null
+++ b/widget/cocoa/VibrancyManager.h
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef VibrancyManager_h
+#define VibrancyManager_h
+
+#include "mozilla/Assertions.h"
+#include "nsClassHashtable.h"
+#include "nsRegion.h"
+#include "nsTArray.h"
+#include "ViewRegion.h"
+
+#import <Foundation/NSGeometry.h>
+
+@class NSColor;
+@class NSView;
+class nsChildView;
+
+namespace mozilla {
+
+enum class VibrancyType {
+  TOOLTIP,
+  MENU,
+  HIGHLIGHTED_MENUITEM,
+  SOURCE_LIST,
+  SOURCE_LIST_SELECTION,
+  ACTIVE_SOURCE_LIST_SELECTION
+};
+
+/**
+ * VibrancyManager takes care of updating the vibrant regions of a window.
+ * Vibrancy is a visual look that was introduced on OS X starting with 10.10.
+ * An app declares vibrant window regions to the window server, and the window
+ * server will display a blurred rendering of the screen contents from behind
+ * the window in these areas, behind the actual window contents. Consequently,
+ * the effect is only visible in areas where the window contents are not
+ * completely opaque. Usually this is achieved by clearing the background of
+ * the window prior to drawing in the vibrant areas. This is possible even if
+ * the window is declared as opaque.
+ */
+class VibrancyManager {
+ public:
+  /**
+   * Create a new VibrancyManager instance and provide it with an NSView
+   * to attach NSVisualEffectViews to.
+   *
+   * @param aCoordinateConverter  The nsChildView to use for converting
+   *   nsIntRect device pixel coordinates into Cocoa NSRect coordinates. Must
+   *   outlive this VibrancyManager instance.
+   * @param aContainerView  The view that's going to be the superview of the
+   *   NSVisualEffectViews which will be created for vibrant regions.
+   */
+  VibrancyManager(const nsChildView& aCoordinateConverter, NSView* aContainerView)
+      : mCoordinateConverter(aCoordinateConverter), mContainerView(aContainerView) {}
+
+  /**
+   * Update the placement of the NSVisualEffectViews inside the container
+   * NSView so that they cover aRegion, and create new NSVisualEffectViews
+   * or remove existing ones as needed.
+   * @param aType   The vibrancy type to use in the region.
+   * @param aRegion The vibrant area, in device pixels.
+   * @return Whether the region changed.
+   */
+  bool UpdateVibrantRegion(VibrancyType aType, const LayoutDeviceIntRegion& aRegion);
+
+  bool HasVibrantRegions() { return !mVibrantRegions.IsEmpty(); }
+
+  LayoutDeviceIntRegion GetUnionOfVibrantRegions() const;
+
+  /**
+   * Create an NSVisualEffectView for the specified vibrancy type. The return
+   * value is not autoreleased. We return an object of type NSView* because we
+   * compile with an SDK that does not contain a definition for
+   * NSVisualEffectView.
+   * @param aIsContainer Whether this NSView will have child views. This value
+   *                     affects hit testing: Container views will pass through
+   *                     hit testing requests to their children, and leaf views
+   *                     will be transparent to hit testing.
+   */
+  static NSView* CreateEffectView(VibrancyType aType, BOOL aIsContainer = NO);
+
+ protected:
+  const nsChildView& mCoordinateConverter;
+  NSView* mContainerView;
+  nsClassHashtable<nsUint32HashKey, ViewRegion> mVibrantRegions;
+};
+
+}  // namespace mozilla
+
+#endif  // VibrancyManager_h
diff --git a/widget/cocoa/VibrancyManager.mm b/widget/cocoa/VibrancyManager.mm
new file mode 100644
index 0000000000..a193f15490
--- /dev/null
+++ b/widget/cocoa/VibrancyManager.mm
@@ -0,0 +1,147 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "VibrancyManager.h"
+
+#import <objc/message.h>
+
+#include "nsChildView.h"
+#include "nsCocoaFeatures.h"
+#include "SDKDeclarations.h"
+
+using namespace mozilla;
+
+@interface MOZVibrantView : NSVisualEffectView {
+  VibrancyType mType;
+}
+- (instancetype)initWithFrame:(NSRect)aRect vibrancyType:(VibrancyType)aVibrancyType;
+@end
+
+@interface MOZVibrantLeafView : MOZVibrantView
+@end
+
+static NSAppearance* AppearanceForVibrancyType(VibrancyType aType) {
+  if (@available(macOS 10.14, *)) {
+    // Inherit the appearance from the window. If the window is using Dark Mode, the vibrancy
+    // will automatically be dark, too. This is available starting with macOS 10.14.
+    return nil;
+  }
+
+  // For 10.13 and below, a vibrant appearance name must be used. There is no system dark mode and
+  // no automatic adaptation to the window; all windows are light.
+  switch (aType) {
+    case VibrancyType::TOOLTIP:
+    case VibrancyType::MENU:
+    case VibrancyType::HIGHLIGHTED_MENUITEM:
+    case VibrancyType::SOURCE_LIST:
+    case VibrancyType::SOURCE_LIST_SELECTION:
+    case VibrancyType::ACTIVE_SOURCE_LIST_SELECTION:
+      return [NSAppearance appearanceNamed:NSAppearanceNameVibrantLight];
+  }
+}
+
+static NSVisualEffectState VisualEffectStateForVibrancyType(VibrancyType aType) {
+  switch (aType) {
+    case VibrancyType::TOOLTIP:
+    case VibrancyType::MENU:
+    case VibrancyType::HIGHLIGHTED_MENUITEM:
+      // Tooltip and menu windows are never "key", so we need to tell the vibrancy effect to look
+      // active regardless of window state.
+      return NSVisualEffectStateActive;
+    default:
+      return NSVisualEffectStateFollowsWindowActiveState;
+  }
+}
+
+static NSVisualEffectMaterial VisualEffectMaterialForVibrancyType(VibrancyType aType,
+                                                                  BOOL* aOutIsEmphasized) {
+  switch (aType) {
+    case VibrancyType::TOOLTIP:
+      if (@available(macOS 10.14, *)) {
+        return (NSVisualEffectMaterial)NSVisualEffectMaterialToolTip;
+      } else {
+        return NSVisualEffectMaterialMenu;
+      }
+    case VibrancyType::MENU:
+      return NSVisualEffectMaterialMenu;
+    case VibrancyType::SOURCE_LIST:
+      return NSVisualEffectMaterialSidebar;
+    case VibrancyType::SOURCE_LIST_SELECTION:
+      return NSVisualEffectMaterialSelection;
+    case VibrancyType::HIGHLIGHTED_MENUITEM:
+    case VibrancyType::ACTIVE_SOURCE_LIST_SELECTION:
+      *aOutIsEmphasized = YES;
+      return NSVisualEffectMaterialSelection;
+  }
+}
+
+static BOOL HasVibrantForeground(VibrancyType aType) {
+  if (@available(macOS 10.14, *)) {
+    return NO;
+  }
+  return aType == VibrancyType::MENU;
+}
+
+@implementation MOZVibrantView
+
+- (instancetype)initWithFrame:(NSRect)aRect vibrancyType:(VibrancyType)aType {
+  self = [super initWithFrame:aRect];
+  mType = aType;
+
+  self.appearance = AppearanceForVibrancyType(mType);
+  self.state = VisualEffectStateForVibrancyType(mType);
+
+  BOOL isEmphasized = NO;
+  self.material = VisualEffectMaterialForVibrancyType(mType, &isEmphasized);
+  self.emphasized = isEmphasized;
+
+  return self;
+}
+
+// Don't override allowsVibrancy here, because this view may have subviews, and
+// returning YES from allowsVibrancy forces on foreground vibrancy for all
+// descendant views, which can have unintended effects.
+
+@end
+
+@implementation MOZVibrantLeafView
+
+- (NSView*)hitTest:(NSPoint)aPoint {
+  // This view must be transparent to mouse events.
+  return nil;
+}
+
+// MOZVibrantLeafView does not have subviews, so we can return YES here without
+// having unintended effects on other contents of the window.
+- (BOOL)allowsVibrancy {
+  return HasVibrantForeground(mType);
+}
+
+@end
+
+bool VibrancyManager::UpdateVibrantRegion(VibrancyType aType,
+                                          const LayoutDeviceIntRegion& aRegion) {
+  if (aRegion.IsEmpty()) {
+    return mVibrantRegions.Remove(uint32_t(aType));
+  }
+  auto& vr = *mVibrantRegions.GetOrInsertNew(uint32_t(aType));
+  return vr.UpdateRegion(aRegion, mCoordinateConverter, mContainerView, ^() {
+    return this->CreateEffectView(aType);
+  });
+}
+
+LayoutDeviceIntRegion VibrancyManager::GetUnionOfVibrantRegions() const {
+  LayoutDeviceIntRegion result;
+  for (const auto& region : mVibrantRegions.Values()) {
+    result.OrWith(region->Region());
+  }
+  return result;
+}
+
+/* static */ NSView* VibrancyManager::CreateEffectView(VibrancyType aType, BOOL aIsContainer) {
+  return aIsContainer ? [[MOZVibrantView alloc] initWithFrame:NSZeroRect vibrancyType:aType]
+                      : [[MOZVibrantLeafView alloc] initWithFrame:NSZeroRect vibrancyType:aType];
+}
diff --git a/widget/cocoa/ViewRegion.h b/widget/cocoa/ViewRegion.h
new file mode 100644
index 0000000000..4c98fab882
--- /dev/null
+++ b/widget/cocoa/ViewRegion.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef ViewRegion_h
+#define ViewRegion_h
+
+#include "Units.h"
+#include "nsTArray.h"
+
+class nsChildView;
+
+@class NSView;
+
+namespace mozilla {
+
+/**
+ * Manages a set of NSViews to cover a LayoutDeviceIntRegion.
+ */
+class ViewRegion {
+ public:
+  ~ViewRegion();
+
+  mozilla::LayoutDeviceIntRegion Region() { return mRegion; }
+
+  /**
+   * Update the region.
+   * @param aRegion  The new region.
+   * @param aCoordinateConverter  The nsChildView to use for converting
+   *   LayoutDeviceIntRect device pixel coordinates into Cocoa NSRect coordinates.
+   * @param aContainerView  The view that's going to be the superview of the
+   *   NSViews which will be created for this region.
+   * @param aViewCreationCallback  A block that instantiates new NSViews.
+   * @return  Whether or not the region changed.
+   */
+  bool UpdateRegion(const mozilla::LayoutDeviceIntRegion& aRegion,
+                    const nsChildView& aCoordinateConverter, NSView* aContainerView,
+                    NSView* (^aViewCreationCallback)());
+
+  /**
+   * Return an NSView from the region, if there is any.
+   */
+  NSView* GetAnyView() { return mViews.Length() > 0 ? mViews[0] : NULL; }
+
+ private:
+  mozilla::LayoutDeviceIntRegion mRegion;
+  nsTArray<NSView*> mViews;
+};
+
+}  // namespace mozilla
+
+#endif  // ViewRegion_h
diff --git a/widget/cocoa/ViewRegion.mm b/widget/cocoa/ViewRegion.mm
new file mode 100644
index 0000000000..c99785f956
--- /dev/null
+++ b/widget/cocoa/ViewRegion.mm
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ViewRegion.h"
+#import <Cocoa/Cocoa.h>
+
+#include "nsChildView.h"
+
+using namespace mozilla;
+
+ViewRegion::~ViewRegion() {
+  for (size_t i = 0; i < mViews.Length(); i++) {
+    [mViews[i] removeFromSuperview];
+  }
+}
+
+bool ViewRegion::UpdateRegion(const LayoutDeviceIntRegion& aRegion,
+                              const nsChildView& aCoordinateConverter, NSView* aContainerView,
+                              NSView* (^aViewCreationCallback)()) {
+  if (mRegion == aRegion) {
+    return false;
+  }
+
+  // We need to construct the required region using as many EffectViews
+  // as necessary. We try to update the geometry of existing views if
+  // possible, or create new ones or remove old ones if the number of
+  // rects in the region has changed.
+
+  nsTArray<NSView*> viewsToRecycle = std::move(mViews);
+  // The mViews array is now empty.
+
+  size_t i = 0;
+  for (auto iter = aRegion.RectIter(); !iter.Done() || i < viewsToRecycle.Length(); i++) {
+    if (!iter.Done()) {
+      NSView* view = nil;
+      NSRect rect = aCoordinateConverter.DevPixelsToCocoaPoints(iter.Get());
+      if (i < viewsToRecycle.Length()) {
+        view = viewsToRecycle[i];
+      } else {
+        view = aViewCreationCallback();
+        [aContainerView addSubview:view];
+
+        // Now that the view is in the view hierarchy, it'll be kept alive by
+        // its superview, so we can drop our reference.
+        [view release];
+      }
+      if (!NSEqualRects(rect, [view frame])) {
+        [view setFrame:rect];
+      }
+      [view setNeedsDisplay:YES];
+      mViews.AppendElement(view);
+      iter.Next();
+    } else {
+      // Our new region is made of fewer rects than the old region, so we can
+      // remove this view. We only have a weak reference to it, so removing it
+      // from the view hierarchy will release it.
+      [viewsToRecycle[i] removeFromSuperview];
+    }
+  }
+
+  mRegion = aRegion;
+  return true;
+}
diff --git a/widget/cocoa/WidgetTraceEvent.mm b/widget/cocoa/WidgetTraceEvent.mm
new file mode 100644
index 0000000000..54fe497e3b
--- /dev/null
+++ b/widget/cocoa/WidgetTraceEvent.mm
@@ -0,0 +1,79 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <Cocoa/Cocoa.h>
+#include "CustomCocoaEvents.h"
+#include <Foundation/NSAutoreleasePool.h>
+#include <mozilla/CondVar.h>
+#include <mozilla/Mutex.h>
+#include "mozilla/WidgetTraceEvent.h"
+
+using mozilla::CondVar;
+using mozilla::Mutex;
+using mozilla::MutexAutoLock;
+
+namespace {
+
+Mutex* sMutex = NULL;
+CondVar* sCondVar = NULL;
+bool sTracerProcessed = false;
+
+}  // namespace
+
+namespace mozilla {
+
+bool InitWidgetTracing() {
+  sMutex = new Mutex("Event tracer thread mutex");
+  sCondVar = new CondVar(*sMutex, "Event tracer thread condvar");
+  return sMutex && sCondVar;
+}
+
+void CleanUpWidgetTracing() {
+  delete sMutex;
+  delete sCondVar;
+  sMutex = NULL;
+  sCondVar = NULL;
+}
+
+// This function is called from the main (UI) thread.
+void SignalTracerThread() {
+  if (!sMutex || !sCondVar) return;
+  MutexAutoLock lock(*sMutex);
+  if (!sTracerProcessed) {
+    sTracerProcessed = true;
+    sCondVar->Notify();
+  }
+}
+
+// This function is called from the background tracer thread.
+bool FireAndWaitForTracerEvent() {
+  MOZ_ASSERT(sMutex && sCondVar, "Tracing not initialized!");
+  NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];
+  MutexAutoLock lock(*sMutex);
+  if (sTracerProcessed) {
+    // Things are out of sync. This is likely because we're in
+    // the middle of shutting down. Just return false and hope the
+    // tracer thread is quitting anyway.
+    return false;
+  }
+
+  // Post an application-defined event to the main thread's event queue
+  // and wait for it to get processed.
+  [NSApp postEvent:[NSEvent otherEventWithType:NSEventTypeApplicationDefined
+                                      location:NSMakePoint(0, 0)
+                                 modifierFlags:0
+                                     timestamp:0
+                                  windowNumber:0
+                                       context:NULL
+                                       subtype:kEventSubtypeTrace
+                                         data1:0
+                                         data2:0]
+           atStart:NO];
+  while (!sTracerProcessed) sCondVar->Wait();
+  sTracerProcessed = false;
+  [pool release];
+  return true;
+}
+
+}  // namespace mozilla
diff --git a/widget/cocoa/components.conf b/widget/cocoa/components.conf
new file mode 100644
index 0000000000..199e5cf255
--- /dev/null
+++ b/widget/cocoa/components.conf
@@ -0,0 +1,168 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+Headers = '/widget/cocoa/nsWidgetFactory.h',
+
+InitFunc = 'nsWidgetCocoaModuleCtor'
+UnloadFunc = 'nsWidgetCocoaModuleDtor'
+
+Classes = [
+    {
+        'cid': '{49f428e8-baf9-4ba3-b1b0-7d2fd3abbcea}',
+        'contract_ids': ['@mozilla.org/widget/parent/clipboard;1'],
+        'interfaces': ['nsIClipboard'],
+        'type': 'nsIClipboard',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'name': 'GfxInfo',
+        'cid': '{d755a760-9f27-11df-0800-200c9a664242}',
+        'contract_ids': ['@mozilla.org/gfx/info;1'],
+        'type': 'mozilla::widget::GfxInfo',
+        'headers': ['/widget/cocoa/GfxInfo.h'],
+        'init_method': 'Init',
+    },
+    {
+        'cid': '{e5170091-c16b-492d-bf00-f45d72470553}',
+        'contract_ids': ['@mozilla.org/parent/filepicker;1'],
+        'type': 'nsFilePicker',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'cid': '{b90f5fdd-c23e-4ad6-a10e-1da8ffe07799}',
+        'contract_ids': ['@mozilla.org/parent/colorpicker;1'],
+        'type': 'nsColorPicker',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'cid': '{2d96b3df-c051-11d1-a827-0040959a28c9}',
+        'contract_ids': ['@mozilla.org/widget/appshell/mac;1'],
+        'legacy_constructor': 'nsAppShellConstructor',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{15cc80a9-5329-4fcb-9a0b-c6cf1440ae51}',
+        'contract_ids': ['@mozilla.org/parent/sound;1'],
+        'type': 'nsSound',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'cid': '{8b5314bc-db01-11d2-96ce-0060b0fb9956}',
+        'contract_ids': ['@mozilla.org/widget/transferable;1'],
+        'type': 'nsTransferable',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{948a0023-e3a7-11d2-96cf-0060b0fb9956}',
+        'contract_ids': ['@mozilla.org/widget/htmlformatconverter;1'],
+        'type': 'nsHTMLFormatConverter',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{77221d5a-1dd2-11b2-8c69-c710f15d2ed5}',
+        'contract_ids': ['@mozilla.org/widget/clipboardhelper;1'],
+        'type': 'nsClipboardHelper',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{9a155bb2-2b67-45de-83e3-13a9dacf8336}',
+        'contract_ids': ['@mozilla.org/widget/parent/dragservice;1'],
+        'type': 'nsDragService',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'cid': '{f0ddedd7-e8d5-4f95-a5b4-0f48f1741b36}',
+        'contract_ids': ['@mozilla.org/gfx/parent/screenmanager;1'],
+        'type': 'mozilla::widget::ScreenManager',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+        'singleton': True,
+    },
+    {
+        'cid': '{d3f69889-e13a-4321-980c-a39332e21f34}',
+        'contract_ids': ['@mozilla.org/gfx/devicecontextspec;1'],
+        'type': 'nsDeviceContextSpecX',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'cid': '{a6cf9129-15b3-11d2-932e-00805f8add32}',
+        'contract_ids': ['@mozilla.org/gfx/printerlist;1'],
+        'type': 'nsPrinterListCUPS',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'cid': '{841387c8-72e6-484b-9296-bf6eea80d58a}',
+        'contract_ids': ['@mozilla.org/gfx/printsettings-service;1'],
+        'type': 'nsPrintSettingsServiceX',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{06beec76-a183-4d9f-85dd-085f26da565a}',
+        'contract_ids': ['@mozilla.org/widget/printdialog-service;1'],
+        'type': 'nsPrintDialogServiceX',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'cid': '{6987230e-0089-4e78-bc5f-1493ee7519fa}',
+        'contract_ids': ['@mozilla.org/widget/useridleservice;1'],
+        'type': 'nsUserIdleServiceX',
+        'singleton': True,
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{84e11f80-ca55-11dd-ad8b-0800200c9a66}',
+        'contract_ids': ['@mozilla.org/system-alerts-service;1'],
+        'type': 'mozilla::OSXNotificationCenter',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{2451baed-8dc3-46d9-9e30-96e1baa03666}',
+        'contract_ids': ['@mozilla.org/widget/macdocksupport;1'],
+        'type': 'nsMacDockSupport',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{74ea4101-a5bb-49bc-9984-66da8b225a37}',
+        'contract_ids': ['@mozilla.org/widget/macfinderprogress;1'],
+        'type': 'nsMacFinderProgress',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{de59fe1a-46c8-490f-b04d-34545acb06c9}',
+        'contract_ids': ['@mozilla.org/widget/macsharingservice;1'],
+        'type': 'nsMacSharingService',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{29046c8f-cba6-4ffa-9141-1685e96c4ea0}',
+        'contract_ids': ['@mozilla.org/widget/macuseractivityupdater;1'],
+        'type': 'nsMacUserActivityUpdater',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{e9096367-ddd9-45e4-b762-49c0c18b7119}',
+        'contract_ids': ['@mozilla.org/widget/mac-web-app-utils;1'],
+        'type': 'nsMacWebAppUtils',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{1f39ae50-b6a0-4b37-90f4-60af614193d8}',
+        'contract_ids': ['@mozilla.org/widget/standalonenativemenu;1'],
+        'type': 'nsStandaloneNativeMenu',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{b6e1a890-b2b8-4883-a65f-9476f6185313}',
+        'contract_ids': ['@mozilla.org/widget/systemstatusbar;1'],
+        'type': 'nsSystemStatusBarCocoa',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{38f396e2-93c9-4a77-aaf7-2d50b9962186}',
+        'contract_ids': ['@mozilla.org/widget/touchbarupdater;1'],
+        'type': 'nsTouchBarUpdater',
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+]
diff --git a/widget/cocoa/crashtests/373122-1-inner.html b/widget/cocoa/crashtests/373122-1-inner.html
new file mode 100644
index 0000000000..5c14166b75
--- /dev/null
+++ b/widget/cocoa/crashtests/373122-1-inner.html
@@ -0,0 +1,39 @@
+<html>
+<head>
+
+<script>
+function boom()
+{
+  document.body.style.position = "fixed"
+  
+  setTimeout(boom2, 1);
+}
+
+function boom2()
+{
+  lappy = document.getElementById("lappy");
+  lappy.style.display = "none"
+
+  setTimeout(boom3, 200);
+}
+
+function boom3()
+{
+  dump("Reloading\n");
+  location.reload();
+}
+
+</script>
+
+
+</head>
+
+
+<body bgcolor="black" onload="boom()">
+
+  <span style="overflow: scroll; display: -moz-box;"></span>
+
+  <embed id="lappy" src="" width=550 height=400 TYPE="application/x-shockwave-flash" ></embed>
+ 
+</body>
+</html>
diff --git a/widget/cocoa/crashtests/373122-1.html b/widget/cocoa/crashtests/373122-1.html
new file mode 100644
index 0000000000..a57e5f4249
--- /dev/null
+++ b/widget/cocoa/crashtests/373122-1.html
@@ -0,0 +1,9 @@
+<html class="reftest-wait">
+<head>
+<script>
+setTimeout('document.documentElement.className = ""', 1000);
+</script>
+<body>
+<iframe src="373122-1-inner.html"></iframe>
+</body>
+</html>
diff --git a/widget/cocoa/crashtests/397209-1.html b/widget/cocoa/crashtests/397209-1.html
new file mode 100644
index 0000000000..554b2dac72
--- /dev/null
+++ b/widget/cocoa/crashtests/397209-1.html
@@ -0,0 +1,7 @@
+<html>
+<head>
+</head>
+<body>
+<button style="width: 8205em;"></button>
+</body>
+</html>
diff --git a/widget/cocoa/crashtests/403296-1.xhtml b/widget/cocoa/crashtests/403296-1.xhtml
new file mode 100644
index 0000000000..800eaa3558
--- /dev/null
+++ b/widget/cocoa/crashtests/403296-1.xhtml
@@ -0,0 +1,10 @@
+<html xmlns="http://www.w3.org/1999/xhtml" 
+      class="reftest-wait"  
+      style="margin: 12em; padding: 20px 10em; opacity: 0.2; font-size: 11.2px; -moz-appearance: toolbar; white-space: nowrap;"><body 
+      style="position: absolute;" 
+      onload="setTimeout(function() { document.body.removeChild(document.getElementById('tr')); document.documentElement.removeAttribute('class'); }, 30);">
+
+xxx
+yyy
+
+<tr id="tr">300</tr></body></html>
diff --git a/widget/cocoa/crashtests/419737-1.html b/widget/cocoa/crashtests/419737-1.html
new file mode 100644
index 0000000000..fe6e4532b4
--- /dev/null
+++ b/widget/cocoa/crashtests/419737-1.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<html>
+<head>
+</head>
+<body>
+<div><span style="-moz-appearance: radio; padding: 15000px;"></span></div>
+</body>
+</html>
diff --git a/widget/cocoa/crashtests/435223-1.html b/widget/cocoa/crashtests/435223-1.html
new file mode 100644
index 0000000000..c7f70860fc
--- /dev/null
+++ b/widget/cocoa/crashtests/435223-1.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<html>
+<head>
+</head>
+<body>
+<div style="min-width: max-content;"><div style="-moz-appearance: button;"><div style="margin: 0 100%;"></div></div></div>
+</body>
+</html>
diff --git a/widget/cocoa/crashtests/444260-1.xhtml b/widget/cocoa/crashtests/444260-1.xhtml
new file mode 100644
index 0000000000..f1a84023df
--- /dev/null
+++ b/widget/cocoa/crashtests/444260-1.xhtml
@@ -0,0 +1,3 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<hbox><button width="7788025414616">S</button></hbox>
+</window>
diff --git a/widget/cocoa/crashtests/444864-1.html b/widget/cocoa/crashtests/444864-1.html
new file mode 100644
index 0000000000..f8bac76e6a
--- /dev/null
+++ b/widget/cocoa/crashtests/444864-1.html
@@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<html>
+<body>
+<div style="padding: 10px;"><input type="button" value="Go" style="letter-spacing: 331989pt;"></div>
+</body>
+</html>
diff --git a/widget/cocoa/crashtests/449111-1.html b/widget/cocoa/crashtests/449111-1.html
new file mode 100644
index 0000000000..4494591803
--- /dev/null
+++ b/widget/cocoa/crashtests/449111-1.html
@@ -0,0 +1,4 @@
+<html>
+<head></head>
+<body><div style="display: -moz-box; word-spacing: 549755813889px;"><button>T </button></div></body>
+</html>
diff --git a/widget/cocoa/crashtests/460349-1.xhtml b/widget/cocoa/crashtests/460349-1.xhtml
new file mode 100644
index 0000000000..cc9b9700c7
--- /dev/null
+++ b/widget/cocoa/crashtests/460349-1.xhtml
@@ -0,0 +1,4 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head></head>
+<body><div><mstyle xmlns="http://www.w3.org/1998/Math/MathML" style="-moz-appearance: button;"/></div></body>
+</html>
diff --git a/widget/cocoa/crashtests/460387-1.html b/widget/cocoa/crashtests/460387-1.html
new file mode 100644
index 0000000000..cab7e7eb32
--- /dev/null
+++ b/widget/cocoa/crashtests/460387-1.html
@@ -0,0 +1,2 @@
+<!DOCTYPE html>
+<html><head></head><body><div style="display: table; padding: 625203mm; -moz-appearance: menulist;"></div></body></html>
diff --git a/widget/cocoa/crashtests/464589-1.html b/widget/cocoa/crashtests/464589-1.html
new file mode 100644
index 0000000000..d25d92315d
--- /dev/null
+++ b/widget/cocoa/crashtests/464589-1.html
@@ -0,0 +1,20 @@
+<html>
+<head>
+<script type="text/javascript">
+
+function boom()
+{
+  var o2 = document.createElement("option");
+  document.getElementById("o1").appendChild(o2);
+  o2.style.padding = "131072cm";
+}
+
+</script>
+</head>
+
+<body onload="boom();">
+
+<select><option id="o1" style="height: 0cm;"></option></select>
+
+</body>
+</html>
diff --git a/widget/cocoa/crashtests/crashtests.list b/widget/cocoa/crashtests/crashtests.list
new file mode 100644
index 0000000000..0559273a43
--- /dev/null
+++ b/widget/cocoa/crashtests/crashtests.list
@@ -0,0 +1,11 @@
+skip-if(!cocoaWidget) load 373122-1.html # bug 1300017
+load 397209-1.html
+load 403296-1.xhtml
+load 419737-1.html
+load 435223-1.html
+load chrome://reftest/content/crashtests/widget/cocoa/crashtests/444260-1.xhtml
+load 444864-1.html
+load 449111-1.html
+load 460349-1.xhtml
+load 460387-1.html
+load 464589-1.html
diff --git a/widget/cocoa/cursors/arrowN.png b/widget/cocoa/cursors/arrowN.png
new file mode 100644
index 0000000000..c65924091a
--- /dev/null
+++ b/widget/cocoa/cursors/arrowN.png
diff --git a/widget/cocoa/cursors/arrowN@2x.png b/widget/cocoa/cursors/arrowN@2x.png
new file mode 100644
index 0000000000..496f856a1d
--- /dev/null
+++ b/widget/cocoa/cursors/arrowN@2x.png
diff --git a/widget/cocoa/cursors/arrowS.png b/widget/cocoa/cursors/arrowS.png
new file mode 100644
index 0000000000..3975e0837b
--- /dev/null
+++ b/widget/cocoa/cursors/arrowS.png
diff --git a/widget/cocoa/cursors/arrowS@2x.png b/widget/cocoa/cursors/arrowS@2x.png
new file mode 100644
index 0000000000..c7f817afd4
--- /dev/null
+++ b/widget/cocoa/cursors/arrowS@2x.png
diff --git a/widget/cocoa/cursors/cell.png b/widget/cocoa/cursors/cell.png
new file mode 100644
index 0000000000..1400d93f6e
--- /dev/null
+++ b/widget/cocoa/cursors/cell.png
diff --git a/widget/cocoa/cursors/cell@2x.png b/widget/cocoa/cursors/cell@2x.png
new file mode 100644
index 0000000000..5a1543b16b
--- /dev/null
+++ b/widget/cocoa/cursors/cell@2x.png
diff --git a/widget/cocoa/cursors/colResize.png b/widget/cocoa/cursors/colResize.png
new file mode 100644
index 0000000000..ef4b24936b
--- /dev/null
+++ b/widget/cocoa/cursors/colResize.png
diff --git a/widget/cocoa/cursors/colResize@2x.png b/widget/cocoa/cursors/colResize@2x.png
new file mode 100644
index 0000000000..d868ee6b57
--- /dev/null
+++ b/widget/cocoa/cursors/colResize@2x.png
diff --git a/widget/cocoa/cursors/help.png b/widget/cocoa/cursors/help.png
new file mode 100644
index 0000000000..7070b4b7bc
--- /dev/null
+++ b/widget/cocoa/cursors/help.png
diff --git a/widget/cocoa/cursors/help@2x.png b/widget/cocoa/cursors/help@2x.png
new file mode 100644
index 0000000000..7ddf157cd3
--- /dev/null
+++ b/widget/cocoa/cursors/help@2x.png
diff --git a/widget/cocoa/cursors/move.png b/widget/cocoa/cursors/move.png
new file mode 100644
index 0000000000..f6291500a4
--- /dev/null
+++ b/widget/cocoa/cursors/move.png
diff --git a/widget/cocoa/cursors/move@2x.png b/widget/cocoa/cursors/move@2x.png
new file mode 100644
index 0000000000..d094ce7a15
--- /dev/null
+++ b/widget/cocoa/cursors/move@2x.png
diff --git a/widget/cocoa/cursors/rowResize.png b/widget/cocoa/cursors/rowResize.png
new file mode 100644
index 0000000000..7f68a4007c
--- /dev/null
+++ b/widget/cocoa/cursors/rowResize.png
diff --git a/widget/cocoa/cursors/rowResize@2x.png b/widget/cocoa/cursors/rowResize@2x.png
new file mode 100644
index 0000000000..e0987a3b95
--- /dev/null
+++ b/widget/cocoa/cursors/rowResize@2x.png
diff --git a/widget/cocoa/cursors/sizeNE.png b/widget/cocoa/cursors/sizeNE.png
new file mode 100644
index 0000000000..fd71dea6ab
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNE.png
diff --git a/widget/cocoa/cursors/sizeNE@2x.png b/widget/cocoa/cursors/sizeNE@2x.png
new file mode 100644
index 0000000000..400f5fe46f
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNE@2x.png
diff --git a/widget/cocoa/cursors/sizeNESW.png b/widget/cocoa/cursors/sizeNESW.png
new file mode 100644
index 0000000000..5b2c300f4a
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNESW.png
diff --git a/widget/cocoa/cursors/sizeNESW@2x.png b/widget/cocoa/cursors/sizeNESW@2x.png
new file mode 100644
index 0000000000..7299b98be1
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNESW@2x.png
diff --git a/widget/cocoa/cursors/sizeNS.png b/widget/cocoa/cursors/sizeNS.png
new file mode 100644
index 0000000000..12b1602f14
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNS.png
diff --git a/widget/cocoa/cursors/sizeNS@2x.png b/widget/cocoa/cursors/sizeNS@2x.png
new file mode 100644
index 0000000000..0dc7d15d75
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNS@2x.png
diff --git a/widget/cocoa/cursors/sizeNW.png b/widget/cocoa/cursors/sizeNW.png
new file mode 100644
index 0000000000..57d270e0db
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNW.png
diff --git a/widget/cocoa/cursors/sizeNW@2x.png b/widget/cocoa/cursors/sizeNW@2x.png
new file mode 100644
index 0000000000..312ee61ce4
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNW@2x.png
diff --git a/widget/cocoa/cursors/sizeNWSE.png b/widget/cocoa/cursors/sizeNWSE.png
new file mode 100644
index 0000000000..d33c2486e4
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNWSE.png
diff --git a/widget/cocoa/cursors/sizeNWSE@2x.png b/widget/cocoa/cursors/sizeNWSE@2x.png
new file mode 100644
index 0000000000..ecf1438265
--- /dev/null
+++ b/widget/cocoa/cursors/sizeNWSE@2x.png
diff --git a/widget/cocoa/cursors/sizeSE.png b/widget/cocoa/cursors/sizeSE.png
new file mode 100644
index 0000000000..1689138419
--- /dev/null
+++ b/widget/cocoa/cursors/sizeSE.png
diff --git a/widget/cocoa/cursors/sizeSE@2x.png b/widget/cocoa/cursors/sizeSE@2x.png
new file mode 100644
index 0000000000..7abce00fd5
--- /dev/null
+++ b/widget/cocoa/cursors/sizeSE@2x.png
diff --git a/widget/cocoa/cursors/sizeSW.png b/widget/cocoa/cursors/sizeSW.png
new file mode 100644
index 0000000000..5eadafb054
--- /dev/null
+++ b/widget/cocoa/cursors/sizeSW.png
diff --git a/widget/cocoa/cursors/sizeSW@2x.png b/widget/cocoa/cursors/sizeSW@2x.png
new file mode 100644
index 0000000000..b9ad862aa5
--- /dev/null
+++ b/widget/cocoa/cursors/sizeSW@2x.png
diff --git a/widget/cocoa/cursors/vtIBeam.png b/widget/cocoa/cursors/vtIBeam.png
new file mode 100644
index 0000000000..4609922319
--- /dev/null
+++ b/widget/cocoa/cursors/vtIBeam.png
diff --git a/widget/cocoa/cursors/vtIBeam@2x.png b/widget/cocoa/cursors/vtIBeam@2x.png
new file mode 100644
index 0000000000..a001362b04
--- /dev/null
+++ b/widget/cocoa/cursors/vtIBeam@2x.png
diff --git a/widget/cocoa/cursors/zoomIn.png b/widget/cocoa/cursors/zoomIn.png
new file mode 100644
index 0000000000..7ddfd4056d
--- /dev/null
+++ b/widget/cocoa/cursors/zoomIn.png
diff --git a/widget/cocoa/cursors/zoomIn@2x.png b/widget/cocoa/cursors/zoomIn@2x.png
new file mode 100644
index 0000000000..b1b844fa8c
--- /dev/null
+++ b/widget/cocoa/cursors/zoomIn@2x.png
diff --git a/widget/cocoa/cursors/zoomOut.png b/widget/cocoa/cursors/zoomOut.png
new file mode 100644
index 0000000000..ebacf25889
--- /dev/null
+++ b/widget/cocoa/cursors/zoomOut.png
diff --git a/widget/cocoa/cursors/zoomOut@2x.png b/widget/cocoa/cursors/zoomOut@2x.png
new file mode 100644
index 0000000000..5f84b767ec
--- /dev/null
+++ b/widget/cocoa/cursors/zoomOut@2x.png
diff --git a/widget/cocoa/docs/index.md b/widget/cocoa/docs/index.md
new file mode 100644
index 0000000000..cda6b2e349
--- /dev/null
+++ b/widget/cocoa/docs/index.md
@@ -0,0 +1,9 @@
+# Firefox on macOS
+
+```{toctree}
+:titlesonly:
+:maxdepth: 1
+:glob:
+
+*
+```
diff --git a/widget/cocoa/docs/macos-apis.md b/widget/cocoa/docs/macos-apis.md
new file mode 100644
index 0000000000..20fa9b6f36
--- /dev/null
+++ b/widget/cocoa/docs/macos-apis.md
@@ -0,0 +1,188 @@
+# Using macOS APIs
+
+With each new macOS release, new APIs are added. Due to the wide range of platforms that Firefox runs on,
+and due to the [wide range of SDKs that we support building with](sdks.md#supported-sdks),
+using macOS APIs in Firefox requires some extra care.
+
+## Availability of APIs, and runtime checks
+
+First of all, if you use an API that is supported by all versions of macOS that Firefox runs on,
+i.e. 10.9 and above, then you don't need to worry about anything:
+The API declaration will be present in any of the supported SDKs, and you don't need any runtime checks.
+
+If you want to use a macOS API that was added after 10.9, then you have to have a runtime check.
+This requirement is completely independent of what SDK is being used for building.
+
+The runtime check [should have the following form](https://developer.apple.com/documentation/macos_release_notes/macos_mojave_10_14_release_notes/appkit_release_notes_for_macos_10_14?language=objc#3014609)
+(replace `10.14` with the appropriate version):
+
+```objc++
+if (@available(macOS 10.14, *)) {
+    // Code for macOS 10.14 or later
+} else {
+    // Code for versions earlier than 10.14.
+}
+```
+
+`@available` guards can be used in Objective-C(++) code.
+(In C++ code, you can use [these `nsCocoaFeatures` methods](https://searchfox.org/mozilla-central/rev/9ad88f80aeedcd3cd7d7f63be07f577861727054/widget/cocoa/nsCocoaFeatures.h#21-27) instead.)
+
+For each API, the API declarations in the SDK headers are annotated with `API_AVAILABLE` macros.
+For example, the definition of the `NSVisualEffectMaterial` enum looks like this:
+
+```objc++
+typedef NS_ENUM(NSInteger, NSVisualEffectMaterial) {
+    NSVisualEffectMaterialTitlebar = 3,
+    NSVisualEffectMaterialSelection = 4,
+    NSVisualEffectMaterialMenu API_AVAILABLE(macos(10.11)) = 5,
+   // [...]
+    NSVisualEffectMaterialSheet API_AVAILABLE(macos(10.14)) = 11,
+   // [...]
+} API_AVAILABLE(macos(10.10));
+```
+
+The compiler understands these annotations and makes sure that you wrap all uses of the annotated APIs
+in appropriate `@available` runtime checks.
+
+### Frameworks
+
+In some rare cases, you need functionality from frameworks that are not available on all supported macOS versions.
+Examples of this are `Metal.framework` (added in 10.11) and `MediaPlayer.framework` (added in 10.12.2).
+
+In that case, you can either `dlopen` your framework at runtime ([like we do for MediaPlayer](https://searchfox.org/mozilla-central/rev/9ad88f80aeedcd3cd7d7f63be07f577861727054/widget/cocoa/MediaPlayerWrapper.mm#21-27)),
+or you can [use `-weak_framework`](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPFrameworks/Concepts/WeakLinking.html#//apple_ref/doc/uid/20002378-107026)
+[like we do for Metal](https://searchfox.org/mozilla-central/rev/9ad88f80aeedcd3cd7d7f63be07f577861727054/toolkit/library/moz.build#301-304):
+
+```python
+if CONFIG['OS_ARCH'] == 'Darwin':
+    OS_LIBS += [
+        # Link to Metal as required by the Metal gfx-hal backend
+        '-weak_framework Metal',
+    ]
+```
+
+## Using new APIs with old SDKs
+
+If you want to use an API that was introduced after 10.12, you now have one extra thing to worry about.
+In addition to the runtime check [described in the previous section](#using-macos-apis), you also
+have to jump through extra hoops in order to allow the build to succeed, because
+[our build target for Firefox has to remain at 10.12 in order for Firefox to run on macOS versions all the way down to macOS 10.12](sdks.md#supported-sdks).
+
+In order to make the compiler accept your code, you will need to copy some amount of the API declaration
+into your own code. Copy it from the newest recent SDK you can get your hands on.
+The exact procedure varies based on the type of API (enum, objc class, method, etc.),
+but the general approach looks like this:
+
+```objc++
+#if !defined(MAC_OS_VERSION_12_0) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_12_0
+@interface NSScreen (NSScreen12_0)
+// https://developer.apple.com/documentation/appkit/nsscreen/3882821-safeareainsets?language=objc&changes=latest_major
+@property(readonly) NSEdgeInsets safeAreaInsets;
+@end
+#endif
+```
+
+See the [Supporting Multiple SDKs](sdks.md#supporting-multiple-sdks) docs for more information on the `MAC_OS_X_VERSION_MAX_ALLOWED` macro.
+
+Keep these three things in mind:
+
+ - Copy only what you need.
+ - Wrap your declaration in `MAC_OS_X_VERSION_MAX_ALLOWED` checks so that, if an SDK is used that
+   already contains these declarations, your declaration does not conflict with the declaration in the SDK.
+ - Include the `API_AVAILABLE` annotations so that the compiler can protect you from accidentally
+   calling the API on unsupported macOS versions.
+
+Our current code does not always follow the `API_AVAILABLE` advice, but it should.
+
+### Enum types and C structs
+
+If you need a new enum type or C struct, copy the entire type declaration and wrap it in the appropriate ifdefs. Example:
+
+```objc++
+#if !defined(MAC_OS_X_VERSION_10_12_2) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_12_2
+typedef NS_ENUM(NSUInteger, MPNowPlayingPlaybackState) {
+    MPNowPlayingPlaybackStateUnknown = 0,
+    MPNowPlayingPlaybackStatePlaying,
+    MPNowPlayingPlaybackStatePaused,
+    MPNowPlayingPlaybackStateStopped,
+    MPNowPlayingPlaybackStateInterrupted
+} MP_API(ios(11.0), tvos(11.0), macos(10.12.2), watchos(5.0));
+#endif
+```
+### New enum values for existing enum type
+
+If the enum type itself already exists, but gained a new value, define the value in an unnamed enum:
+
+```objc++
+#if !defined(MAC_OS_X_VERSION_10_12) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_12
+enum { NSVisualEffectMaterialSelection = 4 };
+#endif
+```
+
+(This is an example of an interesting case: `NSVisualEffectMaterialSelection` is available starting with
+macOS 10.10, but it's only defined in SDKs starting with the 10.12 SDK.)
+
+### Objective-C classes
+
+For a new Objective-C class, copy the entire `@interface` declaration and wrap it in the appropriate ifdefs.
+
+I haven't personally tested this. If this does not compile (or maybe link?), you can use the following workaround:
+
+ - Define your methods and properties as a category on `NSObject`.
+ - Look up the class at runtime using `NSClassFromString()`.
+ - If you need to create a subclass, do it at runtime using `objc_allocateClassPair` and `class_addMethod`.
+   [Here's an example of that.](https://searchfox.org/mozilla-central/rev/9ad88f80aeedcd3cd7d7f63be07f577861727054/widget/cocoa/VibrancyManager.mm#44-60)
+
+### Objective-C properties and methods on an existing class
+
+If an Objective-C class that already exists gains a new method or property, you can "add" it to the
+existing class declaration with the help of a [category](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/CustomizingExistingClasses/CustomizingExistingClasses.html):
+
+```objc++
+@interface ExistingClass (YourMadeUpCategoryName)
+// methods and properties here
+@end
+```
+
+### Functions
+
+With free-standing functions I'm not entirely sure what to do.
+In theory, copying the declarations from the new SDK headers should work. Example:
+
+```objc++
+extern "C" {
+  __attribute__((warn_unused_result)) bool
+SecTrustEvaluateWithError(SecTrustRef trust, CFErrorRef _Nullable * _Nullable CF_RETURNS_RETAINED error)
+    API_AVAILABLE(macos(10.14), ios(12.0), tvos(12.0), watchos(5.0));
+
+  __nullable
+CFDataRef SecCertificateCopyNormalizedSubjectSequence(SecCertificateRef certificate)
+    __OSX_AVAILABLE_STARTING(__MAC_10_12_4, __IPHONE_10_3);
+}
+```
+
+I'm not sure what the linker or the dynamic linker do when the symbol is not available.
+Does this require [`__attribute__((weak_import))` annotations](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPFrameworks/Concepts/WeakLinking.html#//apple_ref/doc/uid/20002378-107262-CJBJAEID)?
+
+And maybe this is where .tbd files in the SDK come in? So that the linker knows which symbols to allow?
+So then that part cannot be worked around by copying code from headers.
+
+Anyway, what always works is the pure runtime approach:
+
+ 1. Define types for the functions you need, but not the functions themselves.
+ 2. At runtime, look up the functions using `dlsym`.
+
+## Notes on Rust
+
+If you call macOS APIs from Rust code, you're kind of on your own. Apple does not provide any Rust
+"headers", so there isn't really an SDK to speak of. So you have to supply your own API declarations
+anyway, regardless of what SDK is being used for building.
+
+In a way, you're side-stepping some of the build time trouble. You don't need to worry about any
+`#ifdefs` because there are no system headers you could conflict with.
+
+On the other hand, you still need to worry about API availability at runtime.
+And in Rust, there are no [availability attributes](https://clang.llvm.org/docs/AttributeReference.html#availability)
+on your API declarations, and there are no
+[`@available` runtime check helpers](https://clang.llvm.org/docs/LanguageExtensions.html#objective-c-available),
+and the compiler cannot warn you if you call APIs outside of availability checks.
diff --git a/widget/cocoa/docs/sdks.md b/widget/cocoa/docs/sdks.md
new file mode 100644
index 0000000000..a7fefa7e51
--- /dev/null
+++ b/widget/cocoa/docs/sdks.md
@@ -0,0 +1,227 @@
+# A primer on macOS SDKs
+
+## Overview
+
+A macOS SDK is an on-disk directory that contains header files and meta information for macOS APIs.
+Apple distributes SDKs as part of the Xcode app bundle. Each Xcode version comes with one macOS SDK,
+the SDK for the most recent released version of macOS at the time of the Xcode release.
+The SDK is located at `/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk`.
+
+Compiling Firefox for macOS requires a macOS SDK. The build system bootstraps an adequate SDK by
+default, but you can select a different SDK using the `mozconfig` option `--with-macos-sdk`:
+
+```text
+ac_add_options --with-macos-sdk=/Users/username/SDKs/MacOSX11.3.sdk
+```
+
+## Supported SDKs
+
+First off, Firefox runs on 10.12 and above. This is called the "minimum deployment target" and is
+independent of the SDK version.
+
+Our official Firefox builds compiled in CI (continuous integration) currently use the 13.3 SDK (last updated in [bug 1833998](https://bugzilla.mozilla.org/show_bug.cgi?id=1833998)). This is also the minimum supported SDK version for local builds.
+
+Compiling with different SDKs breaks from time to time. Such breakages should be [reported in Bugzilla](https://bugzilla.mozilla.org/enter_bug.cgi?blocked=mach-busted&bug_type=defect&cc=:spohl,:mstange&component=General&form_name=enter_bug&keywords=regression&op_sys=macOS&product=Firefox%20Build%20System&rep_platform=All) and fixed quickly.
+
+## Obtaining SDKs
+
+Sometimes you need an SDK that's different from the one in your Xcode.app, for example
+to check whether your code change breaks building with other SDKs, or to verify the
+runtime behavior with the SDK used for CI builds.
+
+The easy but slightly questionable way to obtain an SDK is to download it from a public github repo.
+
+Here's another option:
+
+ 1. Have your Apple ID login details ready, and bring enough time and patience for a 5GB download.
+ 2. Check [these tables in the Xcode wikipedia article](https://en.wikipedia.org/wiki/Xcode#Xcode_7.0_-_10.x_(since_Free_On-Device_Development))
+    and find an Xcode version that contains the SDK you need.
+ 3. Look up the Xcode version number on [xcodereleases.com](https://xcodereleases.com/) and click the Download link for it.
+ 4. Log in with your Apple ID. Then the download should start.
+ 5. Wait for the 5GB Xcode_*.xip download to finish.
+ 6. Open the downloaded xip file. This will extract the Xcode.app bundle.
+ 7. Inside the app bundle, the SDK is at `Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk`.
+
+## Effects of the SDK version
+
+An SDK only contains declarations of APIs. It does not contain the implementations for these APIs.
+
+The implementation of an API is provided by the OS that the app runs on. It is supplied at runtime,
+when your app starts up, by the dynamic linker. For example, the AppKit implementation comes
+from `/System/Library/Frameworks/AppKit.framework` from the OS that the app is run on, regardless
+of what SDK was used when compiling the app.
+
+In other words, building with a macOS SDK of a higher version doesn't magically make new APIs available
+when running on older versions of macOS. And, conversely, building with a lower macOS SDK doesn't limit
+which APIs you can use if your app is run on a newer version of macOS, assuming you manage to convince the
+compiler to accept your code.
+
+The SDK used for building an app determines three things:
+
+ 1. Whether your code compiles at all,
+ 2. which range of macOS versions your app can run on (available deployment targets), and
+ 3. certain aspects of runtime behavior.
+
+The first is straightforward: An SDK contains header files. If you call an API that's not declared
+anywhere - neither in a header file nor in your own code - then your compiler will emit an error.
+(Special case: Calling an unknown Objective-C method usually only emits a warning, not an error.)
+
+The second aspect, available deployment targets, is usually not worth worrying about:
+SDKs have large ranges of supported macOS deployment targets.
+For example, the 10.15 SDK supports running your app on macOS versions all the way back to 10.6.
+This information is written down in the SDK's `SDKSettings.plist`.
+
+The third aspect, varying runtime behavior, is perhaps the most insidious and surprising aspect, and is described
+in the next section.
+
+## Runtime differences based on macOS SDK version
+
+When a new version of macOS is released, existing APIs can change their behavior.
+These changes are usually described in the AppKit release notes:
+
+ - [macOS 10.15 release notes](https://developer.apple.com/documentation/macos_release_notes/macos_catalina_10_15_release_notes?language=objc)
+ - [macOS 10.14 AppKit release notes](https://developer.apple.com/documentation/macos_release_notes/macos_mojave_10_14_release_notes/appkit_release_notes_for_macos_10_14?language=objc)
+ - [macOS 10.13 AppKit release notes](https://developer.apple.com/library/archive/releasenotes/AppKit/RN-AppKit/)
+ - [macOS 10.12 and older AppKit release notes](https://developer.apple.com/library/archive/releasenotes/AppKit/RN-AppKitOlderNotes/)
+
+Sometimes, these differences in behavior have the potential to break existing apps. In those instances,
+Apple often provides the old (compatible) behavior until the app is re-built with the new SDK, expecting
+developers to update their apps so that they work with the new behavior, at the same time as
+they update to the new SDK.
+
+Here's an [example from the 10.13 release notes](https://developer.apple.com/library/archive/releasenotes/AppKit/RN-AppKit/#10_13NSCollectionView%20Responsive%20Scrolling):
+
+> Responsive Scrolling in NSCollectionViews is enabled only for apps linked on or after macOS 10.13.
+
+Here, "linked on or after macOS 10.13" means "linked against the macOS 10.13 SDK or newer".
+
+Apple's expectation is that you upgrade to the new macOS version when it is released, download a new
+Xcode version when it is released, synchronize these updates across the machines of all developers
+that work on your app, use the SDK in the newest Xcode to compile your app, and make changes to your
+app to be compatible with any behavior changes whenever you update Xcode.
+This expectation does not always match reality. It definitely doesn't match what we're doing with Firefox.
+
+For Firefox, SDK-dependent compatibility behaviors mean that developers who build Firefox locally
+can see different runtime behavior than the users of our CI builds, if they use a different SDK than
+the SDK used in CI.
+That is, unless we change the Firefox code so that it has the same behavior regardless of SDK version.
+Often this can be achieved by using APIs in a way that's more in line with the API's recommended use.
+
+For example, we've had cases of
+[broken placeholder text in search fields](https://bugzilla.mozilla.org/show_bug.cgi?id=1273106),
+[missing](https://bugzilla.mozilla.org/show_bug.cgi?id=941325) or [double-drawn focus rings](https://searchfox.org/mozilla-central/rev/9ad88f80aeedcd3cd7d7f63be07f577861727054/widget/cocoa/nsNativeThemeCocoa.mm#149-169),
+[a startup crash](https://bugzilla.mozilla.org/show_bug.cgi?id=1516437),
+[fully black windows](https://bugzilla.mozilla.org/show_bug.cgi?id=1494022),
+[fully gray windows](https://bugzilla.mozilla.org/show_bug.cgi?id=1576113#c4),
+[broken vibrancy](https://bugzilla.mozilla.org/show_bug.cgi?id=1475694), and
+[broken colors in dark mode](https://bugzilla.mozilla.org/show_bug.cgi?id=1578917).
+
+In most of these cases, the breakage was either very minor, or it was caused by Firefox doing things
+that were explicitly discouraged, like creating unexpected NSView hierarchies, or relying on unspecified
+implementation details. (With one exception: In 10.14, HiDPI-aware `NSOpenGLContext` rendering in
+layer-backed windows simply broke.)
+
+And in all of these cases, it was the SDK-dependent compatibility behavior that protected our users from being
+exposed to the breakage. Our CI builds continued to work because they were built with an older SDK.
+
+We have addressed all known cases of breakage when building Firefox with newer SDKs.
+I am not aware of any current instances of this problem as of this writing (June 2020).
+
+For more information about how these compatibility tricks work,
+read the [Overriding SDK-dependent runtime behavior](#overriding-sdk-dependent-runtime-behavior) section.
+
+## Supporting multiple SDKs
+
+As described under [Supported SDKs](#supported-sdks), Firefox can be built with a wide variety of SDK versions.
+
+This ability comes at the cost of some manual labor; it requires some well-placed `#ifdefs` and
+copying of header definitions.
+
+Every SDK defines the macro `MAC_OS_X_VERSION_MAX_ALLOWED` with a value that matches the SDK version,
+in the SDK's `AvailabilityMacros.h` header. This header also defines version constants like `MAC_OS_X_VERSION_10_12`.
+For example, I have a version of the 10.12 SDK which contains the line
+
+```cpp
+#define MAC_OS_X_VERSION_MAX_ALLOWED MAC_OS_X_VERSION_10_12_4
+```
+
+The name `MAC_OS_X_VERSION_MAX_ALLOWED` is rather misleading; a better name would be
+`MAC_OS_X_VERSION_MAX_KNOWN_BY_SDK`. Compiling with an old SDK *does not* prevent apps from running
+on newer versions of macOS.
+
+With the help of the `MAC_OS_X_VERSION_MAX_ALLOWED` macro, we can make our code adapt to the SDK that's
+being used. Here's [an example](https://searchfox.org/mozilla-central/rev/9ad88f80aeedcd3cd7d7f63be07f577861727054/toolkit/xre/MacApplicationDelegate.mm#345-351) where the 10.14 SDK changed the signature of
+[an `NSApplicationDelegate` method](https://developer.apple.com/documentation/appkit/nsapplicationdelegate/1428471-application?language=objc):
+
+```objc++
+- (BOOL)application:(NSApplication*)application
+    continueUserActivity:(NSUserActivity*)userActivity
+#if defined(MAC_OS_X_VERSION_10_14) && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_14
+      restorationHandler:(void (^)(NSArray<id<NSUserActivityRestoring>>*))restorationHandler {
+#else
+      restorationHandler:(void (^)(NSArray*))restorationHandler {
+#endif
+  ...
+}
+```
+
+We can also use this macro to supply missing API definitions in such a way that
+they don't conflict with the definitions from the SDK.
+This is described in the "Using macOS APIs" document, under [Using new APIs with old SDKs](./macos-apis.md#using-new-apis-with-old-sdks).
+
+## Overriding SDK-dependent runtime behavior
+
+This section contains some more details on the compatibility tricks that cause different runtime
+behavior dependent on the SDK, as described in
+[Runtime differences based on macOS SDK version](#runtime-differences-based-on-macos-sdk-version).
+
+### How it works
+
+AppKit is the one system framework I know of that employs these tricks. Let's explore how AppKit makes this work,
+by going back to the [NSCollectionView example](https://developer.apple.com/library/archive/releasenotes/AppKit/RN-AppKit/#10_13NSCollectionView%20Responsive%20Scrolling) from above:
+
+> Responsive Scrolling in NSCollectionViews is enabled only for apps linked on or after macOS 10.13.
+
+For each of these SDK-dependent behavior differences, both the old and the new behavior are implemented
+in the version of AppKit that ships with the new macOS version.
+At runtime, AppKit selects one of the behaviors based on the SDK version, with a call to
+`_CFExecutableLinkedOnOrAfter()`. This call checks the SDK version of the main executable of the
+process that's running AppKit code; in our case that's the `firefox` or `plugin-container` executable.
+The SDK version is stored in the mach-o headers of the executable by the linker.
+
+One interesting design aspect of AppKit's compatibility tricks is the fact that most of these behavior differences
+can be toggled with a "user default" preference.
+For example, the "responsive scrolling in NSCollectionViews" behavior change can be controlled with
+a user default with the name "NSCollectionViewPrefetchingEnabled".
+The SDK check only happens if "NSCollectionViewPrefetchingEnabled" is not set to either YES or NO.
+
+More precisely, this example works as follows:
+
+ - `-[NSCollectionView prepareContentInRect:]` is the function that supports both the old and the new behavior.
+ - It calls `_NSGetBoolAppConfig` for the value "NSCollectionViewPrefetchingEnabled", and also supplies a "default
+   value function".
+ - If the user default is not set, the default value function is called. This function has the name
+   `NSCollectionViewPrefetchingEnabledDefaultValueFunction`.
+ - `NSCollectionViewPrefetchingEnabledDefaultValueFunction` calls `_CFExecutableLinkedOnOrAfter(13)`.
+
+You can find many similar toggles if you list the AppKit symbols that end in `DefaultValueFunction`,
+for example by executing `nm /System/Library/Frameworks/AppKit.framework/AppKit | grep DefaultValueFunction`.
+
+### Overriding SDK-dependent runtime behavior
+
+You can set these preferences programmatically, in a way that `_NSGetBoolAppConfig()` can pick them up,
+for example with [`registerDefaults`](https://developer.apple.com/documentation/foundation/nsuserdefaults/1417065-registerdefaults?language=objc)
+or like this:
+
+```objc++
+[[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"NSViewAllowsRootLayerBacking"];
+```
+
+The AppKit release notes mention this ability but ask for it to only be used for debugging purposes:
+
+> In some cases, we provide defaults (preferences) settings which can be used to get the old or new behavior,
+> independent of what system an application was built against. Often these preferences are provided for
+> debugging purposes only; in some cases the preferences can be used to globally modify the behavior
+> of an application by registering the values (do it somewhere very early, with `-[NSUserDefaults registerDefaults:]`).
+
+It's interesting that they mention this at all because, as far as I can tell, none of these values are documented.
diff --git a/widget/cocoa/metrics.yaml b/widget/cocoa/metrics.yaml
new file mode 100644
index 0000000000..d26bfd21d3
--- /dev/null
+++ b/widget/cocoa/metrics.yaml
@@ -0,0 +1,28 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Adding a new metric? We have docs for that!
+# https://firefox-source-docs.mozilla.org/toolkit/components/glean/user/new_definitions_file.html
+
+---
+$schema: moz://mozilla.org/schemas/glean/metrics/2-0-0
+$tags:
+  - 'Core :: Widget: Cocoa'
+
+startup:
+  is_restored_by_macos:
+    type: boolean
+    description: >
+      Recorded on every launch of a Firefox install on macOS, with a boolean
+      value indicating whether Firefox was restored by macOS or if it was
+      manually launched by a user.
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=639707
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=639707
+    data_sensitivity:
+      - technical
+    notification_emails:
+      - spohl@mozilla.com
+    expires: 116
diff --git a/widget/cocoa/moz.build b/widget/cocoa/moz.build
new file mode 100644
index 0000000000..c996e62ad6
--- /dev/null
+++ b/widget/cocoa/moz.build
@@ -0,0 +1,182 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+with Files("**"):
+    BUG_COMPONENT = ("Core", "Widget: Cocoa")
+    SCHEDULES.exclusive = ["macosx"]
+
+with Files("*TextInput*"):
+    BUG_COMPONENT = ("Core", "DOM: UI Events & Focus Handling")
+
+XPIDL_SOURCES += [
+    "nsPIWidgetCocoa.idl",
+]
+
+XPIDL_MODULE = "widget_cocoa"
+
+EXPORTS += [
+    "CFTypeRefPtr.h",
+    "DesktopBackgroundImage.h",
+    "MediaHardwareKeysEventSourceMac.h",
+    "MediaHardwareKeysEventSourceMacMediaCenter.h",
+    "mozView.h",
+    "nsBidiKeyboard.h",
+    "nsChangeObserver.h",
+    "nsCocoaFeatures.h",
+    "nsCocoaUtils.h",
+    "SDKDeclarations.h",
+]
+
+UNIFIED_SOURCES += [
+    "AppearanceOverride.mm",
+    "GfxInfo.mm",
+    "MOZIconHelper.mm",
+    "MOZMenuOpeningCoordinator.mm",
+    "NativeKeyBindings.mm",
+    "NativeMenuMac.mm",
+    "NativeMenuSupport.mm",
+    "nsAppShell.mm",
+    "nsBidiKeyboard.mm",
+    "nsCocoaFeatures.mm",
+    "nsCocoaUtils.mm",
+    "nsCocoaWindow.mm",
+    "nsColorPicker.mm",
+    "nsCursorManager.mm",
+    "nsDeviceContextSpecX.mm",
+    "nsFilePicker.mm",
+    "nsLookAndFeel.mm",
+    "nsMacCursor.mm",
+    "nsMacDockSupport.mm",
+    "nsMacFinderProgress.mm",
+    "nsMacSharingService.mm",
+    "nsMacUserActivityUpdater.mm",
+    "nsMacWebAppUtils.mm",
+    "nsMenuBarX.mm",
+    "nsMenuGroupOwnerX.mm",
+    "nsMenuItemIconX.mm",
+    "nsMenuItemX.mm",
+    "nsMenuUtilsX.mm",
+    "nsMenuX.mm",
+    "nsPrintDialogX.mm",
+    "nsPrintSettingsServiceX.mm",
+    "nsPrintSettingsX.mm",
+    "nsSound.mm",
+    "nsStandaloneNativeMenu.mm",
+    "nsSystemStatusBarCocoa.mm",
+    "nsToolkit.mm",
+    "nsTouchBar.mm",
+    "nsTouchBarInput.mm",
+    "nsTouchBarInputIcon.mm",
+    "nsTouchBarUpdater.mm",
+    "nsUserIdleServiceX.mm",
+    "nsWidgetFactory.mm",
+    "nsWindowMap.mm",
+    "OSXNotificationCenter.mm",
+    "ScreenHelperCocoa.mm",
+    "TextInputHandler.mm",
+    "TextRecognition.mm",
+    "VibrancyManager.mm",
+    "ViewRegion.mm",
+    "WidgetTraceEvent.mm",
+]
+
+# These files cannot be built in unified mode because they cause symbol conflicts
+SOURCES += [
+    "DesktopBackgroundImage.mm",
+    "MediaHardwareKeysEventSourceMac.mm",
+    "MediaHardwareKeysEventSourceMacMediaCenter.mm",
+    "MediaKeysEventSourceFactory.cpp",
+    "nsChildView.mm",
+    "nsClipboard.mm",
+    "nsDragService.mm",
+    "nsNativeThemeCocoa.mm",
+]
+
+if not CONFIG["RELEASE_OR_BETA"] or CONFIG["MOZ_DEBUG"]:
+    SOURCES += [
+        "nsSandboxViolationSink.mm",
+    ]
+
+XPCOM_MANIFESTS += [
+    "components.conf",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"
+LOCAL_INCLUDES += [
+    "/dom/events",
+    "/dom/media/platforms/apple",
+    "/layout/base",
+    "/layout/forms",
+    "/layout/generic",
+    "/layout/style",
+    "/layout/xul",
+    "/widget",
+    "/widget/headless",
+]
+
+if CONFIG["MOZ_ENABLE_SKIA_PDF"]:
+    # Skia includes because widget code includes PrintTargetSkPDF.h, and that
+    # includes skia headers.
+    LOCAL_INCLUDES += CONFIG["SKIA_INCLUDES"]
+
+RESOURCE_FILES.cursors += [
+    "cursors/arrowN.png",
+    "cursors/arrowN@2x.png",
+    "cursors/arrowS.png",
+    "cursors/arrowS@2x.png",
+    "cursors/cell.png",
+    "cursors/cell@2x.png",
+    "cursors/colResize.png",
+    "cursors/colResize@2x.png",
+    "cursors/help.png",
+    "cursors/help@2x.png",
+    "cursors/move.png",
+    "cursors/move@2x.png",
+    "cursors/rowResize.png",
+    "cursors/rowResize@2x.png",
+    "cursors/sizeNE.png",
+    "cursors/sizeNE@2x.png",
+    "cursors/sizeNESW.png",
+    "cursors/sizeNESW@2x.png",
+    "cursors/sizeNS.png",
+    "cursors/sizeNS@2x.png",
+    "cursors/sizeNW.png",
+    "cursors/sizeNW@2x.png",
+    "cursors/sizeNWSE.png",
+    "cursors/sizeNWSE@2x.png",
+    "cursors/sizeSE.png",
+    "cursors/sizeSE@2x.png",
+    "cursors/sizeSW.png",
+    "cursors/sizeSW@2x.png",
+    "cursors/vtIBeam.png",
+    "cursors/vtIBeam@2x.png",
+    "cursors/zoomIn.png",
+    "cursors/zoomIn@2x.png",
+    "cursors/zoomOut.png",
+    "cursors/zoomOut@2x.png",
+]
+
+# These resources go in $(DIST)/bin/res/MainMenu.nib, but we can't use a magic
+# RESOURCE_FILES.MainMenu.nib attribute, since that would put the files in
+# $(DIST)/bin/res/MainMenu/nib. Instead, we call __setattr__ directly to create
+# an attribute with the correct name.
+RESOURCE_FILES.__setattr__(
+    "MainMenu.nib",
+    [
+        "resources/MainMenu.nib/classes.nib",
+        "resources/MainMenu.nib/info.nib",
+        "resources/MainMenu.nib/keyedobjects.nib",
+    ],
+)
+
+OS_LIBS += [
+    "-framework IOSurface",
+    "-framework Vision",
+]
+
+SPHINX_TREES["/widget/cocoa"] = "docs"
diff --git a/widget/cocoa/mozView.h b/widget/cocoa/mozView.h
new file mode 100644
index 0000000000..deb719254e
--- /dev/null
+++ b/widget/cocoa/mozView.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozView_h_
+#define mozView_h_
+
+#undef DARWIN
+#import <Cocoa/Cocoa.h>
+class nsIWidget;
+
+namespace mozilla {
+namespace widget {
+class TextInputHandler;
+}  // namespace widget
+}  // namespace mozilla
+
+// A protocol with some of the methods that ChildView implements. In the distant
+// past, this protocol was used by embedders: They would create their own NSView
+// subclass, implement mozView on it, and then embed a Gecko ChildView by adding
+// it as a subview of this view. This scenario no longer exists.
+// Now this protocol is mostly just used by TextInputHandler and mozAccessible
+// in order to communicate with ChildView without seeing the entire ChildView
+// interface definition.
+@protocol mozView
+
+// aHandler is Gecko's default text input handler:  It implements the
+// NSTextInput protocol to handle key events.  Don't make aHandler a
+// strong reference -- that causes a memory leak.
+- (void)installTextInputHandler:(mozilla::widget::TextInputHandler*)aHandler;
+- (void)uninstallTextInputHandler;
+
+// access the nsIWidget associated with this view. DOES NOT ADDREF.
+- (nsIWidget*)widget;
+
+// called when our corresponding Gecko view goes away
+- (void)widgetDestroyed;
+
+- (BOOL)isDragInProgress;
+
+// Checks whether the view is first responder or not
+- (BOOL)isFirstResponder;
+
+// Call when you dispatch an event which may cause to open context menu.
+- (void)maybeInitContextMenuTracking;
+
+@end
+
+// An informal protocol implemented by the NSWindow of the host application.
+//
+// It's used to prevent re-entrant calls to -makeKeyAndOrderFront: when gecko
+// focus/activate events propagate out to the embedder's
+// nsIEmbeddingSiteWindow::SetFocus implementation.
+@interface NSObject (mozWindow)
+
+- (BOOL)suppressMakeKeyFront;
+- (void)setSuppressMakeKeyFront:(BOOL)inSuppress;
+
+@end
+
+#endif  // mozView_h_
diff --git a/widget/cocoa/nsAppShell.h b/widget/cocoa/nsAppShell.h
new file mode 100644
index 0000000000..009768794f
--- /dev/null
+++ b/widget/cocoa/nsAppShell.h
@@ -0,0 +1,92 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Runs the main native Cocoa run loop, interrupting it as needed to process
+ * Gecko events.
+ */
+
+#ifndef nsAppShell_h_
+#define nsAppShell_h_
+
+#import <AppKit/NSApplication.h>
+
+#include "nsBaseAppShell.h"
+#include "nsTArray.h"
+
+class ProfilingStack;
+
+namespace mozilla {
+class nsAvailableMemoryWatcherBase;
+}
+
+// GeckoNSApplication
+//
+// Subclass of NSApplication for filtering out certain events.
+@interface GeckoNSApplication : NSApplication {
+}
+@end
+
+@class AppShellDelegate;
+
+class nsAppShell : public nsBaseAppShell {
+ public:
+  NS_IMETHOD ResumeNative(void) override;
+
+  nsAppShell();
+
+  nsresult Init();
+
+  NS_IMETHOD Run(void) override;
+  NS_IMETHOD Exit(void) override;
+  NS_IMETHOD OnProcessNextEvent(nsIThreadInternal* aThread, bool aMayWait) override;
+  NS_IMETHOD AfterProcessNextEvent(nsIThreadInternal* aThread, bool aEventWasProcessed) override;
+
+  void OnRunLoopActivityChanged(CFRunLoopActivity aActivity);
+
+  // public only to be visible to Objective-C code that must call it
+  void WillTerminate();
+
+  static void OnMemoryPressureChanged(dispatch_source_memorypressure_flags_t aPressureLevel);
+
+ protected:
+  virtual ~nsAppShell();
+
+  virtual void ScheduleNativeEventCallback() override;
+  virtual bool ProcessNextNativeEvent(bool aMayWait) override;
+
+  void InitMemoryPressureObserver();
+
+  static void ProcessGeckoEvents(void* aInfo);
+
+ protected:
+  CFMutableArrayRef mAutoreleasePools;
+
+  AppShellDelegate* mDelegate;
+  CFRunLoopRef mCFRunLoop;
+  CFRunLoopSourceRef mCFRunLoopSource;
+
+  // An observer for the profiler that is notified when the event loop enters
+  // and exits the waiting state.
+  CFRunLoopObserverRef mCFRunLoopObserver;
+
+  // Non-null while the native event loop is in the waiting state.
+  ProfilingStack* mProfilingStackWhileWaiting = nullptr;
+
+  // For getting notifications from the OS about memory pressure state changes.
+  dispatch_source_t mMemoryPressureSource = nullptr;
+
+  bool mRunningEventLoop;
+  bool mStarted;
+  bool mTerminated;
+  bool mSkippedNativeCallback;
+  bool mRunningCocoaEmbedded;
+
+  int32_t mNativeEventCallbackDepth;
+  // Can be set from different threads, so must be modified atomically
+  int32_t mNativeEventScheduledDepth;
+};
+
+#endif  // nsAppShell_h_
diff --git a/widget/cocoa/nsAppShell.mm b/widget/cocoa/nsAppShell.mm
new file mode 100644
index 0000000000..9ba512ce49
--- /dev/null
+++ b/widget/cocoa/nsAppShell.mm
@@ -0,0 +1,1120 @@
+/* -*- tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Runs the main native Cocoa run loop, interrupting it as needed to process
+ * Gecko events.
+ */
+
+#import <Cocoa/Cocoa.h>
+
+#include <dlfcn.h>
+
+#include "mozilla/AvailableMemoryWatcher.h"
+#include "CustomCocoaEvents.h"
+#include "mozilla/WidgetTraceEvent.h"
+#include "nsAppShell.h"
+#include "gfxPlatform.h"
+#include "nsCOMPtr.h"
+#include "nsIFile.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsString.h"
+#include "nsIRollupListener.h"
+#include "nsIWidget.h"
+#include "nsMemoryPressure.h"
+#include "nsThreadUtils.h"
+#include "nsServiceManagerUtils.h"
+#include "nsObjCExceptions.h"
+#include "nsCocoaUtils.h"
+#include "nsCocoaFeatures.h"
+#include "nsChildView.h"
+#include "nsToolkit.h"
+#include "TextInputHandler.h"
+#include "mozilla/BackgroundHangMonitor.h"
+#include "ScreenHelperCocoa.h"
+#include "mozilla/Hal.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/ProfilerThreadSleep.h"
+#include "mozilla/widget/ScreenManager.h"
+#include "HeadlessScreenHelper.h"
+#include "MOZMenuOpeningCoordinator.h"
+#include "pratom.h"
+#if !defined(RELEASE_OR_BETA) || defined(DEBUG)
+#  include "nsSandboxViolationSink.h"
+#endif
+
+#include <IOKit/pwr_mgt/IOPMLib.h>
+#include "nsIDOMWakeLockListener.h"
+#include "nsIPowerManagerService.h"
+
+#include "nsIObserverService.h"
+#include "mozilla/Services.h"
+#include "mozilla/StaticPrefs_widget.h"
+
+using namespace mozilla;
+using namespace mozilla::widget;
+
+#define WAKE_LOCK_LOG(...) MOZ_LOG(gMacWakeLockLog, mozilla::LogLevel::Debug, (__VA_ARGS__))
+static mozilla::LazyLogModule gMacWakeLockLog("MacWakeLock");
+
+// A wake lock listener that disables screen saver when requested by
+// Gecko. For example when we're playing video in a foreground tab we
+// don't want the screen saver to turn on.
+
+class MacWakeLockListener final : public nsIDOMMozWakeLockListener {
+ public:
+  NS_DECL_ISUPPORTS;
+
+ private:
+  ~MacWakeLockListener() {}
+
+  IOPMAssertionID mAssertionNoDisplaySleepID = kIOPMNullAssertionID;
+  IOPMAssertionID mAssertionNoIdleSleepID = kIOPMNullAssertionID;
+
+  NS_IMETHOD Callback(const nsAString& aTopic, const nsAString& aState) override {
+    if (!aTopic.EqualsASCII("screen") && !aTopic.EqualsASCII("audio-playing") &&
+        !aTopic.EqualsASCII("video-playing")) {
+      return NS_OK;
+    }
+
+    // we should still hold the lock for background audio.
+    if (aTopic.EqualsASCII("audio-playing") && aState.EqualsASCII("locked-background")) {
+      WAKE_LOCK_LOG("keep audio playing even in background");
+      return NS_OK;
+    }
+
+    bool shouldKeepDisplayOn = aTopic.EqualsASCII("screen") || aTopic.EqualsASCII("video-playing");
+    CFStringRef assertionType =
+        shouldKeepDisplayOn ? kIOPMAssertionTypeNoDisplaySleep : kIOPMAssertionTypeNoIdleSleep;
+    IOPMAssertionID& assertionId =
+        shouldKeepDisplayOn ? mAssertionNoDisplaySleepID : mAssertionNoIdleSleepID;
+    WAKE_LOCK_LOG("topic=%s, state=%s, shouldKeepDisplayOn=%d", NS_ConvertUTF16toUTF8(aTopic).get(),
+                  NS_ConvertUTF16toUTF8(aState).get(), shouldKeepDisplayOn);
+
+    // Note the wake lock code ensures that we're not sent duplicate
+    // "locked-foreground" notifications when multiple wake locks are held.
+    if (aState.EqualsASCII("locked-foreground")) {
+      if (assertionId != kIOPMNullAssertionID) {
+        WAKE_LOCK_LOG("already has a lock");
+        return NS_OK;
+      }
+      // Prevent screen saver.
+      CFStringRef cf_topic = ::CFStringCreateWithCharacters(
+          kCFAllocatorDefault, reinterpret_cast<const UniChar*>(aTopic.Data()), aTopic.Length());
+      IOReturn success = ::IOPMAssertionCreateWithName(assertionType, kIOPMAssertionLevelOn,
+                                                       cf_topic, &assertionId);
+      CFRelease(cf_topic);
+      if (success != kIOReturnSuccess) {
+        WAKE_LOCK_LOG("failed to disable screensaver");
+      }
+      WAKE_LOCK_LOG("create screensaver");
+    } else {
+      // Re-enable screen saver.
+      if (assertionId != kIOPMNullAssertionID) {
+        IOReturn result = ::IOPMAssertionRelease(assertionId);
+        if (result != kIOReturnSuccess) {
+          WAKE_LOCK_LOG("failed to release screensaver");
+        }
+        WAKE_LOCK_LOG("Release screensaver");
+        assertionId = kIOPMNullAssertionID;
+      }
+    }
+    return NS_OK;
+  }
+};  // MacWakeLockListener
+
+// defined in nsCocoaWindow.mm
+extern int32_t gXULModalLevel;
+
+static bool gAppShellMethodsSwizzled = false;
+
+void OnUncaughtException(NSException* aException) {
+  nsObjCExceptionLog(aException);
+  MOZ_CRASH("Uncaught Objective C exception from NSSetUncaughtExceptionHandler");
+}
+
+@implementation GeckoNSApplication
+
+// Load is called very early during startup, when the Objective C runtime loads this class.
++ (void)load {
+  NSSetUncaughtExceptionHandler(OnUncaughtException);
+}
+
+// This method is called from NSDefaultTopLevelErrorHandler, which is invoked when an Objective C
+// exception propagates up into the native event loop. It is possible that it is also called in
+// other cases.
+- (void)reportException:(NSException*)aException {
+  if (ShouldIgnoreObjCException(aException)) {
+    return;
+  }
+
+  nsObjCExceptionLog(aException);
+
+#ifdef NIGHTLY_BUILD
+  MOZ_CRASH("Uncaught Objective C exception from -[GeckoNSApplication reportException:]");
+#endif
+}
+
+- (void)sendEvent:(NSEvent*)anEvent {
+  mozilla::BackgroundHangMonitor().NotifyActivity();
+
+  if ([anEvent type] == NSEventTypeApplicationDefined && [anEvent subtype] == kEventSubtypeTrace) {
+    mozilla::SignalTracerThread();
+    return;
+  }
+  [super sendEvent:anEvent];
+}
+
+- (NSEvent*)nextEventMatchingMask:(NSEventMask)mask
+                        untilDate:(NSDate*)expiration
+                           inMode:(NSString*)mode
+                          dequeue:(BOOL)flag {
+  if (expiration) {
+    mozilla::BackgroundHangMonitor().NotifyWait();
+  }
+  NSEvent* nextEvent = [super nextEventMatchingMask:mask
+                                          untilDate:expiration
+                                             inMode:mode
+                                            dequeue:flag];
+  if (expiration) {
+    mozilla::BackgroundHangMonitor().NotifyActivity();
+  }
+  return nextEvent;
+}
+
+@end
+
+// AppShellDelegate
+//
+// Cocoa bridge class.  An object of this class is registered to receive
+// notifications.
+//
+@interface AppShellDelegate : NSObject {
+ @private
+  nsAppShell* mAppShell;
+}
+
+- (id)initWithAppShell:(nsAppShell*)aAppShell;
+- (void)applicationWillTerminate:(NSNotification*)aNotification;
+- (BOOL)shouldSaveApplicationState:(NSCoder*)coder;
+- (BOOL)shouldRestoreApplicationState:(NSCoder*)coder;
+@end
+
+// nsAppShell implementation
+
+NS_IMETHODIMP
+nsAppShell::ResumeNative(void) {
+  nsresult retval = nsBaseAppShell::ResumeNative();
+  if (NS_SUCCEEDED(retval) && (mSuspendNativeCount == 0) && mSkippedNativeCallback) {
+    mSkippedNativeCallback = false;
+    ScheduleNativeEventCallback();
+  }
+  return retval;
+}
+
+nsAppShell::nsAppShell()
+    : mAutoreleasePools(nullptr),
+      mDelegate(nullptr),
+      mCFRunLoop(NULL),
+      mCFRunLoopSource(NULL),
+      mRunningEventLoop(false),
+      mStarted(false),
+      mTerminated(false),
+      mSkippedNativeCallback(false),
+      mNativeEventCallbackDepth(0),
+      mNativeEventScheduledDepth(0) {
+  // A Cocoa event loop is running here if (and only if) we've been embedded
+  // by a Cocoa app.
+  mRunningCocoaEmbedded = [NSApp isRunning] ? true : false;
+}
+
+nsAppShell::~nsAppShell() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  hal::Shutdown();
+
+  if (mMemoryPressureSource) {
+    dispatch_release(mMemoryPressureSource);
+    mMemoryPressureSource = nullptr;
+  }
+
+  if (mCFRunLoop) {
+    if (mCFRunLoopSource) {
+      ::CFRunLoopRemoveSource(mCFRunLoop, mCFRunLoopSource, kCFRunLoopCommonModes);
+      ::CFRelease(mCFRunLoopSource);
+    }
+    if (mCFRunLoopObserver) {
+      ::CFRunLoopRemoveObserver(mCFRunLoop, mCFRunLoopObserver, kCFRunLoopCommonModes);
+      ::CFRelease(mCFRunLoopObserver);
+    }
+    ::CFRelease(mCFRunLoop);
+  }
+
+  if (mAutoreleasePools) {
+    NS_ASSERTION(::CFArrayGetCount(mAutoreleasePools) == 0,
+                 "nsAppShell destroyed without popping all autorelease pools");
+    ::CFRelease(mAutoreleasePools);
+  }
+
+  [mDelegate release];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK
+}
+
+NS_IMPL_ISUPPORTS(MacWakeLockListener, nsIDOMMozWakeLockListener)
+mozilla::StaticRefPtr<MacWakeLockListener> sWakeLockListener;
+
+static void AddScreenWakeLockListener() {
+  nsCOMPtr<nsIPowerManagerService> sPowerManagerService =
+      do_GetService(POWERMANAGERSERVICE_CONTRACTID);
+  if (sPowerManagerService) {
+    sWakeLockListener = new MacWakeLockListener();
+    sPowerManagerService->AddWakeLockListener(sWakeLockListener);
+  } else {
+    NS_WARNING("Failed to retrieve PowerManagerService, wakelocks will be broken!");
+  }
+}
+
+static void RemoveScreenWakeLockListener() {
+  nsCOMPtr<nsIPowerManagerService> sPowerManagerService =
+      do_GetService(POWERMANAGERSERVICE_CONTRACTID);
+  if (sPowerManagerService) {
+    sPowerManagerService->RemoveWakeLockListener(sWakeLockListener);
+    sPowerManagerService = nullptr;
+    sWakeLockListener = nullptr;
+  }
+}
+
+void RunLoopObserverCallback(CFRunLoopObserverRef aObserver, CFRunLoopActivity aActivity,
+                             void* aInfo) {
+  static_cast<nsAppShell*>(aInfo)->OnRunLoopActivityChanged(aActivity);
+}
+
+void nsAppShell::OnRunLoopActivityChanged(CFRunLoopActivity aActivity) {
+  if (aActivity == kCFRunLoopBeforeWaiting) {
+    mozilla::BackgroundHangMonitor().NotifyWait();
+  }
+
+  // When the event loop is in its waiting state, we would like the profiler to know that the thread
+  // is idle. The usual way to notify the profiler of idleness would be to place a profiler label
+  // frame with the IDLE category on the stack, for the duration of the function that does the
+  // waiting. However, since macOS uses an event loop model where "the event loop calls you", we do
+  // not control the function that does the waiting; the waiting happens inside CFRunLoop code.
+  // Instead, the run loop notifies us when it enters and exits the waiting state, by calling this
+  // function.
+  // So we do not have a function under our control that stays on the stack for the duration of the
+  // wait. So, rather than putting an AutoProfilerLabel on the stack, we will manually push and pop
+  // the label frame here.
+  // The location in the stack where this label frame is inserted is somewhat arbitrary. In
+  // practice, the label frame will be at the very tip of the stack, looking like it's "inside" the
+  // mach_msg_trap wait function.
+  if (aActivity == kCFRunLoopBeforeWaiting) {
+    using ThreadRegistration = mozilla::profiler::ThreadRegistration;
+    ThreadRegistration::WithOnThreadRef([&](ThreadRegistration::OnThreadRef aOnThreadRef) {
+      ProfilingStack& profilingStack =
+          aOnThreadRef.UnlockedConstReaderAndAtomicRWRef().ProfilingStackRef();
+      mProfilingStackWhileWaiting = &profilingStack;
+      uint8_t variableOnStack = 0;
+      profilingStack.pushLabelFrame("Native event loop idle", nullptr, &variableOnStack,
+                                    JS::ProfilingCategoryPair::IDLE, 0);
+      profiler_thread_sleep();
+    });
+  } else {
+    if (mProfilingStackWhileWaiting) {
+      mProfilingStackWhileWaiting->pop();
+      mProfilingStackWhileWaiting = nullptr;
+      profiler_thread_wake();
+    }
+  }
+}
+
+// Init
+//
+// Loads the nib (see bug 316076c21) and sets up the CFRunLoopSource used to
+// interrupt the main native run loop.
+//
+// public
+nsresult nsAppShell::Init() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // No event loop is running yet (unless an embedding app that uses
+  // NSApplicationMain() is running).
+  NSAutoreleasePool* localPool = [[NSAutoreleasePool alloc] init];
+
+  char* mozAppNoDock = PR_GetEnv("MOZ_APP_NO_DOCK");
+  if (mozAppNoDock && strcmp(mozAppNoDock, "") != 0) {
+    [NSApp setActivationPolicy:NSApplicationActivationPolicyAccessory];
+  }
+
+  // mAutoreleasePools is used as a stack of NSAutoreleasePool objects created
+  // by |this|.  CFArray is used instead of NSArray because NSArray wants to
+  // retain each object you add to it, and you can't retain an
+  // NSAutoreleasePool.
+  mAutoreleasePools = ::CFArrayCreateMutable(nullptr, 0, nullptr);
+  NS_ENSURE_STATE(mAutoreleasePools);
+
+  bool isNSApplicationProcessType = (XRE_GetProcessType() != GeckoProcessType_RDD) &&
+                                    (XRE_GetProcessType() != GeckoProcessType_Socket);
+
+  if (isNSApplicationProcessType) {
+    // This call initializes NSApplication unless:
+    // 1) we're using xre -- NSApp's already been initialized by
+    //    MacApplicationDelegate.mm's EnsureUseCocoaDockAPI().
+    // 2) an embedding app that uses NSApplicationMain() is running -- NSApp's
+    //    already been initialized and its main run loop is already running.
+    [[NSBundle mainBundle] loadNibNamed:@"res/MainMenu"
+                                  owner:[GeckoNSApplication sharedApplication]
+                        topLevelObjects:nil];
+  }
+
+  mDelegate = [[AppShellDelegate alloc] initWithAppShell:this];
+  NS_ENSURE_STATE(mDelegate);
+
+  // Add a CFRunLoopSource to the main native run loop.  The source is
+  // responsible for interrupting the run loop when Gecko events are ready.
+
+  mCFRunLoop = [[NSRunLoop currentRunLoop] getCFRunLoop];
+  NS_ENSURE_STATE(mCFRunLoop);
+  ::CFRetain(mCFRunLoop);
+
+  CFRunLoopSourceContext context;
+  bzero(&context, sizeof(context));
+  // context.version = 0;
+  context.info = this;
+  context.perform = ProcessGeckoEvents;
+
+  mCFRunLoopSource = ::CFRunLoopSourceCreate(kCFAllocatorDefault, 0, &context);
+  NS_ENSURE_STATE(mCFRunLoopSource);
+
+  ::CFRunLoopAddSource(mCFRunLoop, mCFRunLoopSource, kCFRunLoopCommonModes);
+
+  // Add a CFRunLoopObserver so that the profiler can be notified when we enter and exit the waiting
+  // state.
+  CFRunLoopObserverContext observerContext;
+  PodZero(&observerContext);
+  observerContext.info = this;
+
+  mCFRunLoopObserver = ::CFRunLoopObserverCreate(
+      kCFAllocatorDefault, kCFRunLoopBeforeWaiting | kCFRunLoopAfterWaiting | kCFRunLoopExit, true,
+      0, RunLoopObserverCallback, &observerContext);
+  NS_ENSURE_STATE(mCFRunLoopObserver);
+
+  ::CFRunLoopAddObserver(mCFRunLoop, mCFRunLoopObserver, kCFRunLoopCommonModes);
+
+  hal::Init();
+
+  if (XRE_IsParentProcess()) {
+    ScreenManager& screenManager = ScreenManager::GetSingleton();
+
+    if (gfxPlatform::IsHeadless()) {
+      screenManager.SetHelper(mozilla::MakeUnique<HeadlessScreenHelper>());
+    } else {
+      screenManager.SetHelper(mozilla::MakeUnique<ScreenHelperCocoa>());
+    }
+
+    InitMemoryPressureObserver();
+  }
+
+  nsresult rv = nsBaseAppShell::Init();
+
+  if (isNSApplicationProcessType && !gAppShellMethodsSwizzled) {
+    // We should only replace the original terminate: method if we're not
+    // running in a Cocoa embedder. See bug 604901.
+    if (!mRunningCocoaEmbedded) {
+      nsToolkit::SwizzleMethods([NSApplication class], @selector(terminate:),
+                                @selector(nsAppShell_NSApplication_terminate:));
+    }
+    gAppShellMethodsSwizzled = true;
+  }
+
+#if !defined(RELEASE_OR_BETA) || defined(DEBUG)
+  if (Preferences::GetBool("security.sandbox.mac.track.violations", false)) {
+    nsSandboxViolationSink::Start();
+  }
+#endif
+
+  [localPool release];
+
+  return rv;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+// ProcessGeckoEvents
+//
+// The "perform" target of mCFRunLoop, called when mCFRunLoopSource is
+// signalled from ScheduleNativeEventCallback.
+//
+// Arrange for Gecko events to be processed on demand (in response to a call
+// to ScheduleNativeEventCallback(), if processing of Gecko events via "native
+// methods" hasn't been suspended).  This happens in NativeEventCallback().
+//
+// protected static
+void nsAppShell::ProcessGeckoEvents(void* aInfo) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+  AUTO_PROFILER_LABEL("nsAppShell::ProcessGeckoEvents", OTHER);
+
+  nsAppShell* self = static_cast<nsAppShell*>(aInfo);
+
+  if (self->mRunningEventLoop) {
+    self->mRunningEventLoop = false;
+
+    // The run loop may be sleeping -- [NSRunLoop runMode:...]
+    // won't return until it's given a reason to wake up.  Awaken it by
+    // posting a bogus event.  There's no need to make the event
+    // presentable.
+    //
+    // But _don't_ set windowNumber to '-1' -- that can lead to nasty
+    // weirdness like bmo bug 397039 (a crash in [NSApp sendEvent:] on one of
+    // these fake events, because the -1 has gotten changed into the number
+    // of an actual NSWindow object, and that NSWindow object has just been
+    // destroyed).  Setting windowNumber to '0' seems to work fine -- this
+    // seems to prevent the OS from ever trying to associate our bogus event
+    // with a particular NSWindow object.
+    [NSApp postEvent:[NSEvent otherEventWithType:NSEventTypeApplicationDefined
+                                        location:NSMakePoint(0, 0)
+                                   modifierFlags:0
+                                       timestamp:0
+                                    windowNumber:0
+                                         context:NULL
+                                         subtype:kEventSubtypeNone
+                                           data1:0
+                                           data2:0]
+             atStart:NO];
+    // Previously we used to send this second event regardless of
+    // self->mRunningEventLoop. However, that was removed in bug 1690687 for
+    // performance reasons. It is still needed for the mRunningEventLoop case
+    // otherwise we'll get in a cycle of sending postEvent followed by the
+    // DummyEvent inserted by nsBaseAppShell::OnProcessNextEvent. This second
+    // event will cause the second call to AcquireFirstMatchingEventInQueue in
+    // nsAppShell::ProcessNextNativeEvent to return true. Which makes
+    // nsBaseAppShell::OnProcessNextEvent call nsAppShell::ProcessNextNativeEvent
+    // again during which it will loop until it sleeps because ProcessGeckoEvents()
+    // won't be called for the DummyEvent.
+    //
+    // This is not a good approach and we should fix things up so that only
+    // one postEvent is needed.
+    [NSApp postEvent:[NSEvent otherEventWithType:NSEventTypeApplicationDefined
+                                        location:NSMakePoint(0, 0)
+                                   modifierFlags:0
+                                       timestamp:0
+                                    windowNumber:0
+                                         context:NULL
+                                         subtype:kEventSubtypeNone
+                                           data1:0
+                                           data2:0]
+             atStart:NO];
+  }
+
+  if (self->mSuspendNativeCount <= 0) {
+    ++self->mNativeEventCallbackDepth;
+    self->NativeEventCallback();
+    --self->mNativeEventCallbackDepth;
+  } else {
+    self->mSkippedNativeCallback = true;
+  }
+
+  if (self->mTerminated) {
+    // Still needed to avoid crashes on quit in most Mochitests.
+    [NSApp postEvent:[NSEvent otherEventWithType:NSEventTypeApplicationDefined
+                                        location:NSMakePoint(0, 0)
+                                   modifierFlags:0
+                                       timestamp:0
+                                    windowNumber:0
+                                         context:NULL
+                                         subtype:kEventSubtypeNone
+                                           data1:0
+                                           data2:0]
+             atStart:NO];
+  }
+  // Normally every call to ScheduleNativeEventCallback() results in
+  // exactly one call to ProcessGeckoEvents().  So each Release() here
+  // normally balances exactly one AddRef() in ScheduleNativeEventCallback().
+  // But if Exit() is called just after ScheduleNativeEventCallback(), the
+  // corresponding call to ProcessGeckoEvents() will never happen.  We check
+  // for this possibility in two different places -- here and in Exit()
+  // itself.  If we find here that Exit() has been called (that mTerminated
+  // is true), it's because we've been called recursively, that Exit() was
+  // called from self->NativeEventCallback() above, and that we're unwinding
+  // the recursion.  In this case we'll never be called again, and we balance
+  // here any extra calls to ScheduleNativeEventCallback().
+  //
+  // When ProcessGeckoEvents() is called recursively, it's because of a
+  // call to ScheduleNativeEventCallback() from NativeEventCallback().  We
+  // balance the "extra" AddRefs here (rather than always in Exit()) in order
+  // to ensure that 'self' stays alive until the end of this method.  We also
+  // make sure not to finish the balancing until all the recursion has been
+  // unwound.
+  if (self->mTerminated) {
+    int32_t releaseCount = 0;
+    if (self->mNativeEventScheduledDepth > self->mNativeEventCallbackDepth) {
+      releaseCount =
+          PR_ATOMIC_SET(&self->mNativeEventScheduledDepth, self->mNativeEventCallbackDepth);
+    }
+    while (releaseCount-- > self->mNativeEventCallbackDepth) self->Release();
+  } else {
+    // As best we can tell, every call to ProcessGeckoEvents() is triggered
+    // by a call to ScheduleNativeEventCallback().  But we've seen a few
+    // (non-reproducible) cases of double-frees that *might* have been caused
+    // by spontaneous calls (from the OS) to ProcessGeckoEvents().  So we
+    // deal with that possibility here.
+    if (PR_ATOMIC_DECREMENT(&self->mNativeEventScheduledDepth) < 0) {
+      PR_ATOMIC_SET(&self->mNativeEventScheduledDepth, 0);
+      NS_WARNING("Spontaneous call to ProcessGeckoEvents()!");
+    } else {
+      self->Release();
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// WillTerminate
+//
+// Called by the AppShellDelegate when an NSApplicationWillTerminate
+// notification is posted.  After this method is called, native events should
+// no longer be processed.  The NSApplicationWillTerminate notification is
+// only posted when [NSApp terminate:] is called, which doesn't happen on a
+// "normal" application quit.
+//
+// public
+void nsAppShell::WillTerminate() {
+  if (mTerminated) return;
+
+  // Make sure that the nsAppExitEvent posted by nsAppStartup::Quit() (called
+  // from [MacApplicationDelegate applicationShouldTerminate:]) gets run.
+  NS_ProcessPendingEvents(NS_GetCurrentThread());
+
+  mTerminated = true;
+}
+
+// ScheduleNativeEventCallback
+//
+// Called (possibly on a non-main thread) when Gecko has an event that
+// needs to be processed.  The Gecko event needs to be processed on the
+// main thread, so the native run loop must be interrupted.
+//
+// In nsBaseAppShell.cpp, the mNativeEventPending variable is used to
+// ensure that ScheduleNativeEventCallback() is called no more than once
+// per call to NativeEventCallback().  ProcessGeckoEvents() can skip its
+// call to NativeEventCallback() if processing of Gecko events by native
+// means is suspended (using nsIAppShell::SuspendNative()), which will
+// suspend calls from nsBaseAppShell::OnDispatchedEvent() to
+// ScheduleNativeEventCallback().  But when Gecko event processing by
+// native means is resumed (in ResumeNative()), an extra call is made to
+// ScheduleNativeEventCallback() (from ResumeNative()).  This triggers
+// another call to ProcessGeckoEvents(), which calls NativeEventCallback(),
+// and nsBaseAppShell::OnDispatchedEvent() resumes calling
+// ScheduleNativeEventCallback().
+//
+// protected virtual
+void nsAppShell::ScheduleNativeEventCallback() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mTerminated) return;
+
+  // Each AddRef() here is normally balanced by exactly one Release() in
+  // ProcessGeckoEvents().  But there are exceptions, for which see
+  // ProcessGeckoEvents() and Exit().
+  NS_ADDREF_THIS();
+  PR_ATOMIC_INCREMENT(&mNativeEventScheduledDepth);
+
+  // This will invoke ProcessGeckoEvents on the main thread.
+  ::CFRunLoopSourceSignal(mCFRunLoopSource);
+  ::CFRunLoopWakeUp(mCFRunLoop);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Undocumented Cocoa Event Manager function, present in the same form since
+// at least OS X 10.6.
+extern "C" EventAttributes GetEventAttributes(EventRef inEvent);
+
+// ProcessNextNativeEvent
+//
+// If aMayWait is false, process a single native event.  If it is true, run
+// the native run loop until stopped by ProcessGeckoEvents.
+//
+// Returns true if more events are waiting in the native event queue.
+//
+// protected virtual
+bool nsAppShell::ProcessNextNativeEvent(bool aMayWait) {
+  bool moreEvents = false;
+
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  bool eventProcessed = false;
+  NSString* currentMode = nil;
+
+  if (mTerminated) return false;
+
+  // Do not call -[NSApplication nextEventMatchingMask:...] when we're trying to close a native
+  // menu. Doing so could confuse the NSMenu's closing mechanism. Instead, we try to unwind the
+  // stack as quickly as possible and return to the parent event loop. At that point, native events
+  // will be processed.
+  if (MOZMenuOpeningCoordinator.needToUnwindForMenuClosing) {
+    return false;
+  }
+
+  bool wasRunningEventLoop = mRunningEventLoop;
+  mRunningEventLoop = aMayWait;
+  NSDate* waitUntil = nil;
+  if (aMayWait) waitUntil = [NSDate distantFuture];
+
+  NSRunLoop* currentRunLoop = [NSRunLoop currentRunLoop];
+
+  EventQueueRef currentEventQueue = GetCurrentEventQueue();
+
+  if (aMayWait) {
+    mozilla::BackgroundHangMonitor().NotifyWait();
+  }
+
+  // Only call -[NSApp sendEvent:] (and indirectly send user-input events to
+  // Gecko) if aMayWait is true.  Tbis ensures most calls to -[NSApp
+  // sendEvent:] happen under nsAppShell::Run(), at the lowest level of
+  // recursion -- thereby making it less likely Gecko will process user-input
+  // events in the wrong order or skip some of them.  It also avoids eating
+  // too much CPU in nsBaseAppShell::OnProcessNextEvent() (which calls
+  // us) -- thereby avoiding the starvation of nsIRunnable events in
+  // nsThread::ProcessNextEvent().  For more information see bug 996848.
+  do {
+    // No autorelease pool is provided here, because OnProcessNextEvent
+    // and AfterProcessNextEvent are responsible for maintaining it.
+    NS_ASSERTION(mAutoreleasePools && ::CFArrayGetCount(mAutoreleasePools),
+                 "No autorelease pool for native event");
+
+    if (aMayWait) {
+      currentMode = [currentRunLoop currentMode];
+      if (!currentMode) currentMode = NSDefaultRunLoopMode;
+      NSEvent* nextEvent = [NSApp nextEventMatchingMask:NSEventMaskAny
+                                              untilDate:waitUntil
+                                                 inMode:currentMode
+                                                dequeue:YES];
+      if (nextEvent) {
+        mozilla::BackgroundHangMonitor().NotifyActivity();
+        [NSApp sendEvent:nextEvent];
+        eventProcessed = true;
+      }
+    } else {
+      // In at least 10.15, AcquireFirstMatchingEventInQueue will move 1
+      // CGEvent from the CGEvent queue into the Carbon event queue. Unfortunately,
+      // once an event has been moved to the Carbon event queue it's no longer a
+      // candidate for coalescing. This means that even if we don't remove the
+      // event from the queue, just calling AcquireFirstMatchingEventInQueue can
+      // cause behaviour change. Prior to bug 1690687 landing, the event that we got
+      // from AcquireFirstMatchingEventInQueue was often our own ApplicationDefined
+      // event. However, once we stopped posting that event on every Gecko
+      // event we're much more likely to get a CGEvent. When we have a high
+      // amount of load on the main thread, we end up alternating between Gecko
+      // events and native events.  Without CGEvent coalescing, the native
+      // event events can accumulate in the Carbon event queue which will
+      // manifest as laggy scrolling.
+#if 1
+      eventProcessed = false;
+      break;
+#else
+      // AcquireFirstMatchingEventInQueue() doesn't spin the (native) event
+      // loop, though it does queue up any newly available events from the
+      // window server.
+      EventRef currentEvent =
+          AcquireFirstMatchingEventInQueue(currentEventQueue, 0, NULL, kEventQueueOptionsNone);
+      if (!currentEvent) {
+        continue;
+      }
+      EventAttributes attrs = GetEventAttributes(currentEvent);
+      UInt32 eventKind = GetEventKind(currentEvent);
+      UInt32 eventClass = GetEventClass(currentEvent);
+      bool osCocoaEvent =
+          ((eventClass == 'appl') || (eventClass == kEventClassAppleEvent) ||
+           ((eventClass == 'cgs ') && (eventKind != NSEventTypeApplicationDefined)));
+      // If attrs is kEventAttributeUserEvent or kEventAttributeMonitored
+      // (i.e. a user input event), we shouldn't process it here while
+      // aMayWait is false.  Likewise if currentEvent will eventually be
+      // turned into an OS-defined Cocoa event, or otherwise needs AppKit
+      // processing.  Doing otherwise risks doing too much work here, and
+      // preventing the event from being properly processed by the AppKit
+      // framework.
+      if ((attrs != kEventAttributeNone) || osCocoaEvent) {
+        // Since we can't process the next event here (while aMayWait is false),
+        // we want moreEvents to be false on return.
+        eventProcessed = false;
+        // This call to ReleaseEvent() matches a call to RetainEvent() in
+        // AcquireFirstMatchingEventInQueue() above.
+        ReleaseEvent(currentEvent);
+        break;
+      }
+      // This call to RetainEvent() matches a call to ReleaseEvent() in
+      // RemoveEventFromQueue() below.
+      RetainEvent(currentEvent);
+      RemoveEventFromQueue(currentEventQueue, currentEvent);
+      EventTargetRef eventDispatcherTarget = GetEventDispatcherTarget();
+      SendEventToEventTarget(currentEvent, eventDispatcherTarget);
+      // This call to ReleaseEvent() matches a call to RetainEvent() in
+      // AcquireFirstMatchingEventInQueue() above.
+      ReleaseEvent(currentEvent);
+      eventProcessed = true;
+#endif
+    }
+  } while (mRunningEventLoop);
+
+  if (eventProcessed) {
+    moreEvents = (AcquireFirstMatchingEventInQueue(currentEventQueue, 0, NULL,
+                                                   kEventQueueOptionsNone) != NULL);
+  }
+
+  mRunningEventLoop = wasRunningEventLoop;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+
+  if (!moreEvents) {
+    nsChildView::UpdateCurrentInputEventCount();
+  }
+
+  return moreEvents;
+}
+
+// Attempt to work around bug 1801419 by loading and initializing the
+// SidecarCore private framework as the app shell starts up. This normally
+// happens on demand, the first time any Cmd-key combination is pressed, and
+// sometimes triggers crashes, caused by an Apple bug. We hope that doing it
+// now, and somewhat more simply, will avoid the crashes. They happen
+// (intermittently) when SidecarCore code tries to access C strings in special
+// sections of its own __TEXT segment, and triggers fatal page faults (which
+// is Apple's bug). Many of the C strings are part of the Objective-C class
+// hierarchy (class names and so forth). We hope that adding them to this
+// hierarchy will "pin" them in place -- so they'll rarely, if ever, be paged
+// out again. Bug 1801419's crashes happen much more often on macOS 13
+// (Ventura) than on other versions of macOS. So we only use this hack on
+// macOS 13 and up.
+static void PinSidecarCoreTextCStringSections() {
+  if (!dlopen("/System/Library/PrivateFrameworks/SidecarCore.framework/SidecarCore", RTLD_LAZY)) {
+    return;
+  }
+
+  // Explicitly run the most basic part of the initialization code that
+  // normally runs automatically on the first Cmd-key combination.
+  Class displayManagerClass = NSClassFromString(@"SidecarDisplayManager");
+  if ([displayManagerClass respondsToSelector:@selector(sharedManager)]) {
+    id sharedManager = [displayManagerClass performSelector:@selector(sharedManager)];
+    if ([sharedManager respondsToSelector:@selector(devices)]) {
+      [sharedManager performSelector:@selector(devices)];
+    }
+  }
+}
+
+// Run
+//
+// Overrides the base class's Run() method to call [NSApp run] (which spins
+// the native run loop until the application quits).  Since (unlike the base
+// class's Run() method) we don't process any Gecko events here, they need
+// to be processed elsewhere (in NativeEventCallback(), called from
+// ProcessGeckoEvents()).
+//
+// Camino called [NSApp run] on its own (via NSApplicationMain()), and so
+// didn't call nsAppShell::Run().
+//
+// public
+NS_IMETHODIMP
+nsAppShell::Run(void) {
+  NS_ASSERTION(!mStarted, "nsAppShell::Run() called multiple times");
+  if (mStarted || mTerminated) return NS_OK;
+
+  mStarted = true;
+
+  if (XRE_IsParentProcess()) {
+    if (nsCocoaFeatures::OnVenturaOrLater()) {
+      PinSidecarCoreTextCStringSections();
+    }
+    AddScreenWakeLockListener();
+  }
+
+  // We use the native Gecko event loop in content processes.
+  nsresult rv = NS_OK;
+  if (XRE_UseNativeEventProcessing()) {
+    NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+    [NSApp run];
+    NS_OBJC_END_TRY_IGNORE_BLOCK;
+  } else {
+    rv = nsBaseAppShell::Run();
+  }
+
+  if (XRE_IsParentProcess()) {
+    RemoveScreenWakeLockListener();
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsAppShell::Exit(void) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // This method is currently called more than once -- from (according to
+  // mento) an nsAppExitEvent dispatched by nsAppStartup::Quit() and from an
+  // XPCOM shutdown notification that nsBaseAppShell has registered to
+  // receive.  So we need to ensure that multiple calls won't break anything.
+  // But we should also complain about it (since it isn't quite kosher).
+  if (mTerminated) {
+    NS_WARNING("nsAppShell::Exit() called redundantly");
+    return NS_OK;
+  }
+
+  mTerminated = true;
+
+#if !defined(RELEASE_OR_BETA) || defined(DEBUG)
+  nsSandboxViolationSink::Stop();
+#endif
+
+  // Quoting from Apple's doc on the [NSApplication stop:] method (from their
+  // doc on the NSApplication class):  "If this method is invoked during a
+  // modal event loop, it will break that loop but not the main event loop."
+  // nsAppShell::Exit() shouldn't be called from a modal event loop.  So if
+  // it is we complain about it (to users of debug builds) and call [NSApp
+  // stop:] one extra time.  (I'm not sure if modal event loops can be nested
+  // -- Apple's docs don't say one way or the other.  But the return value
+  // of [NSApp _isRunningModal] doesn't change immediately after a call to
+  // [NSApp stop:], so we have to assume that one extra call to [NSApp stop:]
+  // will do the job.)
+  BOOL cocoaModal = [NSApp _isRunningModal];
+  NS_ASSERTION(!cocoaModal, "Don't call nsAppShell::Exit() from a modal event loop!");
+  if (cocoaModal) [NSApp stop:nullptr];
+  [NSApp stop:nullptr];
+
+  // A call to Exit() just after a call to ScheduleNativeEventCallback()
+  // prevents the (normally) matching call to ProcessGeckoEvents() from
+  // happening.  If we've been called from ProcessGeckoEvents() (as usually
+  // happens), we take care of it there.  But if we have an unbalanced call
+  // to ScheduleNativeEventCallback() and ProcessGeckoEvents() isn't on the
+  // stack, we need to take care of the problem here.
+  if (!mNativeEventCallbackDepth && mNativeEventScheduledDepth) {
+    int32_t releaseCount = PR_ATOMIC_SET(&mNativeEventScheduledDepth, 0);
+    while (releaseCount-- > 0) NS_RELEASE_THIS();
+  }
+
+  return nsBaseAppShell::Exit();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+// OnProcessNextEvent
+//
+// This nsIThreadObserver method is called prior to processing an event.
+// Set up an autorelease pool that will service any autoreleased Cocoa
+// objects during this event.  This includes native events processed by
+// ProcessNextNativeEvent.  The autorelease pool will be popped by
+// AfterProcessNextEvent, it is important for these two methods to be
+// tightly coupled.
+//
+// public
+NS_IMETHODIMP
+nsAppShell::OnProcessNextEvent(nsIThreadInternal* aThread, bool aMayWait) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NS_ASSERTION(mAutoreleasePools, "No stack on which to store autorelease pool");
+
+  NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];
+  ::CFArrayAppendValue(mAutoreleasePools, pool);
+
+  return nsBaseAppShell::OnProcessNextEvent(aThread, aMayWait);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+// AfterProcessNextEvent
+//
+// This nsIThreadObserver method is called after event processing is complete.
+// The Cocoa implementation cleans up the autorelease pool create by the
+// previous OnProcessNextEvent call.
+//
+// public
+NS_IMETHODIMP
+nsAppShell::AfterProcessNextEvent(nsIThreadInternal* aThread, bool aEventWasProcessed) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  CFIndex count = ::CFArrayGetCount(mAutoreleasePools);
+
+  NS_ASSERTION(mAutoreleasePools && count, "Processed an event, but there's no autorelease pool?");
+
+  const NSAutoreleasePool* pool =
+      static_cast<const NSAutoreleasePool*>(::CFArrayGetValueAtIndex(mAutoreleasePools, count - 1));
+  ::CFArrayRemoveValueAtIndex(mAutoreleasePools, count - 1);
+  [pool release];
+
+  return nsBaseAppShell::AfterProcessNextEvent(aThread, aEventWasProcessed);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsAppShell::InitMemoryPressureObserver() {
+  // Testing shows that sometimes the memory pressure event is not fired for
+  // over a minute after the memory pressure change is reflected in sysctl
+  // values. Hence this may need to be augmented with polling of the memory
+  // pressure sysctls for lower latency reactions to OS memory pressure. This
+  // was also observed when using DISPATCH_QUEUE_PRIORITY_HIGH.
+  mMemoryPressureSource =
+      dispatch_source_create(DISPATCH_SOURCE_TYPE_MEMORYPRESSURE, 0,
+                             DISPATCH_MEMORYPRESSURE_NORMAL | DISPATCH_MEMORYPRESSURE_WARN |
+                                 DISPATCH_MEMORYPRESSURE_CRITICAL,
+                             dispatch_get_main_queue());
+
+  dispatch_source_set_event_handler(mMemoryPressureSource, ^{
+    dispatch_source_memorypressure_flags_t pressureLevel =
+        dispatch_source_get_data(mMemoryPressureSource);
+    nsAppShell::OnMemoryPressureChanged(pressureLevel);
+  });
+
+  dispatch_resume(mMemoryPressureSource);
+
+  // Initialize the memory watcher.
+  RefPtr<mozilla::nsAvailableMemoryWatcherBase> watcher(
+      nsAvailableMemoryWatcherBase::GetSingleton());
+}
+
+void nsAppShell::OnMemoryPressureChanged(dispatch_source_memorypressure_flags_t aPressureLevel) {
+  // The memory pressure dispatch source is created (above) with
+  // dispatch_get_main_queue() which always fires on the main thread.
+  MOZ_ASSERT(NS_IsMainThread());
+
+  MacMemoryPressureLevel geckoPressureLevel;
+  switch (aPressureLevel) {
+    case DISPATCH_MEMORYPRESSURE_NORMAL:
+      geckoPressureLevel = MacMemoryPressureLevel::Value::eNormal;
+      break;
+    case DISPATCH_MEMORYPRESSURE_WARN:
+      geckoPressureLevel = MacMemoryPressureLevel::Value::eWarning;
+      break;
+    case DISPATCH_MEMORYPRESSURE_CRITICAL:
+      geckoPressureLevel = MacMemoryPressureLevel::Value::eCritical;
+      break;
+    default:
+      geckoPressureLevel = MacMemoryPressureLevel::Value::eUnexpected;
+  }
+
+  RefPtr<mozilla::nsAvailableMemoryWatcherBase> watcher(
+      nsAvailableMemoryWatcherBase::GetSingleton());
+  watcher->OnMemoryPressureChanged(geckoPressureLevel);
+}
+
+// AppShellDelegate implementation
+
+@implementation AppShellDelegate
+// initWithAppShell:
+//
+// Constructs the AppShellDelegate object
+- (id)initWithAppShell:(nsAppShell*)aAppShell {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if ((self = [self init])) {
+    mAppShell = aAppShell;
+
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(applicationWillTerminate:)
+                                                 name:NSApplicationWillTerminateNotification
+                                               object:NSApp];
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(applicationDidBecomeActive:)
+                                                 name:NSApplicationDidBecomeActiveNotification
+                                               object:NSApp];
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(timezoneChanged:)
+                                                 name:NSSystemTimeZoneDidChangeNotification
+                                               object:nil];
+  }
+
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)dealloc {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+  [[NSDistributedNotificationCenter defaultCenter] removeObserver:self];
+  [super dealloc];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// applicationWillTerminate:
+//
+// Notify the nsAppShell that native event processing should be discontinued.
+- (void)applicationWillTerminate:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  mAppShell->WillTerminate();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// applicationDidBecomeActive
+//
+// Make sure TextInputHandler::sLastModifierState is updated when we become
+// active (since we won't have received [ChildView flagsChanged:] messages
+// while inactive).
+- (void)applicationDidBecomeActive:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // [NSEvent modifierFlags] is valid on every kind of event, so we don't need
+  // to worry about getting an NSInternalInconsistencyException here.
+  NSEvent* currentEvent = [NSApp currentEvent];
+  if (currentEvent) {
+    TextInputHandler::sLastModifierState =
+        [currentEvent modifierFlags] & NSEventModifierFlagDeviceIndependentFlagsMask;
+  }
+
+  nsCOMPtr<nsIObserverService> observerService = services::GetObserverService();
+  if (observerService) {
+    observerService->NotifyObservers(nullptr, NS_WIDGET_MAC_APP_ACTIVATE_OBSERVER_TOPIC, nullptr);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)timezoneChanged:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  nsBaseAppShell::OnSystemTimezoneChange();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (BOOL)shouldSaveApplicationState:(NSCoder*)coder {
+  return YES;
+}
+
+- (BOOL)shouldRestoreApplicationState:(NSCoder*)coder {
+  return YES;
+}
+
+@end
+
+// We hook terminate: in order to make OS-initiated termination work nicely
+// with Gecko's shutdown sequence.  (Two ways to trigger OS-initiated
+// termination:  1) Quit from the Dock menu; 2) Log out from (or shut down)
+// your computer while the browser is active.)
+@interface NSApplication (MethodSwizzling)
+- (void)nsAppShell_NSApplication_terminate:(id)sender;
+@end
+
+@implementation NSApplication (MethodSwizzling)
+
+// Called by the OS after [MacApplicationDelegate applicationShouldTerminate:]
+// has returned NSTerminateNow.  This method "subclasses" and replaces the
+// OS's original implementation.  The only thing the orginal method does which
+// we need is that it posts NSApplicationWillTerminateNotification.  Everything
+// else is unneeded (because it's handled elsewhere), or actively interferes
+// with Gecko's shutdown sequence.  For example the original terminate: method
+// causes the app to exit() inside [NSApp run] (called from nsAppShell::Run()
+// above), which means that nothing runs after the call to nsAppStartup::Run()
+// in XRE_Main(), which in particular means that ScopedXPCOMStartup's destructor
+// and NS_ShutdownXPCOM() never get called.
+- (void)nsAppShell_NSApplication_terminate:(id)sender {
+  [[NSNotificationCenter defaultCenter] postNotificationName:NSApplicationWillTerminateNotification
+                                                      object:NSApp];
+}
+
+@end
diff --git a/widget/cocoa/nsBidiKeyboard.h b/widget/cocoa/nsBidiKeyboard.h
new file mode 100644
index 0000000000..3a9a6fe2fb
--- /dev/null
+++ b/widget/cocoa/nsBidiKeyboard.h
@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsBidiKeyboard_h_
+#define nsBidiKeyboard_h_
+
+#include "nsIBidiKeyboard.h"
+
+class nsBidiKeyboard : public nsIBidiKeyboard {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIBIDIKEYBOARD
+
+  nsBidiKeyboard();
+
+ protected:
+  virtual ~nsBidiKeyboard();
+};
+
+#endif  // nsBidiKeyboard_h_
diff --git a/widget/cocoa/nsBidiKeyboard.mm b/widget/cocoa/nsBidiKeyboard.mm
new file mode 100644
index 0000000000..4193bdf6f0
--- /dev/null
+++ b/widget/cocoa/nsBidiKeyboard.mm
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsBidiKeyboard.h"
+#include "nsCocoaUtils.h"
+#include "TextInputHandler.h"
+#include "nsIWidget.h"
+
+// This must be the last include:
+#include "nsObjCExceptions.h"
+
+using namespace mozilla::widget;
+
+NS_IMPL_ISUPPORTS(nsBidiKeyboard, nsIBidiKeyboard)
+
+nsBidiKeyboard::nsBidiKeyboard() : nsIBidiKeyboard() { Reset(); }
+
+nsBidiKeyboard::~nsBidiKeyboard() {}
+
+NS_IMETHODIMP nsBidiKeyboard::Reset() { return NS_OK; }
+
+NS_IMETHODIMP nsBidiKeyboard::IsLangRTL(bool* aIsRTL) {
+  *aIsRTL = TISInputSourceWrapper::CurrentInputSource().IsForRTLLanguage();
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsBidiKeyboard::GetHaveBidiKeyboards(bool* aResult) {
+  // not implemented yet
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+// static
+already_AddRefed<nsIBidiKeyboard> nsIWidget::CreateBidiKeyboardInner() {
+  return do_AddRef(new nsBidiKeyboard());
+}
diff --git a/widget/cocoa/nsChangeObserver.h b/widget/cocoa/nsChangeObserver.h
new file mode 100644
index 0000000000..aacf837bb5
--- /dev/null
+++ b/widget/cocoa/nsChangeObserver.h
@@ -0,0 +1,71 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsChangeObserver_h_
+#define nsChangeObserver_h_
+
+class nsIContent;
+class nsAtom;
+namespace mozilla {
+namespace dom {
+class Document;
+}
+}  // namespace mozilla
+
+#define NS_DECL_CHANGEOBSERVER                                            \
+  void ObserveAttributeChanged(mozilla::dom::Document* aDocument,         \
+                               nsIContent* aContent, nsAtom* aAttribute)  \
+      override;                                                           \
+  void ObserveContentRemoved(mozilla::dom::Document* aDocument,           \
+                             nsIContent* aContainer, nsIContent* aChild,  \
+                             nsIContent* aPreviousChild) override;        \
+  void ObserveContentInserted(mozilla::dom::Document* aDocument,          \
+                              nsIContent* aContainer, nsIContent* aChild) \
+      override;
+
+// Something that wants to be alerted to changes in attributes or changes in
+// its corresponding content object.
+//
+// This interface is used by our menu code so we only have to have one
+// nsIMutationObserver per menu subtree root (e.g. per menubar).
+//
+// Any class that implements this interface must take care to unregister itself
+// on deletion.
+//
+// XXXmstange The methods below use nsIContent*. Eventually, the should be
+// converted to use mozilla::dom::Element* instead.
+class nsChangeObserver {
+ public:
+  // Called when the attribute aAttribute on the element aContent has changed.
+  // Only if aContent is being observed by this nsChangeObserver.
+  virtual void ObserveAttributeChanged(mozilla::dom::Document* aDocument,
+                                       nsIContent* aContent,
+                                       nsAtom* aAttribute) = 0;
+
+  // Called when aChild has been removed from its parent aContainer.
+  // aPreviousSibling is the old previous sibling of aChild.
+  // aContainer is always the old parent node of aChild and of aPreviousSibling.
+  // Only called if aContainer or aContainer's parent node are being observed
+  // by this nsChangeObserver.
+  // In other words: If you observe an element, ObserveContentRemoved is called
+  // if that element's children and grandchildren are removed. NOT if the
+  // observed element itself is removed.
+  virtual void ObserveContentRemoved(mozilla::dom::Document* aDocument,
+                                     nsIContent* aContainer, nsIContent* aChild,
+                                     nsIContent* aPreviousSibling) = 0;
+
+  // Called when aChild has been inserted into its new parent aContainer.
+  // Only called if aContainer or aContainer's parent node are being observed
+  // by this nsChangeObserver.
+  // In other words: If you observe an element, ObserveContentInserted is called
+  // if that element receives a new child or grandchild. NOT if the observed
+  // element itself is inserted anywhere.
+  virtual void ObserveContentInserted(mozilla::dom::Document* aDocument,
+                                      nsIContent* aContainer,
+                                      nsIContent* aChild) = 0;
+};
+
+#endif  // nsChangeObserver_h_
diff --git a/widget/cocoa/nsChildView.h b/widget/cocoa/nsChildView.h
new file mode 100644
index 0000000000..b8095b991e
--- /dev/null
+++ b/widget/cocoa/nsChildView.h
@@ -0,0 +1,591 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsChildView_h_
+#define nsChildView_h_
+
+// formal protocols
+#include "mozView.h"
+#ifdef ACCESSIBILITY
+#  include "mozilla/a11y/LocalAccessible.h"
+#  include "mozAccessibleProtocol.h"
+#endif
+
+#include "nsISupports.h"
+#include "nsBaseWidget.h"
+#include "nsIWeakReferenceUtils.h"
+#include "TextInputHandler.h"
+#include "nsCocoaUtils.h"
+#include "gfxQuartzSurface.h"
+#include "GLContextTypes.h"
+#include "mozilla/DataMutex.h"
+#include "mozilla/Mutex.h"
+#include "nsRegion.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/webrender/WebRenderTypes.h"
+
+#include "nsString.h"
+#include "nsIDragService.h"
+#include "ViewRegion.h"
+#include "CFTypeRefPtr.h"
+
+#import <Carbon/Carbon.h>
+#import <Cocoa/Cocoa.h>
+#import <AppKit/NSOpenGL.h>
+
+class nsChildView;
+class nsCocoaWindow;
+
+namespace {
+class GLPresenter;
+}  // namespace
+
+namespace mozilla {
+enum class NativeKeyBindingsType : uint8_t;
+
+class InputData;
+class PanGestureInput;
+class VibrancyManager;
+namespace layers {
+class GLManager;
+class IAPZCTreeManager;
+class NativeLayerRootCA;
+class NativeLayerCA;
+}  // namespace layers
+namespace widget {
+class WidgetRenderingContext;
+}  // namespace widget
+}  // namespace mozilla
+
+@class PixelHostingView;
+
+@interface NSEvent (Undocumented)
+
+// Return Cocoa event's corresponding Carbon event.  Not initialized (on
+// synthetic events) until the OS actually "sends" the event.  This method
+// has been present in the same form since at least OS X 10.2.8.
+- (EventRef)_eventRef;
+
+// stage From 10.10.3 for force touch event
+@property(readonly) NSInteger stage;
+
+@end
+
+@interface NSView (Undocumented)
+
+// Undocumented method of one or more of NSFrameView's subclasses.  Called
+// when one or more of the titlebar buttons needs to be repositioned, to
+// disappear, or to reappear (say if the window's style changes).  If
+// 'redisplay' is true, the entire titlebar (the window's top 22 pixels) is
+// marked as needing redisplay.  This method has been present in the same
+// format since at least OS X 10.5.
+- (void)_tileTitlebarAndRedisplay:(BOOL)redisplay;
+
+// The following undocumented methods are used to work around bug 1069658,
+// which is an Apple bug or design flaw that effects Yosemite.  None of them
+// were present prior to Yosemite (OS X 10.10).
+- (NSView*)titlebarView;                   // Method of NSThemeFrame
+- (NSView*)titlebarContainerView;          // Method of NSThemeFrame
+- (BOOL)transparent;                       // Method of NSTitlebarView and NSTitlebarContainerView
+- (void)setTransparent:(BOOL)transparent;  // Method of NSTitlebarView and
+                                           // NSTitlebarContainerView
+
+// Available since 10.7.4:
+- (void)viewDidChangeBackingProperties;
+@end
+
+@interface ChildView : NSView <
+#ifdef ACCESSIBILITY
+                           mozAccessible,
+#endif
+                           mozView,
+                           NSTextInputClient,
+                           NSDraggingSource,
+                           NSDraggingDestination,
+                           NSPasteboardItemDataProvider> {
+ @private
+  // the nsChildView that created the view. It retains this NSView, so
+  // the link back to it must be weak.
+  nsChildView* mGeckoChild;
+
+  // Text input handler for mGeckoChild and us.  Note that this is a weak
+  // reference.  Ideally, this should be a strong reference but a ChildView
+  // object can live longer than the mGeckoChild that owns it.  And if
+  // mTextInputHandler were a strong reference, this would make it difficult
+  // for Gecko's leak detector to detect leaked TextInputHandler objects.
+  // This is initialized by [mozView installTextInputHandler:aHandler] and
+  // cleared by [mozView uninstallTextInputHandler].
+  mozilla::widget::TextInputHandler* mTextInputHandler;  // [WEAK]
+
+  // when mouseDown: is called, we store its event here (strong)
+  NSEvent* mLastMouseDownEvent;
+
+  // Needed for IME support in e10s mode.  Strong.
+  NSEvent* mLastKeyDownEvent;
+
+  // Whether the last mouse down event was blocked from Gecko.
+  BOOL mBlockedLastMouseDown;
+
+  // when acceptsFirstMouse: is called, we store the event here (strong)
+  NSEvent* mClickThroughMouseDownEvent;
+
+  // WheelStart/Stop events should always come in pairs. This BOOL records the
+  // last received event so that, when we receive one of the events, we make sure
+  // to send its pair event first, in case we didn't yet for any reason.
+  BOOL mExpectingWheelStop;
+
+  // Whether we're inside updateRootCALayer at the moment.
+  BOOL mIsUpdatingLayer;
+
+  // Holds our drag service across multiple drag calls. The reference to the
+  // service is obtained when the mouse enters the view and is released when
+  // the mouse exits or there is a drop. This prevents us from having to
+  // re-establish the connection to the service manager many times per second
+  // when handling |draggingUpdated:| messages.
+  nsIDragService* mDragService;
+
+  // Gestures support
+  //
+  // mGestureState is used to detect when Cocoa has called both
+  // magnifyWithEvent and rotateWithEvent within the same
+  // beginGestureWithEvent and endGestureWithEvent sequence. We
+  // discard the spurious gesture event so as not to confuse Gecko.
+  //
+  // mCumulativeRotation keeps track of the total amount of rotation
+  // performed during a rotate gesture so we can send that value with
+  // the final MozRotateGesture event.
+  enum {
+    eGestureState_None,
+    eGestureState_StartGesture,
+    eGestureState_MagnifyGesture,
+    eGestureState_RotateGesture
+  } mGestureState;
+  float mCumulativeRotation;
+
+#ifdef __LP64__
+  // Support for fluid swipe tracking.
+  BOOL* mCancelSwipeAnimation;
+#endif
+
+  // Whether this uses off-main-thread compositing.
+  BOOL mUsingOMTCompositor;
+
+  // Subviews of self, which act as container views for vibrancy views and
+  // non-draggable views.
+  NSView* mVibrancyViewsContainer;      // [STRONG]
+  NSView* mNonDraggableViewsContainer;  // [STRONG]
+
+  // The layer-backed view that hosts our drawing. Always non-null.
+  // This is a subview of self so that it can be ordered on top of mVibrancyViewsContainer.
+  PixelHostingView* mPixelHostingView;
+
+  // The CALayer that wraps Gecko's rendered contents. It's a sublayer of
+  // mPixelHostingView's backing layer. Always non-null.
+  CALayer* mRootCALayer;  // [STRONG]
+
+  // Last pressure stage by trackpad's force click
+  NSInteger mLastPressureStage;
+}
+
+// class initialization
++ (void)initialize;
+
++ (void)registerViewForDraggedTypes:(NSView*)aView;
+
+// these are sent to the first responder when the window key status changes
+- (void)viewsWindowDidBecomeKey;
+- (void)viewsWindowDidResignKey;
+
+// Stop NSView hierarchy being changed during [ChildView drawRect:]
+- (void)delayedTearDown;
+
+- (void)handleMouseMoved:(NSEvent*)aEvent;
+
+- (void)sendMouseEnterOrExitEvent:(NSEvent*)aEvent
+                            enter:(BOOL)aEnter
+                         exitFrom:(mozilla::WidgetMouseEvent::ExitFrom)aExitFrom;
+
+// Call this during operations that will likely trigger a main thread
+// CoreAnimation paint of the window, during which Gecko should do its own
+// painting and present the results atomically with that main thread transaction.
+// This method will suspend off-thread window updates so that the upcoming paint
+// can be atomic, and mark the layer as needing display so that
+// HandleMainThreadCATransaction gets called and Gecko gets a chance to paint.
+- (void)ensureNextCompositeIsAtomicWithMainThreadPaint;
+
+- (NSView*)vibrancyViewsContainer;
+- (NSView*)nonDraggableViewsContainer;
+- (NSView*)pixelHostingView;
+
+- (BOOL)isCoveringTitlebar;
+
+- (void)viewWillStartLiveResize;
+- (void)viewDidEndLiveResize;
+
+/*
+ * Gestures support
+ *
+ * The prototypes swipeWithEvent, beginGestureWithEvent, smartMagnifyWithEvent,
+ * rotateWithEvent and endGestureWithEvent were obtained from the following
+ * links:
+ * https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ApplicationKit/Classes/NSResponder_Class/Reference/Reference.html
+ * https://developer.apple.com/library/mac/#releasenotes/Cocoa/AppKit.html
+ */
+- (void)swipeWithEvent:(NSEvent*)anEvent;
+- (void)beginGestureWithEvent:(NSEvent*)anEvent;
+- (void)magnifyWithEvent:(NSEvent*)anEvent;
+- (void)smartMagnifyWithEvent:(NSEvent*)anEvent;
+- (void)rotateWithEvent:(NSEvent*)anEvent;
+- (void)endGestureWithEvent:(NSEvent*)anEvent;
+
+- (void)scrollWheel:(NSEvent*)anEvent;
+
+- (void)setUsingOMTCompositor:(BOOL)aUseOMTC;
+
+- (NSEvent*)lastKeyDownEvent;
+
++ (uint32_t)sUniqueKeyEventId;
+
++ (NSMutableDictionary*)sNativeKeyEventsMap;
+@end
+
+class ChildViewMouseTracker {
+ public:
+  static void MouseMoved(NSEvent* aEvent);
+  static void MouseScrolled(NSEvent* aEvent);
+  static void OnDestroyView(ChildView* aView);
+  static void OnDestroyWindow(NSWindow* aWindow);
+  static BOOL WindowAcceptsEvent(NSWindow* aWindow, NSEvent* aEvent, ChildView* aView,
+                                 BOOL isClickThrough = NO);
+  static void MouseExitedWindow(NSEvent* aEvent);
+  static void MouseEnteredWindow(NSEvent* aEvent);
+  static void NativeMenuOpened();
+  static void NativeMenuClosed();
+  static void ReEvaluateMouseEnterState(NSEvent* aEvent = nil, ChildView* aOldView = nil);
+  static void ResendLastMouseMoveEvent();
+  static ChildView* ViewForEvent(NSEvent* aEvent);
+
+  static ChildView* sLastMouseEventView;
+  static NSEvent* sLastMouseMoveEvent;
+  static NSWindow* sWindowUnderMouse;
+  static NSPoint sLastScrollEventScreenLocation;
+};
+
+//-------------------------------------------------------------------------
+//
+// nsChildView
+//
+//-------------------------------------------------------------------------
+
+class nsChildView final : public nsBaseWidget {
+ private:
+  typedef nsBaseWidget Inherited;
+  typedef mozilla::layers::IAPZCTreeManager IAPZCTreeManager;
+
+ public:
+  nsChildView();
+
+  // nsIWidget interface
+  [[nodiscard]] virtual nsresult Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
+                                        const LayoutDeviceIntRect& aRect,
+                                        InitData* = nullptr) override;
+
+  virtual void Destroy() override;
+
+  virtual void Show(bool aState) override;
+  virtual bool IsVisible() const override;
+
+  virtual void SetParent(nsIWidget* aNewParent) override;
+  virtual nsIWidget* GetParent(void) override;
+  virtual float GetDPI() override;
+
+  virtual void Move(double aX, double aY) override;
+  virtual void Resize(double aWidth, double aHeight, bool aRepaint) override;
+  virtual void Resize(double aX, double aY, double aWidth, double aHeight, bool aRepaint) override;
+
+  virtual void Enable(bool aState) override;
+  virtual bool IsEnabled() const override;
+
+  virtual nsSizeMode SizeMode() override { return mSizeMode; }
+  virtual void SetSizeMode(nsSizeMode aMode) override { mSizeMode = aMode; }
+
+  virtual void SetFocus(Raise, mozilla::dom::CallerType aCallerType) override;
+  virtual LayoutDeviceIntRect GetBounds() override;
+  virtual LayoutDeviceIntRect GetClientBounds() override;
+  virtual LayoutDeviceIntRect GetScreenBounds() override;
+
+  // Refresh mBounds with up-to-date values from [mView frame].
+  // Only called if this nsChildView is the popup content view of a popup window.
+  // For popup windows, the nsIWidget interface to Gecko is provided by
+  // nsCocoaWindow, not by nsChildView. So nsCocoaWindow manages resize requests
+  // from Gecko, fires resize events, and resizes the native NSWindow and NSView.
+  void UpdateBoundsFromView();
+
+  // Returns the "backing scale factor" of the view's window, which is the
+  // ratio of pixels in the window's backing store to Cocoa points. Prior to
+  // HiDPI support in OS X 10.7, this was always 1.0, but in HiDPI mode it
+  // will be 2.0 (and might potentially other values as screen resolutions
+  // evolve). This gives the relationship between what Gecko calls "device
+  // pixels" and the Cocoa "points" coordinate system.
+  CGFloat BackingScaleFactor() const;
+
+  mozilla::DesktopToLayoutDeviceScale GetDesktopToDeviceScale() final {
+    return mozilla::DesktopToLayoutDeviceScale(BackingScaleFactor());
+  }
+
+  // Call if the window's backing scale factor changes - i.e., it is moved
+  // between HiDPI and non-HiDPI screens
+  void BackingScaleFactorChanged();
+
+  virtual double GetDefaultScaleInternal() override;
+
+  virtual int32_t RoundsWidgetCoordinatesTo() override;
+
+  virtual void Invalidate(const LayoutDeviceIntRect& aRect) override;
+  void EnsureContentLayerForMainThreadPainting();
+
+  virtual void* GetNativeData(uint32_t aDataType) override;
+  virtual LayoutDeviceIntPoint WidgetToScreenOffset() override;
+  virtual bool ShowsResizeIndicator(LayoutDeviceIntRect* aResizerRect) override { return false; }
+
+  virtual nsresult DispatchEvent(mozilla::WidgetGUIEvent* aEvent, nsEventStatus& aStatus) override;
+
+  virtual bool WidgetTypeSupportsAcceleration() override;
+  virtual bool ShouldUseOffMainThreadCompositing() override;
+
+  virtual void SetCursor(const Cursor&) override;
+
+  virtual nsresult SetTitle(const nsAString& title) override;
+
+  [[nodiscard]] virtual nsresult GetAttention(int32_t aCycleCount) override;
+
+  virtual bool HasPendingInputEvent() override;
+
+  bool SendEventToNativeMenuSystem(NSEvent* aEvent);
+  virtual void PostHandleKeyEvent(mozilla::WidgetKeyboardEvent* aEvent) override;
+  virtual nsresult ActivateNativeMenuItemAt(const nsAString& indexString) override;
+  virtual nsresult ForceUpdateNativeMenuAt(const nsAString& indexString) override;
+  [[nodiscard]] virtual nsresult GetSelectionAsPlaintext(nsAString& aResult) override;
+
+  virtual void SetInputContext(const InputContext& aContext,
+                               const InputContextAction& aAction) override;
+  virtual InputContext GetInputContext() override;
+  virtual TextEventDispatcherListener* GetNativeTextEventDispatcherListener() override;
+  [[nodiscard]] virtual nsresult AttachNativeKeyEvent(
+      mozilla::WidgetKeyboardEvent& aEvent) override;
+  MOZ_CAN_RUN_SCRIPT virtual bool GetEditCommands(
+      mozilla::NativeKeyBindingsType aType, const mozilla::WidgetKeyboardEvent& aEvent,
+      nsTArray<mozilla::CommandInt>& aCommands) override;
+
+  virtual void SuppressAnimation(bool aSuppress) override;
+
+  virtual nsresult SynthesizeNativeKeyEvent(int32_t aNativeKeyboardLayout, int32_t aNativeKeyCode,
+                                            uint32_t aModifierFlags, const nsAString& aCharacters,
+                                            const nsAString& aUnmodifiedCharacters,
+                                            nsIObserver* aObserver) override;
+
+  virtual nsresult SynthesizeNativeMouseEvent(LayoutDeviceIntPoint aPoint,
+                                              NativeMouseMessage aNativeMessage,
+                                              mozilla::MouseButton aButton,
+                                              nsIWidget::Modifiers aModifierFlags,
+                                              nsIObserver* aObserver) override;
+
+  virtual nsresult SynthesizeNativeMouseMove(LayoutDeviceIntPoint aPoint,
+                                             nsIObserver* aObserver) override {
+    return SynthesizeNativeMouseEvent(aPoint, NativeMouseMessage::Move,
+                                      mozilla::MouseButton::eNotPressed,
+                                      nsIWidget::Modifiers::NO_MODIFIERS, aObserver);
+  }
+  virtual nsresult SynthesizeNativeMouseScrollEvent(LayoutDeviceIntPoint aPoint,
+                                                    uint32_t aNativeMessage, double aDeltaX,
+                                                    double aDeltaY, double aDeltaZ,
+                                                    uint32_t aModifierFlags,
+                                                    uint32_t aAdditionalFlags,
+                                                    nsIObserver* aObserver) override;
+  virtual nsresult SynthesizeNativeTouchPoint(uint32_t aPointerId, TouchPointerState aPointerState,
+                                              LayoutDeviceIntPoint aPoint, double aPointerPressure,
+                                              uint32_t aPointerOrientation,
+                                              nsIObserver* aObserver) override;
+
+  virtual nsresult SynthesizeNativeTouchpadDoubleTap(LayoutDeviceIntPoint aPoint,
+                                                     uint32_t aModifierFlags) override;
+
+  // Mac specific methods
+  void WillPaintWindow();
+  bool PaintWindow(LayoutDeviceIntRegion aRegion);
+  bool PaintWindowInDrawTarget(mozilla::gfx::DrawTarget* aDT, const LayoutDeviceIntRegion& aRegion,
+                               const mozilla::gfx::IntSize& aSurfaceSize);
+
+  void PaintWindowInContentLayer();
+  void HandleMainThreadCATransaction();
+
+#ifdef ACCESSIBILITY
+  already_AddRefed<mozilla::a11y::LocalAccessible> GetDocumentAccessible();
+#endif
+
+  virtual void CreateCompositor() override;
+
+  virtual bool WidgetPaintsBackground() override { return true; }
+
+  virtual bool PreRender(mozilla::widget::WidgetRenderingContext* aContext) override;
+  virtual void PostRender(mozilla::widget::WidgetRenderingContext* aContext) override;
+  virtual RefPtr<mozilla::layers::NativeLayerRoot> GetNativeLayerRoot() override;
+
+  virtual void UpdateThemeGeometries(const nsTArray<ThemeGeometry>& aThemeGeometries) override;
+
+  virtual void UpdateWindowDraggingRegion(const LayoutDeviceIntRegion& aRegion) override;
+  LayoutDeviceIntRegion GetNonDraggableRegion() { return mNonDraggableRegion.Region(); }
+
+  virtual void LookUpDictionary(const nsAString& aText,
+                                const nsTArray<mozilla::FontRange>& aFontRangeArray,
+                                const bool aIsVertical,
+                                const LayoutDeviceIntPoint& aPoint) override;
+
+  void ResetParent();
+
+  static bool DoHasPendingInputEvent();
+  static uint32_t GetCurrentInputEventCount();
+  static void UpdateCurrentInputEventCount();
+
+  NSView<mozView>* GetEditorView();
+
+  nsCocoaWindow* GetAppWindowWidget() const;
+
+  virtual void ReparentNativeWidget(nsIWidget* aNewParent) override;
+
+  mozilla::widget::TextInputHandler* GetTextInputHandler() { return mTextInputHandler; }
+
+  // unit conversion convenience functions
+  int32_t CocoaPointsToDevPixels(CGFloat aPts) const {
+    return nsCocoaUtils::CocoaPointsToDevPixels(aPts, BackingScaleFactor());
+  }
+  LayoutDeviceIntPoint CocoaPointsToDevPixels(const NSPoint& aPt) const {
+    return nsCocoaUtils::CocoaPointsToDevPixels(aPt, BackingScaleFactor());
+  }
+  LayoutDeviceIntPoint CocoaPointsToDevPixelsRoundDown(const NSPoint& aPt) const {
+    return nsCocoaUtils::CocoaPointsToDevPixelsRoundDown(aPt, BackingScaleFactor());
+  }
+  LayoutDeviceIntRect CocoaPointsToDevPixels(const NSRect& aRect) const {
+    return nsCocoaUtils::CocoaPointsToDevPixels(aRect, BackingScaleFactor());
+  }
+  CGFloat DevPixelsToCocoaPoints(int32_t aPixels) const {
+    return nsCocoaUtils::DevPixelsToCocoaPoints(aPixels, BackingScaleFactor());
+  }
+  NSRect DevPixelsToCocoaPoints(const LayoutDeviceIntRect& aRect) const {
+    return nsCocoaUtils::DevPixelsToCocoaPoints(aRect, BackingScaleFactor());
+  }
+
+  virtual LayoutDeviceIntPoint GetClientOffset() override;
+
+  void DispatchAPZWheelInputEvent(mozilla::InputData& aEvent);
+  nsEventStatus DispatchAPZInputEvent(mozilla::InputData& aEvent);
+
+  void DispatchDoubleTapGesture(mozilla::TimeStamp aEventTimeStamp,
+                                LayoutDeviceIntPoint aScreenPosition,
+                                mozilla::Modifiers aModifiers);
+
+  // Called when the main thread enters a phase during which visual changes
+  // are imminent and any layer updates on the compositor thread would interfere
+  // with visual atomicity.
+  // "Async" CATransactions are CATransactions which happen on a thread that's
+  // not the main thread.
+  void SuspendAsyncCATransactions();
+
+  // Called when we know that the current main thread paint will be completed once
+  // the main thread goes back to the event loop.
+  void MaybeScheduleUnsuspendAsyncCATransactions();
+
+  // Called from the runnable dispatched by MaybeScheduleUnsuspendAsyncCATransactions().
+  // At this point we know that the main thread is done handling the visual change
+  // (such as a window resize) and we can start modifying CALayers from the
+  // compositor thread again.
+  void UnsuspendAsyncCATransactions();
+
+  // Called by nsCocoaWindow when the window's fullscreen state changes.
+  void UpdateFullscreen(bool aFullscreen);
+
+#ifdef DEBUG
+  // test only.
+  virtual nsresult SetHiDPIMode(bool aHiDPI) override;
+  virtual nsresult RestoreHiDPIMode() override;
+#endif
+
+ protected:
+  virtual ~nsChildView();
+
+  void ReportMoveEvent();
+  void ReportSizeEvent();
+
+  void TearDownView();
+
+  virtual already_AddRefed<nsIWidget> AllocateChildPopupWidget() override {
+    return nsIWidget::CreateTopLevelWindow();
+  }
+
+  void ConfigureAPZCTreeManager() override;
+  void ConfigureAPZControllerThread() override;
+
+  void UpdateVibrancy(const nsTArray<ThemeGeometry>& aThemeGeometries);
+  mozilla::VibrancyManager& EnsureVibrancyManager();
+
+  nsIWidget* GetWidgetForListenerEvents();
+
+ protected:
+  ChildView* mView;  // my parallel cocoa view, [STRONG]
+  RefPtr<mozilla::widget::TextInputHandler> mTextInputHandler;
+  InputContext mInputContext;
+
+  NSView* mParentView;
+  nsIWidget* mParentWidget;
+
+#ifdef ACCESSIBILITY
+  // weak ref to this childview's associated mozAccessible for speed reasons
+  // (we get queried for it *a lot* but don't want to own it)
+  nsWeakPtr mAccessible;
+#endif
+
+  // Held while the compositor (or WR renderer) thread is compositing.
+  // Protects from tearing down the view during compositing and from presenting
+  // half-composited layers to the screen.
+  mozilla::Mutex mCompositingLock MOZ_UNANNOTATED;
+
+  mozilla::ViewRegion mNonDraggableRegion;
+
+  // Cached value of [mView backingScaleFactor], to avoid sending two obj-c
+  // messages (respondsToSelector, backingScaleFactor) every time we need to
+  // use it.
+  // ** We'll need to reinitialize this if the backing resolution changes. **
+  mutable CGFloat mBackingScaleFactor;
+
+  bool mVisible;
+  nsSizeMode mSizeMode;
+  bool mDrawing;
+  bool mIsDispatchPaint;  // Is a paint event being dispatched
+
+  RefPtr<mozilla::layers::NativeLayerRootCA> mNativeLayerRoot;
+
+  // In BasicLayers mode, this is the CoreAnimation layer that contains the
+  // rendering from Gecko. It is a sublayer of mNativeLayerRoot's underlying
+  // wrapper layer.
+  // Lazily created by EnsureContentLayerForMainThreadPainting().
+  RefPtr<mozilla::layers::NativeLayerCA> mContentLayer;
+  RefPtr<mozilla::layers::SurfacePoolHandle> mPoolHandle;
+
+  // In BasicLayers mode, this is the invalid region of mContentLayer.
+  LayoutDeviceIntRegion mContentLayerInvalidRegion;
+
+  mozilla::UniquePtr<mozilla::VibrancyManager> mVibrancyManager;
+
+  RefPtr<mozilla::CancelableRunnable> mUnsuspendAsyncCATransactionsRunnable;
+
+  static uint32_t sLastInputEventCount;
+
+  // This is used by SynthesizeNativeTouchPoint to maintain state between
+  // multiple synthesized points
+  mozilla::UniquePtr<mozilla::MultiTouchInput> mSynthesizedTouchInput;
+};
+
+#endif  // nsChildView_h_
diff --git a/widget/cocoa/nsChildView.mm b/widget/cocoa/nsChildView.mm
new file mode 100644
index 0000000000..4f9e69f2b9
--- /dev/null
+++ b/widget/cocoa/nsChildView.mm
@@ -0,0 +1,4926 @@
+/* -*- Mode: objc; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+
+#include "mozilla/Logging.h"
+#include "mozilla/Unused.h"
+
+#include <unistd.h>
+#include <math.h>
+
+#include "nsChildView.h"
+#include "nsCocoaWindow.h"
+
+#include "mozilla/Maybe.h"
+#include "mozilla/MiscEvents.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/NativeKeyBindingsType.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/SwipeTracker.h"
+#include "mozilla/TextEventDispatcher.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/TouchEvents.h"
+#include "mozilla/WheelHandlingHelper.h"  // for WheelDeltaAdjustmentStrategy
+#include "mozilla/WritingModes.h"
+#include "mozilla/dom/DataTransfer.h"
+#include "mozilla/dom/MouseEventBinding.h"
+#include "mozilla/dom/SimpleGestureEventBinding.h"
+#include "mozilla/dom/WheelEventBinding.h"
+
+#include "nsArrayUtils.h"
+#include "nsExceptionHandler.h"
+#include "nsObjCExceptions.h"
+#include "nsCOMPtr.h"
+#include "nsThreadUtils.h"
+#include "nsToolkit.h"
+#include "nsCRT.h"
+
+#include "nsFontMetrics.h"
+#include "nsIRollupListener.h"
+#include "nsViewManager.h"
+#include "nsIFile.h"
+#include "nsILocalFileMac.h"
+#include "nsGfxCIID.h"
+#include "nsStyleConsts.h"
+#include "nsIWidgetListener.h"
+#include "nsIScreen.h"
+
+#include "nsDragService.h"
+#include "nsClipboard.h"
+#include "nsCursorManager.h"
+#include "nsWindowMap.h"
+#include "nsCocoaFeatures.h"
+#include "nsCocoaUtils.h"
+#include "nsMenuUtilsX.h"
+#include "nsMenuBarX.h"
+#include "NativeKeyBindings.h"
+#include "MacThemeGeometryType.h"
+
+#include "gfxContext.h"
+#include "gfxQuartzSurface.h"
+#include "gfxUtils.h"
+#include "nsRegion.h"
+#include "GfxTexturesReporter.h"
+#include "GLTextureImage.h"
+#include "GLContextProvider.h"
+#include "GLContextCGL.h"
+#include "OGLShaderProgram.h"
+#include "ScopedGLHelpers.h"
+#include "HeapCopyOfStackArray.h"
+#include "mozilla/layers/IAPZCTreeManager.h"
+#include "mozilla/layers/APZInputBridge.h"
+#include "mozilla/layers/APZThreadUtils.h"
+#include "mozilla/layers/CompositorOGL.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/layers/InputAPZContext.h"
+#include "mozilla/layers/IpcResourceUpdateQueue.h"
+#include "mozilla/layers/NativeLayerCA.h"
+#include "mozilla/layers/WebRenderBridgeChild.h"
+#include "mozilla/layers/WebRenderLayerManager.h"
+#include "mozilla/webrender/WebRenderAPI.h"
+#include "mozilla/widget/CompositorWidget.h"
+#include "mozilla/widget/Screen.h"
+#include "gfxUtils.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/BorrowedContext.h"
+#ifdef ACCESSIBILITY
+#  include "nsAccessibilityService.h"
+#  include "mozilla/a11y/Platform.h"
+#endif
+
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_apz.h"
+#include "mozilla/StaticPrefs_browser.h"
+#include "mozilla/StaticPrefs_general.h"
+#include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/StaticPrefs_ui.h"
+
+#include <dlfcn.h>
+
+#include <ApplicationServices/ApplicationServices.h>
+
+#include "GeckoProfiler.h"
+
+#include "mozilla/layers/ChromeProcessController.h"
+#include "nsLayoutUtils.h"
+#include "InputData.h"
+#include "VibrancyManager.h"
+#include "nsNativeThemeCocoa.h"
+#include "nsIDOMWindowUtils.h"
+#include "Units.h"
+#include "UnitTransforms.h"
+#include "mozilla/UniquePtrExtensions.h"
+#include "CustomCocoaEvents.h"
+#include "NativeMenuSupport.h"
+
+using namespace mozilla;
+using namespace mozilla::layers;
+using namespace mozilla::gl;
+using namespace mozilla::widget;
+
+using mozilla::gfx::Matrix4x4;
+
+#undef DEBUG_UPDATE
+#undef INVALIDATE_DEBUGGING  // flash areas as they are invalidated
+
+// Don't put more than this many rects in the dirty region, just fluff
+// out to the bounding-box if there are more
+#define MAX_RECTS_IN_REGION 100
+
+LazyLogModule sCocoaLog("nsCocoaWidgets");
+
+extern "C" {
+CG_EXTERN void CGContextResetCTM(CGContextRef);
+CG_EXTERN void CGContextSetCTM(CGContextRef, CGAffineTransform);
+CG_EXTERN void CGContextResetClip(CGContextRef);
+
+typedef CFTypeRef CGSRegionObj;
+CGError CGSNewRegionWithRect(const CGRect* rect, CGSRegionObj* outRegion);
+CGError CGSNewRegionWithRectList(const CGRect* rects, int rectCount, CGSRegionObj* outRegion);
+}
+
+// defined in nsMenuBarX.mm
+extern NSMenu* sApplicationMenu;  // Application menu shared by all menubars
+
+extern nsIArray* gDraggedTransferables;
+
+ChildView* ChildViewMouseTracker::sLastMouseEventView = nil;
+NSEvent* ChildViewMouseTracker::sLastMouseMoveEvent = nil;
+NSWindow* ChildViewMouseTracker::sWindowUnderMouse = nil;
+NSPoint ChildViewMouseTracker::sLastScrollEventScreenLocation = NSZeroPoint;
+
+#ifdef INVALIDATE_DEBUGGING
+static void blinkRect(Rect* r);
+static void blinkRgn(RgnHandle rgn);
+#endif
+
+bool gUserCancelledDrag = false;
+
+uint32_t nsChildView::sLastInputEventCount = 0;
+
+static bool sIsTabletPointerActivated = false;
+
+static uint32_t sUniqueKeyEventId = 0;
+
+// The view that will do our drawing or host our NSOpenGLContext or Core Animation layer.
+@interface PixelHostingView : NSView {
+}
+
+@end
+
+@interface ChildView (Private)
+
+// sets up our view, attaching it to its owning gecko view
+- (id)initWithFrame:(NSRect)inFrame geckoChild:(nsChildView*)inChild;
+
+// set up a gecko mouse event based on a cocoa mouse event
+- (void)convertCocoaMouseWheelEvent:(NSEvent*)aMouseEvent
+                       toGeckoEvent:(WidgetWheelEvent*)outWheelEvent;
+- (void)convertCocoaMouseEvent:(NSEvent*)aMouseEvent toGeckoEvent:(WidgetInputEvent*)outGeckoEvent;
+- (void)convertCocoaTabletPointerEvent:(NSEvent*)aMouseEvent
+                          toGeckoEvent:(WidgetMouseEvent*)outGeckoEvent;
+- (NSMenu*)contextMenu;
+
+- (void)markLayerForDisplay;
+- (CALayer*)rootCALayer;
+- (void)updateRootCALayer;
+
+#ifdef ACCESSIBILITY
+- (id<mozAccessible>)accessible;
+#endif
+
+- (LayoutDeviceIntPoint)convertWindowCoordinates:(NSPoint)aPoint;
+- (LayoutDeviceIntPoint)convertWindowCoordinatesRoundDown:(NSPoint)aPoint;
+
+- (BOOL)inactiveWindowAcceptsMouseEvent:(NSEvent*)aEvent;
+- (void)updateWindowDraggableState;
+
+- (bool)beginOrEndGestureForEventPhase:(NSEvent*)aEvent;
+
+@end
+
+#pragma mark -
+
+// Flips a screen coordinate from a point in the cocoa coordinate system (bottom-left rect) to a
+// point that is a "flipped" cocoa coordinate system (starts in the top-left).
+static inline void FlipCocoaScreenCoordinate(NSPoint& inPoint) {
+  inPoint.y = nsCocoaUtils::FlippedScreenY(inPoint.y);
+}
+
+#pragma mark -
+
+nsChildView::nsChildView()
+    : nsBaseWidget(),
+      mView(nullptr),
+      mParentView(nil),
+      mParentWidget(nullptr),
+      mCompositingLock("ChildViewCompositing"),
+      mBackingScaleFactor(0.0),
+      mVisible(false),
+      mSizeMode(nsSizeMode_Normal),
+      mDrawing(false),
+      mIsDispatchPaint(false) {}
+
+nsChildView::~nsChildView() {
+  // Notify the children that we're gone.  childView->ResetParent() can change
+  // our list of children while it's being iterated, so the way we iterate the
+  // list must allow for this.
+  for (nsIWidget* kid = mLastChild; kid;) {
+    nsChildView* childView = static_cast<nsChildView*>(kid);
+    kid = kid->GetPrevSibling();
+    childView->ResetParent();
+  }
+
+  NS_WARNING_ASSERTION(mOnDestroyCalled, "nsChildView object destroyed without calling Destroy()");
+
+  if (mContentLayer) {
+    mNativeLayerRoot->RemoveLayer(mContentLayer);  // safe if already removed
+  }
+
+  DestroyCompositor();
+
+  // An nsChildView object that was in use can be destroyed without Destroy()
+  // ever being called on it.  So we also need to do a quick, safe cleanup
+  // here (it's too late to just call Destroy(), which can cause crashes).
+  // It's particularly important to make sure widgetDestroyed is called on our
+  // mView -- this method NULLs mView's mGeckoChild, and NULL checks on
+  // mGeckoChild are used throughout the ChildView class to tell if it's safe
+  // to use a ChildView object.
+  [mView widgetDestroyed];  // Safe if mView is nil.
+  mParentWidget = nil;
+  TearDownView();  // Safe if called twice.
+}
+
+nsresult nsChildView::Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
+                             const LayoutDeviceIntRect& aRect, widget::InitData* aInitData) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Because the hidden window is created outside of an event loop,
+  // we need to provide an autorelease pool to avoid leaking cocoa objects
+  // (see bug 559075).
+  nsAutoreleasePool localPool;
+
+  mBounds = aRect;
+
+  // Ensure that the toolkit is created.
+  nsToolkit::GetToolkit();
+
+  BaseCreate(aParent, aInitData);
+
+  mParentView = nil;
+  if (aParent) {
+    // This is the popup window case. aParent is the nsCocoaWindow for the
+    // popup window, and mParentView will be its content view.
+    mParentView = (NSView*)aParent->GetNativeData(NS_NATIVE_WIDGET);
+    mParentWidget = aParent;
+  } else {
+    // This is the top-level window case.
+    // aNativeParent will be the contentView of our window, since that's what
+    // nsCocoaWindow returns when asked for an NS_NATIVE_VIEW.
+    // We do not have a direct "parent widget" association with the top level
+    // window's nsCocoaWindow object.
+    mParentView = reinterpret_cast<NSView*>(aNativeParent);
+  }
+
+  // create our parallel NSView and hook it up to our parent. Recall
+  // that NS_NATIVE_WIDGET is the NSView.
+  CGFloat scaleFactor = nsCocoaUtils::GetBackingScaleFactor(mParentView);
+  NSRect r = nsCocoaUtils::DevPixelsToCocoaPoints(mBounds, scaleFactor);
+  mView = [[ChildView alloc] initWithFrame:r geckoChild:this];
+
+  mNativeLayerRoot = NativeLayerRootCA::CreateForCALayer([mView rootCALayer]);
+  mNativeLayerRoot->SetBackingScale(scaleFactor);
+
+  // If this view was created in a Gecko view hierarchy, the initial state
+  // is hidden.  If the view is attached only to a native NSView but has
+  // no Gecko parent (as in embedding), the initial state is visible.
+  if (mParentWidget)
+    [mView setHidden:YES];
+  else
+    mVisible = true;
+
+  // Hook it up in the NSView hierarchy.
+  if (mParentView) {
+    [mParentView addSubview:mView];
+  }
+
+  // if this is a ChildView, make sure that our per-window data
+  // is set up
+  if ([mView isKindOfClass:[ChildView class]])
+    [[WindowDataMap sharedWindowDataMap] ensureDataForWindow:[mView window]];
+
+  NS_ASSERTION(!mTextInputHandler, "mTextInputHandler has already existed");
+  mTextInputHandler = new TextInputHandler(this, mView);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsChildView::TearDownView() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mView) return;
+
+  NSWindow* win = [mView window];
+  NSResponder* responder = [win firstResponder];
+
+  // We're being unhooked from the view hierarchy, don't leave our view
+  // or a child view as the window first responder.
+  if (responder && [responder isKindOfClass:[NSView class]] &&
+      [(NSView*)responder isDescendantOf:mView]) {
+    [win makeFirstResponder:[mView superview]];
+  }
+
+  // If mView is win's contentView, win (mView's NSWindow) "owns" mView --
+  // win has retained mView, and will detach it from the view hierarchy and
+  // release it when necessary (when win is itself destroyed (in a call to
+  // [win dealloc])).  So all we need to do here is call [mView release] (to
+  // match the call to [mView retain] in nsChildView::StandardCreate()).
+  // Also calling [mView removeFromSuperviewWithoutNeedingDisplay] causes
+  // mView to be released again and dealloced, while remaining win's
+  // contentView.  So if we do that here, win will (for a short while) have
+  // an invalid contentView (for the consequences see bmo bugs 381087 and
+  // 374260).
+  if ([mView isEqual:[win contentView]]) {
+    [mView release];
+  } else {
+    // Stop NSView hierarchy being changed during [ChildView drawRect:]
+    [mView performSelectorOnMainThread:@selector(delayedTearDown)
+                            withObject:nil
+                         waitUntilDone:false];
+  }
+  mView = nil;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsCocoaWindow* nsChildView::GetAppWindowWidget() const {
+  id windowDelegate = [[mView window] delegate];
+  if (windowDelegate && [windowDelegate isKindOfClass:[WindowDelegate class]]) {
+    return [(WindowDelegate*)windowDelegate geckoWidget];
+  }
+  return nullptr;
+}
+
+void nsChildView::Destroy() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mOnDestroyCalled) return;
+  mOnDestroyCalled = true;
+
+  // Stuff below may delete the last ref to this
+  nsCOMPtr<nsIWidget> kungFuDeathGrip(this);
+
+  {
+    // Make sure that no composition is in progress while disconnecting
+    // ourselves from the view.
+    MutexAutoLock lock(mCompositingLock);
+
+    [mView widgetDestroyed];
+  }
+
+  nsBaseWidget::Destroy();
+
+  NotifyWindowDestroyed();
+  mParentWidget = nil;
+
+  TearDownView();
+
+  nsBaseWidget::OnDestroy();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+#pragma mark -
+
+#if 0
+static void PrintViewHierarchy(NSView *view)
+{
+  while (view) {
+    NSLog(@"  view is %x, frame %@", view, NSStringFromRect([view frame]));
+    view = [view superview];
+  }
+}
+#endif
+
+// Return native data according to aDataType
+void* nsChildView::GetNativeData(uint32_t aDataType) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  void* retVal = nullptr;
+
+  switch (aDataType) {
+    case NS_NATIVE_WIDGET:
+      retVal = (void*)mView;
+      break;
+
+    case NS_NATIVE_WINDOW:
+      retVal = [mView window];
+      break;
+
+    case NS_NATIVE_GRAPHIC:
+      NS_ERROR("Requesting NS_NATIVE_GRAPHIC on a Mac OS X child view!");
+      retVal = nullptr;
+      break;
+
+    case NS_NATIVE_OFFSETX:
+      retVal = 0;
+      break;
+
+    case NS_NATIVE_OFFSETY:
+      retVal = 0;
+      break;
+
+    case NS_RAW_NATIVE_IME_CONTEXT:
+      retVal = GetPseudoIMEContext();
+      if (retVal) {
+        break;
+      }
+      retVal = [mView inputContext];
+      // If input context isn't available on this widget, we should set |this|
+      // instead of nullptr since if this returns nullptr, IMEStateManager
+      // cannot manage composition with TextComposition instance.  Although,
+      // this case shouldn't occur.
+      if (NS_WARN_IF(!retVal)) {
+        retVal = this;
+      }
+      break;
+
+    case NS_NATIVE_WINDOW_WEBRTC_DEVICE_ID: {
+      NSWindow* win = [mView window];
+      if (win) {
+        retVal = (void*)[win windowNumber];
+      }
+      break;
+    }
+  }
+
+  return retVal;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nullptr);
+}
+
+#pragma mark -
+
+void nsChildView::SuppressAnimation(bool aSuppress) {
+  GetAppWindowWidget()->SuppressAnimation(aSuppress);
+}
+
+bool nsChildView::IsVisible() const {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mVisible) {
+    return mVisible;
+  }
+
+  if (!GetAppWindowWidget()->IsVisible()) {
+    return false;
+  }
+
+  // mVisible does not accurately reflect the state of a hidden tabbed view
+  // so verify that the view has a window as well
+  // then check native widget hierarchy visibility
+  return ([mView window] != nil) && !NSIsEmptyRect([mView visibleRect]);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+// Some NSView methods (e.g. setFrame and setHidden) invalidate the view's
+// bounds in our window. However, we don't want these invalidations because
+// they are unnecessary and because they actually slow us down since we
+// block on the compositor inside drawRect.
+// When we actually need something invalidated, there will be an explicit call
+// to Invalidate from Gecko, so turning these automatic invalidations off
+// won't hurt us in the non-OMTC case.
+// The invalidations inside these NSView methods happen via a call to the
+// private method -[NSWindow _setNeedsDisplayInRect:]. Our BaseWindow
+// implementation of that method is augmented to let us ignore those calls
+// using -[BaseWindow disable/enableSetNeedsDisplay].
+static void ManipulateViewWithoutNeedingDisplay(NSView* aView, void (^aCallback)()) {
+  BaseWindow* win = nil;
+  if ([[aView window] isKindOfClass:[BaseWindow class]]) {
+    win = (BaseWindow*)[aView window];
+  }
+  [win disableSetNeedsDisplay];
+  aCallback();
+  [win enableSetNeedsDisplay];
+}
+
+// Hide or show this component
+void nsChildView::Show(bool aState) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (aState != mVisible) {
+    // Provide an autorelease pool because this gets called during startup
+    // on the "hidden window", resulting in cocoa object leakage if there's
+    // no pool in place.
+    nsAutoreleasePool localPool;
+
+    ManipulateViewWithoutNeedingDisplay(mView, ^{
+      [mView setHidden:!aState];
+    });
+
+    mVisible = aState;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Change the parent of this widget
+void nsChildView::SetParent(nsIWidget* aNewParent) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mOnDestroyCalled) return;
+
+  nsCOMPtr<nsIWidget> kungFuDeathGrip(this);
+
+  if (mParentWidget) {
+    mParentWidget->RemoveChild(this);
+  }
+
+  if (aNewParent) {
+    ReparentNativeWidget(aNewParent);
+  } else {
+    [mView removeFromSuperview];
+    mParentView = nil;
+  }
+
+  mParentWidget = aNewParent;
+
+  if (mParentWidget) {
+    mParentWidget->AddChild(this);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsChildView::ReparentNativeWidget(nsIWidget* aNewParent) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_ASSERT(aNewParent, "null widget");
+
+  if (mOnDestroyCalled) return;
+
+  NSView<mozView>* newParentView = (NSView<mozView>*)aNewParent->GetNativeData(NS_NATIVE_WIDGET);
+  NS_ENSURE_TRUE_VOID(newParentView);
+
+  // we hold a ref to mView, so this is safe
+  [mView removeFromSuperview];
+  mParentView = newParentView;
+  [mParentView addSubview:mView];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsChildView::ResetParent() {
+  if (!mOnDestroyCalled) {
+    if (mParentWidget) mParentWidget->RemoveChild(this);
+    if (mView) [mView removeFromSuperview];
+  }
+  mParentWidget = nullptr;
+}
+
+nsIWidget* nsChildView::GetParent() { return mParentWidget; }
+
+float nsChildView::GetDPI() {
+  float dpi = 96.0;
+  nsCOMPtr<nsIScreen> screen = GetWidgetScreen();
+  if (screen) {
+    screen->GetDpi(&dpi);
+  }
+  return dpi;
+}
+
+void nsChildView::Enable(bool aState) {}
+
+bool nsChildView::IsEnabled() const { return true; }
+
+void nsChildView::SetFocus(Raise, mozilla::dom::CallerType aCallerType) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSWindow* window = [mView window];
+  if (window) [window makeFirstResponder:mView];
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Override to set the cursor on the mac
+void nsChildView::SetCursor(const Cursor& aCursor) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if ([mView isDragInProgress]) {
+    return;  // Don't change the cursor during dragging.
+  }
+
+  nsBaseWidget::SetCursor(aCursor);
+
+  if (NS_SUCCEEDED([[nsCursorManager sharedInstance] setCustomCursor:aCursor
+                                                   widgetScaleFactor:BackingScaleFactor()])) {
+    return;
+  }
+
+  [[nsCursorManager sharedInstance] setNonCustomCursor:aCursor];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+#pragma mark -
+
+// Get this component dimension
+LayoutDeviceIntRect nsChildView::GetBounds() {
+  return !mView ? mBounds : CocoaPointsToDevPixels([mView frame]);
+}
+
+LayoutDeviceIntRect nsChildView::GetClientBounds() {
+  LayoutDeviceIntRect rect = GetBounds();
+  if (!mParentWidget) {
+    // For top level widgets we want the position on screen, not the position
+    // of this view inside the window.
+    rect.MoveTo(WidgetToScreenOffset());
+  }
+  return rect;
+}
+
+LayoutDeviceIntRect nsChildView::GetScreenBounds() {
+  LayoutDeviceIntRect rect = GetBounds();
+  rect.MoveTo(WidgetToScreenOffset());
+  return rect;
+}
+
+double nsChildView::GetDefaultScaleInternal() { return BackingScaleFactor(); }
+
+CGFloat nsChildView::BackingScaleFactor() const {
+  if (mBackingScaleFactor > 0.0) {
+    return mBackingScaleFactor;
+  }
+  if (!mView) {
+    return 1.0;
+  }
+  mBackingScaleFactor = nsCocoaUtils::GetBackingScaleFactor(mView);
+  return mBackingScaleFactor;
+}
+
+void nsChildView::BackingScaleFactorChanged() {
+  CGFloat newScale = nsCocoaUtils::GetBackingScaleFactor(mView);
+
+  // ignore notification if it hasn't really changed (or maybe we have
+  // disabled HiDPI mode via prefs)
+  if (mBackingScaleFactor == newScale) {
+    return;
+  }
+
+  SuspendAsyncCATransactions();
+  mBackingScaleFactor = newScale;
+  NSRect frame = [mView frame];
+  mBounds = nsCocoaUtils::CocoaRectToGeckoRectDevPix(frame, newScale);
+
+  mNativeLayerRoot->SetBackingScale(mBackingScaleFactor);
+
+  if (mWidgetListener && !mWidgetListener->GetAppWindow()) {
+    if (PresShell* presShell = mWidgetListener->GetPresShell()) {
+      presShell->BackingScaleFactorChanged();
+    }
+  }
+}
+
+int32_t nsChildView::RoundsWidgetCoordinatesTo() {
+  if (BackingScaleFactor() == 2.0) {
+    return 2;
+  }
+  return 1;
+}
+
+// Move this component, aX and aY are in the parent widget coordinate system
+void nsChildView::Move(double aX, double aY) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  int32_t x = NSToIntRound(aX);
+  int32_t y = NSToIntRound(aY);
+
+  if (!mView || (mBounds.x == x && mBounds.y == y)) return;
+
+  mBounds.x = x;
+  mBounds.y = y;
+
+  ManipulateViewWithoutNeedingDisplay(mView, ^{
+    [mView setFrame:DevPixelsToCocoaPoints(mBounds)];
+  });
+
+  ReportMoveEvent();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsChildView::Resize(double aWidth, double aHeight, bool aRepaint) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  int32_t width = NSToIntRound(aWidth);
+  int32_t height = NSToIntRound(aHeight);
+
+  if (!mView || (mBounds.width == width && mBounds.height == height)) return;
+
+  SuspendAsyncCATransactions();
+  mBounds.width = width;
+  mBounds.height = height;
+
+  ManipulateViewWithoutNeedingDisplay(mView, ^{
+    [mView setFrame:DevPixelsToCocoaPoints(mBounds)];
+  });
+
+  if (mVisible && aRepaint) {
+    [[mView pixelHostingView] setNeedsDisplay:YES];
+  }
+
+  ReportSizeEvent();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsChildView::Resize(double aX, double aY, double aWidth, double aHeight, bool aRepaint) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  int32_t x = NSToIntRound(aX);
+  int32_t y = NSToIntRound(aY);
+  int32_t width = NSToIntRound(aWidth);
+  int32_t height = NSToIntRound(aHeight);
+
+  BOOL isMoving = (mBounds.x != x || mBounds.y != y);
+  BOOL isResizing = (mBounds.width != width || mBounds.height != height);
+  if (!mView || (!isMoving && !isResizing)) return;
+
+  if (isMoving) {
+    mBounds.x = x;
+    mBounds.y = y;
+  }
+  if (isResizing) {
+    SuspendAsyncCATransactions();
+    mBounds.width = width;
+    mBounds.height = height;
+
+    CALayer* layer = [mView rootCALayer];
+    double scale = BackingScaleFactor();
+    layer.bounds = CGRectMake(0, 0, width / scale, height / scale);
+  }
+
+  ManipulateViewWithoutNeedingDisplay(mView, ^{
+    [mView setFrame:DevPixelsToCocoaPoints(mBounds)];
+  });
+
+  if (mVisible && aRepaint) {
+    [[mView pixelHostingView] setNeedsDisplay:YES];
+  }
+
+  if (isMoving) {
+    ReportMoveEvent();
+    if (mOnDestroyCalled) return;
+  }
+  if (isResizing) ReportSizeEvent();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// The following three methods are primarily an attempt to avoid glitches during
+// window resizing.
+// Here's some background on how these glitches come to be:
+// CoreAnimation transactions are per-thread. They don't nest across threads.
+// If you submit a transaction on the main thread and a transaction on a
+// different thread, the two will race to the window server and show up on the
+// screen in the order that they happen to arrive in at the window server.
+// When the window size changes, there's another event that needs to be
+// synchronized with: the window "shape" change. Cocoa has built-in synchronization
+// mechanics that make sure that *main thread* window paints during window resizes
+// are synchronized properly with the window shape change. But no such built-in
+// synchronization exists for CATransactions that are triggered on a non-main
+// thread.
+// To cope with this, we define a "danger zone" during which we simply avoid
+// triggering any CATransactions on a non-main thread (called "async" CATransactions
+// here). This danger zone starts at the earliest opportunity at which we know
+// about the size change, which is nsChildView::Resize, and ends at a point at
+// which we know for sure that the paint has been handled completely, which is
+// when we return to the event loop after layer display.
+void nsChildView::SuspendAsyncCATransactions() {
+  if (mUnsuspendAsyncCATransactionsRunnable) {
+    mUnsuspendAsyncCATransactionsRunnable->Cancel();
+    mUnsuspendAsyncCATransactionsRunnable = nullptr;
+  }
+
+  // Make sure that there actually will be a CATransaction on the main thread
+  // during which we get a chance to schedule unsuspension. Otherwise we might
+  // accidentally stay suspended indefinitely.
+  [mView markLayerForDisplay];
+
+  mNativeLayerRoot->SuspendOffMainThreadCommits();
+}
+
+void nsChildView::MaybeScheduleUnsuspendAsyncCATransactions() {
+  if (mNativeLayerRoot->AreOffMainThreadCommitsSuspended() &&
+      !mUnsuspendAsyncCATransactionsRunnable) {
+    mUnsuspendAsyncCATransactionsRunnable =
+        NewCancelableRunnableMethod("nsChildView::MaybeScheduleUnsuspendAsyncCATransactions", this,
+                                    &nsChildView::UnsuspendAsyncCATransactions);
+    NS_DispatchToMainThread(mUnsuspendAsyncCATransactionsRunnable);
+  }
+}
+
+void nsChildView::UnsuspendAsyncCATransactions() {
+  mUnsuspendAsyncCATransactionsRunnable = nullptr;
+
+  if (mNativeLayerRoot->UnsuspendOffMainThreadCommits()) {
+    // We need to call mNativeLayerRoot->CommitToScreen() at the next available
+    // opportunity.
+    // The easiest way to handle this request is to mark the layer as needing
+    // display, because this will schedule a main thread CATransaction, during
+    // which HandleMainThreadCATransaction will call CommitToScreen().
+    [mView markLayerForDisplay];
+  }
+}
+
+void nsChildView::UpdateFullscreen(bool aFullscreen) {
+  if (mNativeLayerRoot) {
+    mNativeLayerRoot->SetWindowIsFullscreen(aFullscreen);
+  }
+}
+
+nsresult nsChildView::SynthesizeNativeKeyEvent(int32_t aNativeKeyboardLayout,
+                                               int32_t aNativeKeyCode, uint32_t aModifierFlags,
+                                               const nsAString& aCharacters,
+                                               const nsAString& aUnmodifiedCharacters,
+                                               nsIObserver* aObserver) {
+  AutoObserverNotifier notifier(aObserver, "keyevent");
+  return mTextInputHandler->SynthesizeNativeKeyEvent(
+      aNativeKeyboardLayout, aNativeKeyCode, aModifierFlags, aCharacters, aUnmodifiedCharacters);
+}
+
+nsresult nsChildView::SynthesizeNativeMouseEvent(LayoutDeviceIntPoint aPoint,
+                                                 NativeMouseMessage aNativeMessage,
+                                                 MouseButton aButton,
+                                                 nsIWidget::Modifiers aModifierFlags,
+                                                 nsIObserver* aObserver) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  AutoObserverNotifier notifier(aObserver, "mouseevent");
+
+  NSPoint pt = nsCocoaUtils::DevPixelsToCocoaPoints(aPoint, BackingScaleFactor());
+
+  // Move the mouse cursor to the requested position and reconnect it to the mouse.
+  CGWarpMouseCursorPosition(NSPointToCGPoint(pt));
+  CGAssociateMouseAndMouseCursorPosition(true);
+
+  // aPoint is given with the origin on the top left, but convertScreenToBase
+  // expects a point in a coordinate system that has its origin on the bottom left.
+  NSPoint screenPoint = NSMakePoint(pt.x, nsCocoaUtils::FlippedScreenY(pt.y));
+  NSPoint windowPoint = nsCocoaUtils::ConvertPointFromScreen([mView window], screenPoint);
+  NSEventModifierFlags modifierFlags =
+      nsCocoaUtils::ConvertWidgetModifiersToMacModifierFlags(aModifierFlags);
+
+  if (aButton == MouseButton::eX1 || aButton == MouseButton::eX2) {
+    // NSEvent has `buttonNumber` for `NSEventTypeOther*`.  However, it seems that
+    // there is no way to specify it.  Therefore, we should return error for now.
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  NSEventType nativeEventType;
+  switch (aNativeMessage) {
+    case NativeMouseMessage::ButtonDown:
+    case NativeMouseMessage::ButtonUp: {
+      switch (aButton) {
+        case MouseButton::ePrimary:
+          nativeEventType = aNativeMessage == NativeMouseMessage::ButtonDown
+                                ? NSEventTypeLeftMouseDown
+                                : NSEventTypeLeftMouseUp;
+          break;
+        case MouseButton::eMiddle:
+          nativeEventType = aNativeMessage == NativeMouseMessage::ButtonDown
+                                ? NSEventTypeOtherMouseDown
+                                : NSEventTypeOtherMouseUp;
+          break;
+        case MouseButton::eSecondary:
+          nativeEventType = aNativeMessage == NativeMouseMessage::ButtonDown
+                                ? NSEventTypeRightMouseDown
+                                : NSEventTypeRightMouseUp;
+          break;
+        default:
+          return NS_ERROR_INVALID_ARG;
+      }
+      break;
+    }
+    case NativeMouseMessage::Move:
+      nativeEventType = NSEventTypeMouseMoved;
+      break;
+    case NativeMouseMessage::EnterWindow:
+      nativeEventType = NSEventTypeMouseEntered;
+      break;
+    case NativeMouseMessage::LeaveWindow:
+      nativeEventType = NSEventTypeMouseExited;
+      break;
+  }
+
+  NSEvent* event = [NSEvent mouseEventWithType:nativeEventType
+                                      location:windowPoint
+                                 modifierFlags:modifierFlags
+                                     timestamp:[[NSProcessInfo processInfo] systemUptime]
+                                  windowNumber:[[mView window] windowNumber]
+                                       context:nil
+                                   eventNumber:0
+                                    clickCount:1
+                                      pressure:0.0];
+
+  if (!event) return NS_ERROR_FAILURE;
+
+  if ([[mView window] isKindOfClass:[BaseWindow class]]) {
+    // Tracking area events don't end up in their tracking areas when sent
+    // through [NSApp sendEvent:], so pass them directly to the right methods.
+    BaseWindow* window = (BaseWindow*)[mView window];
+    if (nativeEventType == NSEventTypeMouseEntered) {
+      [window mouseEntered:event];
+      return NS_OK;
+    }
+    if (nativeEventType == NSEventTypeMouseExited) {
+      [window mouseExited:event];
+      return NS_OK;
+    }
+    if (nativeEventType == NSEventTypeMouseMoved) {
+      [window mouseMoved:event];
+      return NS_OK;
+    }
+  }
+
+  [NSApp sendEvent:event];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsChildView::SynthesizeNativeMouseScrollEvent(
+    mozilla::LayoutDeviceIntPoint aPoint, uint32_t aNativeMessage, double aDeltaX, double aDeltaY,
+    double aDeltaZ, uint32_t aModifierFlags, uint32_t aAdditionalFlags, nsIObserver* aObserver) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  AutoObserverNotifier notifier(aObserver, "mousescrollevent");
+
+  NSPoint pt = nsCocoaUtils::DevPixelsToCocoaPoints(aPoint, BackingScaleFactor());
+
+  // Move the mouse cursor to the requested position and reconnect it to the mouse.
+  CGWarpMouseCursorPosition(NSPointToCGPoint(pt));
+  CGAssociateMouseAndMouseCursorPosition(true);
+
+  // Mostly copied from http://stackoverflow.com/a/6130349
+  CGScrollEventUnit units = (aAdditionalFlags & nsIDOMWindowUtils::MOUSESCROLL_SCROLL_LINES)
+                                ? kCGScrollEventUnitLine
+                                : kCGScrollEventUnitPixel;
+  CGEventRef cgEvent = CGEventCreateScrollWheelEvent(NULL, units, 3, (int32_t)aDeltaY,
+                                                     (int32_t)aDeltaX, (int32_t)aDeltaZ);
+  if (!cgEvent) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (aNativeMessage) {
+    CGEventSetIntegerValueField(cgEvent, kCGScrollWheelEventScrollPhase, aNativeMessage);
+  }
+
+  // On macOS 10.14 and up CGEventPost won't work because of changes in macOS
+  // to improve security. This code makes an NSEvent corresponding to the
+  // wheel event and dispatches it directly to the scrollWheel handler. Some
+  // fiddling is needed with the coordinates in order to simulate what macOS
+  // would do; this code adapted from the Chromium equivalent function at
+  // https://chromium.googlesource.com/chromium/src.git/+/62.0.3178.1/ui/events/test/cocoa_test_event_utils.mm#38
+  CGPoint location = CGEventGetLocation(cgEvent);
+  location.y += NSMinY([[mView window] frame]);
+  location.x -= NSMinX([[mView window] frame]);
+  CGEventSetLocation(cgEvent, location);
+
+  uint64_t kNanosPerSec = 1000000000L;
+  CGEventSetTimestamp(cgEvent, [[NSProcessInfo processInfo] systemUptime] * kNanosPerSec);
+
+  NSEvent* event = [NSEvent eventWithCGEvent:cgEvent];
+  [event setValue:[mView window] forKey:@"_window"];
+  [mView scrollWheel:event];
+
+  CFRelease(cgEvent);
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsChildView::SynthesizeNativeTouchPoint(
+    uint32_t aPointerId, TouchPointerState aPointerState, mozilla::LayoutDeviceIntPoint aPoint,
+    double aPointerPressure, uint32_t aPointerOrientation, nsIObserver* aObserver) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  AutoObserverNotifier notifier(aObserver, "touchpoint");
+
+  MOZ_ASSERT(NS_IsMainThread());
+  if (aPointerState == TOUCH_HOVER) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (!mSynthesizedTouchInput) {
+    mSynthesizedTouchInput = MakeUnique<MultiTouchInput>();
+  }
+
+  LayoutDeviceIntPoint pointInWindow = aPoint - WidgetToScreenOffset();
+  MultiTouchInput inputToDispatch = UpdateSynthesizedTouchState(
+      mSynthesizedTouchInput.get(), TimeStamp::Now(), aPointerId, aPointerState, pointInWindow,
+      aPointerPressure, aPointerOrientation);
+  DispatchTouchInput(inputToDispatch);
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsChildView::SynthesizeNativeTouchpadDoubleTap(mozilla::LayoutDeviceIntPoint aPoint,
+                                                        uint32_t aModifierFlags) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  DispatchDoubleTapGesture(TimeStamp::Now(), aPoint - WidgetToScreenOffset(),
+                           static_cast<Modifiers>(aModifierFlags));
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+bool nsChildView::SendEventToNativeMenuSystem(NSEvent* aEvent) {
+  bool handled = false;
+  nsCocoaWindow* widget = GetAppWindowWidget();
+  if (widget) {
+    nsMenuBarX* mb = widget->GetMenuBar();
+    if (mb) {
+      // Check if main menu wants to handle the event.
+      handled = mb->PerformKeyEquivalent(aEvent);
+    }
+  }
+
+  if (!handled && sApplicationMenu) {
+    // Check if application menu wants to handle the event.
+    handled = [sApplicationMenu performKeyEquivalent:aEvent];
+  }
+
+  return handled;
+}
+
+void nsChildView::PostHandleKeyEvent(mozilla::WidgetKeyboardEvent* aEvent) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // We always allow keyboard events to propagate to keyDown: but if they are
+  // not handled we give menu items a chance to act. This allows for handling of
+  // custom shortcuts. Note that existing shortcuts cannot be reassigned yet and
+  // will have been handled by keyDown: before we get here.
+  NSMutableDictionary* nativeKeyEventsMap = [ChildView sNativeKeyEventsMap];
+  NSEvent* cocoaEvent = [nativeKeyEventsMap objectForKey:@(aEvent->mUniqueId)];
+  if (!cocoaEvent) {
+    return;
+  }
+
+  // If the escape key is pressed, the expectations are as follows:
+  // 1. If the page is loading, interrupt loading.
+  // 2. Give a website an opportunity to handle the event and call
+  //    preventDefault() on it.
+  // 3. If the browser is fullscreen and the page isn't loading, exit
+  //    fullscreen.
+  // 4. Ignore.
+  // Case 1 and 2 are handled before we get here. Below, we handle case 3.
+  if (StaticPrefs::browser_fullscreen_exit_on_escape() && [cocoaEvent keyCode] == kVK_Escape &&
+      [[mView window] styleMask] & NSWindowStyleMaskFullScreen) {
+    [[mView window] toggleFullScreen:nil];
+  }
+
+  if (SendEventToNativeMenuSystem(cocoaEvent)) {
+    aEvent->PreventDefault();
+  }
+  [nativeKeyEventsMap removeObjectForKey:@(aEvent->mUniqueId)];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Used for testing native menu system structure and event handling.
+nsresult nsChildView::ActivateNativeMenuItemAt(const nsAString& indexString) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsMenuUtilsX::CheckNativeMenuConsistency([NSApp mainMenu]);
+
+  NSString* locationString =
+      [NSString stringWithCharacters:reinterpret_cast<const unichar*>(indexString.BeginReading())
+                              length:indexString.Length()];
+  NSMenuItem* item =
+      nsMenuUtilsX::NativeMenuItemWithLocation([NSApp mainMenu], locationString, true);
+  // We can't perform an action on an item with a submenu, that will raise
+  // an obj-c exception.
+  if (item && ![item hasSubmenu]) {
+    NSMenu* parent = [item menu];
+    if (parent) {
+      // NSLog(@"Performing action for native menu item titled: %@\n",
+      //       [[currentSubmenu itemAtIndex:targetIndex] title]);
+      mozilla::AutoRestore<bool> autoRestore(
+          nsMenuUtilsX::gIsSynchronouslyActivatingNativeMenuItemDuringTest);
+      nsMenuUtilsX::gIsSynchronouslyActivatingNativeMenuItemDuringTest = true;
+      [parent performActionForItemAtIndex:[parent indexOfItem:item]];
+      return NS_OK;
+    }
+  }
+  return NS_ERROR_FAILURE;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+// Used for testing native menu system structure and event handling.
+nsresult nsChildView::ForceUpdateNativeMenuAt(const nsAString& indexString) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsCocoaWindow* widget = GetAppWindowWidget();
+  if (widget) {
+    nsMenuBarX* mb = widget->GetMenuBar();
+    if (mb) {
+      if (indexString.IsEmpty())
+        mb->ForceNativeMenuReload();
+      else
+        mb->ForceUpdateNativeMenuAt(indexString);
+    }
+  }
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+#pragma mark -
+
+#ifdef INVALIDATE_DEBUGGING
+
+static Boolean KeyDown(const UInt8 theKey) {
+  KeyMap map;
+  GetKeys(map);
+  return ((*((UInt8*)map + (theKey >> 3)) >> (theKey & 7)) & 1) != 0;
+}
+
+static Boolean caps_lock() { return KeyDown(0x39); }
+
+static void blinkRect(Rect* r) {
+  StRegionFromPool oldClip;
+  if (oldClip != NULL) ::GetClip(oldClip);
+
+  ::ClipRect(r);
+  ::InvertRect(r);
+  UInt32 end = ::TickCount() + 5;
+  while (::TickCount() < end)
+    ;
+  ::InvertRect(r);
+
+  if (oldClip != NULL) ::SetClip(oldClip);
+}
+
+static void blinkRgn(RgnHandle rgn) {
+  StRegionFromPool oldClip;
+  if (oldClip != NULL) ::GetClip(oldClip);
+
+  ::SetClip(rgn);
+  ::InvertRgn(rgn);
+  UInt32 end = ::TickCount() + 5;
+  while (::TickCount() < end)
+    ;
+  ::InvertRgn(rgn);
+
+  if (oldClip != NULL) ::SetClip(oldClip);
+}
+
+#endif
+
+// Invalidate this component's visible area
+void nsChildView::Invalidate(const LayoutDeviceIntRect& aRect) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mView || !mVisible) return;
+
+  NS_ASSERTION(GetWindowRenderer()->GetBackendType() != LayersBackend::LAYERS_WR,
+               "Shouldn't need to invalidate with accelerated OMTC layers!");
+
+  EnsureContentLayerForMainThreadPainting();
+  mContentLayerInvalidRegion.OrWith(aRect.Intersect(GetBounds()));
+  [mView markLayerForDisplay];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+bool nsChildView::WidgetTypeSupportsAcceleration() {
+  // All widget types support acceleration.
+  return true;
+}
+
+bool nsChildView::ShouldUseOffMainThreadCompositing() {
+  // We need to enable OMTC in popups which contain remote layer
+  // trees, since the remote content won't be rendered at all otherwise.
+  if (HasRemoteContent()) {
+    return true;
+  }
+
+  // Don't use OMTC for popup windows, because we do not want context menus to
+  // pay the overhead of starting up a compositor. With the OpenGL compositor,
+  // new windows are expensive because of shader re-compilation, and with
+  // WebRender, new windows are expensive because they create their own threads
+  // and texture caches.
+  // Using OMTC with BasicCompositor for context menus would probably be fine
+  // but isn't a well-tested configuration.
+  if ([mView window] && [[mView window] isKindOfClass:[PopupWindow class]]) {
+    // Use main-thread BasicLayerManager for drawing menus.
+    return false;
+  }
+
+  return nsBaseWidget::ShouldUseOffMainThreadCompositing();
+}
+
+#pragma mark -
+
+// Invokes callback and ProcessEvent methods on Event Listener object
+nsresult nsChildView::DispatchEvent(WidgetGUIEvent* event, nsEventStatus& aStatus) {
+  RefPtr<nsChildView> kungFuDeathGrip(this);
+
+#ifdef DEBUG
+  debug_DumpEvent(stdout, event->mWidget, event, "something", 0);
+#endif
+
+  if (event->mFlags.mIsSynthesizedForTests) {
+    WidgetKeyboardEvent* keyEvent = event->AsKeyboardEvent();
+    if (keyEvent) {
+      nsresult rv = mTextInputHandler->AttachNativeKeyEvent(*keyEvent);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+  }
+
+  aStatus = nsEventStatus_eIgnore;
+
+  nsIWidgetListener* listener = mWidgetListener;
+
+  // If the listener is NULL, check if the parent is a popup. If it is, then
+  // this child is the popup content view attached to a popup. Get the
+  // listener from the parent popup instead.
+  nsCOMPtr<nsIWidget> parentWidget = mParentWidget;
+  if (!listener && parentWidget) {
+    if (parentWidget->GetWindowType() == WindowType::Popup) {
+      // Check just in case event->mWidget isn't this widget
+      if (event->mWidget) {
+        listener = event->mWidget->GetWidgetListener();
+      }
+      if (!listener) {
+        event->mWidget = parentWidget;
+        listener = parentWidget->GetWidgetListener();
+      }
+    }
+  }
+
+  if (listener) aStatus = listener->HandleEvent(event, mUseAttachedEvents);
+
+  return NS_OK;
+}
+
+nsIWidget* nsChildView::GetWidgetForListenerEvents() {
+  // If there is no listener, use the parent popup's listener if that exists.
+  if (!mWidgetListener && mParentWidget && mParentWidget->GetWindowType() == WindowType::Popup) {
+    return mParentWidget;
+  }
+
+  return this;
+}
+
+void nsChildView::WillPaintWindow() {
+  nsCOMPtr<nsIWidget> widget = GetWidgetForListenerEvents();
+
+  nsIWidgetListener* listener = widget->GetWidgetListener();
+  if (listener) {
+    listener->WillPaintWindow(widget);
+  }
+}
+
+bool nsChildView::PaintWindow(LayoutDeviceIntRegion aRegion) {
+  nsCOMPtr<nsIWidget> widget = GetWidgetForListenerEvents();
+
+  nsIWidgetListener* listener = widget->GetWidgetListener();
+  if (!listener) return false;
+
+  bool returnValue = false;
+  bool oldDispatchPaint = mIsDispatchPaint;
+  mIsDispatchPaint = true;
+  returnValue = listener->PaintWindow(widget, aRegion);
+
+  listener = widget->GetWidgetListener();
+  if (listener) {
+    listener->DidPaintWindow();
+  }
+
+  mIsDispatchPaint = oldDispatchPaint;
+  return returnValue;
+}
+
+bool nsChildView::PaintWindowInDrawTarget(gfx::DrawTarget* aDT,
+                                          const LayoutDeviceIntRegion& aRegion,
+                                          const gfx::IntSize& aSurfaceSize) {
+  if (!aDT || !aDT->IsValid()) {
+    return false;
+  }
+  gfxContext targetContext(aDT);
+
+  // Set up the clip region and clear existing contents in the backing surface.
+  targetContext.NewPath();
+  for (auto iter = aRegion.RectIter(); !iter.Done(); iter.Next()) {
+    const LayoutDeviceIntRect& r = iter.Get();
+    targetContext.Rectangle(gfxRect(r.x, r.y, r.width, r.height));
+    aDT->ClearRect(gfx::Rect(r.ToUnknownRect()));
+  }
+  targetContext.Clip();
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(mView);
+  if (GetWindowRenderer()->GetBackendType() == LayersBackend::LAYERS_NONE) {
+    nsBaseWidget::AutoLayerManagerSetup setupLayerManager(this, &targetContext,
+                                                          BufferMode::BUFFER_NONE);
+    return PaintWindow(aRegion);
+  }
+  return false;
+}
+
+void nsChildView::EnsureContentLayerForMainThreadPainting() {
+  // Ensure we have an mContentLayer of the correct size.
+  // The content layer gets created on demand for BasicLayers windows. We do
+  // not create it during widget creation because, for non-BasicLayers windows,
+  // the compositing layer manager will create any layers it needs.
+  gfx::IntSize size = GetBounds().Size().ToUnknownSize();
+  if (mContentLayer && mContentLayer->GetSize() != size) {
+    mNativeLayerRoot->RemoveLayer(mContentLayer);
+    mContentLayer = nullptr;
+  }
+  if (!mContentLayer) {
+    mPoolHandle = SurfacePool::Create(0)->GetHandleForGL(nullptr);
+    RefPtr<NativeLayer> contentLayer = mNativeLayerRoot->CreateLayer(size, false, mPoolHandle);
+    mNativeLayerRoot->AppendLayer(contentLayer);
+    mContentLayer = contentLayer->AsNativeLayerCA();
+    mContentLayer->SetSurfaceIsFlipped(false);
+    mContentLayerInvalidRegion = GetBounds();
+  }
+}
+
+void nsChildView::PaintWindowInContentLayer() {
+  EnsureContentLayerForMainThreadPainting();
+  mPoolHandle->OnBeginFrame();
+  RefPtr<DrawTarget> dt = mContentLayer->NextSurfaceAsDrawTarget(
+      gfx::IntRect({}, mContentLayer->GetSize()), mContentLayerInvalidRegion.ToUnknownRegion(),
+      gfx::BackendType::SKIA);
+  if (!dt) {
+    return;
+  }
+
+  PaintWindowInDrawTarget(dt, mContentLayerInvalidRegion, dt->GetSize());
+  mContentLayer->NotifySurfaceReady();
+  mContentLayerInvalidRegion.SetEmpty();
+  mPoolHandle->OnEndFrame();
+}
+
+void nsChildView::HandleMainThreadCATransaction() {
+  WillPaintWindow();
+
+  if (GetWindowRenderer()->GetBackendType() == LayersBackend::LAYERS_NONE) {
+    // We're in BasicLayers mode, i.e. main thread software compositing.
+    // Composite the window into our layer's surface.
+    PaintWindowInContentLayer();
+  } else {
+    // Trigger a synchronous OMTC composite. This will call NextSurface and
+    // NotifySurfaceReady on the compositor thread to update mNativeLayerRoot's
+    // contents, and the main thread (this thread) will wait inside PaintWindow
+    // during that time.
+    PaintWindow(LayoutDeviceIntRegion(GetBounds()));
+  }
+
+  {
+    // Apply the changes inside mNativeLayerRoot to the underlying CALayers. Now is a
+    // good time to call this because we know we're currently inside a main thread
+    // CATransaction, and the lock makes sure that no composition is currently in
+    // progress, so we won't present half-composited state to the screen.
+    MutexAutoLock lock(mCompositingLock);
+    mNativeLayerRoot->CommitToScreen();
+  }
+
+  MaybeScheduleUnsuspendAsyncCATransactions();
+}
+
+#pragma mark -
+
+void nsChildView::ReportMoveEvent() { NotifyWindowMoved(mBounds.x, mBounds.y); }
+
+void nsChildView::ReportSizeEvent() {
+  if (mWidgetListener) mWidgetListener->WindowResized(this, mBounds.width, mBounds.height);
+}
+
+#pragma mark -
+
+LayoutDeviceIntPoint nsChildView::GetClientOffset() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSPoint origin = [mView convertPoint:NSMakePoint(0, 0) toView:nil];
+  origin.y = [[mView window] frame].size.height - origin.y;
+  return CocoaPointsToDevPixels(origin);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntPoint(0, 0));
+}
+
+//    Return the offset between this child view and the screen.
+//    @return       -- widget origin in device-pixel coords
+LayoutDeviceIntPoint nsChildView::WidgetToScreenOffset() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSPoint origin = NSMakePoint(0, 0);
+
+  // 1. First translate view origin point into window coords.
+  // The returned point is in bottom-left coordinates.
+  origin = [mView convertPoint:origin toView:nil];
+
+  // 2. We turn the window-coord rect's origin into screen (still bottom-left) coords.
+  origin = nsCocoaUtils::ConvertPointToScreen([mView window], origin);
+
+  // 3. Since we're dealing in bottom-left coords, we need to make it top-left coords
+  //    before we pass it back to Gecko.
+  FlipCocoaScreenCoordinate(origin);
+
+  // convert to device pixels
+  return CocoaPointsToDevPixels(origin);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntPoint(0, 0));
+}
+
+nsresult nsChildView::SetTitle(const nsAString& title) {
+  // child views don't have titles
+  return NS_OK;
+}
+
+nsresult nsChildView::GetAttention(int32_t aCycleCount) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  [NSApp requestUserAttention:NSInformationalRequest];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+/* static */
+bool nsChildView::DoHasPendingInputEvent() {
+  return sLastInputEventCount != GetCurrentInputEventCount();
+}
+
+/* static */
+uint32_t nsChildView::GetCurrentInputEventCount() {
+  // Can't use kCGAnyInputEventType because that updates too rarely for us (and
+  // always in increments of 30+!) and because apparently it's sort of broken
+  // on Tiger.  So just go ahead and query the counters we care about.
+  static const CGEventType eventTypes[] = {
+      kCGEventLeftMouseDown,     kCGEventLeftMouseUp,      kCGEventRightMouseDown,
+      kCGEventRightMouseUp,      kCGEventMouseMoved,       kCGEventLeftMouseDragged,
+      kCGEventRightMouseDragged, kCGEventKeyDown,          kCGEventKeyUp,
+      kCGEventScrollWheel,       kCGEventTabletPointer,    kCGEventOtherMouseDown,
+      kCGEventOtherMouseUp,      kCGEventOtherMouseDragged};
+
+  uint32_t eventCount = 0;
+  for (uint32_t i = 0; i < ArrayLength(eventTypes); ++i) {
+    eventCount +=
+        CGEventSourceCounterForEventType(kCGEventSourceStateCombinedSessionState, eventTypes[i]);
+  }
+  return eventCount;
+}
+
+/* static */
+void nsChildView::UpdateCurrentInputEventCount() {
+  sLastInputEventCount = GetCurrentInputEventCount();
+}
+
+bool nsChildView::HasPendingInputEvent() { return DoHasPendingInputEvent(); }
+
+#pragma mark -
+
+void nsChildView::SetInputContext(const InputContext& aContext, const InputContextAction& aAction) {
+  NS_ENSURE_TRUE_VOID(mTextInputHandler);
+
+  if (mTextInputHandler->IsFocused()) {
+    if (aContext.IsPasswordEditor()) {
+      TextInputHandler::EnableSecureEventInput();
+    } else {
+      TextInputHandler::EnsureSecureEventInputDisabled();
+    }
+  }
+
+  // IMEInputHandler::IsEditableContent() returns false when both
+  // IsASCIICableOnly() and IsIMEEnabled() return false.  So, be careful
+  // when you change the following code.  You might need to change
+  // IMEInputHandler::IsEditableContent() too.
+  mInputContext = aContext;
+  switch (aContext.mIMEState.mEnabled) {
+    case IMEEnabled::Enabled:
+      mTextInputHandler->SetASCIICapableOnly(false);
+      mTextInputHandler->EnableIME(true);
+      if (mInputContext.mIMEState.mOpen != IMEState::DONT_CHANGE_OPEN_STATE) {
+        mTextInputHandler->SetIMEOpenState(mInputContext.mIMEState.mOpen == IMEState::OPEN);
+      }
+      break;
+    case IMEEnabled::Disabled:
+      mTextInputHandler->SetASCIICapableOnly(false);
+      mTextInputHandler->EnableIME(false);
+      break;
+    case IMEEnabled::Password:
+      mTextInputHandler->SetASCIICapableOnly(true);
+      mTextInputHandler->EnableIME(false);
+      break;
+    default:
+      NS_ERROR("not implemented!");
+  }
+}
+
+InputContext nsChildView::GetInputContext() {
+  switch (mInputContext.mIMEState.mEnabled) {
+    case IMEEnabled::Enabled:
+      if (mTextInputHandler) {
+        mInputContext.mIMEState.mOpen =
+            mTextInputHandler->IsIMEOpened() ? IMEState::OPEN : IMEState::CLOSED;
+        break;
+      }
+      // If mTextInputHandler is null, set CLOSED instead...
+      [[fallthrough]];
+    default:
+      mInputContext.mIMEState.mOpen = IMEState::CLOSED;
+      break;
+  }
+  return mInputContext;
+}
+
+TextEventDispatcherListener* nsChildView::GetNativeTextEventDispatcherListener() {
+  if (NS_WARN_IF(!mTextInputHandler)) {
+    return nullptr;
+  }
+  return mTextInputHandler;
+}
+
+nsresult nsChildView::AttachNativeKeyEvent(mozilla::WidgetKeyboardEvent& aEvent) {
+  NS_ENSURE_TRUE(mTextInputHandler, NS_ERROR_NOT_AVAILABLE);
+  return mTextInputHandler->AttachNativeKeyEvent(aEvent);
+}
+
+bool nsChildView::GetEditCommands(NativeKeyBindingsType aType, const WidgetKeyboardEvent& aEvent,
+                                  nsTArray<CommandInt>& aCommands) {
+  // Validate the arguments.
+  if (NS_WARN_IF(!nsIWidget::GetEditCommands(aType, aEvent, aCommands))) {
+    return false;
+  }
+
+  Maybe<WritingMode> writingMode;
+  if (aEvent.NeedsToRemapNavigationKey()) {
+    if (RefPtr<TextEventDispatcher> dispatcher = GetTextEventDispatcher()) {
+      writingMode = dispatcher->MaybeQueryWritingModeAtSelection();
+    }
+  }
+
+  NativeKeyBindings* keyBindings = NativeKeyBindings::GetInstance(aType);
+  keyBindings->GetEditCommands(aEvent, writingMode, aCommands);
+  return true;
+}
+
+NSView<mozView>* nsChildView::GetEditorView() {
+  NSView<mozView>* editorView = mView;
+  // We need to get editor's view. E.g., when the focus is in the bookmark
+  // dialog, the view is <panel> element of the dialog.  At this time, the key
+  // events are processed the parent window's view that has native focus.
+  WidgetQueryContentEvent queryContentState(true, eQueryContentState, this);
+  // This may be called during creating a menu popup frame due to creating
+  // widget synchronously and that causes Cocoa asking current window level.
+  // In this case, it's not safe to flush layout on the document and we don't
+  // need any layout information right now.
+  queryContentState.mNeedsToFlushLayout = false;
+  DispatchWindowEvent(queryContentState);
+  if (queryContentState.Succeeded() && queryContentState.mReply->mFocusedWidget) {
+    NSView<mozView>* view = static_cast<NSView<mozView>*>(
+        queryContentState.mReply->mFocusedWidget->GetNativeData(NS_NATIVE_WIDGET));
+    if (view) editorView = view;
+  }
+  return editorView;
+}
+
+#pragma mark -
+
+void nsChildView::CreateCompositor() {
+  nsBaseWidget::CreateCompositor();
+  if (mCompositorBridgeChild) {
+    [mView setUsingOMTCompositor:true];
+  }
+}
+
+void nsChildView::ConfigureAPZCTreeManager() { nsBaseWidget::ConfigureAPZCTreeManager(); }
+
+void nsChildView::ConfigureAPZControllerThread() { nsBaseWidget::ConfigureAPZControllerThread(); }
+
+bool nsChildView::PreRender(WidgetRenderingContext* aContext) MOZ_NO_THREAD_SAFETY_ANALYSIS {
+  // The lock makes sure that we don't attempt to tear down the view while
+  // compositing. That would make us unable to call postRender on it when the
+  // composition is done, thus keeping the GL context locked forever.
+  mCompositingLock.Lock();
+
+  if (aContext->mGL && gfxPlatform::CanMigrateMacGPUs()) {
+    GLContextCGL::Cast(aContext->mGL)->MigrateToActiveGPU();
+  }
+
+  return true;
+}
+
+void nsChildView::PostRender(WidgetRenderingContext* aContext) MOZ_NO_THREAD_SAFETY_ANALYSIS {
+  mCompositingLock.Unlock();
+}
+
+RefPtr<layers::NativeLayerRoot> nsChildView::GetNativeLayerRoot() { return mNativeLayerRoot; }
+
+static int32_t FindTitlebarBottom(const nsTArray<nsIWidget::ThemeGeometry>& aThemeGeometries,
+                                  int32_t aWindowWidth) {
+  int32_t titlebarBottom = 0;
+  for (auto& g : aThemeGeometries) {
+    if (g.mType == eThemeGeometryTypeTitlebar && g.mRect.X() <= 0 &&
+        g.mRect.XMost() >= aWindowWidth && g.mRect.Y() <= 0) {
+      titlebarBottom = std::max(titlebarBottom, g.mRect.YMost());
+    }
+  }
+  return titlebarBottom;
+}
+
+static int32_t FindUnifiedToolbarBottom(const nsTArray<nsIWidget::ThemeGeometry>& aThemeGeometries,
+                                        int32_t aWindowWidth, int32_t aTitlebarBottom) {
+  int32_t unifiedToolbarBottom = aTitlebarBottom;
+  for (uint32_t i = 0; i < aThemeGeometries.Length(); ++i) {
+    const nsIWidget::ThemeGeometry& g = aThemeGeometries[i];
+    if ((g.mType == eThemeGeometryTypeToolbar) && g.mRect.X() <= 0 &&
+        g.mRect.XMost() >= aWindowWidth && g.mRect.Y() <= aTitlebarBottom) {
+      unifiedToolbarBottom = std::max(unifiedToolbarBottom, g.mRect.YMost());
+    }
+  }
+  return unifiedToolbarBottom;
+}
+
+static LayoutDeviceIntRect FindFirstRectOfType(
+    const nsTArray<nsIWidget::ThemeGeometry>& aThemeGeometries,
+    nsITheme::ThemeGeometryType aThemeGeometryType) {
+  for (uint32_t i = 0; i < aThemeGeometries.Length(); ++i) {
+    const nsIWidget::ThemeGeometry& g = aThemeGeometries[i];
+    if (g.mType == aThemeGeometryType) {
+      return g.mRect;
+    }
+  }
+  return LayoutDeviceIntRect();
+}
+
+void nsChildView::UpdateThemeGeometries(const nsTArray<ThemeGeometry>& aThemeGeometries) {
+  if (![mView window]) return;
+
+  UpdateVibrancy(aThemeGeometries);
+
+  if (![[mView window] isKindOfClass:[ToolbarWindow class]]) return;
+
+  // Update unified toolbar height and sheet attachment position.
+  int32_t windowWidth = mBounds.width;
+  int32_t titlebarBottom = FindTitlebarBottom(aThemeGeometries, windowWidth);
+  int32_t unifiedToolbarBottom =
+      FindUnifiedToolbarBottom(aThemeGeometries, windowWidth, titlebarBottom);
+  int32_t toolboxBottom = FindFirstRectOfType(aThemeGeometries, eThemeGeometryTypeToolbox).YMost();
+
+  ToolbarWindow* win = (ToolbarWindow*)[mView window];
+  int32_t titlebarHeight =
+      [win drawsContentsIntoWindowFrame] ? 0 : CocoaPointsToDevPixels([win titlebarHeight]);
+  int32_t devUnifiedHeight = titlebarHeight + unifiedToolbarBottom;
+  [win setUnifiedToolbarHeight:DevPixelsToCocoaPoints(devUnifiedHeight)];
+
+  int32_t sheetPositionDevPx = std::max(toolboxBottom, unifiedToolbarBottom);
+  NSPoint sheetPositionView = {0, DevPixelsToCocoaPoints(sheetPositionDevPx)};
+  NSPoint sheetPositionWindow = [mView convertPoint:sheetPositionView toView:nil];
+  [win setSheetAttachmentPosition:sheetPositionWindow.y];
+
+  // Update titlebar control offsets.
+  LayoutDeviceIntRect windowButtonRect =
+      FindFirstRectOfType(aThemeGeometries, eThemeGeometryTypeWindowButtons);
+  [win placeWindowButtons:[mView convertRect:DevPixelsToCocoaPoints(windowButtonRect) toView:nil]];
+}
+
+static Maybe<VibrancyType> ThemeGeometryTypeToVibrancyType(
+    nsITheme::ThemeGeometryType aThemeGeometryType) {
+  switch (aThemeGeometryType) {
+    case eThemeGeometryTypeTooltip:
+      return Some(VibrancyType::TOOLTIP);
+    case eThemeGeometryTypeMenu:
+      return Some(VibrancyType::MENU);
+    case eThemeGeometryTypeHighlightedMenuItem:
+      return Some(VibrancyType::HIGHLIGHTED_MENUITEM);
+    case eThemeGeometryTypeSourceList:
+      return Some(VibrancyType::SOURCE_LIST);
+    case eThemeGeometryTypeSourceListSelection:
+      return Some(VibrancyType::SOURCE_LIST_SELECTION);
+    case eThemeGeometryTypeActiveSourceListSelection:
+      return Some(VibrancyType::ACTIVE_SOURCE_LIST_SELECTION);
+    default:
+      return Nothing();
+  }
+}
+
+static LayoutDeviceIntRegion GatherVibrantRegion(
+    const nsTArray<nsIWidget::ThemeGeometry>& aThemeGeometries, VibrancyType aVibrancyType) {
+  LayoutDeviceIntRegion region;
+  for (auto& geometry : aThemeGeometries) {
+    if (ThemeGeometryTypeToVibrancyType(geometry.mType) == Some(aVibrancyType)) {
+      region.OrWith(geometry.mRect);
+    }
+  }
+  return region;
+}
+
+template <typename Region>
+static void MakeRegionsNonOverlappingImpl(Region& aOutUnion) {}
+
+template <typename Region, typename... Regions>
+static void MakeRegionsNonOverlappingImpl(Region& aOutUnion, Region& aFirst, Regions&... aRest) {
+  MakeRegionsNonOverlappingImpl(aOutUnion, aRest...);
+  aFirst.SubOut(aOutUnion);
+  aOutUnion.OrWith(aFirst);
+}
+
+// Subtracts parts from regions in such a way that they don't have any overlap.
+// Each region in the argument list will have the union of all the regions
+// *following* it subtracted from itself. In other words, the arguments are
+// sorted low priority to high priority.
+template <typename Region, typename... Regions>
+static void MakeRegionsNonOverlapping(Region& aFirst, Regions&... aRest) {
+  Region unionOfAll;
+  MakeRegionsNonOverlappingImpl(unionOfAll, aFirst, aRest...);
+}
+
+void nsChildView::UpdateVibrancy(const nsTArray<ThemeGeometry>& aThemeGeometries) {
+  LayoutDeviceIntRegion menuRegion = GatherVibrantRegion(aThemeGeometries, VibrancyType::MENU);
+  LayoutDeviceIntRegion tooltipRegion =
+      GatherVibrantRegion(aThemeGeometries, VibrancyType::TOOLTIP);
+  LayoutDeviceIntRegion highlightedMenuItemRegion =
+      GatherVibrantRegion(aThemeGeometries, VibrancyType::HIGHLIGHTED_MENUITEM);
+  LayoutDeviceIntRegion sourceListRegion =
+      GatherVibrantRegion(aThemeGeometries, VibrancyType::SOURCE_LIST);
+  LayoutDeviceIntRegion sourceListSelectionRegion =
+      GatherVibrantRegion(aThemeGeometries, VibrancyType::SOURCE_LIST_SELECTION);
+  LayoutDeviceIntRegion activeSourceListSelectionRegion =
+      GatherVibrantRegion(aThemeGeometries, VibrancyType::ACTIVE_SOURCE_LIST_SELECTION);
+
+  MakeRegionsNonOverlapping(menuRegion, tooltipRegion, highlightedMenuItemRegion, sourceListRegion,
+                            sourceListSelectionRegion, activeSourceListSelectionRegion);
+
+  auto& vm = EnsureVibrancyManager();
+  bool changed = false;
+  changed |= vm.UpdateVibrantRegion(VibrancyType::MENU, menuRegion);
+  changed |= vm.UpdateVibrantRegion(VibrancyType::TOOLTIP, tooltipRegion);
+  changed |= vm.UpdateVibrantRegion(VibrancyType::HIGHLIGHTED_MENUITEM, highlightedMenuItemRegion);
+  changed |= vm.UpdateVibrantRegion(VibrancyType::SOURCE_LIST, sourceListRegion);
+  changed |= vm.UpdateVibrantRegion(VibrancyType::SOURCE_LIST_SELECTION, sourceListSelectionRegion);
+  changed |= vm.UpdateVibrantRegion(VibrancyType::ACTIVE_SOURCE_LIST_SELECTION,
+                                    activeSourceListSelectionRegion);
+
+  if (changed) {
+    SuspendAsyncCATransactions();
+  }
+}
+
+mozilla::VibrancyManager& nsChildView::EnsureVibrancyManager() {
+  MOZ_ASSERT(mView, "Only call this once we have a view!");
+  if (!mVibrancyManager) {
+    mVibrancyManager = MakeUnique<VibrancyManager>(*this, [mView vibrancyViewsContainer]);
+  }
+  return *mVibrancyManager;
+}
+
+void nsChildView::UpdateBoundsFromView() {
+  auto oldSize = mBounds.Size();
+  mBounds = CocoaPointsToDevPixels([mView frame]);
+  if (mBounds.Size() != oldSize) {
+    SuspendAsyncCATransactions();
+  }
+}
+
+@interface NonDraggableView : NSView
+@end
+
+@implementation NonDraggableView
+- (BOOL)mouseDownCanMoveWindow {
+  return NO;
+}
+- (NSView*)hitTest:(NSPoint)aPoint {
+  return nil;
+}
+- (NSRect)_opaqueRectForWindowMoveWhenInTitlebar {
+  // In NSWindows that use NSWindowStyleMaskFullSizeContentView, NSViews which
+  // overlap the titlebar do not disable window dragging in the overlapping
+  // areas even if they return NO from mouseDownCanMoveWindow. This can have
+  // unfortunate effects: For example, dragging tabs in a browser window would
+  // move the window if those tabs are in the titlebar.
+  // macOS does not seem to offer a documented way to opt-out of the forced
+  // window dragging in the titlebar.
+  // Overriding _opaqueRectForWindowMoveWhenInTitlebar is an undocumented way
+  // of opting out of this behavior. This method was added in 10.11 and is used
+  // by some NSControl subclasses to prevent window dragging in the titlebar.
+  // The function which assembles the draggable area of the window calls
+  // _opaqueRect for the content area and _opaqueRectForWindowMoveWhenInTitlebar
+  // for the titlebar area, on all visible NSViews. The default implementation
+  // of _opaqueRect returns [self visibleRect], and the default implementation
+  // of _opaqueRectForWindowMoveWhenInTitlebar returns NSZeroRect unless it's
+  // overridden.
+  return [self visibleRect];
+}
+@end
+
+void nsChildView::UpdateWindowDraggingRegion(const LayoutDeviceIntRegion& aRegion) {
+  // mView returns YES from mouseDownCanMoveWindow, so we need to put NSViews
+  // that return NO from mouseDownCanMoveWindow in the places that shouldn't
+  // be draggable. We can't do it the other way round because returning
+  // YES from mouseDownCanMoveWindow doesn't have any effect if there's a
+  // superview that returns NO.
+  LayoutDeviceIntRegion nonDraggable;
+  nonDraggable.Sub(LayoutDeviceIntRect(0, 0, mBounds.width, mBounds.height), aRegion);
+
+  __block bool changed = false;
+
+  // Suppress calls to setNeedsDisplay during NSView geometry changes.
+  ManipulateViewWithoutNeedingDisplay(mView, ^() {
+    changed = mNonDraggableRegion.UpdateRegion(
+        nonDraggable, *this, [mView nonDraggableViewsContainer], ^() {
+          return [[NonDraggableView alloc] initWithFrame:NSZeroRect];
+        });
+  });
+
+  if (changed) {
+    // Trigger an update to the window server. This will call
+    // mouseDownCanMoveWindow.
+    // Doing this manually is only necessary because we're suppressing
+    // setNeedsDisplay calls above.
+    [[mView window] setMovableByWindowBackground:NO];
+    [[mView window] setMovableByWindowBackground:YES];
+  }
+}
+
+nsEventStatus nsChildView::DispatchAPZInputEvent(InputData& aEvent) {
+  APZEventResult result;
+
+  if (mAPZC) {
+    result = mAPZC->InputBridge()->ReceiveInputEvent(aEvent);
+  }
+
+  if (result.GetStatus() == nsEventStatus_eConsumeNoDefault) {
+    return result.GetStatus();
+  }
+
+  if (aEvent.mInputType == PINCHGESTURE_INPUT) {
+    PinchGestureInput& pinchEvent = aEvent.AsPinchGestureInput();
+    WidgetWheelEvent wheelEvent = pinchEvent.ToWidgetEvent(this);
+    ProcessUntransformedAPZEvent(&wheelEvent, result);
+  } else if (aEvent.mInputType == TAPGESTURE_INPUT) {
+    TapGestureInput& tapEvent = aEvent.AsTapGestureInput();
+    WidgetSimpleGestureEvent gestureEvent = tapEvent.ToWidgetEvent(this);
+    ProcessUntransformedAPZEvent(&gestureEvent, result);
+  } else {
+    MOZ_ASSERT_UNREACHABLE();
+  }
+
+  return result.GetStatus();
+}
+
+void nsChildView::DispatchAPZWheelInputEvent(InputData& aEvent) {
+  if (mSwipeTracker && aEvent.mInputType == PANGESTURE_INPUT) {
+    // Give the swipe tracker a first pass at the event. If a new pan gesture
+    // has been started since the beginning of the swipe, the swipe tracker
+    // will know to ignore the event.
+    nsEventStatus status = mSwipeTracker->ProcessEvent(aEvent.AsPanGestureInput());
+    if (status == nsEventStatus_eConsumeNoDefault) {
+      return;
+    }
+  }
+
+  WidgetWheelEvent event(true, eWheel, this);
+
+  if (mAPZC) {
+    APZEventResult result;
+
+    switch (aEvent.mInputType) {
+      case PANGESTURE_INPUT: {
+        result = mAPZC->InputBridge()->ReceiveInputEvent(aEvent);
+        if (result.GetStatus() == nsEventStatus_eConsumeNoDefault) {
+          return;
+        }
+
+        event = MayStartSwipeForAPZ(aEvent.AsPanGestureInput(), result);
+        break;
+      }
+      case SCROLLWHEEL_INPUT: {
+        // For wheel events on OS X, send it to APZ using the WidgetInputEvent
+        // variant of ReceiveInputEvent, because the APZInputBridge version of
+        // that function has special handling (for delta multipliers etc.) that
+        // we need to run. Using the InputData variant would bypass that and
+        // go straight to the APZCTreeManager subclass.
+        event = aEvent.AsScrollWheelInput().ToWidgetEvent(this);
+        result = mAPZC->InputBridge()->ReceiveInputEvent(event);
+        if (result.GetStatus() == nsEventStatus_eConsumeNoDefault) {
+          return;
+        }
+        break;
+      };
+      default:
+        MOZ_CRASH("unsupported event type");
+        return;
+    }
+    if (event.mMessage == eWheel && (event.mDeltaX != 0 || event.mDeltaY != 0)) {
+      ProcessUntransformedAPZEvent(&event, result);
+    }
+    return;
+  }
+
+  nsEventStatus status;
+  switch (aEvent.mInputType) {
+    case PANGESTURE_INPUT: {
+      if (MayStartSwipeForNonAPZ(aEvent.AsPanGestureInput())) {
+        return;
+      }
+      event = aEvent.AsPanGestureInput().ToWidgetEvent(this);
+      break;
+    }
+    case SCROLLWHEEL_INPUT: {
+      event = aEvent.AsScrollWheelInput().ToWidgetEvent(this);
+      break;
+    }
+    default:
+      MOZ_CRASH("unexpected event type");
+      return;
+  }
+  if (event.mMessage == eWheel && (event.mDeltaX != 0 || event.mDeltaY != 0)) {
+    DispatchEvent(&event, status);
+  }
+}
+
+void nsChildView::DispatchDoubleTapGesture(TimeStamp aEventTimeStamp,
+                                           LayoutDeviceIntPoint aScreenPosition,
+                                           mozilla::Modifiers aModifiers) {
+  if (StaticPrefs::apz_mac_enable_double_tap_zoom_touchpad_gesture()) {
+    TapGestureInput event{
+        TapGestureInput::TAPGESTURE_DOUBLE, aEventTimeStamp,
+        ViewAs<ScreenPixel>(aScreenPosition,
+                            PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent),
+        aModifiers};
+
+    DispatchAPZInputEvent(event);
+  } else {
+    // Setup the "double tap" event.
+    WidgetSimpleGestureEvent geckoEvent(true, eTapGesture, this);
+    // do what convertCocoaMouseEvent does basically.
+    geckoEvent.mRefPoint = aScreenPosition;
+    geckoEvent.mModifiers = aModifiers;
+    geckoEvent.mTimeStamp = aEventTimeStamp;
+    geckoEvent.mClickCount = 1;
+
+    // Send the event.
+    DispatchWindowEvent(geckoEvent);
+  }
+}
+
+void nsChildView::LookUpDictionary(const nsAString& aText,
+                                   const nsTArray<mozilla::FontRange>& aFontRangeArray,
+                                   const bool aIsVertical, const LayoutDeviceIntPoint& aPoint) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NSMutableAttributedString* attrStr = nsCocoaUtils::GetNSMutableAttributedString(
+      aText, aFontRangeArray, aIsVertical, BackingScaleFactor());
+  NSPoint pt = nsCocoaUtils::DevPixelsToCocoaPoints(aPoint, BackingScaleFactor());
+  NSDictionary* attributes = [attrStr attributesAtIndex:0 effectiveRange:nil];
+  NSFont* font = [attributes objectForKey:NSFontAttributeName];
+  if (font) {
+    if (aIsVertical) {
+      pt.x -= [font descender];
+    } else {
+      pt.y += [font ascender];
+    }
+  }
+
+  [mView showDefinitionForAttributedString:attrStr atPoint:pt];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+#ifdef ACCESSIBILITY
+already_AddRefed<a11y::LocalAccessible> nsChildView::GetDocumentAccessible() {
+  if (!mozilla::a11y::ShouldA11yBeEnabled()) return nullptr;
+
+  // mAccessible might be dead if accessibility was previously disabled and is
+  // now being enabled again.
+  if (mAccessible && mAccessible->IsAlive()) {
+    RefPtr<a11y::LocalAccessible> ret;
+    CallQueryReferent(mAccessible.get(), static_cast<a11y::LocalAccessible**>(getter_AddRefs(ret)));
+    return ret.forget();
+  }
+
+  // need to fetch the accessible anew, because it has gone away.
+  // cache the accessible in our weak ptr
+  RefPtr<a11y::LocalAccessible> acc = GetRootAccessible();
+  mAccessible = do_GetWeakReference(acc.get());
+
+  return acc.forget();
+}
+#endif
+
+class WidgetsReleaserRunnable final : public mozilla::Runnable {
+ public:
+  explicit WidgetsReleaserRunnable(nsTArray<nsCOMPtr<nsIWidget>>&& aWidgetArray)
+      : mozilla::Runnable("WidgetsReleaserRunnable"), mWidgetArray(std::move(aWidgetArray)) {}
+
+  // Do nothing; all this runnable does is hold a reference the widgets in
+  // mWidgetArray, and those references will be dropped when this runnable
+  // is destroyed.
+
+ private:
+  nsTArray<nsCOMPtr<nsIWidget>> mWidgetArray;
+};
+
+#pragma mark -
+
+// ViewRegionContainerView is a view class for certain subviews of ChildView
+// which contain the NSViews created for ViewRegions (see ViewRegion.h).
+// It doesn't do anything interesting, it only acts as a container so that it's
+// easier for ChildView to control the z order of its children.
+@interface ViewRegionContainerView : NSView {
+}
+@end
+
+@implementation ViewRegionContainerView
+
+- (NSView*)hitTest:(NSPoint)aPoint {
+  return nil;  // Be transparent to mouse events.
+}
+
+- (BOOL)isFlipped {
+  return [[self superview] isFlipped];
+}
+
+- (BOOL)mouseDownCanMoveWindow {
+  return [[self superview] mouseDownCanMoveWindow];
+}
+
+@end
+
+@implementation ChildView
+
+// globalDragPboard is non-null during native drag sessions that did not originate
+// in our native NSView (it is set in |draggingEntered:|). It is unset when the
+// drag session ends for this view, either with the mouse exiting or when a drop
+// occurs in this view.
+NSPasteboard* globalDragPboard = nil;
+
+// gLastDragView and gLastDragMouseDownEvent are used to communicate information
+// to the drag service during drag invocation (starting a drag in from the view).
+// gLastDragView is only non-null while a mouse button is pressed, so between
+// mouseDown and mouseUp.
+NSView* gLastDragView = nil;             // [weak]
+NSEvent* gLastDragMouseDownEvent = nil;  // [strong]
+
++ (void)initialize {
+  static BOOL initialized = NO;
+
+  if (!initialized) {
+    // Inform the OS about the types of services (from the "Services" menu)
+    // that we can handle.
+    NSArray* types = @[
+      [UTIHelper stringFromPboardType:NSPasteboardTypeString],
+      [UTIHelper stringFromPboardType:NSPasteboardTypeHTML]
+    ];
+    [NSApp registerServicesMenuSendTypes:types returnTypes:types];
+    initialized = YES;
+  }
+}
+
++ (void)registerViewForDraggedTypes:(NSView*)aView {
+  [aView
+      registerForDraggedTypes:
+          [NSArray
+              arrayWithObjects:[UTIHelper stringFromPboardType:NSFilenamesPboardType],
+                               [UTIHelper stringFromPboardType:kMozFileUrlsPboardType],
+                               [UTIHelper stringFromPboardType:NSPasteboardTypeString],
+                               [UTIHelper stringFromPboardType:NSPasteboardTypeHTML],
+                               [UTIHelper
+                                   stringFromPboardType:(NSString*)kPasteboardTypeFileURLPromise],
+                               [UTIHelper stringFromPboardType:kMozWildcardPboardType],
+                               [UTIHelper stringFromPboardType:kPublicUrlPboardType],
+                               [UTIHelper stringFromPboardType:kPublicUrlNamePboardType],
+                               [UTIHelper stringFromPboardType:kUrlsWithTitlesPboardType], nil]];
+}
+
+// initWithFrame:geckoChild:
+- (id)initWithFrame:(NSRect)inFrame geckoChild:(nsChildView*)inChild {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if ((self = [super initWithFrame:inFrame])) {
+    mGeckoChild = inChild;
+    mBlockedLastMouseDown = NO;
+    mExpectingWheelStop = NO;
+
+    mLastMouseDownEvent = nil;
+    mLastKeyDownEvent = nil;
+    mClickThroughMouseDownEvent = nil;
+    mDragService = nullptr;
+
+    mGestureState = eGestureState_None;
+    mCumulativeRotation = 0.0;
+
+    mIsUpdatingLayer = NO;
+
+    [self setFocusRingType:NSFocusRingTypeNone];
+
+#ifdef __LP64__
+    mCancelSwipeAnimation = nil;
+#endif
+
+    mNonDraggableViewsContainer = [[ViewRegionContainerView alloc] initWithFrame:[self bounds]];
+    mVibrancyViewsContainer = [[ViewRegionContainerView alloc] initWithFrame:[self bounds]];
+
+    [mNonDraggableViewsContainer setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
+    [mVibrancyViewsContainer setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
+
+    [self addSubview:mNonDraggableViewsContainer];
+    [self addSubview:mVibrancyViewsContainer];
+
+    mPixelHostingView = [[PixelHostingView alloc] initWithFrame:[self bounds]];
+    [mPixelHostingView setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
+
+    [self addSubview:mPixelHostingView];
+
+    mRootCALayer = [[CALayer layer] retain];
+    mRootCALayer.position = NSZeroPoint;
+    mRootCALayer.bounds = NSZeroRect;
+    mRootCALayer.anchorPoint = NSZeroPoint;
+    mRootCALayer.contentsGravity = kCAGravityTopLeft;
+    [[mPixelHostingView layer] addSublayer:mRootCALayer];
+
+    mLastPressureStage = 0;
+  }
+
+  // register for things we'll take from other applications
+  [ChildView registerViewForDraggedTypes:self];
+
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (NSTextInputContext*)inputContext {
+  if (!mGeckoChild) {
+    // -[ChildView widgetDestroyed] has been called, but
+    // -[ChildView delayedTearDown] has not yet completed.  Accessing
+    // [super inputContext] now would uselessly recreate a text input context
+    // for us, under which -[ChildView validAttributesForMarkedText] would
+    // be called and the assertion checking for mTextInputHandler would fail.
+    // We return nil to avoid that.
+    return nil;
+  }
+  return [super inputContext];
+}
+
+- (void)installTextInputHandler:(TextInputHandler*)aHandler {
+  mTextInputHandler = aHandler;
+}
+
+- (void)uninstallTextInputHandler {
+  mTextInputHandler = nullptr;
+}
+
+- (NSView*)vibrancyViewsContainer {
+  return mVibrancyViewsContainer;
+}
+
+- (NSView*)nonDraggableViewsContainer {
+  return mNonDraggableViewsContainer;
+}
+
+- (NSView*)pixelHostingView {
+  return mPixelHostingView;
+}
+
+- (void)dealloc {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mLastMouseDownEvent release];
+  [mLastKeyDownEvent release];
+  [mClickThroughMouseDownEvent release];
+  ChildViewMouseTracker::OnDestroyView(self);
+
+  [mVibrancyViewsContainer removeFromSuperview];
+  [mVibrancyViewsContainer release];
+  [mNonDraggableViewsContainer removeFromSuperview];
+  [mNonDraggableViewsContainer release];
+  [mPixelHostingView removeFromSuperview];
+  [mPixelHostingView release];
+  [mRootCALayer release];
+
+  if (gLastDragView == self) {
+    gLastDragView = nil;
+  }
+
+  [super dealloc];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)widgetDestroyed {
+  if (mTextInputHandler) {
+    mTextInputHandler->OnDestroyWidget(mGeckoChild);
+    mTextInputHandler = nullptr;
+  }
+  mGeckoChild = nullptr;
+
+  // Just in case we're destroyed abruptly and missed the draggingExited
+  // or performDragOperation message.
+  NS_IF_RELEASE(mDragService);
+}
+
+// mozView method, return our gecko child view widget. Note this does not AddRef.
+- (nsIWidget*)widget {
+  return static_cast<nsIWidget*>(mGeckoChild);
+}
+
+- (NSString*)description {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [NSString stringWithFormat:@"ChildView %p, gecko child %p, frame %@", self, mGeckoChild,
+                                    NSStringFromRect([self frame])];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+// Make the origin of this view the topLeft corner (gecko origin) rather
+// than the bottomLeft corner (standard cocoa origin).
+- (BOOL)isFlipped {
+  return YES;
+}
+
+// We accept key and mouse events, so don't keep passing them up the chain. Allow
+// this to be a 'focused' widget for event dispatch.
+- (BOOL)acceptsFirstResponder {
+  return YES;
+}
+
+// Accept mouse down events on background windows
+- (BOOL)acceptsFirstMouse:(NSEvent*)aEvent {
+  if (![[self window] isKindOfClass:[PopupWindow class]]) {
+    // We rely on this function to tell us that the mousedown was on a
+    // background window. Inside mouseDown we can't tell whether we were
+    // inactive because at that point we've already been made active.
+    // Unfortunately, acceptsFirstMouse is called for PopupWindows even when
+    // their parent window is active, so ignore this on them for now.
+    mClickThroughMouseDownEvent = [aEvent retain];
+  }
+  return YES;
+}
+
+- (BOOL)mouseDownCanMoveWindow {
+  // Return YES so that parts of this view can be draggable. The non-draggable
+  // parts will be covered by NSViews that return NO from
+  // mouseDownCanMoveWindow and thus override draggability from the inside.
+  // These views are assembled in nsChildView::UpdateWindowDraggingRegion.
+  return YES;
+}
+
+- (void)viewDidChangeBackingProperties {
+  [super viewDidChangeBackingProperties];
+  if (mGeckoChild) {
+    // actually, it could be the color space that's changed,
+    // but we can't tell the difference here except by retrieving
+    // the backing scale factor and comparing to the old value
+    mGeckoChild->BackingScaleFactorChanged();
+  }
+}
+
+- (BOOL)isCoveringTitlebar {
+  return [[self window] isKindOfClass:[BaseWindow class]] &&
+         [(BaseWindow*)[self window] mainChildView] == self &&
+         [(BaseWindow*)[self window] drawsContentsIntoWindowFrame];
+}
+
+- (void)viewWillStartLiveResize {
+  nsCocoaWindow* windowWidget = mGeckoChild ? mGeckoChild->GetAppWindowWidget() : nullptr;
+  if (windowWidget) {
+    windowWidget->NotifyLiveResizeStarted();
+  }
+}
+
+- (void)viewDidEndLiveResize {
+  // mGeckoChild may legitimately be null here. It should also have been null
+  // in viewWillStartLiveResize, so there's no problem. However if we run into
+  // cases where the windowWidget was non-null in viewWillStartLiveResize but
+  // is null here, that might be problematic because we might get stuck with
+  // a content process that has the displayport suppressed. If that scenario
+  // arises (I'm not sure that it does) we will need to handle it gracefully.
+  nsCocoaWindow* windowWidget = mGeckoChild ? mGeckoChild->GetAppWindowWidget() : nullptr;
+  if (windowWidget) {
+    windowWidget->NotifyLiveResizeStopped();
+  }
+}
+
+- (void)markLayerForDisplay {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  if (!mIsUpdatingLayer) {
+    // This call will cause updateRootCALayer to be called during the upcoming
+    // main thread CoreAnimation transaction. It will also trigger a transaction
+    // if no transaction is currently pending.
+    [[mPixelHostingView layer] setNeedsDisplay];
+  }
+}
+
+- (void)ensureNextCompositeIsAtomicWithMainThreadPaint {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  if (mGeckoChild) {
+    mGeckoChild->SuspendAsyncCATransactions();
+  }
+}
+
+- (void)updateRootCALayer {
+  if (NS_IsMainThread() && mGeckoChild) {
+    MOZ_RELEASE_ASSERT(!mIsUpdatingLayer, "Re-entrant layer display?");
+    mIsUpdatingLayer = YES;
+    mGeckoChild->HandleMainThreadCATransaction();
+    mIsUpdatingLayer = NO;
+  }
+}
+
+- (CALayer*)rootCALayer {
+  return mRootCALayer;
+}
+
+// If we've just created a non-native context menu, we need to mark it as
+// such and let the OS (and other programs) know when it opens and closes
+// (this is how the OS knows to close other programs' context menus when
+// ours open).  We send the initial notification here, but others are sent
+// in nsCocoaWindow::Show().
+- (void)maybeInitContextMenuTracking {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mozilla::widget::NativeMenuSupport::ShouldUseNativeContextMenus()) {
+    return;
+  }
+
+  nsIRollupListener* rollupListener = nsBaseWidget::GetActiveRollupListener();
+  NS_ENSURE_TRUE_VOID(rollupListener);
+  nsCOMPtr<nsIWidget> widget = rollupListener->GetRollupWidget();
+  NS_ENSURE_TRUE_VOID(widget);
+
+  NSWindow* popupWindow = (NSWindow*)widget->GetNativeData(NS_NATIVE_WINDOW);
+  if (!popupWindow || ![popupWindow isKindOfClass:[PopupWindow class]]) return;
+
+  [[NSDistributedNotificationCenter defaultCenter]
+      postNotificationName:@"com.apple.HIToolbox.beginMenuTrackingNotification"
+                    object:@"org.mozilla.gecko.PopupWindow"];
+  [(PopupWindow*)popupWindow setIsContextMenu:YES];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Returns true if the event should no longer be processed, false otherwise.
+// This does not return whether or not anything was rolled up.
+- (BOOL)maybeRollup:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  BOOL consumeEvent = NO;
+
+  nsIRollupListener* rollupListener = nsBaseWidget::GetActiveRollupListener();
+  NS_ENSURE_TRUE(rollupListener, false);
+
+  BOOL isWheelTypeEvent = [theEvent type] == NSEventTypeScrollWheel ||
+                          [theEvent type] == NSEventTypeMagnify ||
+                          [theEvent type] == NSEventTypeSmartMagnify;
+
+  if (!isWheelTypeEvent && rollupListener->RollupNativeMenu()) {
+    // A native menu was rolled up.
+    // Don't consume this event; if the menu wanted to consume this event it would already have done
+    // so and we wouldn't even get here. For example, we won't get here for left clicks that close
+    // native menus (because the native menu consumes it), but we will get here for right clicks
+    // that close native menus, and we do not want to consume those right clicks.
+    return NO;
+  }
+
+  nsCOMPtr<nsIWidget> rollupWidget = rollupListener->GetRollupWidget();
+  if (!rollupWidget) {
+    return consumeEvent;
+  }
+
+  NSWindow* currentPopup = static_cast<NSWindow*>(rollupWidget->GetNativeData(NS_NATIVE_WINDOW));
+  if (nsCocoaUtils::IsEventOverWindow(theEvent, currentPopup)) {
+    return consumeEvent;
+  }
+
+  // Check to see if scroll/zoom events should roll up the popup
+  if (isWheelTypeEvent) {
+    // consume scroll events that aren't over the popup unless the popup is an
+    // arrow panel.
+    consumeEvent = rollupListener->ShouldConsumeOnMouseWheelEvent();
+    if (!rollupListener->ShouldRollupOnMouseWheelEvent()) {
+      return consumeEvent;
+    }
+  }
+
+  // if we're dealing with menus, we probably have submenus and
+  // we don't want to rollup if the click is in a parent menu of
+  // the current submenu
+  uint32_t popupsToRollup = UINT32_MAX;
+  AutoTArray<nsIWidget*, 5> widgetChain;
+  uint32_t sameTypeCount = rollupListener->GetSubmenuWidgetChain(&widgetChain);
+  for (uint32_t i = 0; i < widgetChain.Length(); i++) {
+    nsIWidget* widget = widgetChain[i];
+    NSWindow* currWindow = (NSWindow*)widget->GetNativeData(NS_NATIVE_WINDOW);
+    if (nsCocoaUtils::IsEventOverWindow(theEvent, currWindow)) {
+      // don't roll up if the mouse event occurred within a menu of the
+      // same type. If the mouse event occurred in a menu higher than
+      // that, roll up, but pass the number of popups to Rollup so
+      // that only those of the same type close up.
+      if (i < sameTypeCount) {
+        return consumeEvent;
+      }
+      popupsToRollup = sameTypeCount;
+      break;
+    }
+  }
+
+  LayoutDeviceIntPoint devPoint;
+  nsIRollupListener::RollupOptions rollupOptions{popupsToRollup,
+                                                 nsIRollupListener::FlushViews::Yes};
+  if ([theEvent type] == NSEventTypeLeftMouseDown) {
+    NSPoint point = [NSEvent mouseLocation];
+    FlipCocoaScreenCoordinate(point);
+    devPoint = mGeckoChild->CocoaPointsToDevPixels(point);
+    rollupOptions.mPoint = &devPoint;
+  }
+  consumeEvent = (BOOL)rollupListener->Rollup(rollupOptions);
+  return consumeEvent;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+- (void)swipeWithEvent:(NSEvent*)anEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!anEvent || !mGeckoChild) {
+    return;
+  }
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  float deltaX = [anEvent deltaX];  // left=1.0, right=-1.0
+  float deltaY = [anEvent deltaY];  // up=1.0, down=-1.0
+
+  // Setup the "swipe" event.
+  WidgetSimpleGestureEvent geckoEvent(true, eSwipeGesture, mGeckoChild);
+  [self convertCocoaMouseEvent:anEvent toGeckoEvent:&geckoEvent];
+
+  // Record the left/right direction.
+  if (deltaX > 0.0)
+    geckoEvent.mDirection |= dom::SimpleGestureEvent_Binding::DIRECTION_LEFT;
+  else if (deltaX < 0.0)
+    geckoEvent.mDirection |= dom::SimpleGestureEvent_Binding::DIRECTION_RIGHT;
+
+  // Record the up/down direction.
+  if (deltaY > 0.0)
+    geckoEvent.mDirection |= dom::SimpleGestureEvent_Binding::DIRECTION_UP;
+  else if (deltaY < 0.0)
+    geckoEvent.mDirection |= dom::SimpleGestureEvent_Binding::DIRECTION_DOWN;
+
+  // Send the event.
+  mGeckoChild->DispatchWindowEvent(geckoEvent);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Pinch zoom gesture.
+- (void)magnifyWithEvent:(NSEvent*)anEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if ([self maybeRollup:anEvent]) {
+    return;
+  }
+
+  if (!mGeckoChild) {
+    return;
+  }
+
+  // Instead of calling beginOrEndGestureForEventPhase we basically inline
+  // the effects of it here, because that function doesn't play too well with
+  // how we create PinchGestureInput events below. The main point of that
+  // function is to avoid flip-flopping between rotation/magnify gestures, which
+  // we can do by checking and setting mGestureState appropriately. A secondary
+  // result of that function is to send the final eMagnifyGesture event when
+  // the gesture ends, but APZ takes care of that for us.
+  if (mGestureState == eGestureState_RotateGesture && [anEvent phase] != NSEventPhaseBegan) {
+    // If we're already in a rotation and not "starting" a magnify, abort.
+    return;
+  }
+  mGestureState = eGestureState_MagnifyGesture;
+
+  NSPoint locationInWindow = nsCocoaUtils::EventLocationForWindow(anEvent, [self window]);
+  ScreenPoint position =
+      ViewAs<ScreenPixel>([self convertWindowCoordinatesRoundDown:locationInWindow],
+                          PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent);
+  ExternalPoint screenOffset =
+      ViewAs<ExternalPixel>(mGeckoChild->WidgetToScreenOffset(),
+                            PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent);
+
+  TimeStamp eventTimeStamp = nsCocoaUtils::GetEventTimeStamp([anEvent timestamp]);
+  NSEventPhase eventPhase = [anEvent phase];
+  PinchGestureInput::PinchGestureType pinchGestureType;
+
+  switch (eventPhase) {
+    case NSEventPhaseBegan: {
+      pinchGestureType = PinchGestureInput::PINCHGESTURE_START;
+      break;
+    }
+    case NSEventPhaseChanged: {
+      pinchGestureType = PinchGestureInput::PINCHGESTURE_SCALE;
+      break;
+    }
+    case NSEventPhaseEnded: {
+      pinchGestureType = PinchGestureInput::PINCHGESTURE_END;
+      mGestureState = eGestureState_None;
+      break;
+    }
+    default: {
+      NS_WARNING("Unexpected phase for pinch gesture event.");
+      return;
+    }
+  }
+
+  PinchGestureInput event{pinchGestureType,
+                          PinchGestureInput::TRACKPAD,
+                          eventTimeStamp,
+                          screenOffset,
+                          position,
+                          100.0,
+                          100.0 * (1.0 - [anEvent magnification]),
+                          nsCocoaUtils::ModifiersForEvent(anEvent)};
+
+  mGeckoChild->DispatchAPZInputEvent(event);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Smart zoom gesture, i.e. two-finger double tap on trackpads.
+- (void)smartMagnifyWithEvent:(NSEvent*)anEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!anEvent || !mGeckoChild || [self beginOrEndGestureForEventPhase:anEvent]) {
+    return;
+  }
+
+  if ([self maybeRollup:anEvent]) {
+    return;
+  }
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  if (StaticPrefs::apz_mac_enable_double_tap_zoom_touchpad_gesture()) {
+    TimeStamp eventTimeStamp = nsCocoaUtils::GetEventTimeStamp([anEvent timestamp]);
+    NSPoint locationInWindow = nsCocoaUtils::EventLocationForWindow(anEvent, [self window]);
+    LayoutDevicePoint position = [self convertWindowCoordinatesRoundDown:locationInWindow];
+
+    mGeckoChild->DispatchDoubleTapGesture(eventTimeStamp, RoundedToInt(position),
+                                          nsCocoaUtils::ModifiersForEvent(anEvent));
+  } else {
+    // Setup the "double tap" event.
+    WidgetSimpleGestureEvent geckoEvent(true, eTapGesture, mGeckoChild);
+    [self convertCocoaMouseEvent:anEvent toGeckoEvent:&geckoEvent];
+    geckoEvent.mClickCount = 1;
+
+    // Send the event.
+    mGeckoChild->DispatchWindowEvent(geckoEvent);
+  }
+
+  // Clear the gesture state
+  mGestureState = eGestureState_None;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)rotateWithEvent:(NSEvent*)anEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!anEvent || !mGeckoChild || [self beginOrEndGestureForEventPhase:anEvent]) {
+    return;
+  }
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  float rotation = [anEvent rotation];
+
+  EventMessage msg;
+  switch (mGestureState) {
+    case eGestureState_StartGesture:
+      msg = eRotateGestureStart;
+      mGestureState = eGestureState_RotateGesture;
+      break;
+
+    case eGestureState_RotateGesture:
+      msg = eRotateGestureUpdate;
+      break;
+
+    case eGestureState_None:
+    case eGestureState_MagnifyGesture:
+    default:
+      return;
+  }
+
+  // Setup the event.
+  WidgetSimpleGestureEvent geckoEvent(true, msg, mGeckoChild);
+  [self convertCocoaMouseEvent:anEvent toGeckoEvent:&geckoEvent];
+  geckoEvent.mDelta = -rotation;
+  if (rotation > 0.0) {
+    geckoEvent.mDirection = dom::SimpleGestureEvent_Binding::ROTATION_COUNTERCLOCKWISE;
+  } else {
+    geckoEvent.mDirection = dom::SimpleGestureEvent_Binding::ROTATION_CLOCKWISE;
+  }
+
+  // Send the event.
+  mGeckoChild->DispatchWindowEvent(geckoEvent);
+
+  // Keep track of the cumulative rotation for the final "rotate" event.
+  mCumulativeRotation += rotation;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// `beginGestureWithEvent` and `endGestureWithEvent` are not called for
+// applications that link against the macOS 10.11 or later SDK when we're
+// running on macOS 10.11 or later. For compatibility with all supported macOS
+// versions, we have to call {begin,end}GestureWithEvent ourselves based on
+// the event phase when we're handling gestures.
+- (bool)beginOrEndGestureForEventPhase:(NSEvent*)aEvent {
+  if (!aEvent) {
+    return false;
+  }
+
+  if (aEvent.phase == NSEventPhaseBegan) {
+    [self beginGestureWithEvent:aEvent];
+    return true;
+  }
+
+  if (aEvent.phase == NSEventPhaseEnded || aEvent.phase == NSEventPhaseCancelled) {
+    [self endGestureWithEvent:aEvent];
+    return true;
+  }
+
+  return false;
+}
+
+- (void)beginGestureWithEvent:(NSEvent*)aEvent {
+  if (!aEvent) {
+    return;
+  }
+
+  mGestureState = eGestureState_StartGesture;
+  mCumulativeRotation = 0.0;
+}
+
+- (void)endGestureWithEvent:(NSEvent*)anEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!anEvent || !mGeckoChild) {
+    // Clear the gestures state if we cannot send an event.
+    mGestureState = eGestureState_None;
+    mCumulativeRotation = 0.0;
+    return;
+  }
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  switch (mGestureState) {
+    case eGestureState_RotateGesture: {
+      // Setup the "rotate" event.
+      WidgetSimpleGestureEvent geckoEvent(true, eRotateGesture, mGeckoChild);
+      [self convertCocoaMouseEvent:anEvent toGeckoEvent:&geckoEvent];
+      geckoEvent.mDelta = -mCumulativeRotation;
+      if (mCumulativeRotation > 0.0) {
+        geckoEvent.mDirection = dom::SimpleGestureEvent_Binding::ROTATION_COUNTERCLOCKWISE;
+      } else {
+        geckoEvent.mDirection = dom::SimpleGestureEvent_Binding::ROTATION_CLOCKWISE;
+      }
+
+      // Send the event.
+      mGeckoChild->DispatchWindowEvent(geckoEvent);
+    } break;
+
+    case eGestureState_MagnifyGesture:  // APZ handles sending the widget events
+    case eGestureState_None:
+    case eGestureState_StartGesture:
+    default:
+      break;
+  }
+
+  // Clear the gestures state.
+  mGestureState = eGestureState_None;
+  mCumulativeRotation = 0.0;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)setUsingOMTCompositor:(BOOL)aUseOMTC {
+  mUsingOMTCompositor = aUseOMTC;
+}
+
+// Returning NO from this method only disallows ordering on mousedown - in order
+// to prevent it for mouseup too, we need to call [NSApp preventWindowOrdering]
+// when handling the mousedown event.
+- (BOOL)shouldDelayWindowOrderingForEvent:(NSEvent*)aEvent {
+  // Always using system-provided window ordering for normal windows.
+  if (![[self window] isKindOfClass:[PopupWindow class]]) return NO;
+
+  // Don't reorder when we don't have a parent window, like when we're a
+  // context menu or a tooltip.
+  return ![[self window] parentWindow];
+}
+
+- (void)mouseDown:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if ([self shouldDelayWindowOrderingForEvent:theEvent]) {
+    [NSApp preventWindowOrdering];
+  }
+
+  // If we've already seen this event due to direct dispatch from menuForEvent:
+  // just bail; if not, remember it.
+  if (mLastMouseDownEvent == theEvent) {
+    [mLastMouseDownEvent release];
+    mLastMouseDownEvent = nil;
+    return;
+  } else {
+    [mLastMouseDownEvent release];
+    mLastMouseDownEvent = [theEvent retain];
+  }
+
+  [gLastDragMouseDownEvent release];
+  gLastDragMouseDownEvent = [theEvent retain];
+  gLastDragView = self;
+
+  // We need isClickThrough because at this point the window we're in might
+  // already have become main, so the check for isMainWindow in
+  // WindowAcceptsEvent isn't enough. It also has to check isClickThrough.
+  BOOL isClickThrough = (theEvent == mClickThroughMouseDownEvent);
+  [mClickThroughMouseDownEvent release];
+  mClickThroughMouseDownEvent = nil;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  if ([self maybeRollup:theEvent] ||
+      !ChildViewMouseTracker::WindowAcceptsEvent([self window], theEvent, self, isClickThrough)) {
+    // Remember blocking because that means we want to block mouseup as well.
+    mBlockedLastMouseDown = YES;
+    return;
+  }
+
+  // in order to send gecko events we'll need a gecko widget
+  if (!mGeckoChild) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  WidgetMouseEvent geckoEvent(true, eMouseDown, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+
+  NSInteger clickCount = [theEvent clickCount];
+  if (mBlockedLastMouseDown && clickCount > 1) {
+    // Don't send a double click if the first click of the double click was
+    // blocked.
+    clickCount--;
+  }
+  geckoEvent.mClickCount = clickCount;
+
+  if (!StaticPrefs::dom_event_treat_ctrl_click_as_right_click_disabled() &&
+      geckoEvent.IsControl()) {
+    geckoEvent.mButton = MouseButton::eSecondary;
+  } else {
+    geckoEvent.mButton = MouseButton::ePrimary;
+    // Don't send a click if ctrl key is pressed.
+    geckoEvent.mClickEventPrevented = geckoEvent.IsControl();
+  }
+
+  mGeckoChild->DispatchInputEvent(&geckoEvent);
+  mBlockedLastMouseDown = NO;
+
+  // XXX maybe call markedTextSelectionChanged:client: here?
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)mouseUp:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  gLastDragView = nil;
+
+  if (!mGeckoChild || mBlockedLastMouseDown) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  WidgetMouseEvent geckoEvent(true, eMouseUp, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+
+  if (!StaticPrefs::dom_event_treat_ctrl_click_as_right_click_disabled() &&
+      ([theEvent modifierFlags] & NSEventModifierFlagControl)) {
+    geckoEvent.mButton = MouseButton::eSecondary;
+  } else {
+    geckoEvent.mButton = MouseButton::ePrimary;
+  }
+
+  // Remember the event's position before calling DispatchInputEvent, because
+  // that call can mutate it and convert it into a different coordinate space.
+  LayoutDeviceIntPoint pos = geckoEvent.mRefPoint;
+
+  // This might destroy our widget (and null out mGeckoChild).
+  bool defaultPrevented = (mGeckoChild->DispatchInputEvent(&geckoEvent).mContentStatus ==
+                           nsEventStatus_eConsumeNoDefault);
+
+  if (!mGeckoChild) {
+    return;
+  }
+
+  // Check to see if we are double-clicking in draggable parts of the window.
+  if (!defaultPrevented && [theEvent clickCount] == 2 &&
+      !mGeckoChild->GetNonDraggableRegion().Contains(pos.x, pos.y)) {
+    if (nsCocoaUtils::ShouldZoomOnTitlebarDoubleClick()) {
+      [[self window] performZoom:nil];
+    } else if (nsCocoaUtils::ShouldMinimizeOnTitlebarDoubleClick()) {
+      [[self window] performMiniaturize:nil];
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)sendMouseEnterOrExitEvent:(NSEvent*)aEvent
+                            enter:(BOOL)aEnter
+                         exitFrom:(WidgetMouseEvent::ExitFrom)aExitFrom {
+  if (!mGeckoChild) return;
+
+  NSPoint windowEventLocation = nsCocoaUtils::EventLocationForWindow(aEvent, [self window]);
+  NSPoint localEventLocation = [self convertPoint:windowEventLocation fromView:nil];
+
+  EventMessage msg = aEnter ? eMouseEnterIntoWidget : eMouseExitFromWidget;
+  WidgetMouseEvent event(true, msg, mGeckoChild, WidgetMouseEvent::eReal);
+  event.mRefPoint = mGeckoChild->CocoaPointsToDevPixels(localEventLocation);
+  if (event.mMessage == eMouseExitFromWidget) {
+    event.mExitFrom = Some(aExitFrom);
+  }
+  nsEventStatus status;  // ignored
+  mGeckoChild->DispatchEvent(&event, status);
+}
+
+- (void)handleMouseMoved:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mGeckoChild) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  WidgetMouseEvent geckoEvent(true, eMouseMove, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+
+  mGeckoChild->DispatchInputEvent(&geckoEvent);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)mouseDragged:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mGeckoChild) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  WidgetMouseEvent geckoEvent(true, eMouseMove, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+
+  mGeckoChild->DispatchInputEvent(&geckoEvent);
+
+  // Note, sending the above event might have destroyed our widget since we didn't retain.
+  // Fine so long as we don't access any local variables from here on.
+
+  // XXX maybe call markedTextSelectionChanged:client: here?
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)rightMouseDown:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  [self maybeRollup:theEvent];
+  if (!mGeckoChild) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  // The right mouse went down, fire off a right mouse down event to gecko
+  WidgetMouseEvent geckoEvent(true, eMouseDown, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+  geckoEvent.mButton = MouseButton::eSecondary;
+  geckoEvent.mClickCount = [theEvent clickCount];
+
+  nsIWidget::ContentAndAPZEventStatus eventStatus = mGeckoChild->DispatchInputEvent(&geckoEvent);
+  if (!mGeckoChild) return;
+
+  if (!StaticPrefs::ui_context_menus_after_mouseup() &&
+      eventStatus.mApzStatus != nsEventStatus_eConsumeNoDefault) {
+    // Let the superclass do the context menu stuff.
+    [super rightMouseDown:theEvent];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)rightMouseUp:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mGeckoChild) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  WidgetMouseEvent geckoEvent(true, eMouseUp, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+  geckoEvent.mButton = MouseButton::eSecondary;
+  geckoEvent.mClickCount = [theEvent clickCount];
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+  nsIWidget::ContentAndAPZEventStatus eventStatus = mGeckoChild->DispatchInputEvent(&geckoEvent);
+  if (!mGeckoChild) return;
+
+  if (StaticPrefs::ui_context_menus_after_mouseup() &&
+      eventStatus.mApzStatus != nsEventStatus_eConsumeNoDefault) {
+    // Let the superclass do the context menu stuff, but pretend it's rightMouseDown.
+    NSEvent* dupeEvent = [NSEvent mouseEventWithType:NSEventTypeRightMouseDown
+                                            location:theEvent.locationInWindow
+                                       modifierFlags:theEvent.modifierFlags
+                                           timestamp:theEvent.timestamp
+                                        windowNumber:theEvent.windowNumber
+                                             context:nil
+                                         eventNumber:theEvent.eventNumber
+                                          clickCount:theEvent.clickCount
+                                            pressure:theEvent.pressure];
+
+    [super rightMouseDown:dupeEvent];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)rightMouseDragged:(NSEvent*)theEvent {
+  if (!mGeckoChild) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  WidgetMouseEvent geckoEvent(true, eMouseMove, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+  geckoEvent.mButton = MouseButton::eSecondary;
+
+  // send event into Gecko by going directly to the
+  // the widget.
+  mGeckoChild->DispatchInputEvent(&geckoEvent);
+}
+
+static bool ShouldDispatchBackForwardCommandForMouseButton(int16_t aButton) {
+  return (aButton == MouseButton::eX1 && Preferences::GetBool("mousebutton.4th.enabled", true)) ||
+         (aButton == MouseButton::eX2 && Preferences::GetBool("mousebutton.5th.enabled", true));
+}
+
+- (void)otherMouseDown:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  if ([self maybeRollup:theEvent] ||
+      !ChildViewMouseTracker::WindowAcceptsEvent([self window], theEvent, self))
+    return;
+
+  if (!mGeckoChild) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  int16_t button = nsCocoaUtils::ButtonForEvent(theEvent);
+  if (ShouldDispatchBackForwardCommandForMouseButton(button)) {
+    WidgetCommandEvent appCommandEvent(
+        true, (button == MouseButton::eX2) ? nsGkAtoms::Forward : nsGkAtoms::Back, mGeckoChild);
+    mGeckoChild->DispatchWindowEvent(appCommandEvent);
+    return;
+  }
+
+  WidgetMouseEvent geckoEvent(true, eMouseDown, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+  geckoEvent.mButton = button;
+  geckoEvent.mClickCount = [theEvent clickCount];
+
+  mGeckoChild->DispatchInputEvent(&geckoEvent);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)otherMouseUp:(NSEvent*)theEvent {
+  if (!mGeckoChild) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  int16_t button = nsCocoaUtils::ButtonForEvent(theEvent);
+  if (ShouldDispatchBackForwardCommandForMouseButton(button)) {
+    return;
+  }
+
+  WidgetMouseEvent geckoEvent(true, eMouseUp, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+  geckoEvent.mButton = button;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+  mGeckoChild->DispatchInputEvent(&geckoEvent);
+}
+
+- (void)otherMouseDragged:(NSEvent*)theEvent {
+  if (!mGeckoChild) return;
+  if (mTextInputHandler->OnHandleEvent(theEvent)) {
+    return;
+  }
+
+  WidgetMouseEvent geckoEvent(true, eMouseMove, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+  int16_t button = nsCocoaUtils::ButtonForEvent(theEvent);
+  geckoEvent.mButton = button;
+
+  // send event into Gecko by going directly to the
+  // the widget.
+  mGeckoChild->DispatchInputEvent(&geckoEvent);
+}
+
+- (void)sendWheelStartOrStop:(EventMessage)msg forEvent:(NSEvent*)theEvent {
+  WidgetWheelEvent wheelEvent(true, msg, mGeckoChild);
+  [self convertCocoaMouseWheelEvent:theEvent toGeckoEvent:&wheelEvent];
+  mExpectingWheelStop = (msg == eWheelOperationStart);
+  mGeckoChild->DispatchInputEvent(wheelEvent.AsInputEvent());
+}
+
+- (void)sendWheelCondition:(BOOL)condition
+                     first:(EventMessage)first
+                    second:(EventMessage)second
+                  forEvent:(NSEvent*)theEvent {
+  if (mExpectingWheelStop == condition) {
+    [self sendWheelStartOrStop:first forEvent:theEvent];
+  }
+  [self sendWheelStartOrStop:second forEvent:theEvent];
+}
+
+static int32_t RoundUp(double aDouble) {
+  return aDouble < 0 ? static_cast<int32_t>(floor(aDouble)) : static_cast<int32_t>(ceil(aDouble));
+}
+
+static gfx::IntPoint GetIntegerDeltaForEvent(NSEvent* aEvent) {
+  if ([aEvent hasPreciseScrollingDeltas]) {
+    // Pixel scroll events (events with hasPreciseScrollingDeltas == YES)
+    // carry pixel deltas in the scrollingDeltaX/Y fields and line scroll
+    // information in the deltaX/Y fields.
+    // Prior to 10.12, these line scroll fields would be zero for most pixel
+    // scroll events and non-zero for some, whenever at least a full line
+    // worth of pixel scrolling had accumulated. That's the behavior we want.
+    // Starting with 10.12 however, pixel scroll events no longer accumulate
+    // deltaX and deltaY; they just report floating point values for every
+    // single event. So we need to do our own accumulation.
+    return PanGestureInput::GetIntegerDeltaForEvent([aEvent phase] == NSEventPhaseBegan,
+                                                    [aEvent deltaX], [aEvent deltaY]);
+  }
+
+  // For line scrolls, or pre-10.12, just use the rounded up value of deltaX / deltaY.
+  return gfx::IntPoint(RoundUp([aEvent deltaX]), RoundUp([aEvent deltaY]));
+}
+
+- (void)scrollWheel:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  ChildViewMouseTracker::MouseScrolled(theEvent);
+
+  if ([self maybeRollup:theEvent]) {
+    return;
+  }
+
+  if (!mGeckoChild) {
+    return;
+  }
+
+  NSEventPhase phase = [theEvent phase];
+  // Fire eWheelOperationStart/End events when 2 fingers touch/release the
+  // touchpad.
+  if (phase & NSEventPhaseMayBegin) {
+    [self sendWheelCondition:YES
+                       first:eWheelOperationEnd
+                      second:eWheelOperationStart
+                    forEvent:theEvent];
+  } else if (phase & (NSEventPhaseEnded | NSEventPhaseCancelled)) {
+    [self sendWheelCondition:NO
+                       first:eWheelOperationStart
+                      second:eWheelOperationEnd
+                    forEvent:theEvent];
+  }
+
+  if (!mGeckoChild) {
+    return;
+  }
+  RefPtr<nsChildView> geckoChildDeathGrip(mGeckoChild);
+
+  NSPoint locationInWindow = nsCocoaUtils::EventLocationForWindow(theEvent, [self window]);
+
+  // Use convertWindowCoordinatesRoundDown when converting the position to
+  // integer screen pixels in order to ensure that coordinates which are just
+  // inside the right / bottom edges of the window don't end up outside of the
+  // window after rounding.
+  ScreenPoint position =
+      ViewAs<ScreenPixel>([self convertWindowCoordinatesRoundDown:locationInWindow],
+                          PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent);
+
+  bool usePreciseDeltas = [theEvent hasPreciseScrollingDeltas] &&
+                          Preferences::GetBool("mousewheel.enable_pixel_scrolling", true);
+  bool hasPhaseInformation = nsCocoaUtils::EventHasPhaseInformation(theEvent);
+
+  gfx::IntPoint lineOrPageDelta = -GetIntegerDeltaForEvent(theEvent);
+
+  Modifiers modifiers = nsCocoaUtils::ModifiersForEvent(theEvent);
+
+  TimeStamp eventTimeStamp = nsCocoaUtils::GetEventTimeStamp([theEvent timestamp]);
+
+  ScreenPoint preciseDelta;
+  if (usePreciseDeltas) {
+    CGFloat pixelDeltaX = [theEvent scrollingDeltaX];
+    CGFloat pixelDeltaY = [theEvent scrollingDeltaY];
+    double scale = geckoChildDeathGrip->BackingScaleFactor();
+    preciseDelta = ScreenPoint(-pixelDeltaX * scale, -pixelDeltaY * scale);
+  }
+
+  if (usePreciseDeltas && hasPhaseInformation) {
+    PanGestureInput panEvent = nsCocoaUtils::CreatePanGestureEvent(
+        theEvent, eventTimeStamp, position, preciseDelta, lineOrPageDelta, modifiers);
+
+    geckoChildDeathGrip->DispatchAPZWheelInputEvent(panEvent);
+  } else if (usePreciseDeltas) {
+    // This is on 10.6 or old touchpads that don't have any phase information.
+    ScrollWheelInput wheelEvent(eventTimeStamp, modifiers, ScrollWheelInput::SCROLLMODE_INSTANT,
+                                ScrollWheelInput::SCROLLDELTA_PIXEL, position, preciseDelta.x,
+                                preciseDelta.y, false,
+                                // This parameter is used for wheel delta
+                                // adjustment, such as auto-dir scrolling,
+                                // but we do't need to do anything special here
+                                // since this wheel event is sent to
+                                // DispatchAPZWheelInputEvent, which turns this
+                                // ScrollWheelInput back into a WidgetWheelEvent
+                                // and then it goes through the regular handling
+                                // in APZInputBridge. So passing |eNone| won't
+                                // pass up the necessary wheel delta adjustment.
+                                WheelDeltaAdjustmentStrategy::eNone);
+    wheelEvent.mLineOrPageDeltaX = lineOrPageDelta.x;
+    wheelEvent.mLineOrPageDeltaY = lineOrPageDelta.y;
+    wheelEvent.mIsMomentum = nsCocoaUtils::IsMomentumScrollEvent(theEvent);
+    geckoChildDeathGrip->DispatchAPZWheelInputEvent(wheelEvent);
+  } else {
+    ScrollWheelInput::ScrollMode scrollMode = ScrollWheelInput::SCROLLMODE_INSTANT;
+    if (StaticPrefs::general_smoothScroll() && StaticPrefs::general_smoothScroll_mouseWheel()) {
+      scrollMode = ScrollWheelInput::SCROLLMODE_SMOOTH;
+    }
+    ScrollWheelInput wheelEvent(eventTimeStamp, modifiers, scrollMode,
+                                ScrollWheelInput::SCROLLDELTA_LINE, position, lineOrPageDelta.x,
+                                lineOrPageDelta.y, false,
+                                // This parameter is used for wheel delta
+                                // adjustment, such as auto-dir scrolling,
+                                // but we do't need to do anything special here
+                                // since this wheel event is sent to
+                                // DispatchAPZWheelInputEvent, which turns this
+                                // ScrollWheelInput back into a WidgetWheelEvent
+                                // and then it goes through the regular handling
+                                // in APZInputBridge. So passing |eNone| won't
+                                // pass up the necessary wheel delta adjustment.
+                                WheelDeltaAdjustmentStrategy::eNone);
+    wheelEvent.mLineOrPageDeltaX = lineOrPageDelta.x;
+    wheelEvent.mLineOrPageDeltaY = lineOrPageDelta.y;
+    geckoChildDeathGrip->DispatchAPZWheelInputEvent(wheelEvent);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (NSMenu*)menuForEvent:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mGeckoChild) return nil;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  [self maybeRollup:theEvent];
+  if (!mGeckoChild) return nil;
+
+  // Cocoa doesn't always dispatch a mouseDown: for a control-click event,
+  // depends on what we return from menuForEvent:. Gecko always expects one
+  // and expects the mouse down event before the context menu event, so
+  // get that event sent first if this is a left mouse click.
+  if ([theEvent type] == NSEventTypeLeftMouseDown) {
+    [self mouseDown:theEvent];
+    if (!mGeckoChild) return nil;
+  }
+
+  WidgetMouseEvent geckoEvent(true, eContextMenu, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:theEvent toGeckoEvent:&geckoEvent];
+  if (StaticPrefs::dom_event_treat_ctrl_click_as_right_click_disabled() &&
+      [theEvent type] == NSEventTypeLeftMouseDown) {
+    geckoEvent.mContextMenuTrigger = WidgetMouseEvent::eControlClick;
+    geckoEvent.mButton = MouseButton::ePrimary;
+  } else {
+    geckoEvent.mButton = MouseButton::eSecondary;
+  }
+
+  mGeckoChild->DispatchInputEvent(&geckoEvent);
+  if (!mGeckoChild) return nil;
+
+  [self maybeInitContextMenuTracking];
+
+  // We never return an actual NSMenu* for the context menu. Gecko might have
+  // responded to the eContextMenu event by putting up a fake context menu.
+  return nil;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)willOpenMenu:(NSMenu*)aMenu withEvent:(NSEvent*)aEvent {
+  ChildViewMouseTracker::NativeMenuOpened();
+}
+
+- (void)didCloseMenu:(NSMenu*)aMenu withEvent:(NSEvent*)aEvent {
+  ChildViewMouseTracker::NativeMenuClosed();
+}
+
+- (void)convertCocoaMouseWheelEvent:(NSEvent*)aMouseEvent
+                       toGeckoEvent:(WidgetWheelEvent*)outWheelEvent {
+  [self convertCocoaMouseEvent:aMouseEvent toGeckoEvent:outWheelEvent];
+
+  bool usePreciseDeltas = [aMouseEvent hasPreciseScrollingDeltas] &&
+                          Preferences::GetBool("mousewheel.enable_pixel_scrolling", true);
+
+  outWheelEvent->mDeltaMode = usePreciseDeltas ? dom::WheelEvent_Binding::DOM_DELTA_PIXEL
+                                               : dom::WheelEvent_Binding::DOM_DELTA_LINE;
+  outWheelEvent->mIsMomentum = nsCocoaUtils::IsMomentumScrollEvent(aMouseEvent);
+}
+
+- (void)convertCocoaMouseEvent:(NSEvent*)aMouseEvent toGeckoEvent:(WidgetInputEvent*)outGeckoEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NS_ASSERTION(outGeckoEvent,
+               "convertCocoaMouseEvent:toGeckoEvent: requires non-null aoutGeckoEvent");
+  if (!outGeckoEvent) return;
+
+  nsCocoaUtils::InitInputEvent(*outGeckoEvent, aMouseEvent);
+
+  // convert point to view coordinate system
+  NSPoint locationInWindow = nsCocoaUtils::EventLocationForWindow(aMouseEvent, [self window]);
+
+  outGeckoEvent->mRefPoint = [self convertWindowCoordinates:locationInWindow];
+
+  WidgetMouseEventBase* mouseEvent = outGeckoEvent->AsMouseEventBase();
+  mouseEvent->mButtons = 0;
+  NSUInteger mouseButtons = [NSEvent pressedMouseButtons];
+
+  if (mouseButtons & 0x01) {
+    mouseEvent->mButtons |= MouseButtonsFlag::ePrimaryFlag;
+  }
+  if (mouseButtons & 0x02) {
+    mouseEvent->mButtons |= MouseButtonsFlag::eSecondaryFlag;
+  }
+  if (mouseButtons & 0x04) {
+    mouseEvent->mButtons |= MouseButtonsFlag::eMiddleFlag;
+  }
+  if (mouseButtons & 0x08) {
+    mouseEvent->mButtons |= MouseButtonsFlag::e4thFlag;
+  }
+  if (mouseButtons & 0x10) {
+    mouseEvent->mButtons |= MouseButtonsFlag::e5thFlag;
+  }
+
+  switch ([aMouseEvent type]) {
+    case NSEventTypeLeftMouseDown:
+    case NSEventTypeLeftMouseUp:
+    case NSEventTypeLeftMouseDragged:
+    case NSEventTypeRightMouseDown:
+    case NSEventTypeRightMouseUp:
+    case NSEventTypeRightMouseDragged:
+    case NSEventTypeOtherMouseDown:
+    case NSEventTypeOtherMouseUp:
+    case NSEventTypeOtherMouseDragged:
+    case NSEventTypeMouseMoved:
+      if ([aMouseEvent subtype] == NSEventSubtypeTabletPoint) {
+        [self convertCocoaTabletPointerEvent:aMouseEvent toGeckoEvent:mouseEvent->AsMouseEvent()];
+      }
+      break;
+
+    default:
+      // Don't check other NSEvents for pressure.
+      break;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)convertCocoaTabletPointerEvent:(NSEvent*)aPointerEvent
+                          toGeckoEvent:(WidgetMouseEvent*)aOutGeckoEvent {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN
+  if (!aOutGeckoEvent || !sIsTabletPointerActivated) {
+    return;
+  }
+  if ([aPointerEvent type] != NSEventTypeMouseMoved) {
+    aOutGeckoEvent->mPressure = [aPointerEvent pressure];
+    MOZ_ASSERT(aOutGeckoEvent->mPressure >= 0.0 && aOutGeckoEvent->mPressure <= 1.0);
+  }
+  aOutGeckoEvent->mInputSource = dom::MouseEvent_Binding::MOZ_SOURCE_PEN;
+  aOutGeckoEvent->tiltX = (int32_t)lround([aPointerEvent tilt].x * 90);
+  aOutGeckoEvent->tiltY = (int32_t)lround([aPointerEvent tilt].y * 90);
+  aOutGeckoEvent->tangentialPressure = [aPointerEvent tangentialPressure];
+  // Make sure the twist value is in the range of 0-359.
+  int32_t twist = (int32_t)fmod([aPointerEvent rotation], 360);
+  aOutGeckoEvent->twist = twist >= 0 ? twist : twist + 360;
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)tabletProximity:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN
+  sIsTabletPointerActivated = [theEvent isEnteringProximity];
+  NS_OBJC_END_TRY_IGNORE_BLOCK
+}
+
+#pragma mark -
+// NSTextInputClient implementation
+
+- (NSRange)markedRange {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NS_ENSURE_TRUE(mTextInputHandler, NSMakeRange(NSNotFound, 0));
+  return mTextInputHandler->MarkedRange();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSMakeRange(0, 0));
+}
+
+- (NSRange)selectedRange {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NS_ENSURE_TRUE(mTextInputHandler, NSMakeRange(NSNotFound, 0));
+  return mTextInputHandler->SelectedRange();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSMakeRange(0, 0));
+}
+
+- (BOOL)drawsVerticallyForCharacterAtIndex:(NSUInteger)charIndex {
+  NS_ENSURE_TRUE(mTextInputHandler, NO);
+  if (charIndex == NSNotFound) {
+    return NO;
+  }
+  return mTextInputHandler->DrawsVerticallyForCharacterAtIndex(charIndex);
+}
+
+- (NSUInteger)characterIndexForPoint:(NSPoint)thePoint {
+  NS_ENSURE_TRUE(mTextInputHandler, 0);
+  return mTextInputHandler->CharacterIndexForPoint(thePoint);
+}
+
+- (NSArray*)validAttributesForMarkedText {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NS_ENSURE_TRUE(mTextInputHandler, [NSArray array]);
+  return mTextInputHandler->GetValidAttributesForMarkedText();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)insertText:(id)aString replacementRange:(NSRange)replacementRange {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NS_ENSURE_TRUE_VOID(mGeckoChild);
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  NSAttributedString* attrStr;
+  if ([aString isKindOfClass:[NSAttributedString class]]) {
+    attrStr = static_cast<NSAttributedString*>(aString);
+  } else {
+    attrStr = [[[NSAttributedString alloc] initWithString:aString] autorelease];
+  }
+
+  mTextInputHandler->InsertText(attrStr, &replacementRange);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)doCommandBySelector:(SEL)aSelector {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mGeckoChild || !mTextInputHandler) {
+    return;
+  }
+
+  const char* sel = reinterpret_cast<const char*>(aSelector);
+  if (!mTextInputHandler->DoCommandBySelector(sel)) {
+    [super doCommandBySelector:aSelector];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)unmarkText {
+  NS_ENSURE_TRUE_VOID(mTextInputHandler);
+  mTextInputHandler->CommitIMEComposition();
+}
+
+- (BOOL)hasMarkedText {
+  NS_ENSURE_TRUE(mTextInputHandler, NO);
+  return mTextInputHandler->HasMarkedText();
+}
+
+- (void)setMarkedText:(id)aString
+        selectedRange:(NSRange)selectedRange
+     replacementRange:(NSRange)replacementRange {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NS_ENSURE_TRUE_VOID(mTextInputHandler);
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  NSAttributedString* attrStr;
+  if ([aString isKindOfClass:[NSAttributedString class]]) {
+    attrStr = static_cast<NSAttributedString*>(aString);
+  } else {
+    attrStr = [[[NSAttributedString alloc] initWithString:aString] autorelease];
+  }
+
+  mTextInputHandler->SetMarkedText(attrStr, selectedRange, &replacementRange);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (NSAttributedString*)attributedSubstringForProposedRange:(NSRange)aRange
+                                               actualRange:(NSRangePointer)actualRange {
+  NS_ENSURE_TRUE(mTextInputHandler, nil);
+  return mTextInputHandler->GetAttributedSubstringFromRange(aRange, actualRange);
+}
+
+- (NSRect)firstRectForCharacterRange:(NSRange)aRange actualRange:(NSRangePointer)actualRange {
+  NS_ENSURE_TRUE(mTextInputHandler, NSMakeRect(0.0, 0.0, 0.0, 0.0));
+  return mTextInputHandler->FirstRectForCharacterRange(aRange, actualRange);
+}
+
+- (void)quickLookWithEvent:(NSEvent*)event {
+  // Show dictionary by current point
+  WidgetContentCommandEvent contentCommandEvent(true, eContentCommandLookUpDictionary, mGeckoChild);
+  NSPoint point = [self convertPoint:[event locationInWindow] fromView:nil];
+  contentCommandEvent.mRefPoint = mGeckoChild->CocoaPointsToDevPixels(point);
+  mGeckoChild->DispatchWindowEvent(contentCommandEvent);
+  // The widget might have been destroyed.
+}
+
+- (NSInteger)windowLevel {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NS_ENSURE_TRUE(mTextInputHandler, [[self window] level]);
+  return mTextInputHandler->GetWindowLevel();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSNormalWindowLevel);
+}
+
+#pragma mark -
+
+// This is a private API that Cocoa uses.
+// Cocoa will call this after the menu system returns "NO" for "performKeyEquivalent:".
+// We want all they key events we can get so just return YES. In particular, this fixes
+// ctrl-tab - we don't get a "keyDown:" call for that without this.
+- (BOOL)_wantsKeyDownForEvent:(NSEvent*)event {
+  return YES;
+}
+
+- (NSEvent*)lastKeyDownEvent {
+  return mLastKeyDownEvent;
+}
+
+- (void)keyDown:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mLastKeyDownEvent release];
+  mLastKeyDownEvent = [theEvent retain];
+
+  // Weird things can happen on keyboard input if the key window isn't in the
+  // current space.  For example see bug 1056251.  To get around this, always
+  // make sure that, if our window is key, it's also made frontmost.  Doing
+  // this automatically switches to whatever space our window is in.  Safari
+  // does something similar.  Our window should normally always be key --
+  // otherwise why is the OS sending us a key down event?  But it's just
+  // possible we're in Gecko's hidden window, so we check first.
+  NSWindow* viewWindow = [self window];
+  if (viewWindow && [viewWindow isKeyWindow]) {
+    [viewWindow orderWindow:NSWindowAbove relativeTo:0];
+  }
+
+#if !defined(RELEASE_OR_BETA) || defined(DEBUG)
+  if (!Preferences::GetBool("intl.allow-insecure-text-input", false) && mGeckoChild &&
+      mTextInputHandler && mTextInputHandler->IsFocused()) {
+    NSWindow* window = [self window];
+    NSString* info = [NSString
+        stringWithFormat:
+            @"\nview [%@], window [%@], window is key %i, is fullscreen %i, app is active %i", self,
+            window, [window isKeyWindow], ([window styleMask] & NSWindowStyleMaskFullScreen) != 0,
+            [NSApp isActive]];
+    nsAutoCString additionalInfo([info UTF8String]);
+
+    if (mGeckoChild->GetInputContext().IsPasswordEditor() &&
+        !TextInputHandler::IsSecureEventInputEnabled()) {
+#  define CRASH_MESSAGE "A password editor has focus, but not in secure input mode"
+
+      CrashReporter::AppendAppNotesToCrashReport("\nBug 893973: "_ns +
+                                                 nsLiteralCString(CRASH_MESSAGE));
+      CrashReporter::AppendAppNotesToCrashReport(additionalInfo);
+
+      MOZ_CRASH(CRASH_MESSAGE);
+#  undef CRASH_MESSAGE
+    } else if (!mGeckoChild->GetInputContext().IsPasswordEditor() &&
+               TextInputHandler::IsSecureEventInputEnabled()) {
+#  define CRASH_MESSAGE "A non-password editor has focus, but in secure input mode"
+
+      CrashReporter::AppendAppNotesToCrashReport("\nBug 893973: "_ns +
+                                                 nsLiteralCString(CRASH_MESSAGE));
+      CrashReporter::AppendAppNotesToCrashReport(additionalInfo);
+
+      MOZ_CRASH(CRASH_MESSAGE);
+#  undef CRASH_MESSAGE
+    }
+  }
+#endif  // #if !defined(RELEASE_OR_BETA) || defined(DEBUG)
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+  if (mGeckoChild) {
+    if (mTextInputHandler) {
+      sUniqueKeyEventId++;
+      NSMutableDictionary* nativeKeyEventsMap = [ChildView sNativeKeyEventsMap];
+      [nativeKeyEventsMap setObject:theEvent forKey:@(sUniqueKeyEventId)];
+      // Purge old native events, in case we're still holding on to them. We
+      // keep at most 10 references to 10 different native events.
+      [nativeKeyEventsMap removeObjectForKey:@(sUniqueKeyEventId - 10)];
+      mTextInputHandler->HandleKeyDownEvent(theEvent, sUniqueKeyEventId);
+    } else {
+      // There was no text input handler. Offer the event to the native menu
+      // system to check if there are any registered custom shortcuts for this
+      // event.
+      mGeckoChild->SendEventToNativeMenuSystem(theEvent);
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)keyUp:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NS_ENSURE_TRUE(mGeckoChild, );
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  mTextInputHandler->HandleKeyUpEvent(theEvent);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)insertNewline:(id)sender {
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::InsertParagraph);
+  }
+}
+
+- (void)insertLineBreak:(id)sender {
+  // Ctrl + Enter in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::InsertLineBreak);
+  }
+}
+
+- (void)deleteBackward:(id)sender {
+  // Backspace in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::DeleteCharBackward);
+  }
+}
+
+- (void)deleteBackwardByDecomposingPreviousCharacter:(id)sender {
+  // Ctrl + Backspace in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::DeleteCharBackward);
+  }
+}
+
+- (void)deleteWordBackward:(id)sender {
+  // Alt + Backspace in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::DeleteWordBackward);
+  }
+}
+
+- (void)deleteToBeginningOfBackward:(id)sender {
+  // Command + Backspace in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::DeleteToBeginningOfLine);
+  }
+}
+
+- (void)deleteForward:(id)sender {
+  // Delete in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::DeleteCharForward);
+  }
+}
+
+- (void)deleteWordForward:(id)sender {
+  // Alt + Delete in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::DeleteWordForward);
+  }
+}
+
+- (void)insertTab:(id)sender {
+  // Tab in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::InsertTab);
+  }
+}
+
+- (void)insertBacktab:(id)sender {
+  // Shift + Tab in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::InsertBacktab);
+  }
+}
+
+- (void)moveRight:(id)sender {
+  // RightArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::CharNext);
+  }
+}
+
+- (void)moveRightAndModifySelection:(id)sender {
+  // Shift + RightArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectCharNext);
+  }
+}
+
+- (void)moveWordRight:(id)sender {
+  // Alt + RightArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::WordNext);
+  }
+}
+
+- (void)moveWordRightAndModifySelection:(id)sender {
+  // Alt + Shift + RightArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectWordNext);
+  }
+}
+
+- (void)moveToRightEndOfLine:(id)sender {
+  // Command + RightArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::EndLine);
+  }
+}
+
+- (void)moveToRightEndOfLineAndModifySelection:(id)sender {
+  // Command + Shift + RightArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectEndLine);
+  }
+}
+
+- (void)moveLeft:(id)sender {
+  // LeftArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::CharPrevious);
+  }
+}
+
+- (void)moveLeftAndModifySelection:(id)sender {
+  // Shift + LeftArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectCharPrevious);
+  }
+}
+
+- (void)moveWordLeft:(id)sender {
+  // Alt + LeftArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::WordPrevious);
+  }
+}
+
+- (void)moveWordLeftAndModifySelection:(id)sender {
+  // Alt + Shift + LeftArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectWordPrevious);
+  }
+}
+
+- (void)moveToLeftEndOfLine:(id)sender {
+  // Command + LeftArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::BeginLine);
+  }
+}
+
+- (void)moveToLeftEndOfLineAndModifySelection:(id)sender {
+  // Command + Shift + LeftArrow in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectBeginLine);
+  }
+}
+
+- (void)moveUp:(id)sender {
+  // ArrowUp in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::LinePrevious);
+  }
+}
+
+- (void)moveUpAndModifySelection:(id)sender {
+  // Shift + ArrowUp in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectLinePrevious);
+  }
+}
+
+- (void)moveToBeginningOfDocument:(id)sender {
+  // Command + ArrowUp in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::MoveTop);
+  }
+}
+
+- (void)moveToBeginningOfDocumentAndModifySelection:(id)sender {
+  // Command + Shift + ArrowUp or Shift + Home in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectTop);
+  }
+}
+
+- (void)moveDown:(id)sender {
+  // ArrowDown in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::LineNext);
+  }
+}
+
+- (void)moveDownAndModifySelection:(id)sender {
+  // Shift + ArrowDown in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectLineNext);
+  }
+}
+
+- (void)moveToEndOfDocument:(id)sender {
+  // Command + ArrowDown in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::MoveBottom);
+  }
+}
+
+- (void)moveToEndOfDocumentAndModifySelection:(id)sender {
+  // Command + Shift + ArrowDown or Shift + End in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectBottom);
+  }
+}
+
+- (void)scrollPageUp:(id)sender {
+  // PageUp in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::ScrollPageUp);
+  }
+}
+
+- (void)pageUpAndModifySelection:(id)sender {
+  // Shift + PageUp in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectPageUp);
+  }
+}
+
+- (void)scrollPageDown:(id)sender {
+  // PageDown in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::ScrollPageDown);
+  }
+}
+
+- (void)pageDownAndModifySelection:(id)sender {
+  // Shift + PageDown in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::SelectPageDown);
+  }
+}
+
+- (void)scrollToEndOfDocument:(id)sender {
+  // End in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::ScrollBottom);
+  }
+}
+
+- (void)scrollToBeginningOfDocument:(id)sender {
+  // Home in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::ScrollTop);
+  }
+}
+
+// XXX Don't decleare nor implement calcelOperation: because it
+//     causes not calling keyDown: for Command + Period.
+//     We need to handle it from doCommandBySelector:.
+
+- (void)complete:(id)sender {
+  // Alt + Escape or Alt + Shift + Escape in the default settings.
+  if (mTextInputHandler) {
+    mTextInputHandler->HandleCommand(Command::Complete);
+  }
+}
+
+- (void)flagsChanged:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NS_ENSURE_TRUE(mGeckoChild, );
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+  mTextInputHandler->HandleFlagsChanged(theEvent);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (BOOL)isFirstResponder {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSResponder* resp = [[self window] firstResponder];
+  return (resp == (NSResponder*)self);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+- (BOOL)isDragInProgress {
+  if (!mDragService) return NO;
+
+  nsCOMPtr<nsIDragSession> dragSession;
+  mDragService->GetCurrentSession(getter_AddRefs(dragSession));
+  return dragSession != nullptr;
+}
+
+- (BOOL)inactiveWindowAcceptsMouseEvent:(NSEvent*)aEvent {
+  // If we're being destroyed assume the default -- return YES.
+  if (!mGeckoChild) return YES;
+
+  WidgetMouseEvent geckoEvent(true, eMouseActivate, mGeckoChild, WidgetMouseEvent::eReal);
+  [self convertCocoaMouseEvent:aEvent toGeckoEvent:&geckoEvent];
+  return (mGeckoChild->DispatchInputEvent(&geckoEvent).mContentStatus !=
+          nsEventStatus_eConsumeNoDefault);
+}
+
+// We must always call through to our superclass, even when mGeckoChild is
+// nil -- otherwise the keyboard focus can end up in the wrong NSView.
+- (BOOL)becomeFirstResponder {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [super becomeFirstResponder];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(YES);
+}
+
+- (void)viewsWindowDidBecomeKey {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mGeckoChild) return;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  // check to see if the window implements the mozWindow protocol. This
+  // allows embedders to avoid re-entrant calls to -makeKeyAndOrderFront,
+  // which can happen because these activate calls propagate out
+  // to the embedder via nsIEmbeddingSiteWindow::SetFocus().
+  BOOL isMozWindow = [[self window] respondsToSelector:@selector(setSuppressMakeKeyFront:)];
+  if (isMozWindow) [[self window] setSuppressMakeKeyFront:YES];
+
+  nsIWidgetListener* listener = mGeckoChild->GetWidgetListener();
+  if (listener) listener->WindowActivated();
+
+  if (isMozWindow) [[self window] setSuppressMakeKeyFront:NO];
+
+  if (mGeckoChild->GetInputContext().IsPasswordEditor()) {
+    TextInputHandler::EnableSecureEventInput();
+  } else {
+    TextInputHandler::EnsureSecureEventInputDisabled();
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)viewsWindowDidResignKey {
+  if (!mGeckoChild) return;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  nsIWidgetListener* listener = mGeckoChild->GetWidgetListener();
+  if (listener) listener->WindowDeactivated();
+
+  TextInputHandler::EnsureSecureEventInputDisabled();
+}
+
+// If the call to removeFromSuperview isn't delayed from nsChildView::
+// TearDownView(), the NSView hierarchy might get changed during calls to
+// [ChildView drawRect:], which leads to "beyond bounds" exceptions in
+// NSCFArray.  For more info see bmo bug 373122.  Apple's docs claim that
+// removeFromSuperviewWithoutNeedingDisplay "can be safely invoked during
+// display" (whatever "display" means).  But it's _not_ true that it can be
+// safely invoked during calls to [NSView drawRect:].  We use
+// removeFromSuperview here because there's no longer any danger of being
+// "invoked during display", and because doing do clears up bmo bug 384343.
+- (void)delayedTearDown {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [self removeFromSuperview];
+  [self release];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+#pragma mark -
+
+// drag'n'drop stuff
+#define kDragServiceContractID "@mozilla.org/widget/dragservice;1"
+
+- (NSDragOperation)dragOperationFromDragAction:(int32_t)aDragAction {
+  if (nsIDragService::DRAGDROP_ACTION_LINK & aDragAction) return NSDragOperationLink;
+  if (nsIDragService::DRAGDROP_ACTION_COPY & aDragAction) return NSDragOperationCopy;
+  if (nsIDragService::DRAGDROP_ACTION_MOVE & aDragAction) return NSDragOperationGeneric;
+  return NSDragOperationNone;
+}
+
+- (LayoutDeviceIntPoint)convertWindowCoordinates:(NSPoint)aPoint {
+  if (!mGeckoChild) {
+    return LayoutDeviceIntPoint(0, 0);
+  }
+
+  NSPoint localPoint = [self convertPoint:aPoint fromView:nil];
+  return mGeckoChild->CocoaPointsToDevPixels(localPoint);
+}
+
+- (LayoutDeviceIntPoint)convertWindowCoordinatesRoundDown:(NSPoint)aPoint {
+  if (!mGeckoChild) {
+    return LayoutDeviceIntPoint(0, 0);
+  }
+
+  NSPoint localPoint = [self convertPoint:aPoint fromView:nil];
+  return mGeckoChild->CocoaPointsToDevPixelsRoundDown(localPoint);
+}
+
+// This is a utility function used by NSView drag event methods
+// to send events. It contains all of the logic needed for Gecko
+// dragging to work. Returns the appropriate cocoa drag operation code.
+- (NSDragOperation)doDragAction:(EventMessage)aMessage sender:(id)aSender {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mGeckoChild) return NSDragOperationNone;
+
+  MOZ_LOG(sCocoaLog, LogLevel::Info, ("ChildView doDragAction: entered\n"));
+
+  if (!mDragService) {
+    CallGetService(kDragServiceContractID, &mDragService);
+    NS_ASSERTION(mDragService, "Couldn't get a drag service - big problem!");
+    if (!mDragService) return NSDragOperationNone;
+  }
+
+  if (aMessage == eDragEnter) {
+    mDragService->StartDragSession();
+  }
+
+  nsCOMPtr<nsIDragSession> dragSession;
+  mDragService->GetCurrentSession(getter_AddRefs(dragSession));
+  if (dragSession) {
+    if (aMessage == eDragOver) {
+      // fire the drag event at the source. Just ignore whether it was
+      // cancelled or not as there isn't actually a means to stop the drag
+      nsCOMPtr<nsIDragService> dragService = mDragService;
+      dragService->FireDragEventAtSource(eDrag,
+                                         nsCocoaUtils::ModifiersForEvent([NSApp currentEvent]));
+      dragSession->SetCanDrop(false);
+    } else if (aMessage == eDrop) {
+      // We make the assumption that the dragOver handlers have correctly set
+      // the |canDrop| property of the Drag Session.
+      bool canDrop = false;
+      if (!NS_SUCCEEDED(dragSession->GetCanDrop(&canDrop)) || !canDrop) {
+        [self doDragAction:eDragExit sender:aSender];
+
+        nsCOMPtr<nsINode> sourceNode;
+        dragSession->GetSourceNode(getter_AddRefs(sourceNode));
+        if (!sourceNode) {
+          nsCOMPtr<nsIDragService> dragService = mDragService;
+          dragService->EndDragSession(false, nsCocoaUtils::ModifiersForEvent([NSApp currentEvent]));
+        }
+        return NSDragOperationNone;
+      }
+    }
+
+    unsigned int modifierFlags = [[NSApp currentEvent] modifierFlags];
+    uint32_t action = nsIDragService::DRAGDROP_ACTION_MOVE;
+    // force copy = option, alias = cmd-option, default is move
+    if (modifierFlags & NSEventModifierFlagOption) {
+      if (modifierFlags & NSEventModifierFlagCommand)
+        action = nsIDragService::DRAGDROP_ACTION_LINK;
+      else
+        action = nsIDragService::DRAGDROP_ACTION_COPY;
+    }
+    dragSession->SetDragAction(action);
+  }
+
+  // set up gecko event
+  WidgetDragEvent geckoEvent(true, aMessage, mGeckoChild);
+  nsCocoaUtils::InitInputEvent(geckoEvent, [NSApp currentEvent]);
+
+  // Use our own coordinates in the gecko event.
+  // Convert event from gecko global coords to gecko view coords.
+  NSPoint draggingLoc = [aSender draggingLocation];
+
+  geckoEvent.mRefPoint = [self convertWindowCoordinates:draggingLoc];
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+  mGeckoChild->DispatchInputEvent(&geckoEvent);
+  if (!mGeckoChild) return NSDragOperationNone;
+
+  if (dragSession) {
+    switch (aMessage) {
+      case eDragEnter:
+      case eDragOver: {
+        uint32_t dragAction;
+        dragSession->GetDragAction(&dragAction);
+
+        // If TakeChildProcessDragAction returns something other than
+        // DRAGDROP_ACTION_UNINITIALIZED, it means that the last event was sent
+        // to the child process and this event is also being sent to the child
+        // process. In this case, use the last event's action instead.
+        nsDragService* dragService = static_cast<nsDragService*>(mDragService);
+        int32_t childDragAction = dragService->TakeChildProcessDragAction();
+        if (childDragAction != nsIDragService::DRAGDROP_ACTION_UNINITIALIZED) {
+          dragAction = childDragAction;
+        }
+
+        return [self dragOperationFromDragAction:dragAction];
+      }
+      case eDragExit:
+      case eDrop: {
+        nsCOMPtr<nsINode> sourceNode;
+        dragSession->GetSourceNode(getter_AddRefs(sourceNode));
+        if (!sourceNode) {
+          // We're leaving a window while doing a drag that was
+          // initiated in a different app. End the drag session,
+          // since we're done with it for now (until the user
+          // drags back into mozilla).
+          nsCOMPtr<nsIDragService> dragService = mDragService;
+          dragService->EndDragSession(false, nsCocoaUtils::ModifiersForEvent([NSApp currentEvent]));
+        }
+        break;
+      }
+      default:
+        break;
+    }
+  }
+
+  return NSDragOperationGeneric;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSDragOperationNone);
+}
+
+// NSDraggingDestination
+- (NSDragOperation)draggingEntered:(id<NSDraggingInfo>)sender {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_LOG(sCocoaLog, LogLevel::Info, ("ChildView draggingEntered: entered\n"));
+
+  // there should never be a globalDragPboard when "draggingEntered:" is
+  // called, but just in case we'll take care of it here.
+  [globalDragPboard release];
+
+  // Set the global drag pasteboard that will be used for this drag session.
+  // This will be set back to nil when the drag session ends (mouse exits
+  // the view or a drop happens within the view).
+  globalDragPboard = [[sender draggingPasteboard] retain];
+
+  return [self doDragAction:eDragEnter sender:sender];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSDragOperationNone);
+}
+
+// NSDraggingDestination
+- (NSDragOperation)draggingUpdated:(id<NSDraggingInfo>)sender {
+  MOZ_LOG(sCocoaLog, LogLevel::Info, ("ChildView draggingUpdated: entered\n"));
+  return [self doDragAction:eDragOver sender:sender];
+}
+
+// NSDraggingDestination
+- (void)draggingExited:(id<NSDraggingInfo>)sender {
+  MOZ_LOG(sCocoaLog, LogLevel::Info, ("ChildView draggingExited: entered\n"));
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+  [self doDragAction:eDragExit sender:sender];
+  NS_IF_RELEASE(mDragService);
+}
+
+// NSDraggingDestination
+- (BOOL)performDragOperation:(id<NSDraggingInfo>)sender {
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+  BOOL handled = [self doDragAction:eDrop sender:sender] != NSDragOperationNone;
+  NS_IF_RELEASE(mDragService);
+  return handled;
+}
+
+// NSDraggingSource
+// This is just implemented so we comply with the NSDraggingSource protocol.
+- (NSDragOperation)draggingSession:(NSDraggingSession*)session
+    sourceOperationMaskForDraggingContext:(NSDraggingContext)context {
+  return UINT_MAX;
+}
+
+// NSDraggingSource
+- (BOOL)ignoreModifierKeysForDraggingSession:(NSDraggingSession*)session {
+  return YES;
+}
+
+// NSDraggingSource
+- (void)draggingSession:(NSDraggingSession*)aSession
+           endedAtPoint:(NSPoint)aPoint
+              operation:(NSDragOperation)aOperation {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+#ifdef NIGHTLY_BUILD
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+#endif
+
+  gDraggedTransferables = nullptr;
+
+  NSEvent* currentEvent = [NSApp currentEvent];
+  gUserCancelledDrag =
+      ([currentEvent type] == NSEventTypeKeyDown && [currentEvent keyCode] == kVK_Escape);
+
+  if (!mDragService) {
+    CallGetService(kDragServiceContractID, &mDragService);
+    NS_ASSERTION(mDragService, "Couldn't get a drag service - big problem!");
+  }
+
+  if (mDragService) {
+    RefPtr<nsDragService> dragService = static_cast<nsDragService*>(mDragService);
+
+    // Set the dragend point from the current mouse location
+    // FIXME(emilio): Weird that we wouldn't use aPoint instead? Seems to work
+    // locally as well...
+    // NSPoint pnt = aPoint;
+    NSPoint pnt = [NSEvent mouseLocation];
+    NSPoint locationInWindow = nsCocoaUtils::ConvertPointFromScreen([self window], pnt);
+    FlipCocoaScreenCoordinate(pnt);
+    dragService->SetDragEndPoint([self convertWindowCoordinates:locationInWindow]);
+
+    // XXX: dropEffect should be updated per |aOperation|.
+    // As things stand though, |aOperation| isn't well handled within "our"
+    // events, that is, when the drop happens within the window: it is set
+    // either to NSDragOperationGeneric or to NSDragOperationNone.
+    // For that reason, it's not yet possible to override dropEffect per the
+    // given OS value, and it's also unclear what's the correct dropEffect
+    // value for NSDragOperationGeneric that is passed by other applications.
+    // All that said, NSDragOperationNone is still reliable.
+    if (aOperation == NSDragOperationNone) {
+      RefPtr<dom::DataTransfer> dataTransfer = dragService->GetDataTransfer();
+      if (dataTransfer) {
+        dataTransfer->SetDropEffectInt(nsIDragService::DRAGDROP_ACTION_NONE);
+      }
+    }
+
+    dragService->EndDragSession(true, nsCocoaUtils::ModifiersForEvent(currentEvent));
+    NS_RELEASE(mDragService);
+  }
+
+  [globalDragPboard release];
+  globalDragPboard = nil;
+  [gLastDragMouseDownEvent release];
+  gLastDragMouseDownEvent = nil;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// NSDraggingSource
+- (void)draggingSession:(NSDraggingSession*)aSession movedToPoint:(NSPoint)aPoint {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Get the drag service if it isn't already cached. The drag service
+  // isn't cached when dragging over a different application.
+  nsCOMPtr<nsIDragService> dragService = mDragService;
+  if (!dragService) {
+    dragService = do_GetService(kDragServiceContractID);
+  }
+
+  if (dragService) {
+    nsDragService* ds = static_cast<nsDragService*>(dragService.get());
+    ds->DragMovedWithView(aSession, aPoint);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// NSDraggingSource
+- (void)draggingSession:(NSDraggingSession*)aSession willBeginAtPoint:(NSPoint)aPoint {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // there should never be a globalDragPboard when "willBeginAtPoint:" is
+  // called, but just in case we'll take care of it here.
+  [globalDragPboard release];
+
+  // Set the global drag pasteboard that will be used for this drag session.
+  // This will be set back to nil when the drag session ends (mouse exits
+  // the view or a drop happens within the view).
+  globalDragPboard = [[aSession draggingPasteboard] retain];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Get the paste location from the low level pasteboard.
+static CFTypeRefPtr<CFURLRef> GetPasteLocation(NSPasteboard* aPasteboard) {
+  PasteboardRef pboardRef = nullptr;
+  PasteboardCreate((CFStringRef)[aPasteboard name], &pboardRef);
+  if (!pboardRef) {
+    return nullptr;
+  }
+
+  auto pasteBoard = CFTypeRefPtr<PasteboardRef>::WrapUnderCreateRule(pboardRef);
+  PasteboardSynchronize(pasteBoard.get());
+
+  CFURLRef urlRef = nullptr;
+  PasteboardCopyPasteLocation(pasteBoard.get(), &urlRef);
+  return CFTypeRefPtr<CFURLRef>::WrapUnderCreateRule(urlRef);
+}
+
+// NSPasteboardItemDataProvider
+- (void)pasteboard:(NSPasteboard*)aPasteboard
+                  item:(NSPasteboardItem*)aItem
+    provideDataForType:(NSString*)aType {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+#ifdef NIGHTLY_BUILD
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+#endif
+
+  if (!gDraggedTransferables) {
+    return;
+  }
+
+  uint32_t count = 0;
+  gDraggedTransferables->GetLength(&count);
+
+  for (uint32_t j = 0; j < count; j++) {
+    nsCOMPtr<nsITransferable> currentTransferable = do_QueryElementAt(gDraggedTransferables, j);
+    if (!currentTransferable) {
+      return;
+    }
+
+    // Transform the transferable to an NSDictionary.
+    NSDictionary* pasteboardOutputDict =
+        nsClipboard::PasteboardDictFromTransferable(currentTransferable);
+    if (!pasteboardOutputDict) {
+      return;
+    }
+
+    // Write everything out to the pasteboard.
+    unsigned int typeCount = [pasteboardOutputDict count];
+    NSMutableArray* types = [NSMutableArray arrayWithCapacity:typeCount + 1];
+    [types addObjectsFromArray:[pasteboardOutputDict allKeys]];
+    [types addObject:[UTIHelper stringFromPboardType:kMozWildcardPboardType]];
+    for (unsigned int k = 0; k < typeCount; k++) {
+      NSString* curType = [types objectAtIndex:k];
+      if ([curType isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeString]] ||
+          [curType isEqualToString:[UTIHelper stringFromPboardType:kPublicUrlPboardType]] ||
+          [curType isEqualToString:[UTIHelper stringFromPboardType:kPublicUrlNamePboardType]] ||
+          [curType isEqualToString:[UTIHelper stringFromPboardType:(NSString*)kUTTypeFileURL]]) {
+        [aPasteboard setString:[pasteboardOutputDict valueForKey:curType] forType:curType];
+      } else if ([curType
+                     isEqualToString:[UTIHelper stringFromPboardType:kUrlsWithTitlesPboardType]]) {
+        [aPasteboard setPropertyList:[pasteboardOutputDict valueForKey:curType] forType:curType];
+      } else if ([curType isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeHTML]]) {
+        [aPasteboard setString:(nsClipboard::WrapHtmlForSystemPasteboard(
+                                   [pasteboardOutputDict valueForKey:curType]))
+                       forType:curType];
+      } else if ([curType isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeTIFF]] ||
+                 [curType
+                     isEqualToString:[UTIHelper stringFromPboardType:kMozCustomTypesPboardType]]) {
+        [aPasteboard setData:[pasteboardOutputDict valueForKey:curType] forType:curType];
+      } else if ([curType
+                     isEqualToString:[UTIHelper stringFromPboardType:kMozFileUrlsPboardType]]) {
+        [aPasteboard writeObjects:[pasteboardOutputDict valueForKey:curType]];
+      } else if ([curType
+                     isEqualToString:[UTIHelper
+                                         stringFromPboardType:(NSString*)
+                                                                  kPasteboardTypeFileURLPromise]]) {
+        nsCOMPtr<nsIFile> targFile;
+        NS_NewLocalFile(u""_ns, true, getter_AddRefs(targFile));
+        nsCOMPtr<nsILocalFileMac> macLocalFile = do_QueryInterface(targFile);
+        if (!macLocalFile) {
+          NS_ERROR("No Mac local file");
+          continue;
+        }
+
+        CFTypeRefPtr<CFURLRef> url = GetPasteLocation(aPasteboard);
+        if (!url) {
+          continue;
+        }
+
+        if (!NS_SUCCEEDED(macLocalFile->InitWithCFURL(url.get()))) {
+          NS_ERROR("failed InitWithCFURL");
+          continue;
+        }
+
+        if (!gDraggedTransferables) {
+          continue;
+        }
+
+        uint32_t transferableCount;
+        nsresult rv = gDraggedTransferables->GetLength(&transferableCount);
+        if (NS_FAILED(rv)) {
+          continue;
+        }
+
+        for (uint32_t i = 0; i < transferableCount; i++) {
+          nsCOMPtr<nsITransferable> item = do_QueryElementAt(gDraggedTransferables, i);
+          if (!item) {
+            NS_ERROR("no transferable");
+            continue;
+          }
+
+          item->SetTransferData(kFilePromiseDirectoryMime, macLocalFile);
+
+          // Now request the kFilePromiseMime data, which will invoke the data
+          // provider. If successful, the file will have been created.
+          nsCOMPtr<nsISupports> fileDataPrimitive;
+          Unused << item->GetTransferData(kFilePromiseMime, getter_AddRefs(fileDataPrimitive));
+        }
+
+        [aPasteboard setPropertyList:[pasteboardOutputDict valueForKey:curType] forType:curType];
+      }
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+#pragma mark -
+
+// Support for the "Services" menu. We currently only support sending strings
+// and HTML to system services.
+// This method can be called on any thread (see bug 1751687). We can only usefully
+// handle it on the main thread.
+- (id)validRequestorForSendType:(NSString*)sendType returnType:(NSString*)returnType {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!NS_IsMainThread()) {
+    // We don't have any thread-safe ways of checking whether we can send
+    // or receive content. Just say no. In normal cases, we expect this
+    // method to be called on the main thread.
+    return [super validRequestorForSendType:sendType returnType:returnType];
+  }
+
+  // sendType contains the type of data that the service would like this
+  // application to send to it.  sendType is nil if the service is not
+  // requesting any data.
+  //
+  // returnType contains the type of data the the service would like to
+  // return to this application (e.g., to overwrite the selection).
+  // returnType is nil if the service will not return any data.
+  //
+  // The following condition thus triggers when the service expects a string
+  // or HTML from us or no data at all AND when the service will either not
+  // send back any data to us or will send a string or HTML back to us.
+
+  id result = nil;
+
+  NSString* stringType = [UTIHelper stringFromPboardType:NSPasteboardTypeString];
+  NSString* htmlType = [UTIHelper stringFromPboardType:NSPasteboardTypeHTML];
+  if ((!sendType || [sendType isEqualToString:stringType] || [sendType isEqualToString:htmlType]) &&
+      (!returnType || [returnType isEqualToString:stringType] ||
+       [returnType isEqualToString:htmlType])) {
+    if (mGeckoChild) {
+      // Assume that this object will be able to handle this request.
+      result = self;
+
+      // Keep the ChildView alive during this operation.
+      nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+      if (sendType) {
+        // Determine if there is a current selection (chrome/content).
+        if (!nsClipboard::sSelectionCache) {
+          result = nil;
+        }
+      }
+
+      // Determine if we can paste (if receiving data from the service).
+      if (mGeckoChild && returnType) {
+        WidgetContentCommandEvent command(true, eContentCommandPasteTransferable, mGeckoChild,
+                                          true);
+        // This might possibly destroy our widget (and null out mGeckoChild).
+        mGeckoChild->DispatchWindowEvent(command);
+        if (!mGeckoChild || !command.mSucceeded || !command.mIsEnabled) result = nil;
+      }
+    }
+  }
+
+  // Give the superclass a chance if this object will not handle this request.
+  if (!result) result = [super validRequestorForSendType:sendType returnType:returnType];
+
+  return result;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (BOOL)writeSelectionToPasteboard:(NSPasteboard*)pboard types:(NSArray*)types {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+
+  // Make sure that the service will accept strings or HTML.
+  if (![types containsObject:[UTIHelper stringFromPboardType:NSStringPboardType]] &&
+      ![types containsObject:[UTIHelper stringFromPboardType:NSPasteboardTypeString]] &&
+      ![types containsObject:[UTIHelper stringFromPboardType:NSPasteboardTypeHTML]]) {
+    return NO;
+  }
+
+  // Bail out if there is no Gecko object.
+  if (!mGeckoChild) return NO;
+
+  // Transform the transferable to an NSDictionary.
+  NSDictionary* pasteboardOutputDict = nullptr;
+
+  pasteboardOutputDict = nsClipboard::PasteboardDictFromTransferable(nsClipboard::sSelectionCache);
+
+  if (!pasteboardOutputDict) return NO;
+
+  // Declare the pasteboard types.
+  unsigned int typeCount = [pasteboardOutputDict count];
+  NSMutableArray* declaredTypes = [NSMutableArray arrayWithCapacity:typeCount];
+  [declaredTypes addObjectsFromArray:[pasteboardOutputDict allKeys]];
+  [pboard declareTypes:declaredTypes owner:nil];
+
+  // Write the data to the pasteboard.
+  for (unsigned int i = 0; i < typeCount; i++) {
+    NSString* currentKey = [declaredTypes objectAtIndex:i];
+    id currentValue = [pasteboardOutputDict valueForKey:currentKey];
+
+    if ([currentKey isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeString]] ||
+        [currentKey isEqualToString:[UTIHelper stringFromPboardType:kPublicUrlPboardType]] ||
+        [currentKey isEqualToString:[UTIHelper stringFromPboardType:kPublicUrlNamePboardType]]) {
+      [pboard setString:currentValue forType:currentKey];
+    } else if ([currentKey isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeHTML]]) {
+      [pboard setString:(nsClipboard::WrapHtmlForSystemPasteboard(currentValue))
+                forType:currentKey];
+    } else if ([currentKey isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeTIFF]]) {
+      [pboard setData:currentValue forType:currentKey];
+    } else if ([currentKey
+                   isEqualToString:[UTIHelper
+                                       stringFromPboardType:(NSString*)
+                                                                kPasteboardTypeFileURLPromise]] ||
+               [currentKey
+                   isEqualToString:[UTIHelper stringFromPboardType:kUrlsWithTitlesPboardType]]) {
+      [pboard setPropertyList:currentValue forType:currentKey];
+    }
+  }
+  return YES;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+// Called if the service wants us to replace the current selection.
+- (BOOL)readSelectionFromPasteboard:(NSPasteboard*)pboard {
+  nsresult rv;
+  nsCOMPtr<nsITransferable> trans = do_CreateInstance("@mozilla.org/widget/transferable;1", &rv);
+  if (NS_FAILED(rv)) return NO;
+  trans->Init(nullptr);
+
+  trans->AddDataFlavor(kTextMime);
+  trans->AddDataFlavor(kHTMLMime);
+
+  rv = nsClipboard::TransferableFromPasteboard(trans, pboard);
+  if (NS_FAILED(rv)) return NO;
+
+  NS_ENSURE_TRUE(mGeckoChild, false);
+
+  WidgetContentCommandEvent command(true, eContentCommandPasteTransferable, mGeckoChild);
+  command.mTransferable = trans;
+  mGeckoChild->DispatchWindowEvent(command);
+
+  return command.mSucceeded && command.mIsEnabled;
+}
+
+- (void)pressureChangeWithEvent:(NSEvent*)event {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK
+
+  NSInteger stage = [event stage];
+  if (mLastPressureStage == 1 && stage == 2) {
+    NSUserDefaults* userDefaults = [NSUserDefaults standardUserDefaults];
+    if ([userDefaults integerForKey:@"com.apple.trackpad.forceClick"] == 1) {
+      // This is no public API to get configuration for current force click.
+      // This is filed as radar 29294285.
+      [self quickLookWithEvent:event];
+    }
+  }
+  mLastPressureStage = stage;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK
+}
+
+nsresult nsChildView::GetSelectionAsPlaintext(nsAString& aResult) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!nsClipboard::sSelectionCache) {
+    MOZ_ASSERT(aResult.IsEmpty());
+    return NS_OK;
+  }
+
+  // Get the current chrome or content selection.
+  NSDictionary* pasteboardOutputDict = nullptr;
+  pasteboardOutputDict = nsClipboard::PasteboardDictFromTransferable(nsClipboard::sSelectionCache);
+
+  if (NS_WARN_IF(!pasteboardOutputDict)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Declare the pasteboard types.
+  unsigned int typeCount = [pasteboardOutputDict count];
+  NSMutableArray* declaredTypes = [NSMutableArray arrayWithCapacity:typeCount];
+  [declaredTypes addObjectsFromArray:[pasteboardOutputDict allKeys]];
+  NSString* currentKey = [declaredTypes objectAtIndex:0];
+  NSString* currentValue = [pasteboardOutputDict valueForKey:currentKey];
+  const char* textSelection = [currentValue UTF8String];
+  aResult = NS_ConvertUTF8toUTF16(textSelection);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+#ifdef DEBUG
+nsresult nsChildView::SetHiDPIMode(bool aHiDPI) {
+  nsCocoaUtils::InvalidateHiDPIState();
+  Preferences::SetInt("gfx.hidpi.enabled", aHiDPI ? 1 : 0);
+  BackingScaleFactorChanged();
+  return NS_OK;
+}
+
+nsresult nsChildView::RestoreHiDPIMode() {
+  nsCocoaUtils::InvalidateHiDPIState();
+  Preferences::ClearUser("gfx.hidpi.enabled");
+  BackingScaleFactorChanged();
+  return NS_OK;
+}
+#endif
+
+#pragma mark -
+
+#ifdef ACCESSIBILITY
+
+/* Every ChildView has a corresponding mozDocAccessible object that is doing all
+   the heavy lifting. The topmost ChildView corresponds to a mozRootAccessible
+   object.
+
+   All ChildView needs to do is to route all accessibility calls (from the NSAccessibility APIs)
+   down to its object, pretending that they are the same.
+*/
+- (id<mozAccessible>)accessible {
+  if (!mGeckoChild) return nil;
+
+  id<mozAccessible> nativeAccessible = nil;
+
+  nsAutoRetainCocoaObject kungFuDeathGrip(self);
+  RefPtr<nsChildView> geckoChild(mGeckoChild);
+  RefPtr<a11y::LocalAccessible> accessible = geckoChild->GetDocumentAccessible();
+  if (!accessible) return nil;
+
+  accessible->GetNativeInterface((void**)&nativeAccessible);
+
+#  ifdef DEBUG_hakan
+  NSAssert(![nativeAccessible isExpired], @"native acc is expired!!!");
+#  endif
+
+  return nativeAccessible;
+}
+
+/* Implementation of formal mozAccessible formal protocol (enabling mozViews
+   to talk to mozAccessible objects in the accessibility module). */
+
+- (BOOL)hasRepresentedView {
+  return YES;
+}
+
+- (id)representedView {
+  return self;
+}
+
+- (BOOL)isRoot {
+  return [[self accessible] isRoot];
+}
+
+#  pragma mark -
+
+// general
+
+- (BOOL)isAccessibilityElement {
+  if (!mozilla::a11y::ShouldA11yBeEnabled()) return [super isAccessibilityElement];
+
+  return [[self accessible] isAccessibilityElement];
+}
+
+- (id)accessibilityHitTest:(NSPoint)point {
+  if (!mozilla::a11y::ShouldA11yBeEnabled()) return [super accessibilityHitTest:point];
+
+  return [[self accessible] accessibilityHitTest:point];
+}
+
+- (id)accessibilityFocusedUIElement {
+  if (!mozilla::a11y::ShouldA11yBeEnabled()) return [super accessibilityFocusedUIElement];
+
+  return [[self accessible] accessibilityFocusedUIElement];
+}
+
+// actions
+
+- (NSArray*)accessibilityActionNames {
+  if (!mozilla::a11y::ShouldA11yBeEnabled()) return [super accessibilityActionNames];
+
+  return [[self accessible] accessibilityActionNames];
+}
+
+- (NSString*)accessibilityActionDescription:(NSString*)action {
+  if (!mozilla::a11y::ShouldA11yBeEnabled()) return [super accessibilityActionDescription:action];
+
+  return [[self accessible] accessibilityActionDescription:action];
+}
+
+- (void)accessibilityPerformAction:(NSString*)action {
+  if (!mozilla::a11y::ShouldA11yBeEnabled()) return [super accessibilityPerformAction:action];
+
+  return [[self accessible] accessibilityPerformAction:action];
+}
+
+// attributes
+
+- (NSArray*)accessibilityAttributeNames {
+  if (!mozilla::a11y::ShouldA11yBeEnabled()) return [super accessibilityAttributeNames];
+
+  return [[self accessible] accessibilityAttributeNames];
+}
+
+- (BOOL)accessibilityIsAttributeSettable:(NSString*)attribute {
+  if (!mozilla::a11y::ShouldA11yBeEnabled())
+    return [super accessibilityIsAttributeSettable:attribute];
+
+  return [[self accessible] accessibilityIsAttributeSettable:attribute];
+}
+
+- (id)accessibilityAttributeValue:(NSString*)attribute {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mozilla::a11y::ShouldA11yBeEnabled()) return [super accessibilityAttributeValue:attribute];
+
+  id<mozAccessible> accessible = [self accessible];
+
+  // if we're the root (topmost) accessible, we need to return our native AXParent as we
+  // traverse outside to the hierarchy of whoever embeds us. thus, fall back on NSView's
+  // default implementation for this attribute.
+  if ([attribute isEqualToString:NSAccessibilityParentAttribute] && [accessible isRoot]) {
+    id parentAccessible = [super accessibilityAttributeValue:attribute];
+    return parentAccessible;
+  }
+
+  return [accessible accessibilityAttributeValue:attribute];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+#endif /* ACCESSIBILITY */
+
++ (uint32_t)sUniqueKeyEventId {
+  return sUniqueKeyEventId;
+}
+
++ (NSMutableDictionary*)sNativeKeyEventsMap {
+  // This dictionary is "leaked".
+  static NSMutableDictionary* sNativeKeyEventsMap = [[NSMutableDictionary alloc] init];
+  return sNativeKeyEventsMap;
+}
+
+@end
+
+@implementation PixelHostingView
+
+- (id)initWithFrame:(NSRect)aRect {
+  self = [super initWithFrame:aRect];
+
+  self.wantsLayer = YES;
+  self.layerContentsRedrawPolicy = NSViewLayerContentsRedrawDuringViewResize;
+
+  return self;
+}
+
+- (BOOL)isFlipped {
+  return YES;
+}
+
+- (NSView*)hitTest:(NSPoint)aPoint {
+  return nil;
+}
+
+- (void)drawRect:(NSRect)aRect {
+  NS_WARNING("Unexpected call to drawRect: This view returns YES from wantsUpdateLayer, so "
+             "drawRect should not be called.");
+}
+
+- (BOOL)wantsUpdateLayer {
+  return YES;
+}
+
+- (void)updateLayer {
+  [(ChildView*)[self superview] updateRootCALayer];
+}
+
+- (BOOL)wantsBestResolutionOpenGLSurface {
+  return nsCocoaUtils::HiDPIEnabled() ? YES : NO;
+}
+
+@end
+
+#pragma mark -
+
+void ChildViewMouseTracker::OnDestroyView(ChildView* aView) {
+  if (sLastMouseEventView == aView) {
+    sLastMouseEventView = nil;
+    [sLastMouseMoveEvent release];
+    sLastMouseMoveEvent = nil;
+  }
+}
+
+void ChildViewMouseTracker::OnDestroyWindow(NSWindow* aWindow) {
+  if (sWindowUnderMouse == aWindow) {
+    sWindowUnderMouse = nil;
+  }
+}
+
+void ChildViewMouseTracker::MouseEnteredWindow(NSEvent* aEvent) {
+  sWindowUnderMouse = [aEvent window];
+  ReEvaluateMouseEnterState(aEvent);
+}
+
+void ChildViewMouseTracker::MouseExitedWindow(NSEvent* aEvent) {
+  if (sWindowUnderMouse == [aEvent window]) {
+    sWindowUnderMouse = nil;
+    [sLastMouseMoveEvent release];
+    sLastMouseMoveEvent = nil;
+    ReEvaluateMouseEnterState(aEvent);
+  }
+}
+
+void ChildViewMouseTracker::NativeMenuOpened() {
+  // Send a mouse exit event now.
+  // The menu consumes all mouse events while it's open, and we don't want to be stuck thinking the
+  // mouse is still hovering our window after the mouse has already moved. This could result in
+  // unintended cursor changes or tooltips.
+  sWindowUnderMouse = nil;
+  ReEvaluateMouseEnterState(nil);
+}
+
+void ChildViewMouseTracker::NativeMenuClosed() {
+  // If a window was hovered before the menu opened, re-enter that window at the last known mouse
+  // position.
+  // After -[NSView didCloseMenu:withEvent:] is called, any NSTrackingArea updates that were
+  // buffered while the menu was open will be replayed.
+  if (sLastMouseMoveEvent) {
+    sWindowUnderMouse = sLastMouseMoveEvent.window;
+    ReEvaluateMouseEnterState(sLastMouseMoveEvent);
+  }
+}
+
+void ChildViewMouseTracker::ReEvaluateMouseEnterState(NSEvent* aEvent, ChildView* aOldView) {
+  ChildView* oldView = aOldView ? aOldView : sLastMouseEventView;
+  sLastMouseEventView = ViewForEvent(aEvent);
+  if (sLastMouseEventView != oldView) {
+    // Send enter and / or exit events.
+    WidgetMouseEvent::ExitFrom exitFrom = [sLastMouseEventView window] == [oldView window]
+                                              ? WidgetMouseEvent::ePlatformChild
+                                              : WidgetMouseEvent::ePlatformTopLevel;
+    [oldView sendMouseEnterOrExitEvent:aEvent enter:NO exitFrom:exitFrom];
+    // After the cursor exits the window set it to a visible regular arrow cursor.
+    if (exitFrom == WidgetMouseEvent::ePlatformTopLevel) {
+      [[nsCursorManager sharedInstance] setNonCustomCursor:nsIWidget::Cursor{eCursor_standard}];
+    }
+    [sLastMouseEventView sendMouseEnterOrExitEvent:aEvent enter:YES exitFrom:exitFrom];
+  }
+}
+
+void ChildViewMouseTracker::ResendLastMouseMoveEvent() {
+  if (sLastMouseMoveEvent) {
+    MouseMoved(sLastMouseMoveEvent);
+  }
+}
+
+void ChildViewMouseTracker::MouseMoved(NSEvent* aEvent) {
+  MouseEnteredWindow(aEvent);
+  [sLastMouseEventView handleMouseMoved:aEvent];
+  if (sLastMouseMoveEvent != aEvent) {
+    [sLastMouseMoveEvent release];
+    sLastMouseMoveEvent = [aEvent retain];
+  }
+}
+
+void ChildViewMouseTracker::MouseScrolled(NSEvent* aEvent) {
+  if (!nsCocoaUtils::IsMomentumScrollEvent(aEvent)) {
+    // Store the position so we can pin future momentum scroll events.
+    sLastScrollEventScreenLocation = nsCocoaUtils::ScreenLocationForEvent(aEvent);
+  }
+}
+
+ChildView* ChildViewMouseTracker::ViewForEvent(NSEvent* aEvent) {
+  NSWindow* window = sWindowUnderMouse;
+  if (!window) return nil;
+
+  NSPoint windowEventLocation = nsCocoaUtils::EventLocationForWindow(aEvent, window);
+  NSView* view = [[[window contentView] superview] hitTest:windowEventLocation];
+
+  if (![view isKindOfClass:[ChildView class]]) return nil;
+
+  ChildView* childView = (ChildView*)view;
+  // If childView is being destroyed return nil.
+  if (![childView widget]) return nil;
+  return WindowAcceptsEvent(window, aEvent, childView) ? childView : nil;
+}
+
+BOOL ChildViewMouseTracker::WindowAcceptsEvent(NSWindow* aWindow, NSEvent* aEvent, ChildView* aView,
+                                               BOOL aIsClickThrough) {
+  // Right mouse down events may get through to all windows, even to a top level
+  // window with an open sheet.
+  if (!aWindow || [aEvent type] == NSEventTypeRightMouseDown) return YES;
+
+  id delegate = [aWindow delegate];
+  if (!delegate || ![delegate isKindOfClass:[WindowDelegate class]]) return YES;
+
+  nsIWidget* windowWidget = [(WindowDelegate*)delegate geckoWidget];
+  if (!windowWidget) return YES;
+
+  NSWindow* topLevelWindow = nil;
+
+  switch (windowWidget->GetWindowType()) {
+    case WindowType::Popup:
+      // If this is a context menu, it won't have a parent. So we'll always
+      // accept mouse move events on context menus even when none of our windows
+      // is active, which is the right thing to do.
+      // For panels, the parent window is the XUL window that owns the panel.
+      return WindowAcceptsEvent([aWindow parentWindow], aEvent, aView, aIsClickThrough);
+
+    case WindowType::TopLevel:
+    case WindowType::Dialog:
+      if ([aWindow attachedSheet]) return NO;
+
+      topLevelWindow = aWindow;
+      break;
+    case WindowType::Sheet: {
+      nsIWidget* parentWidget = windowWidget->GetSheetWindowParent();
+      if (!parentWidget) return YES;
+
+      topLevelWindow = (NSWindow*)parentWidget->GetNativeData(NS_NATIVE_WINDOW);
+      break;
+    }
+
+    default:
+      return YES;
+  }
+
+  if (!topLevelWindow || ([topLevelWindow isMainWindow] && !aIsClickThrough) ||
+      [aEvent type] == NSEventTypeOtherMouseDown ||
+      (([aEvent modifierFlags] & NSEventModifierFlagCommand) != 0 &&
+       [aEvent type] != NSEventTypeMouseMoved))
+    return YES;
+
+  // If we're here then we're dealing with a left click or mouse move on an
+  // inactive window or something similar. Ask Gecko what to do.
+  return [aView inactiveWindowAcceptsMouseEvent:aEvent];
+}
+
+#pragma mark -
diff --git a/widget/cocoa/nsClipboard.h b/widget/cocoa/nsClipboard.h
new file mode 100644
index 0000000000..c838f531d0
--- /dev/null
+++ b/widget/cocoa/nsClipboard.h
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsClipboard_h_
+#define nsClipboard_h_
+
+#include "nsBaseClipboard.h"
+#include "nsCOMPtr.h"
+#include "nsIClipboard.h"
+#include "nsString.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/StaticPtr.h"
+
+#import <Cocoa/Cocoa.h>
+
+class nsITransferable;
+
+class nsClipboard : public nsBaseClipboard {
+ public:
+  nsClipboard();
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+  // nsIClipboard
+  NS_IMETHOD HasDataMatchingFlavors(const nsTArray<nsCString>& aFlavorList, int32_t aWhichClipboard,
+                                    bool* _retval) override;
+  NS_IMETHOD EmptyClipboard(int32_t aWhichClipboard) override;
+
+  // On macOS, cache the transferable of the current selection (chrome/content)
+  // in the parent process. This is needed for the services menu which
+  // requires synchronous access to the current selection.
+  static mozilla::StaticRefPtr<nsITransferable> sSelectionCache;
+
+  // Helper methods, used also by nsDragService
+  static NSDictionary* PasteboardDictFromTransferable(nsITransferable* aTransferable);
+  // aPasteboardType is being retained and needs to be released by the caller.
+  static bool IsStringType(const nsCString& aMIMEType, NSString** aPasteboardType);
+  static bool IsImageType(const nsACString& aMIMEType);
+  static NSString* WrapHtmlForSystemPasteboard(NSString* aString);
+  static nsresult TransferableFromPasteboard(nsITransferable* aTransferable, NSPasteboard* pboard);
+
+ protected:
+  // Implement the native clipboard behavior.
+  NS_IMETHOD SetNativeClipboardData(nsITransferable* aTransferable, nsIClipboardOwner* aOwner,
+                                    int32_t aWhichClipboard) override;
+  NS_IMETHOD GetNativeClipboardData(nsITransferable* aTransferable,
+                                    int32_t aWhichClipboard) override;
+  void ClearSelectionCache();
+  void SetSelectionCache(nsITransferable* aTransferable);
+
+ private:
+  virtual ~nsClipboard();
+
+  static mozilla::Maybe<uint32_t> FindIndexOfImageFlavor(const nsTArray<nsCString>& aMIMETypes);
+
+  int32_t mCachedClipboard = -1;
+  // Set to the native change count after any modification of the clipboard.
+  int32_t mChangeCount = 0;
+};
+
+#endif  // nsClipboard_h_
diff --git a/widget/cocoa/nsClipboard.mm b/widget/cocoa/nsClipboard.mm
new file mode 100644
index 0000000000..0d1c7c688b
--- /dev/null
+++ b/widget/cocoa/nsClipboard.mm
@@ -0,0 +1,776 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <algorithm>
+
+#include "mozilla/gfx/2D.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Unused.h"
+
+#include "gfxPlatform.h"
+#include "nsArrayUtils.h"
+#include "nsCOMPtr.h"
+#include "nsClipboard.h"
+#include "nsString.h"
+#include "nsISupportsPrimitives.h"
+#include "nsPrimitiveHelpers.h"
+#include "nsIFile.h"
+#include "nsStringStream.h"
+#include "nsEscape.h"
+#include "nsPrintfCString.h"
+#include "nsObjCExceptions.h"
+#include "imgIContainer.h"
+#include "nsCocoaUtils.h"
+
+using mozilla::LogLevel;
+using mozilla::gfx::DataSourceSurface;
+using mozilla::gfx::SourceSurface;
+
+mozilla::StaticRefPtr<nsITransferable> nsClipboard::sSelectionCache;
+
+nsClipboard::nsClipboard()
+    : nsBaseClipboard(mozilla::dom::ClipboardCapabilities(false /* supportsSelectionClipboard */,
+                                                          true /* supportsFindClipboard */,
+                                                          true /* supportsSelectionCache */)) {}
+
+nsClipboard::~nsClipboard() { ClearSelectionCache(); }
+
+NS_IMPL_ISUPPORTS_INHERITED0(nsClipboard, nsBaseClipboard)
+
+namespace {
+
+// We separate this into its own function because after an @try, all local
+// variables within that function get marked as volatile, and our C++ type
+// system doesn't like volatile things.
+static NSData* GetDataFromPasteboard(NSPasteboard* aPasteboard, NSString* aType) {
+  NSData* data = nil;
+  @try {
+    data = [aPasteboard dataForType:aType];
+  } @catch (NSException* e) {
+    NS_WARNING(
+        nsPrintfCString("Exception raised while getting data from the pasteboard: \"%s - %s\"",
+                        [[e name] UTF8String], [[e reason] UTF8String])
+            .get());
+    mozilla::Unused << e;
+  }
+  return data;
+}
+
+static NSPasteboard* GetPasteboard(int32_t aWhichClipboard) {
+  switch (aWhichClipboard) {
+    case nsIClipboard::kGlobalClipboard:
+      return [NSPasteboard generalPasteboard];
+    case nsIClipboard::kFindClipboard:
+      if (@available(macOS 10.13, *)) {
+        return [NSPasteboard pasteboardWithName:NSPasteboardNameFind];
+      }
+      return [NSPasteboard pasteboardWithName:NSFindPboard];
+    default:
+      return nil;
+  }
+}
+
+}  // namespace
+
+void nsClipboard::SetSelectionCache(nsITransferable* aTransferable) {
+  sSelectionCache = aTransferable;
+}
+
+void nsClipboard::ClearSelectionCache() { sSelectionCache = nullptr; }
+
+NS_IMETHODIMP
+nsClipboard::SetNativeClipboardData(nsITransferable* aTransferable, nsIClipboardOwner* aOwner,
+                                    int32_t aWhichClipboard) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_ASSERT(aTransferable);
+  MOZ_ASSERT(nsIClipboard::IsClipboardTypeSupported(aWhichClipboard));
+
+  if (aWhichClipboard == kSelectionCache) {
+    SetSelectionCache(aTransferable);
+    return NS_OK;
+  }
+
+  NSDictionary* pasteboardOutputDict = PasteboardDictFromTransferable(aTransferable);
+  if (!pasteboardOutputDict) return NS_ERROR_FAILURE;
+
+  unsigned int outputCount = [pasteboardOutputDict count];
+  NSArray* outputKeys = [pasteboardOutputDict allKeys];
+  NSPasteboard* cocoaPasteboard = GetPasteboard(aWhichClipboard);
+  MOZ_ASSERT(cocoaPasteboard);
+  if (aWhichClipboard == kFindClipboard) {
+    NSString* stringType = [UTIHelper stringFromPboardType:NSPasteboardTypeString];
+    [cocoaPasteboard declareTypes:[NSArray arrayWithObject:stringType] owner:nil];
+  } else {
+    // Write everything else out to the general pasteboard.
+    MOZ_ASSERT(aWhichClipboard == kGlobalClipboard);
+    [cocoaPasteboard declareTypes:outputKeys owner:nil];
+  }
+
+  for (unsigned int i = 0; i < outputCount; i++) {
+    NSString* currentKey = [outputKeys objectAtIndex:i];
+    id currentValue = [pasteboardOutputDict valueForKey:currentKey];
+    if (aWhichClipboard == kFindClipboard) {
+      if ([currentKey isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeString]]) {
+        [cocoaPasteboard setString:currentValue forType:currentKey];
+      }
+    } else {
+      if ([currentKey isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeString]] ||
+          [currentKey isEqualToString:[UTIHelper stringFromPboardType:kPublicUrlPboardType]] ||
+          [currentKey isEqualToString:[UTIHelper stringFromPboardType:kPublicUrlNamePboardType]]) {
+        [cocoaPasteboard setString:currentValue forType:currentKey];
+      } else if ([currentKey
+                     isEqualToString:[UTIHelper stringFromPboardType:kUrlsWithTitlesPboardType]]) {
+        [cocoaPasteboard setPropertyList:[pasteboardOutputDict valueForKey:currentKey]
+                                 forType:currentKey];
+      } else if ([currentKey
+                     isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeHTML]]) {
+        [cocoaPasteboard setString:(nsClipboard::WrapHtmlForSystemPasteboard(currentValue))
+                           forType:currentKey];
+      } else if ([currentKey
+                     isEqualToString:[UTIHelper stringFromPboardType:kMozFileUrlsPboardType]]) {
+        [cocoaPasteboard writeObjects:currentValue];
+      } else if ([currentKey
+                     isEqualToString:[UTIHelper stringFromPboardType:(NSString*)kUTTypeFileURL]]) {
+        [cocoaPasteboard setString:currentValue forType:currentKey];
+      } else {
+        [cocoaPasteboard setData:currentValue forType:currentKey];
+      }
+    }
+  }
+
+  mCachedClipboard = aWhichClipboard;
+  mChangeCount = [cocoaPasteboard changeCount];
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsClipboard::TransferableFromPasteboard(nsITransferable* aTransferable,
+                                                 NSPasteboard* cocoaPasteboard) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // get flavor list that includes all acceptable flavors (including ones obtained through
+  // conversion)
+  nsTArray<nsCString> flavors;
+  nsresult rv = aTransferable->FlavorsTransferableCanImport(flavors);
+  if (NS_FAILED(rv)) return NS_ERROR_FAILURE;
+
+  for (uint32_t i = 0; i < flavors.Length(); i++) {
+    nsCString& flavorStr = flavors[i];
+
+    // printf("looking for clipboard data of type %s\n", flavorStr.get());
+
+    NSString* pboardType = nil;
+    if (nsClipboard::IsStringType(flavorStr, &pboardType)) {
+      NSString* pString = [cocoaPasteboard stringForType:pboardType];
+      if (!pString) {
+        continue;
+      }
+
+      NSData* stringData;
+      bool isRTF =
+          [pboardType isEqualToString:[UTIHelper stringFromPboardType:NSPasteboardTypeRTF]];
+      if (isRTF) {
+        stringData = [pString dataUsingEncoding:NSASCIIStringEncoding];
+      } else {
+        stringData = [pString dataUsingEncoding:NSUnicodeStringEncoding];
+      }
+      unsigned int dataLength = [stringData length];
+      void* clipboardDataPtr = malloc(dataLength);
+      if (!clipboardDataPtr) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+      [stringData getBytes:clipboardDataPtr length:dataLength];
+
+      // The DOM only wants LF, so convert from MacOS line endings to DOM line endings.
+      int32_t signedDataLength = dataLength;
+      nsLinebreakHelpers::ConvertPlatformToDOMLinebreaks(isRTF, &clipboardDataPtr,
+                                                         &signedDataLength);
+      dataLength = signedDataLength;
+
+      // skip BOM (Byte Order Mark to distinguish little or big endian)
+      char16_t* clipboardDataPtrNoBOM = (char16_t*)clipboardDataPtr;
+      if ((dataLength > 2) &&
+          ((clipboardDataPtrNoBOM[0] == 0xFEFF) || (clipboardDataPtrNoBOM[0] == 0xFFFE))) {
+        dataLength -= sizeof(char16_t);
+        clipboardDataPtrNoBOM += 1;
+      }
+
+      nsCOMPtr<nsISupports> genericDataWrapper;
+      nsPrimitiveHelpers::CreatePrimitiveForData(flavorStr, clipboardDataPtrNoBOM, dataLength,
+                                                 getter_AddRefs(genericDataWrapper));
+      aTransferable->SetTransferData(flavorStr.get(), genericDataWrapper);
+      free(clipboardDataPtr);
+      break;
+    } else if (flavorStr.EqualsLiteral(kFileMime)) {
+      NSArray* items = [cocoaPasteboard pasteboardItems];
+      if (!items || [items count] <= 0) {
+        continue;
+      }
+
+      // XXX we don't support multiple clipboard item on DOM and XPCOM interface
+      // for now, so we only get the data from the first pasteboard item.
+      NSPasteboardItem* item = [items objectAtIndex:0];
+      if (!item) {
+        continue;
+      }
+
+      nsCocoaUtils::SetTransferDataForTypeFromPasteboardItem(aTransferable, flavorStr, item);
+    } else if (flavorStr.EqualsLiteral(kCustomTypesMime)) {
+      NSString* type = [cocoaPasteboard
+          availableTypeFromArray:
+              [NSArray arrayWithObject:[UTIHelper stringFromPboardType:kMozCustomTypesPboardType]]];
+      if (!type) {
+        continue;
+      }
+
+      NSData* pasteboardData = GetDataFromPasteboard(cocoaPasteboard, type);
+      if (!pasteboardData) {
+        continue;
+      }
+
+      unsigned int dataLength = [pasteboardData length];
+      void* clipboardDataPtr = malloc(dataLength);
+      if (!clipboardDataPtr) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+      [pasteboardData getBytes:clipboardDataPtr length:dataLength];
+
+      nsCOMPtr<nsISupports> genericDataWrapper;
+      nsPrimitiveHelpers::CreatePrimitiveForData(flavorStr, clipboardDataPtr, dataLength,
+                                                 getter_AddRefs(genericDataWrapper));
+
+      aTransferable->SetTransferData(flavorStr.get(), genericDataWrapper);
+      free(clipboardDataPtr);
+    } else if (flavorStr.EqualsLiteral(kJPEGImageMime) || flavorStr.EqualsLiteral(kJPGImageMime) ||
+               flavorStr.EqualsLiteral(kPNGImageMime) || flavorStr.EqualsLiteral(kGIFImageMime)) {
+      // Figure out if there's data on the pasteboard we can grab (sanity check)
+      NSString* type = [cocoaPasteboard
+          availableTypeFromArray:
+              [NSArray arrayWithObjects:[UTIHelper stringFromPboardType:(NSString*)kUTTypeFileURL],
+                                        [UTIHelper stringFromPboardType:NSPasteboardTypeTIFF],
+                                        [UTIHelper stringFromPboardType:NSPasteboardTypePNG], nil]];
+      if (!type) continue;
+
+      // Read data off the clipboard
+      NSData* pasteboardData = GetDataFromPasteboard(cocoaPasteboard, type);
+      if (!pasteboardData) continue;
+
+      // Figure out what type we're converting to
+      CFStringRef outputType = NULL;
+      if (flavorStr.EqualsLiteral(kJPEGImageMime) || flavorStr.EqualsLiteral(kJPGImageMime))
+        outputType = CFSTR("public.jpeg");
+      else if (flavorStr.EqualsLiteral(kPNGImageMime))
+        outputType = CFSTR("public.png");
+      else if (flavorStr.EqualsLiteral(kGIFImageMime))
+        outputType = CFSTR("com.compuserve.gif");
+      else
+        continue;
+
+      // Use ImageIO to interpret the data on the clipboard and transcode.
+      // Note that ImageIO, like all CF APIs, allows NULLs to propagate freely
+      // and safely in most cases (like ObjC). A notable exception is CFRelease.
+      NSDictionary* options = [NSDictionary
+          dictionaryWithObjectsAndKeys:(NSNumber*)kCFBooleanTrue, kCGImageSourceShouldAllowFloat,
+                                       type, kCGImageSourceTypeIdentifierHint, nil];
+      CGImageSourceRef source = nullptr;
+      if (type == [UTIHelper stringFromPboardType:(NSString*)kUTTypeFileURL]) {
+        NSString* urlStr = [cocoaPasteboard stringForType:type];
+        NSURL* url = [NSURL URLWithString:urlStr];
+        source = CGImageSourceCreateWithURL((CFURLRef)url, (CFDictionaryRef)options);
+      } else {
+        source = CGImageSourceCreateWithData((CFDataRef)pasteboardData, (CFDictionaryRef)options);
+      }
+
+      NSMutableData* encodedData = [NSMutableData data];
+      CGImageDestinationRef dest =
+          CGImageDestinationCreateWithData((CFMutableDataRef)encodedData, outputType, 1, NULL);
+      CGImageDestinationAddImageFromSource(dest, source, 0, NULL);
+      bool successfullyConverted = CGImageDestinationFinalize(dest);
+
+      if (successfullyConverted) {
+        // Put the converted data in a form Gecko can understand
+        nsCOMPtr<nsIInputStream> byteStream;
+        NS_NewByteInputStream(getter_AddRefs(byteStream),
+                              mozilla::Span((const char*)[encodedData bytes], [encodedData length]),
+                              NS_ASSIGNMENT_COPY);
+
+        aTransferable->SetTransferData(flavorStr.get(), byteStream);
+      }
+
+      if (dest) CFRelease(dest);
+      if (source) CFRelease(source);
+
+      if (successfullyConverted)
+        break;
+      else
+        continue;
+    }
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsClipboard::GetNativeClipboardData(nsITransferable* aTransferable, int32_t aWhichClipboard) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if ((aWhichClipboard != kGlobalClipboard && aWhichClipboard != kFindClipboard) || !aTransferable)
+    return NS_ERROR_FAILURE;
+
+  NSPasteboard* cocoaPasteboard = GetPasteboard(aWhichClipboard);
+  if (!cocoaPasteboard) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // get flavor list that includes all acceptable flavors (including ones obtained through
+  // conversion)
+  nsTArray<nsCString> flavors;
+  nsresult rv = aTransferable->FlavorsTransferableCanImport(flavors);
+  if (NS_FAILED(rv)) return NS_ERROR_FAILURE;
+
+  // If we were the last ones to put something on the pasteboard, then just use the cached
+  // transferable. Otherwise clear it because it isn't relevant any more.
+  if (mCachedClipboard == aWhichClipboard) {
+    const auto& clipboardCache = mCaches[aWhichClipboard];
+    MOZ_ASSERT(clipboardCache);
+    if (mChangeCount == [cocoaPasteboard changeCount]) {
+      if (nsITransferable* cachedTrans = clipboardCache->GetTransferable()) {
+        for (uint32_t i = 0; i < flavors.Length(); i++) {
+          nsCString& flavorStr = flavors[i];
+
+          nsCOMPtr<nsISupports> dataSupports;
+          rv = cachedTrans->GetTransferData(flavorStr.get(), getter_AddRefs(dataSupports));
+          if (NS_SUCCEEDED(rv)) {
+            aTransferable->SetTransferData(flavorStr.get(), dataSupports);
+            return NS_OK;  // maybe try to fill in more types? Is there a point?
+          }
+        }
+      }
+    } else {
+      // Remove transferable cache only. Don't clear system clipboard.
+      clipboardCache->Clear();
+    }
+  }
+
+  // at this point we can't satisfy the request from cache data so let's look
+  // for things other people put on the system clipboard
+
+  return nsClipboard::TransferableFromPasteboard(aTransferable, cocoaPasteboard);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+// returns true if we have *any* of the passed in flavors available for pasting
+NS_IMETHODIMP
+nsClipboard::HasDataMatchingFlavors(const nsTArray<nsCString>& aFlavorList, int32_t aWhichClipboard,
+                                    bool* outResult) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  CLIPBOARD_LOG("%s: clipboard=%i", __FUNCTION__, aWhichClipboard);
+  CLIPBOARD_LOG("    Asking for content:\n");
+  for (auto& flavor : aFlavorList) {
+    CLIPBOARD_LOG("        MIME %s\n", flavor.get());
+  }
+
+  *outResult = false;
+
+  // We only support the set operation on kSelectionCache type, see bug 1835059.
+  if ((aWhichClipboard != kGlobalClipboard && aWhichClipboard != kFindClipboard)) {
+    return NS_OK;
+  }
+
+  NSPasteboard* cocoaPasteboard = GetPasteboard(aWhichClipboard);
+  MOZ_ASSERT(cocoaPasteboard);
+  if (mCachedClipboard == aWhichClipboard) {
+    const auto& clipboardCache = mCaches[mCachedClipboard];
+    MOZ_ASSERT(clipboardCache);
+    if (mChangeCount != [cocoaPasteboard changeCount]) {
+      // Clear the cached transferable as it is no longer valid.
+      clipboardCache->Clear();
+    } else if (nsITransferable* cachedTrans = clipboardCache->GetTransferable()) {
+      // See if we have data for this in our cached transferable.
+      nsTArray<nsCString> flavors;
+      nsresult rv = cachedTrans->FlavorsTransferableCanImport(flavors);
+      if (NS_SUCCEEDED(rv)) {
+        if (CLIPBOARD_LOG_ENABLED()) {
+          CLIPBOARD_LOG("    Cached transferable types (nums %zu)\n", flavors.Length());
+          for (uint32_t j = 0; j < flavors.Length(); j++) {
+            CLIPBOARD_LOG("        MIME %s\n", flavors[j].get());
+          }
+        }
+
+        for (uint32_t j = 0; j < flavors.Length(); j++) {
+          const nsCString& transferableFlavorStr = flavors[j];
+
+          for (uint32_t k = 0; k < aFlavorList.Length(); k++) {
+            if (transferableFlavorStr.Equals(aFlavorList[k])) {
+              CLIPBOARD_LOG("    has %s\n", aFlavorList[k].get());
+              *outResult = true;
+              return NS_OK;
+            }
+          }
+        }
+      }
+    }
+  }
+
+  if (CLIPBOARD_LOG_ENABLED()) {
+    NSArray* types = [cocoaPasteboard types];
+    uint32_t count = [types count];
+    CLIPBOARD_LOG("    Pasteboard types (nums %d)\n", count);
+    for (uint32_t i = 0; i < count; i++) {
+      NSPasteboardType type = [types objectAtIndex:i];
+      if (!type) {
+        CLIPBOARD_LOG("        failed to get MIME\n");
+        continue;
+      }
+      CLIPBOARD_LOG("        MIME %s\n", [type UTF8String]);
+    }
+  }
+
+  for (auto& mimeType : aFlavorList) {
+    NSString* pboardType = nil;
+    if (nsClipboard::IsStringType(mimeType, &pboardType)) {
+      NSString* availableType =
+          [cocoaPasteboard availableTypeFromArray:[NSArray arrayWithObject:pboardType]];
+      if (availableType && [availableType isEqualToString:pboardType]) {
+        CLIPBOARD_LOG("    has %s\n", mimeType.get());
+        *outResult = true;
+        break;
+      }
+    } else if (mimeType.EqualsLiteral(kCustomTypesMime)) {
+      NSString* availableType = [cocoaPasteboard
+          availableTypeFromArray:
+              [NSArray arrayWithObject:[UTIHelper stringFromPboardType:kMozCustomTypesPboardType]]];
+      if (availableType) {
+        CLIPBOARD_LOG("    has %s\n", mimeType.get());
+        *outResult = true;
+        break;
+      }
+    } else if (mimeType.EqualsLiteral(kJPEGImageMime) || mimeType.EqualsLiteral(kJPGImageMime) ||
+               mimeType.EqualsLiteral(kPNGImageMime) || mimeType.EqualsLiteral(kGIFImageMime)) {
+      NSString* availableType = [cocoaPasteboard
+          availableTypeFromArray:
+              [NSArray arrayWithObjects:[UTIHelper stringFromPboardType:NSPasteboardTypeTIFF],
+                                        [UTIHelper stringFromPboardType:NSPasteboardTypePNG], nil]];
+      if (availableType) {
+        CLIPBOARD_LOG("    has %s\n", mimeType.get());
+        *outResult = true;
+        break;
+      }
+    } else if (mimeType.EqualsLiteral(kFileMime)) {
+      NSArray* items = [cocoaPasteboard pasteboardItems];
+      if (items && [items count] > 0) {
+        // XXX we only check the first pasteboard item as we only get data from
+        // first item in TransferableFromPasteboard for now.
+        if (NSPasteboardItem* item = [items objectAtIndex:0]) {
+          if (NSString *availableType = [item
+                  availableTypeFromArray:
+                      [NSArray arrayWithObjects:[UTIHelper
+                                                    stringFromPboardType:(NSString*)kUTTypeFileURL],
+                                                nil]]) {
+            CLIPBOARD_LOG("    has %s\n", mimeType.get());
+            *outResult = true;
+            break;
+          }
+        }
+      }
+    }
+  }
+
+  if (CLIPBOARD_LOG_ENABLED() && !(*outResult)) {
+    CLIPBOARD_LOG("    no targets at clipboard (bad match)\n");
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+// static
+mozilla::Maybe<uint32_t> nsClipboard::FindIndexOfImageFlavor(
+    const nsTArray<nsCString>& aMIMETypes) {
+  for (uint32_t i = 0; i < aMIMETypes.Length(); ++i) {
+    if (nsClipboard::IsImageType(aMIMETypes[i])) {
+      return mozilla::Some(i);
+    }
+  }
+
+  return mozilla::Nothing();
+}
+
+// This function converts anything that other applications might understand into the system format
+// and puts it into a dictionary which it returns.
+// static
+NSDictionary* nsClipboard::PasteboardDictFromTransferable(nsITransferable* aTransferable) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!aTransferable) {
+    return nil;
+  }
+
+  NSMutableDictionary* pasteboardOutputDict = [NSMutableDictionary dictionary];
+
+  nsTArray<nsCString> flavors;
+  nsresult rv = aTransferable->FlavorsTransferableCanExport(flavors);
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+
+  const mozilla::Maybe<uint32_t> imageFlavorIndex = nsClipboard::FindIndexOfImageFlavor(flavors);
+
+  if (imageFlavorIndex) {
+    // When right-clicking and "Copy Image" is clicked on macOS, some apps expect the
+    // first flavor to be the image flavor. See bug 1689992. For other apps, the
+    // order shouldn't matter.
+    std::swap(*flavors.begin(), flavors[*imageFlavorIndex]);
+  }
+  for (uint32_t i = 0; i < flavors.Length(); i++) {
+    nsCString& flavorStr = flavors[i];
+
+    CLIPBOARD_LOG("writing out clipboard data of type %s (%d)\n", flavorStr.get(), i);
+
+    NSString* pboardType = nil;
+    if (nsClipboard::IsStringType(flavorStr, &pboardType)) {
+      nsCOMPtr<nsISupports> genericDataWrapper;
+      rv = aTransferable->GetTransferData(flavorStr.get(), getter_AddRefs(genericDataWrapper));
+      if (NS_FAILED(rv)) {
+        continue;
+      }
+
+      nsAutoString data;
+      if (nsCOMPtr<nsISupportsString> text = do_QueryInterface(genericDataWrapper)) {
+        text->GetData(data);
+      }
+
+      NSString* nativeString;
+      if (!data.IsEmpty()) {
+        nativeString = [NSString stringWithCharacters:(const unichar*)data.get()
+                                               length:data.Length()];
+      } else {
+        nativeString = [NSString string];
+      }
+
+      // be nice to Carbon apps, normalize the receiver's contents using Form C.
+      nativeString = [nativeString precomposedStringWithCanonicalMapping];
+      if (nativeString) {
+        [pasteboardOutputDict setObject:nativeString forKey:pboardType];
+      }
+    } else if (flavorStr.EqualsLiteral(kCustomTypesMime)) {
+      nsCOMPtr<nsISupports> genericDataWrapper;
+      rv = aTransferable->GetTransferData(flavorStr.get(), getter_AddRefs(genericDataWrapper));
+      if (NS_FAILED(rv)) {
+        continue;
+      }
+
+      nsAutoCString data;
+      if (nsCOMPtr<nsISupportsCString> text = do_QueryInterface(genericDataWrapper)) {
+        text->GetData(data);
+      }
+
+      if (!data.IsEmpty()) {
+        NSData* nativeData = [NSData dataWithBytes:data.get() length:data.Length()];
+        NSString* customType = [UTIHelper stringFromPboardType:kMozCustomTypesPboardType];
+        if (!nativeData) {
+          continue;
+        }
+        [pasteboardOutputDict setObject:nativeData forKey:customType];
+      }
+    } else if (nsClipboard::IsImageType(flavorStr)) {
+      nsCOMPtr<nsISupports> transferSupports;
+      rv = aTransferable->GetTransferData(flavorStr.get(), getter_AddRefs(transferSupports));
+      if (NS_FAILED(rv)) {
+        continue;
+      }
+
+      nsCOMPtr<imgIContainer> image(do_QueryInterface(transferSupports));
+      if (!image) {
+        NS_WARNING("Image isn't an imgIContainer in transferable");
+        continue;
+      }
+
+      RefPtr<SourceSurface> surface =
+          image->GetFrame(imgIContainer::FRAME_CURRENT,
+                          imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
+      if (!surface) {
+        continue;
+      }
+      CGImageRef imageRef = NULL;
+      rv = nsCocoaUtils::CreateCGImageFromSurface(surface, &imageRef);
+      if (NS_FAILED(rv) || !imageRef) {
+        continue;
+      }
+
+      // Convert the CGImageRef to TIFF data.
+      CFMutableDataRef tiffData = CFDataCreateMutable(kCFAllocatorDefault, 0);
+      CGImageDestinationRef destRef =
+          CGImageDestinationCreateWithData(tiffData, CFSTR("public.tiff"), 1, NULL);
+      CGImageDestinationAddImage(destRef, imageRef, NULL);
+      bool successfullyConverted = CGImageDestinationFinalize(destRef);
+
+      CGImageRelease(imageRef);
+      if (destRef) {
+        CFRelease(destRef);
+      }
+
+      if (!successfullyConverted || !tiffData) {
+        if (tiffData) {
+          CFRelease(tiffData);
+        }
+        continue;
+      }
+
+      NSString* tiffType = [UTIHelper stringFromPboardType:NSPasteboardTypeTIFF];
+      [pasteboardOutputDict setObject:(NSMutableData*)tiffData forKey:tiffType];
+      CFRelease(tiffData);
+    } else if (flavorStr.EqualsLiteral(kFileMime)) {
+      nsCOMPtr<nsISupports> genericFile;
+      rv = aTransferable->GetTransferData(flavorStr.get(), getter_AddRefs(genericFile));
+      if (NS_FAILED(rv)) {
+        continue;
+      }
+
+      nsCOMPtr<nsIFile> file(do_QueryInterface(genericFile));
+      if (!file) {
+        continue;
+      }
+
+      nsAutoString fileURI;
+      rv = file->GetPath(fileURI);
+      if (NS_FAILED(rv)) {
+        continue;
+      }
+
+      NSString* str = nsCocoaUtils::ToNSString(fileURI);
+      NSURL* url = [NSURL fileURLWithPath:str isDirectory:NO];
+      if (!url || ![url absoluteString]) {
+        continue;
+      }
+      NSString* fileUTType = [UTIHelper stringFromPboardType:(NSString*)kUTTypeFileURL];
+      [pasteboardOutputDict setObject:[url absoluteString] forKey:fileUTType];
+    } else if (flavorStr.EqualsLiteral(kFilePromiseMime)) {
+      NSString* urlPromise =
+          [UTIHelper stringFromPboardType:(NSString*)kPasteboardTypeFileURLPromise];
+      NSString* urlPromiseContent =
+          [UTIHelper stringFromPboardType:(NSString*)kPasteboardTypeFilePromiseContent];
+      [pasteboardOutputDict setObject:[NSArray arrayWithObject:@""] forKey:urlPromise];
+      [pasteboardOutputDict setObject:[NSArray arrayWithObject:@""] forKey:urlPromiseContent];
+    } else if (flavorStr.EqualsLiteral(kURLMime)) {
+      nsCOMPtr<nsISupports> genericURL;
+      rv = aTransferable->GetTransferData(flavorStr.get(), getter_AddRefs(genericURL));
+      nsCOMPtr<nsISupportsString> urlObject(do_QueryInterface(genericURL));
+
+      nsAutoString url;
+      urlObject->GetData(url);
+
+      NSString* nativeTitle = nil;
+
+      // A newline embedded in the URL means that the form is actually URL +
+      // title. This embedding occurs in nsDragService::GetData.
+      int32_t newlinePos = url.FindChar(char16_t('\n'));
+      if (newlinePos >= 0) {
+        url.Truncate(newlinePos);
+
+        nsAutoString urlTitle;
+        urlObject->GetData(urlTitle);
+        urlTitle.Mid(urlTitle, newlinePos + 1, urlTitle.Length() - (newlinePos + 1));
+
+        nativeTitle =
+            [NSString stringWithCharacters:reinterpret_cast<const unichar*>(urlTitle.get())
+                                    length:urlTitle.Length()];
+      }
+      // The Finder doesn't like getting random binary data aka
+      // Unicode, so change it into an escaped URL containing only
+      // ASCII.
+      nsAutoCString utf8Data = NS_ConvertUTF16toUTF8(url.get(), url.Length());
+      nsAutoCString escData;
+      NS_EscapeURL(utf8Data.get(), utf8Data.Length(), esc_OnlyNonASCII | esc_AlwaysCopy, escData);
+
+      NSString* nativeURL = [NSString stringWithUTF8String:escData.get()];
+      NSString* publicUrl = [UTIHelper stringFromPboardType:kPublicUrlPboardType];
+      if (!nativeURL) {
+        continue;
+      }
+      [pasteboardOutputDict setObject:nativeURL forKey:publicUrl];
+      if (nativeTitle) {
+        NSArray* urlsAndTitles = @[ @[ nativeURL ], @[ nativeTitle ] ];
+        NSString* urlName = [UTIHelper stringFromPboardType:kPublicUrlNamePboardType];
+        NSString* urlsWithTitles = [UTIHelper stringFromPboardType:kUrlsWithTitlesPboardType];
+        [pasteboardOutputDict setObject:nativeTitle forKey:urlName];
+        [pasteboardOutputDict setObject:urlsAndTitles forKey:urlsWithTitles];
+      }
+    }
+    // If it wasn't a type that we recognize as exportable we don't put it on the system
+    // clipboard. We'll just access it from our cached transferable when we need it.
+  }
+
+  return pasteboardOutputDict;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+bool nsClipboard::IsStringType(const nsCString& aMIMEType, NSString** aPboardType) {
+  if (aMIMEType.EqualsLiteral(kTextMime)) {
+    *aPboardType = [UTIHelper stringFromPboardType:NSPasteboardTypeString];
+    return true;
+  } else if (aMIMEType.EqualsLiteral(kRTFMime)) {
+    *aPboardType = [UTIHelper stringFromPboardType:NSPasteboardTypeRTF];
+    return true;
+  } else if (aMIMEType.EqualsLiteral(kHTMLMime)) {
+    *aPboardType = [UTIHelper stringFromPboardType:NSPasteboardTypeHTML];
+    return true;
+  } else {
+    return false;
+  }
+}
+
+// static
+bool nsClipboard::IsImageType(const nsACString& aMIMEType) {
+  return aMIMEType.EqualsLiteral(kPNGImageMime) || aMIMEType.EqualsLiteral(kJPEGImageMime) ||
+         aMIMEType.EqualsLiteral(kJPGImageMime) || aMIMEType.EqualsLiteral(kGIFImageMime) ||
+         aMIMEType.EqualsLiteral(kNativeImageMime);
+}
+
+NSString* nsClipboard::WrapHtmlForSystemPasteboard(NSString* aString) {
+  NSString* wrapped = [NSString
+      stringWithFormat:@"<html>"
+                        "<head>"
+                        "<meta http-equiv=\"content-type\" content=\"text/html; charset=utf-8\">"
+                        "</head>"
+                        "<body>"
+                        "%@"
+                        "</body>"
+                        "</html>",
+                       aString];
+  return wrapped;
+}
+
+NS_IMETHODIMP
+nsClipboard::EmptyClipboard(int32_t aWhichClipboard) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mEmptyingForSetData) {
+    if (aWhichClipboard == kSelectionCache) {
+      ClearSelectionCache();
+    } else {
+      if (NSPasteboard* cocoaPasteboard = GetPasteboard(aWhichClipboard)) {
+        [cocoaPasteboard clearContents];
+      }
+      if (mCachedClipboard == aWhichClipboard) {
+        mCachedClipboard = -1;
+        mChangeCount = 0;
+      }
+    }
+  }
+
+  return nsBaseClipboard::EmptyClipboard(aWhichClipboard);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
diff --git a/widget/cocoa/nsCocoaFeatures.h b/widget/cocoa/nsCocoaFeatures.h
new file mode 100644
index 0000000000..e998e82658
--- /dev/null
+++ b/widget/cocoa/nsCocoaFeatures.h
@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCocoaFeatures_h_
+#define nsCocoaFeatures_h_
+
+#include <stdint.h>
+
+/// Note that this class assumes we support the platform we are running on.
+/// For better or worse, if the version is unknown or less than what we
+/// support, we set it to the minimum supported version. GetSystemVersion
+/// is the only call that returns the unadjusted values.
+class nsCocoaFeatures {
+ public:
+  static int32_t macOSVersion();
+  static int32_t macOSVersionMajor();
+  static int32_t macOSVersionMinor();
+  static int32_t macOSVersionBugFix();
+  static bool OnSierraExactly();
+  static bool OnHighSierraOrLater();
+  static bool OnMojaveOrLater();
+  static bool OnCatalinaOrLater();
+  static bool OnBigSurOrLater();
+  static bool OnMontereyOrLater();
+  static bool OnVenturaOrLater();
+
+  static bool IsAtLeastVersion(int32_t aMajor, int32_t aMinor,
+                               int32_t aBugFix = 0);
+
+  static bool ProcessIsRosettaTranslated();
+
+  // These are utilities that do not change or depend on the value of
+  // mOSVersion and instead just encapsulate the encoding algorithm. Note that
+  // GetVersion actually adjusts to the lowest supported OS, so it will always
+  // return a "supported" version. GetSystemVersion does not make any
+  // modifications.
+  static void GetSystemVersion(int& aMajor, int& aMinor, int& aBugFix);
+  static int32_t GetVersion(int32_t aMajor, int32_t aMinor, int32_t aBugFix);
+  static int32_t ExtractMajorVersion(int32_t aVersion);
+  static int32_t ExtractMinorVersion(int32_t aVersion);
+  static int32_t ExtractBugFixVersion(int32_t aVersion);
+
+ private:
+  nsCocoaFeatures() = delete;  // Prevent instantiation.
+  static void InitializeVersionNumbers();
+
+  static int32_t mOSVersion;
+};
+
+// C-callable helper for cairo-quartz-font.c and SkFontHost_mac.cpp
+extern "C" {
+bool Gecko_OnSierraExactly();
+}
+
+#endif  // nsCocoaFeatures_h_
diff --git a/widget/cocoa/nsCocoaFeatures.mm b/widget/cocoa/nsCocoaFeatures.mm
new file mode 100644
index 0000000000..cf68755078
--- /dev/null
+++ b/widget/cocoa/nsCocoaFeatures.mm
@@ -0,0 +1,220 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This file makes some assumptions about the versions of macOS.
+// We are assuming that the major, minor and bugfix versions are each less than
+// 256.
+// There are MOZ_ASSERTs for that.
+
+// The formula for the version integer is (major << 16) + (minor << 8) + bugfix.
+
+#define MACOS_VERSION_MASK 0x00FFFFFF
+#define MACOS_MAJOR_VERSION_MASK 0x00FFFFFF
+#define MACOS_MINOR_VERSION_MASK 0x00FFFFFF
+#define MACOS_BUGFIX_VERSION_MASK 0x00FFFFFF
+#define MACOS_VERSION_10_0_HEX 0x000A0000
+#define MACOS_VERSION_10_9_HEX 0x000A0900
+#define MACOS_VERSION_10_10_HEX 0x000A0A00
+#define MACOS_VERSION_10_11_HEX 0x000A0B00
+#define MACOS_VERSION_10_12_HEX 0x000A0C00
+#define MACOS_VERSION_10_13_HEX 0x000A0D00
+#define MACOS_VERSION_10_14_HEX 0x000A0E00
+#define MACOS_VERSION_10_15_HEX 0x000A0F00
+#define MACOS_VERSION_10_16_HEX 0x000A1000
+#define MACOS_VERSION_11_0_HEX 0x000B0000
+#define MACOS_VERSION_12_0_HEX 0x000C0000
+#define MACOS_VERSION_13_0_HEX 0x000D0000
+
+#include "nsCocoaFeatures.h"
+#include "nsCocoaUtils.h"
+#include "nsDebug.h"
+#include "nsObjCExceptions.h"
+
+#import <Cocoa/Cocoa.h>
+#include <sys/sysctl.h>
+
+/*static*/ int32_t nsCocoaFeatures::mOSVersion = 0;
+
+// This should not be called with unchecked aMajor, which should be >= 10.
+inline int32_t AssembleVersion(int32_t aMajor, int32_t aMinor, int32_t aBugFix) {
+  MOZ_ASSERT(aMajor >= 10);
+  return (aMajor << 16) + (aMinor << 8) + aBugFix;
+}
+
+int32_t nsCocoaFeatures::ExtractMajorVersion(int32_t aVersion) {
+  MOZ_ASSERT((aVersion & MACOS_VERSION_MASK) == aVersion);
+  return (aVersion & 0xFF0000) >> 16;
+}
+
+int32_t nsCocoaFeatures::ExtractMinorVersion(int32_t aVersion) {
+  MOZ_ASSERT((aVersion & MACOS_VERSION_MASK) == aVersion);
+  return (aVersion & 0xFF00) >> 8;
+}
+
+int32_t nsCocoaFeatures::ExtractBugFixVersion(int32_t aVersion) {
+  MOZ_ASSERT((aVersion & MACOS_VERSION_MASK) == aVersion);
+  return aVersion & 0xFF;
+}
+
+static int intAtStringIndex(NSArray* array, int index) {
+  return [(NSString*)[array objectAtIndex:index] integerValue];
+}
+
+void nsCocoaFeatures::GetSystemVersion(int& major, int& minor, int& bugfix) {
+  major = minor = bugfix = 0;
+
+  NSString* versionString = [[NSDictionary
+      dictionaryWithContentsOfFile:@"/System/Library/CoreServices/SystemVersion.plist"]
+      objectForKey:@"ProductVersion"];
+  if (!versionString) {
+    NS_ERROR("Couldn't read /System/Library/CoreServices/SystemVersion.plist to determine macOS "
+             "version.");
+    return;
+  }
+  NSArray* versions = [versionString componentsSeparatedByString:@"."];
+  NSUInteger count = [versions count];
+  if (count > 0) {
+    major = intAtStringIndex(versions, 0);
+    if (count > 1) {
+      minor = intAtStringIndex(versions, 1);
+      if (count > 2) {
+        bugfix = intAtStringIndex(versions, 2);
+      }
+    }
+  }
+}
+
+int32_t nsCocoaFeatures::GetVersion(int32_t aMajor, int32_t aMinor, int32_t aBugFix) {
+  int32_t macOSVersion;
+  if (aMajor < 10) {
+    aMajor = 10;
+    NS_ERROR("Couldn't determine macOS version, assuming 10.9");
+    macOSVersion = MACOS_VERSION_10_9_HEX;
+  } else if (aMajor == 10 && aMinor < 9) {
+    aMinor = 9;
+    NS_ERROR("macOS version too old, assuming 10.9");
+    macOSVersion = MACOS_VERSION_10_9_HEX;
+  } else {
+    MOZ_ASSERT(aMajor >= 10);
+    MOZ_ASSERT(aMajor < 256);
+    MOZ_ASSERT(aMinor >= 0);
+    MOZ_ASSERT(aMinor < 256);
+    MOZ_ASSERT(aBugFix >= 0);
+    MOZ_ASSERT(aBugFix < 256);
+    macOSVersion = AssembleVersion(aMajor, aMinor, aBugFix);
+  }
+  MOZ_ASSERT(aMajor == ExtractMajorVersion(macOSVersion));
+  MOZ_ASSERT(aMinor == ExtractMinorVersion(macOSVersion));
+  MOZ_ASSERT(aBugFix == ExtractBugFixVersion(macOSVersion));
+  return macOSVersion;
+}
+
+/*static*/ void nsCocoaFeatures::InitializeVersionNumbers() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Provide an autorelease pool to avoid leaking Cocoa objects,
+  // as this gets called before the main autorelease pool is in place.
+  nsAutoreleasePool localPool;
+
+  int major, minor, bugfix;
+  GetSystemVersion(major, minor, bugfix);
+  mOSVersion = GetVersion(major, minor, bugfix);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+/* static */ int32_t nsCocoaFeatures::macOSVersion() {
+  // Don't let this be called while we're first setting the value...
+  MOZ_ASSERT((mOSVersion & MACOS_VERSION_MASK) >= 0);
+  if (!mOSVersion) {
+    mOSVersion = -1;
+    InitializeVersionNumbers();
+  }
+  return mOSVersion;
+}
+
+/* static */ int32_t nsCocoaFeatures::macOSVersionMajor() {
+  return ExtractMajorVersion(macOSVersion());
+}
+
+/* static */ int32_t nsCocoaFeatures::macOSVersionMinor() {
+  return ExtractMinorVersion(macOSVersion());
+}
+
+/* static */ int32_t nsCocoaFeatures::macOSVersionBugFix() {
+  return ExtractBugFixVersion(macOSVersion());
+}
+
+/* static */ bool nsCocoaFeatures::OnSierraExactly() {
+  return (macOSVersion() >= MACOS_VERSION_10_12_HEX) && (macOSVersion() < MACOS_VERSION_10_13_HEX);
+}
+
+/* Version of OnSierraExactly as global function callable from cairo & skia */
+bool Gecko_OnSierraExactly() { return nsCocoaFeatures::OnSierraExactly(); }
+
+/* static */ bool nsCocoaFeatures::OnHighSierraOrLater() {
+  return (macOSVersion() >= MACOS_VERSION_10_13_HEX);
+}
+
+/* static */ bool nsCocoaFeatures::OnMojaveOrLater() {
+  return (macOSVersion() >= MACOS_VERSION_10_14_HEX);
+}
+
+/* static */ bool nsCocoaFeatures::OnCatalinaOrLater() {
+  return (macOSVersion() >= MACOS_VERSION_10_15_HEX);
+}
+
+/* static */ bool nsCocoaFeatures::OnBigSurOrLater() {
+  // Account for the version being 10.16 or 11.0 on Big Sur.
+  // The version is reported as 10.16 if SYSTEM_VERSION_COMPAT is set to 1,
+  // or if SYSTEM_VERSION_COMPAT is not set and the application is linked
+  // with a pre-Big Sur SDK.
+  // Firefox sets SYSTEM_VERSION_COMPAT to 0 in its Info.plist, so it'll
+  // usually see the correct 11.* version, despite being linked against an
+  // old SDK. However, it still sees the 10.16 compatibility version when
+  // launched from the command line, see bug 1727624. (This only applies to
+  // the Intel build - the arm64 build is linked against a Big Sur SDK and
+  // always sees the correct version.)
+  return ((macOSVersion() >= MACOS_VERSION_10_16_HEX) ||
+          (macOSVersion() >= MACOS_VERSION_11_0_HEX));
+}
+
+/* static */ bool nsCocoaFeatures::OnMontereyOrLater() {
+  // This check only works if SYSTEM_VERSION_COMPAT is off, otherwise
+  // Monterey pretends to be 10.16 and is indistinguishable from Big Sur.
+  // In practice, this means that an Intel Firefox build can return false
+  // from this function if it's launched from the command line, see bug 1727624.
+  // This will not be an issue anymore once we link against the Big Sur SDK.
+  return (macOSVersion() >= MACOS_VERSION_12_0_HEX);
+}
+
+/* static */ bool nsCocoaFeatures::OnVenturaOrLater() {
+  // See comments above regarding SYSTEM_VERSION_COMPAT.
+  return (macOSVersion() >= MACOS_VERSION_13_0_HEX);
+}
+
+/* static */ bool nsCocoaFeatures::IsAtLeastVersion(int32_t aMajor, int32_t aMinor,
+                                                    int32_t aBugFix) {
+  return macOSVersion() >= GetVersion(aMajor, aMinor, aBugFix);
+}
+
+/*
+ * Returns true if the process is running under Rosetta translation. Returns
+ * false if running natively or if an error was encountered. We use the
+ * `sysctl.proc_translated` sysctl which is documented by Apple to be used
+ * for this purpose. Note: using this in a sandboxed process requires allowing
+ * the sysctl in the sandbox policy.
+ */
+/* static */ bool nsCocoaFeatures::ProcessIsRosettaTranslated() {
+  int ret = 0;
+  size_t size = sizeof(ret);
+  if (sysctlbyname("sysctl.proc_translated", &ret, &size, NULL, 0) == -1) {
+    if (errno != ENOENT) {
+      fprintf(stderr, "Failed to check for translation environment\n");
+    }
+    return false;
+  }
+  return (ret == 1);
+}
diff --git a/widget/cocoa/nsCocoaUtils.h b/widget/cocoa/nsCocoaUtils.h
new file mode 100644
index 0000000000..30332cf8a6
--- /dev/null
+++ b/widget/cocoa/nsCocoaUtils.h
@@ -0,0 +1,574 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCocoaUtils_h_
+#define nsCocoaUtils_h_
+
+#import <Cocoa/Cocoa.h>
+
+#include "InputData.h"
+#include "nsRect.h"
+#include "imgIContainer.h"
+#include "nsTArray.h"
+#include "Units.h"
+
+// This must be the last include:
+#include "nsObjCExceptions.h"
+
+#include "mozilla/EventForwards.h"
+#include "mozilla/StaticMutex.h"
+#include "mozilla/StaticPtr.h"
+#include "nsIWidget.h"
+
+// Declare the backingScaleFactor method that we want to call
+// on NSView/Window/Screen objects, if they recognize it.
+@interface NSObject (BackingScaleFactorCategory)
+- (CGFloat)backingScaleFactor;
+@end
+
+// Pasteborad types
+extern NSString* const kPublicUrlPboardType;
+extern NSString* const kPublicUrlNamePboardType;
+extern NSString* const kUrlsWithTitlesPboardType;
+extern NSString* const kMozWildcardPboardType;
+extern NSString* const kMozCustomTypesPboardType;
+extern NSString* const kMozFileUrlsPboardType;
+
+@interface UTIHelper : NSObject
++ (NSString*)stringFromPboardType:(NSString*)aType;
+@end
+
+class nsITransferable;
+class nsIWidget;
+
+namespace mozilla {
+class TimeStamp;
+namespace gfx {
+class SourceSurface;
+}  // namespace gfx
+namespace dom {
+class Promise;
+}  // namespace dom
+}  // namespace mozilla
+
+using mozilla::StaticAutoPtr;
+using mozilla::StaticMutex;
+
+// Used to retain a Cocoa object for the remainder of a method's execution.
+class nsAutoRetainCocoaObject {
+ public:
+  explicit nsAutoRetainCocoaObject(id anObject) {
+    NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+    mObject = [anObject retain];
+    NS_OBJC_END_TRY_IGNORE_BLOCK;
+  }
+  ~nsAutoRetainCocoaObject() {
+    NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+    [mObject release];
+    NS_OBJC_END_TRY_IGNORE_BLOCK;
+  }
+
+ private:
+  id mObject;  // [STRONG]
+};
+
+// Provide a local autorelease pool for the remainder of a method's execution.
+class nsAutoreleasePool {
+ public:
+  nsAutoreleasePool() { mLocalPool = [[NSAutoreleasePool alloc] init]; }
+  ~nsAutoreleasePool() { [mLocalPool release]; }
+
+ private:
+  NSAutoreleasePool* mLocalPool;
+};
+
+@interface NSApplication (Undocumented)
+
+// Present in all versions of OS X from (at least) 10.2.8 through 10.5.
+- (BOOL)_isRunningModal;
+- (BOOL)_isRunningAppModal;
+
+// Send an event to the current Cocoa app-modal session.  Present in all
+// versions of OS X from (at least) 10.2.8 through 10.5.
+- (void)_modalSession:(NSModalSession)aSession sendEvent:(NSEvent*)theEvent;
+
+@end
+
+struct KeyBindingsCommand {
+  SEL selector;
+  id data;
+};
+
+@interface NativeKeyBindingsRecorder : NSResponder {
+ @private
+  nsTArray<KeyBindingsCommand>* mCommands;
+}
+
+- (void)startRecording:(nsTArray<KeyBindingsCommand>&)aCommands;
+
+- (void)doCommandBySelector:(SEL)aSelector;
+
+- (void)insertText:(id)aString;
+
+@end  // NativeKeyBindingsRecorder
+
+#if !defined(MAC_OS_X_VERSION_10_14) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_14
+typedef NSString* AVMediaType;
+#endif
+
+class nsCocoaUtils {
+  typedef mozilla::gfx::SourceSurface SourceSurface;
+  typedef mozilla::LayoutDeviceIntPoint LayoutDeviceIntPoint;
+  typedef mozilla::LayoutDeviceIntRect LayoutDeviceIntRect;
+  typedef mozilla::dom::Promise Promise;
+  typedef StaticAutoPtr<nsTArray<RefPtr<Promise>>> PromiseArray;
+
+ public:
+  // Get the backing scale factor from an object that supports this selector
+  // (NSView/Window/Screen, on 10.7 or later), returning 1.0 if not supported
+  static CGFloat GetBackingScaleFactor(id aObject) {
+    if (HiDPIEnabled() && [aObject respondsToSelector:@selector(backingScaleFactor)]) {
+      return [aObject backingScaleFactor];
+    }
+    return 1.0;
+  }
+
+  // Conversions between Cocoa points and device pixels, given the backing
+  // scale factor from a view/window/screen.
+  static int32_t CocoaPointsToDevPixels(CGFloat aPts, CGFloat aBackingScale) {
+    return NSToIntRound(aPts * aBackingScale);
+  }
+
+  static LayoutDeviceIntPoint CocoaPointsToDevPixels(const NSPoint& aPt, CGFloat aBackingScale) {
+    return LayoutDeviceIntPoint(NSToIntRound(aPt.x * aBackingScale),
+                                NSToIntRound(aPt.y * aBackingScale));
+  }
+
+  static LayoutDeviceIntPoint CocoaPointsToDevPixelsRoundDown(const NSPoint& aPt,
+                                                              CGFloat aBackingScale) {
+    return LayoutDeviceIntPoint(NSToIntFloor(aPt.x * aBackingScale),
+                                NSToIntFloor(aPt.y * aBackingScale));
+  }
+
+  static LayoutDeviceIntRect CocoaPointsToDevPixels(const NSRect& aRect, CGFloat aBackingScale) {
+    return LayoutDeviceIntRect(NSToIntRound(aRect.origin.x * aBackingScale),
+                               NSToIntRound(aRect.origin.y * aBackingScale),
+                               NSToIntRound(aRect.size.width * aBackingScale),
+                               NSToIntRound(aRect.size.height * aBackingScale));
+  }
+
+  static CGFloat DevPixelsToCocoaPoints(int32_t aPixels, CGFloat aBackingScale) {
+    return (CGFloat)aPixels / aBackingScale;
+  }
+
+  static NSPoint DevPixelsToCocoaPoints(const mozilla::LayoutDeviceIntPoint& aPt,
+                                        CGFloat aBackingScale) {
+    return NSMakePoint((CGFloat)aPt.x / aBackingScale, (CGFloat)aPt.y / aBackingScale);
+  }
+
+  // Implements an NSPoint equivalent of -[NSWindow convertRectFromScreen:].
+  static NSPoint ConvertPointFromScreen(NSWindow* aWindow, const NSPoint& aPt) {
+    return [aWindow convertRectFromScreen:NSMakeRect(aPt.x, aPt.y, 0, 0)].origin;
+  }
+
+  // Implements an NSPoint equivalent of -[NSWindow convertRectToScreen:].
+  static NSPoint ConvertPointToScreen(NSWindow* aWindow, const NSPoint& aPt) {
+    return [aWindow convertRectToScreen:NSMakeRect(aPt.x, aPt.y, 0, 0)].origin;
+  }
+
+  static NSRect DevPixelsToCocoaPoints(const LayoutDeviceIntRect& aRect, CGFloat aBackingScale) {
+    return NSMakeRect((CGFloat)aRect.X() / aBackingScale, (CGFloat)aRect.Y() / aBackingScale,
+                      (CGFloat)aRect.Width() / aBackingScale,
+                      (CGFloat)aRect.Height() / aBackingScale);
+  }
+
+  // Returns the given y coordinate, which must be in screen coordinates,
+  // flipped from Gecko to Cocoa or Cocoa to Gecko.
+  static float FlippedScreenY(float y);
+
+  // The following functions come in "DevPix" variants that work with
+  // backing-store (device pixel) coordinates, as well as the original
+  // versions that expect coordinates in Cocoa points/CSS pixels.
+  // The difference becomes important in HiDPI display modes, where Cocoa
+  // points and backing-store pixels are no longer 1:1.
+
+  // Gecko rects (nsRect) contain an origin (x,y) in a coordinate
+  // system with (0,0) in the top-left of the primary screen. Cocoa rects
+  // (NSRect) contain an origin (x,y) in a coordinate system with (0,0)
+  // in the bottom-left of the primary screen. Both nsRect and NSRect
+  // contain width/height info, with no difference in their use.
+  // This function does no scaling, so the Gecko coordinates are
+  // expected to be desktop pixels, which are equal to Cocoa points
+  // (by definition).
+  static NSRect GeckoRectToCocoaRect(const mozilla::DesktopIntRect& geckoRect);
+  static NSPoint GeckoPointToCocoaPoint(const mozilla::DesktopPoint& aPoint);
+
+  // Converts aGeckoRect in dev pixels to points in Cocoa coordinates
+  static NSRect GeckoRectToCocoaRectDevPix(const mozilla::LayoutDeviceIntRect& aGeckoRect,
+                                           CGFloat aBackingScale);
+
+  // See explanation for geckoRectToCocoaRect, guess what this does...
+  static mozilla::DesktopIntRect CocoaRectToGeckoRect(const NSRect& cocoaRect);
+
+  static mozilla::LayoutDeviceIntRect CocoaRectToGeckoRectDevPix(const NSRect& aCocoaRect,
+                                                                 CGFloat aBackingScale);
+
+  // Gives the location for the event in screen coordinates. Do not call this
+  // unless the window the event was originally targeted at is still alive!
+  // anEvent may be nil -- in that case the current mouse location is returned.
+  static NSPoint ScreenLocationForEvent(NSEvent* anEvent);
+
+  // Determines if an event happened over a window, whether or not the event
+  // is for the window. Does not take window z-order into account.
+  static BOOL IsEventOverWindow(NSEvent* anEvent, NSWindow* aWindow);
+
+  // Events are set up so that their coordinates refer to the window to which they
+  // were originally sent. If we reroute the event somewhere else, we'll have
+  // to get the window coordinates this way. Do not call this unless the window
+  // the event was originally targeted at is still alive!
+  static NSPoint EventLocationForWindow(NSEvent* anEvent, NSWindow* aWindow);
+
+  static BOOL IsMomentumScrollEvent(NSEvent* aEvent);
+  static BOOL EventHasPhaseInformation(NSEvent* aEvent);
+
+  // Hides the Menu bar and the Dock. Multiple hide/show requests can be nested.
+  static void HideOSChromeOnScreen(bool aShouldHide);
+
+  static nsIWidget* GetHiddenWindowWidget();
+
+  /**
+   * Should the application restore its state because it was launched by the OS
+   * at login?
+   */
+  static BOOL ShouldRestoreStateDueToLaunchAtLogin();
+
+  static void PrepareForNativeAppModalDialog();
+  static void CleanUpAfterNativeAppModalDialog();
+
+  // 3 utility functions to go from a frame of imgIContainer to CGImage and then to NSImage
+  // Convert imgIContainer -> CGImageRef, caller owns result
+
+  /** Creates a <code>CGImageRef</code> from a frame contained in an <code>imgIContainer</code>.
+      Copies the pixel data from the indicated frame of the <code>imgIContainer</code> into a new
+     <code>CGImageRef</code>. The caller owns the <code>CGImageRef</code>.
+      @param aFrame the frame to convert
+      @param aResult the resulting CGImageRef
+      @param aIsEntirelyBlack an outparam that, if non-null, will be set to a
+                              bool that indicates whether the RGB values on all
+                              pixels are zero
+      @return NS_OK if the conversion worked, NS_ERROR_FAILURE otherwise
+   */
+  static nsresult CreateCGImageFromSurface(SourceSurface* aSurface, CGImageRef* aResult,
+                                           bool* aIsEntirelyBlack = nullptr);
+
+  /** Creates a Cocoa <code>NSImage</code> from a <code>CGImageRef</code>.
+      Copies the pixel data from the <code>CGImageRef</code> into a new <code>NSImage</code>.
+      The caller owns the <code>NSImage</code>.
+      @param aInputImage the image to convert
+      @param aResult the resulting NSImage
+      @return NS_OK if the conversion worked, NS_ERROR_FAILURE otherwise
+   */
+  static nsresult CreateNSImageFromCGImage(CGImageRef aInputImage, NSImage** aResult);
+
+  /** Creates a Cocoa <code>NSImage</code> from a frame of an <code>imgIContainer</code>.
+      Combines the two methods above. The caller owns the <code>NSImage</code>.
+      @param aImage the image to extract a frame from
+      @param aWhichFrame the frame to extract (see imgIContainer FRAME_*)
+      @param aComputedStyle the ComputedStyle of the element that the image is for, to support SVG
+                            context paint properties, can be null
+      @param aResult the resulting NSImage
+      @param scaleFactor the desired scale factor of the NSImage (2 for a retina display)
+      @param aIsEntirelyBlack an outparam that, if non-null, will be set to a
+                              bool that indicates whether the RGB values on all
+                              pixels are zero
+      @return NS_OK if the conversion worked, NS_ERROR_FAILURE otherwise
+   */
+  static nsresult CreateNSImageFromImageContainer(imgIContainer* aImage, uint32_t aWhichFrame,
+                                                  const nsPresContext* aPresContext,
+                                                  const mozilla::ComputedStyle* aComputedStyle,
+                                                  NSImage** aResult, CGFloat scaleFactor,
+                                                  bool* aIsEntirelyBlack = nullptr);
+
+  /** Creates a Cocoa <code>NSImage</code> from a frame of an <code>imgIContainer</code>.
+      The new <code>NSImage</code> will have both a regular and HiDPI representation.
+      The caller owns the <code>NSImage</code>.
+      @param aImage the image to extract a frame from
+      @param aWhichFrame the frame to extract (see imgIContainer FRAME_*)
+      @param aComputedStyle the ComputedStyle of the element that the image is for, to support SVG
+                            context paint properties, can be null
+      @param aResult the resulting NSImage
+      @param aIsEntirelyBlack an outparam that, if non-null, will be set to a
+                              bool that indicates whether the RGB values on all
+                              pixels are zero
+      @return NS_OK if the conversion worked, NS_ERROR_FAILURE otherwise
+   */
+  static nsresult CreateDualRepresentationNSImageFromImageContainer(
+      imgIContainer* aImage, uint32_t aWhichFrame, const nsPresContext* aPresContext,
+      const mozilla::ComputedStyle* aComputedStyle, NSImage** aResult,
+      bool* aIsEntirelyBlack = nullptr);
+
+  /**
+   * Returns nsAString for aSrc.
+   */
+  static void GetStringForNSString(const NSString* aSrc, nsAString& aDist);
+
+  /**
+   * Makes NSString instance for aString.
+   */
+  static NSString* ToNSString(const nsAString& aString);
+
+  /**
+   * Returns an NSURL instance for the provided string.
+   */
+  static NSURL* ToNSURL(const nsAString& aURLString);
+
+  /**
+   * Makes NSString instance for aCString.
+   */
+  static NSString* ToNSString(const nsACString& aCString);
+
+  /**
+   * Returns NSRect for aGeckoRect.
+   * Just copies values between the two types; it does no coordinate-system
+   * conversion, so both rects must have the same coordinate origin/direction.
+   */
+  static void GeckoRectToNSRect(const nsIntRect& aGeckoRect, NSRect& aOutCocoaRect);
+
+  /**
+   * Returns Gecko rect for aCocoaRect.
+   * Just copies values between the two types; it does no coordinate-system
+   * conversion, so both rects must have the same coordinate origin/direction.
+   */
+  static void NSRectToGeckoRect(const NSRect& aCocoaRect, nsIntRect& aOutGeckoRect);
+
+  /**
+   * Makes NSEvent instance for aEventTytpe and aEvent.
+   */
+  static NSEvent* MakeNewCocoaEventWithType(NSEventType aEventType, NSEvent* aEvent);
+
+  /**
+   * Makes a cocoa event from a widget keyboard event.
+   */
+  static NSEvent* MakeNewCococaEventFromWidgetEvent(const mozilla::WidgetKeyboardEvent& aKeyEvent,
+                                                    NSInteger aWindowNumber,
+                                                    NSGraphicsContext* aContext);
+
+  /**
+   * Initializes WidgetInputEvent for aNativeEvent or aModifiers.
+   */
+  static void InitInputEvent(mozilla::WidgetInputEvent& aInputEvent, NSEvent* aNativeEvent);
+
+  /**
+   * Converts the native modifiers from aNativeEvent into WidgetMouseEvent
+   * Modifiers. aNativeEvent can be null.
+   */
+  static mozilla::Modifiers ModifiersForEvent(NSEvent* aNativeEvent);
+
+  /**
+   * ConvertToCarbonModifier() returns carbon modifier flags for the cocoa
+   * modifier flags.
+   * NOTE: The result never includes right*Key.
+   */
+  static UInt32 ConvertToCarbonModifier(NSUInteger aCocoaModifier);
+
+  /**
+   * Whether to support HiDPI rendering. For testing purposes, to be removed
+   * once we're comfortable with the HiDPI behavior.
+   */
+  static bool HiDPIEnabled();
+
+  /**
+   * Keys can optionally be bound by system or user key bindings to one or more
+   * commands based on selectors. This collects any such commands in the
+   * provided array.
+   */
+  static void GetCommandsFromKeyEvent(NSEvent* aEvent, nsTArray<KeyBindingsCommand>& aCommands);
+
+  /**
+   * Converts the string name of a Gecko key (like "VK_HOME") to the
+   * corresponding Cocoa Unicode character.
+   */
+  static uint32_t ConvertGeckoNameToMacCharCode(const nsAString& aKeyCodeName);
+
+  /**
+   * Converts a Gecko key code (like NS_VK_HOME) to the corresponding Cocoa
+   * Unicode character.
+   */
+  static uint32_t ConvertGeckoKeyCodeToMacCharCode(uint32_t aKeyCode);
+
+  /**
+   * Converts Gecko native modifier flags for `nsIWidget::SynthesizeNative*()`
+   * to native modifier flags of macOS.
+   */
+  static NSEventModifierFlags ConvertWidgetModifiersToMacModifierFlags(
+      nsIWidget::Modifiers aNativeModifiers);
+
+  /**
+   * Get the mouse button, which depends on the event's type and buttonNumber.
+   * Returns MouseButton::ePrimary for non-mouse events.
+   */
+  static mozilla::MouseButton ButtonForEvent(NSEvent* aEvent);
+
+  /**
+   * Convert string with font attribute to NSMutableAttributedString
+   */
+  static NSMutableAttributedString* GetNSMutableAttributedString(
+      const nsAString& aText, const nsTArray<mozilla::FontRange>& aFontRanges,
+      const bool aIsVertical, const CGFloat aBackingScaleFactor);
+
+  /**
+   * Compute TimeStamp from an event's timestamp.
+   * If aEventTime is 0, this returns current timestamp.
+   */
+  static mozilla::TimeStamp GetEventTimeStamp(NSTimeInterval aEventTime);
+
+  /**
+   * Check whether double clicking on the titlebar should cause the window to
+   * zoom (maximize).
+   */
+  static bool ShouldZoomOnTitlebarDoubleClick();
+
+  /**
+   * Check whether double clicking on the titlebar should cause the window to
+   * minimize.
+   */
+  static bool ShouldMinimizeOnTitlebarDoubleClick();
+
+  /**
+   * Get the current video capture permission status.
+   * Returns NS_ERROR_NOT_IMPLEMENTED on 10.13 and earlier macOS versions.
+   */
+  static nsresult GetVideoCapturePermissionState(uint16_t& aPermissionState);
+
+  /**
+   * Get the current audio capture permission status.
+   * Returns NS_ERROR_NOT_IMPLEMENTED on 10.13 and earlier macOS versions.
+   */
+  static nsresult GetAudioCapturePermissionState(uint16_t& aPermissionState);
+
+  /**
+   * Get the current screen capture permission status.
+   * Returns NS_ERROR_NOT_IMPLEMENTED on 10.14 and earlier macOS versions.
+   */
+  static nsresult GetScreenCapturePermissionState(uint16_t& aPermissionState);
+
+  /**
+   * Request video capture permission from the OS. Caller must be running
+   * on the main thread and the promise will be resolved on the main thread.
+   * Returns NS_ERROR_NOT_IMPLEMENTED on 10.13 and earlier macOS versions.
+   */
+  static nsresult RequestVideoCapturePermission(RefPtr<Promise>& aPromise);
+
+  /**
+   * Request audio capture permission from the OS. Caller must be running
+   * on the main thread and the promise will be resolved on the main thread.
+   * Returns NS_ERROR_NOT_IMPLEMENTED on 10.13 and earlier macOS versions.
+   */
+  static nsresult RequestAudioCapturePermission(RefPtr<Promise>& aPromise);
+
+  /**
+   * Request screen capture permission from the OS using an unreliable method.
+   */
+  static nsresult MaybeRequestScreenCapturePermission();
+
+  static void InvalidateHiDPIState();
+
+  static mozilla::PanGestureInput CreatePanGestureEvent(
+      NSEvent* aNativeEvent, mozilla::TimeStamp aTimeStamp,
+      const mozilla::ScreenPoint& aPanStartPoint, const mozilla::ScreenPoint& aPreciseDelta,
+      const mozilla::gfx::IntPoint& aLineOrPageDelta, mozilla::Modifiers aModifiers);
+
+  /**
+   * Return true if aAvailableType is a vaild NSPasteboard type.
+   */
+  static bool IsValidPasteboardType(NSString* aAvailableType, bool aAllowFileURL);
+
+  /**
+   * Set data for specific type from NSPasteboardItem to Transferable.
+   */
+  static void SetTransferDataForTypeFromPasteboardItem(nsITransferable* aTransferable,
+                                                       const nsCString& aFlavor,
+                                                       NSPasteboardItem* aItem);
+
+ private:
+  /**
+   * Completion handlers used as an argument to the macOS API to
+   * request media capture permission. These are called asynchronously
+   * on an arbitrary dispatch queue.
+   */
+  static void (^AudioCompletionHandler)(BOOL);
+  static void (^VideoCompletionHandler)(BOOL);
+
+  /**
+   * Called from the audio and video completion handlers in order to
+   * dispatch the handling back to the main thread.
+   */
+  static void ResolveAudioCapturePromises(bool aGranted);
+  static void ResolveVideoCapturePromises(bool aGranted);
+
+  /**
+   * Main implementation for Request{Audio,Video}CapturePermission.
+   * @param aType the AVMediaType to request capture permission for
+   * @param aPromise the Promise to resolve when capture permission
+   *                 is either allowed or denied
+   * @param aPromiseList the array of promises to save |aPromise| in
+   * @param aHandler the block function (either ResolveAudioCapturePromises
+   *                 or ResolveVideoCapturePromises) to be used as
+   *                 the requestAccessForMediaType callback.
+   */
+  static nsresult RequestCapturePermission(NSString* aType, RefPtr<Promise>& aPromise,
+                                           PromiseArray& aPromiseList,
+                                           void (^aHandler)(BOOL granted));
+  /**
+   * Resolves the pending promises that are waiting for a response
+   * to a request video or audio capture permission.
+   */
+  static void ResolveMediaCapturePromises(bool aGranted, PromiseArray& aPromiseList);
+
+  /**
+   * Get string data for a specific type from NSPasteboardItem.
+   */
+  static NSString* GetStringForTypeFromPasteboardItem(NSPasteboardItem* aItem,
+                                                      const NSString* aType,
+                                                      bool aAllowFileURL = false);
+
+  /**
+   * Get the file path from NSPasteboardItem.
+   */
+  static NSString* GetFilePathFromPasteboardItem(NSPasteboardItem* aItem);
+
+  /**
+   * Get the title for URL from NSPasteboardItem.
+   */
+  static NSString* GetTitleForURLFromPasteboardItem(NSPasteboardItem* item);
+
+  /**
+   * Did the OS launch the application at login?
+   */
+  static BOOL WasLaunchedAtLogin();
+
+  /**
+   * Should the application restore its state because it was launched by the OS
+   * at login?
+   */
+  static BOOL ShouldRestoreStateDueToLaunchAtLoginImpl();
+
+  /**
+   * Array of promises waiting to be resolved due to a video capture request.
+   */
+  static PromiseArray sVideoCapturePromises;
+
+  /**
+   * Array of promises waiting to be resolved due to an audio capture request.
+   */
+  static PromiseArray sAudioCapturePromises;
+
+  /**
+   * Lock protecting |sVideoCapturePromises| and |sAudioCapturePromises|.
+   */
+  static StaticMutex sMediaCaptureMutex MOZ_UNANNOTATED;
+};
+
+#endif  // nsCocoaUtils_h_
diff --git a/widget/cocoa/nsCocoaUtils.mm b/widget/cocoa/nsCocoaUtils.mm
new file mode 100644
index 0000000000..b6eaa5dc31
--- /dev/null
+++ b/widget/cocoa/nsCocoaUtils.mm
@@ -0,0 +1,1819 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <AVFoundation/AVFoundation.h>
+
+#include <cmath>
+
+#include "AppleUtils.h"
+#include "gfx2DGlue.h"
+#include "gfxContext.h"
+#include "gfxPlatform.h"
+#include "gfxUtils.h"
+#include "ImageRegion.h"
+#include "nsClipboard.h"
+#include "nsCocoaUtils.h"
+#include "nsChildView.h"
+#include "nsMenuBarX.h"
+#include "nsCocoaFeatures.h"
+#include "nsCocoaWindow.h"
+#include "nsCOMPtr.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIAppShellService.h"
+#include "nsIOSPermissionRequest.h"
+#include "nsIRunnable.h"
+#include "nsIAppWindow.h"
+#include "nsIBaseWindow.h"
+#include "nsITransferable.h"
+#include "nsMenuUtilsX.h"
+#include "nsNetUtil.h"
+#include "nsPrimitiveHelpers.h"
+#include "nsToolkit.h"
+#include "nsCRT.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/glean/GleanMetrics.h"
+#include "mozilla/Logging.h"
+#include "mozilla/MiscEvents.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/StaticMutex.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "mozilla/SVGImageContext.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/gfx/2D.h"
+
+using namespace mozilla;
+using namespace mozilla::widget;
+
+using mozilla::dom::Promise;
+using mozilla::gfx::DataSourceSurface;
+using mozilla::gfx::DrawTarget;
+using mozilla::gfx::IntPoint;
+using mozilla::gfx::IntRect;
+using mozilla::gfx::IntSize;
+using mozilla::gfx::SamplingFilter;
+using mozilla::gfx::SourceSurface;
+using mozilla::gfx::SurfaceFormat;
+using mozilla::image::ImageRegion;
+
+LazyLogModule gCocoaUtilsLog("nsCocoaUtils");
+#undef LOG
+#define LOG(...) MOZ_LOG(gCocoaUtilsLog, LogLevel::Debug, (__VA_ARGS__))
+
+/*
+ * For each audio and video capture request, we hold an owning reference
+ * to a promise to be resolved when the request's async callback is invoked.
+ * sVideoCapturePromises and sAudioCapturePromises are arrays of video and
+ * audio promises waiting for to be resolved. Each array is protected by a
+ * mutex.
+ */
+nsCocoaUtils::PromiseArray nsCocoaUtils::sVideoCapturePromises;
+nsCocoaUtils::PromiseArray nsCocoaUtils::sAudioCapturePromises;
+StaticMutex nsCocoaUtils::sMediaCaptureMutex;
+
+/**
+ * Pasteboard types
+ */
+NSString* const kPublicUrlPboardType = @"public.url";
+NSString* const kPublicUrlNamePboardType = @"public.url-name";
+NSString* const kUrlsWithTitlesPboardType = @"WebURLsWithTitlesPboardType";
+NSString* const kMozWildcardPboardType = @"org.mozilla.MozillaWildcard";
+NSString* const kMozCustomTypesPboardType = @"org.mozilla.custom-clipdata";
+NSString* const kMozFileUrlsPboardType = @"org.mozilla.file-urls";
+
+@implementation UTIHelper
+
++ (NSString*)stringFromPboardType:(NSString*)aType {
+  if ([aType isEqualToString:kMozWildcardPboardType] ||
+      [aType isEqualToString:kMozCustomTypesPboardType] ||
+      [aType isEqualToString:kPublicUrlPboardType] ||
+      [aType isEqualToString:kPublicUrlNamePboardType] ||
+      [aType isEqualToString:kMozFileUrlsPboardType] ||
+      [aType isEqualToString:(NSString*)kPasteboardTypeFileURLPromise] ||
+      [aType isEqualToString:(NSString*)kPasteboardTypeFilePromiseContent] ||
+      [aType isEqualToString:(NSString*)kUTTypeFileURL] ||
+      [aType isEqualToString:NSStringPboardType] ||
+      [aType isEqualToString:NSPasteboardTypeString] ||
+      [aType isEqualToString:NSPasteboardTypeHTML] || [aType isEqualToString:NSPasteboardTypeRTF] ||
+      [aType isEqualToString:NSPasteboardTypeTIFF] || [aType isEqualToString:NSPasteboardTypePNG]) {
+    return [NSString stringWithString:aType];
+  }
+  NSString* dynamicType = (NSString*)UTTypeCreatePreferredIdentifierForTag(
+      kUTTagClassNSPboardType, (CFStringRef)aType, kUTTypeData);
+  NSString* result = [NSString stringWithString:dynamicType];
+  [dynamicType release];
+  return result;
+}
+
+@end  // UTIHelper
+
+static float MenuBarScreenHeight() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSArray* allScreens = [NSScreen screens];
+  if ([allScreens count]) {
+    return [[allScreens objectAtIndex:0] frame].size.height;
+  }
+
+  return 0.0;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(0.0);
+}
+
+float nsCocoaUtils::FlippedScreenY(float y) { return MenuBarScreenHeight() - y; }
+
+NSRect nsCocoaUtils::GeckoRectToCocoaRect(const DesktopIntRect& geckoRect) {
+  // We only need to change the Y coordinate by starting with the primary screen
+  // height and subtracting the gecko Y coordinate of the bottom of the rect.
+  return NSMakeRect(geckoRect.x, MenuBarScreenHeight() - geckoRect.YMost(), geckoRect.width,
+                    geckoRect.height);
+}
+
+NSPoint nsCocoaUtils::GeckoPointToCocoaPoint(const mozilla::DesktopPoint& aPoint) {
+  return NSMakePoint(aPoint.x, MenuBarScreenHeight() - aPoint.y);
+}
+
+NSRect nsCocoaUtils::GeckoRectToCocoaRectDevPix(const LayoutDeviceIntRect& aGeckoRect,
+                                                CGFloat aBackingScale) {
+  return NSMakeRect(aGeckoRect.x / aBackingScale,
+                    MenuBarScreenHeight() - aGeckoRect.YMost() / aBackingScale,
+                    aGeckoRect.width / aBackingScale, aGeckoRect.height / aBackingScale);
+}
+
+DesktopIntRect nsCocoaUtils::CocoaRectToGeckoRect(const NSRect& cocoaRect) {
+  // We only need to change the Y coordinate by starting with the primary screen
+  // height and subtracting both the cocoa y origin and the height of the
+  // cocoa rect.
+  DesktopIntRect rect;
+  rect.x = NSToIntRound(cocoaRect.origin.x);
+  rect.y = NSToIntRound(FlippedScreenY(cocoaRect.origin.y + cocoaRect.size.height));
+  rect.width = NSToIntRound(cocoaRect.origin.x + cocoaRect.size.width) - rect.x;
+  rect.height = NSToIntRound(FlippedScreenY(cocoaRect.origin.y)) - rect.y;
+  return rect;
+}
+
+LayoutDeviceIntRect nsCocoaUtils::CocoaRectToGeckoRectDevPix(const NSRect& aCocoaRect,
+                                                             CGFloat aBackingScale) {
+  LayoutDeviceIntRect rect;
+  rect.x = NSToIntRound(aCocoaRect.origin.x * aBackingScale);
+  rect.y =
+      NSToIntRound(FlippedScreenY(aCocoaRect.origin.y + aCocoaRect.size.height) * aBackingScale);
+  rect.width = NSToIntRound((aCocoaRect.origin.x + aCocoaRect.size.width) * aBackingScale) - rect.x;
+  rect.height = NSToIntRound(FlippedScreenY(aCocoaRect.origin.y) * aBackingScale) - rect.y;
+  return rect;
+}
+
+NSPoint nsCocoaUtils::ScreenLocationForEvent(NSEvent* anEvent) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // Don't trust mouse locations of mouse move events, see bug 443178.
+  if (!anEvent || [anEvent type] == NSEventTypeMouseMoved) return [NSEvent mouseLocation];
+
+  // Pin momentum scroll events to the location of the last user-controlled
+  // scroll event.
+  if (IsMomentumScrollEvent(anEvent)) return ChildViewMouseTracker::sLastScrollEventScreenLocation;
+
+  return nsCocoaUtils::ConvertPointToScreen([anEvent window], [anEvent locationInWindow]);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSMakePoint(0.0, 0.0));
+}
+
+BOOL nsCocoaUtils::IsEventOverWindow(NSEvent* anEvent, NSWindow* aWindow) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return NSPointInRect(ScreenLocationForEvent(anEvent), [aWindow frame]);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+NSPoint nsCocoaUtils::EventLocationForWindow(NSEvent* anEvent, NSWindow* aWindow) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return nsCocoaUtils::ConvertPointFromScreen(aWindow, ScreenLocationForEvent(anEvent));
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NSMakePoint(0.0, 0.0));
+}
+
+BOOL nsCocoaUtils::IsMomentumScrollEvent(NSEvent* aEvent) {
+  return [aEvent type] == NSEventTypeScrollWheel && [aEvent momentumPhase] != NSEventPhaseNone;
+}
+
+BOOL nsCocoaUtils::EventHasPhaseInformation(NSEvent* aEvent) {
+  return [aEvent phase] != NSEventPhaseNone || [aEvent momentumPhase] != NSEventPhaseNone;
+}
+
+void nsCocoaUtils::HideOSChromeOnScreen(bool aShouldHide) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Keep track of how many hiding requests have been made, so that they can
+  // be nested.
+  static int sHiddenCount = 0;
+
+  sHiddenCount += aShouldHide ? 1 : -1;
+  NS_ASSERTION(sHiddenCount >= 0, "Unbalanced HideMenuAndDockForWindow calls");
+
+  NSApplicationPresentationOptions options =
+      sHiddenCount <= 0 ? NSApplicationPresentationDefault
+                        : NSApplicationPresentationHideDock | NSApplicationPresentationHideMenuBar;
+  [NSApp setPresentationOptions:options];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+#define NS_APPSHELLSERVICE_CONTRACTID "@mozilla.org/appshell/appShellService;1"
+nsIWidget* nsCocoaUtils::GetHiddenWindowWidget() {
+  nsCOMPtr<nsIAppShellService> appShell(do_GetService(NS_APPSHELLSERVICE_CONTRACTID));
+  if (!appShell) {
+    NS_WARNING("Couldn't get AppShellService in order to get hidden window ref");
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIAppWindow> hiddenWindow;
+  appShell->GetHiddenWindow(getter_AddRefs(hiddenWindow));
+  if (!hiddenWindow) {
+    // Don't warn, this happens during shutdown, bug 358607.
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIBaseWindow> baseHiddenWindow;
+  baseHiddenWindow = do_GetInterface(hiddenWindow);
+  if (!baseHiddenWindow) {
+    NS_WARNING("Couldn't get nsIBaseWindow from hidden window (nsIAppWindow)");
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIWidget> hiddenWindowWidget;
+  if (NS_FAILED(baseHiddenWindow->GetMainWidget(getter_AddRefs(hiddenWindowWidget)))) {
+    NS_WARNING("Couldn't get nsIWidget from hidden window (nsIBaseWindow)");
+    return nullptr;
+  }
+
+  return hiddenWindowWidget;
+}
+
+BOOL nsCocoaUtils::WasLaunchedAtLogin() {
+  ProcessSerialNumber processSerialNumber = {0, kCurrentProcess};
+  ProcessInfoRec processInfoRec = {};
+  processInfoRec.processInfoLength = sizeof(processInfoRec);
+
+  // There is currently no replacement for ::GetProcessInformation, which has
+  // been deprecated since macOS 10.9.
+  if (::GetProcessInformation(&processSerialNumber, &processInfoRec) == noErr) {
+    ProcessInfoRec parentProcessInfo = {};
+    parentProcessInfo.processInfoLength = sizeof(parentProcessInfo);
+    if (::GetProcessInformation(&processInfoRec.processLauncher, &parentProcessInfo) == noErr) {
+      return parentProcessInfo.processSignature == 'lgnw';
+    }
+  }
+  return NO;
+}
+
+BOOL nsCocoaUtils::ShouldRestoreStateDueToLaunchAtLoginImpl() {
+  // Check if we were launched by macOS as a result of having
+  // "Reopen windows..." selected during a restart.
+  if (!WasLaunchedAtLogin()) {
+    return NO;
+  }
+
+  CFStringRef lgnwPlistName = CFSTR("com.apple.loginwindow");
+  CFStringRef saveStateKey = CFSTR("TALLogoutSavesState");
+  CFPropertyListRef lgnwPlist =
+      (CFPropertyListRef)(::CFPreferencesCopyAppValue(saveStateKey, lgnwPlistName));
+  // The .plist doesn't exist unless the user changed the "Reopen windows..."
+  // preference. If it doesn't exist, restore by default (as this is the macOS
+  // default).
+  // https://developer.apple.com/library/mac/documentation/macosx/conceptual/bpsystemstartup/chapters/CustomLogin.html
+  if (!lgnwPlist) {
+    return YES;
+  }
+
+  if (CFBooleanRef shouldRestoreState = static_cast<CFBooleanRef>(lgnwPlist)) {
+    return ::CFBooleanGetValue(shouldRestoreState);
+  }
+
+  return NO;
+}
+
+BOOL nsCocoaUtils::ShouldRestoreStateDueToLaunchAtLogin() {
+  BOOL shouldRestore = ShouldRestoreStateDueToLaunchAtLoginImpl();
+  Telemetry::ScalarSet(Telemetry::ScalarID::STARTUP_IS_RESTORED_BY_MACOS, !!shouldRestore);
+  mozilla::glean::startup::is_restored_by_macos.Set(!!shouldRestore);
+  return shouldRestore;
+}
+
+void nsCocoaUtils::PrepareForNativeAppModalDialog() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Don't do anything if this is embedding. We'll assume that if there is no hidden
+  // window we shouldn't do anything, and that should cover the embedding case.
+  nsMenuBarX* hiddenWindowMenuBar = nsMenuUtilsX::GetHiddenWindowMenuBar();
+  if (!hiddenWindowMenuBar) return;
+
+  // First put up the hidden window menu bar so that app menu event handling is correct.
+  hiddenWindowMenuBar->Paint();
+
+  NSMenu* mainMenu = [NSApp mainMenu];
+  NS_ASSERTION([mainMenu numberOfItems] > 0,
+               "Main menu does not have any items, something is terribly wrong!");
+
+  // Create new menu bar for use with modal dialog
+  NSMenu* newMenuBar = [[NSMenu alloc] initWithTitle:@""];
+
+  // Swap in our app menu. Note that the event target is whatever window is up when
+  // the app modal dialog goes up.
+  NSMenuItem* firstMenuItem = [[mainMenu itemAtIndex:0] retain];
+  [mainMenu removeItemAtIndex:0];
+  [newMenuBar insertItem:firstMenuItem atIndex:0];
+  [firstMenuItem release];
+
+  // Add standard edit menu
+  [newMenuBar addItem:nsMenuUtilsX::GetStandardEditMenuItem()];
+
+  // Show the new menu bar
+  [NSApp setMainMenu:newMenuBar];
+  [newMenuBar release];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaUtils::CleanUpAfterNativeAppModalDialog() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Don't do anything if this is embedding. We'll assume that if there is no hidden
+  // window we shouldn't do anything, and that should cover the embedding case.
+  nsMenuBarX* hiddenWindowMenuBar = nsMenuUtilsX::GetHiddenWindowMenuBar();
+  if (!hiddenWindowMenuBar) return;
+
+  NSWindow* mainWindow = [NSApp mainWindow];
+  if (!mainWindow)
+    hiddenWindowMenuBar->Paint();
+  else
+    [WindowDelegate paintMenubarForWindow:mainWindow];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static void data_ss_release_callback(void* aDataSourceSurface, const void* data, size_t size) {
+  if (aDataSourceSurface) {
+    static_cast<DataSourceSurface*>(aDataSourceSurface)->Unmap();
+    static_cast<DataSourceSurface*>(aDataSourceSurface)->Release();
+  }
+}
+
+// This function assumes little endian byte order.
+static bool ComputeIsEntirelyBlack(const DataSourceSurface::MappedSurface& aMap,
+                                   const IntSize& aSize) {
+  for (int32_t y = 0; y < aSize.height; y++) {
+    size_t rowStart = y * aMap.mStride;
+    for (int32_t x = 0; x < aSize.width; x++) {
+      size_t index = rowStart + x * 4;
+      if (aMap.mData[index + 0] != 0 || aMap.mData[index + 1] != 0 || aMap.mData[index + 2] != 0) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+nsresult nsCocoaUtils::CreateCGImageFromSurface(SourceSurface* aSurface, CGImageRef* aResult,
+                                                bool* aIsEntirelyBlack) {
+  RefPtr<DataSourceSurface> dataSurface;
+
+  if (aSurface->GetFormat() == SurfaceFormat::B8G8R8A8) {
+    dataSurface = aSurface->GetDataSurface();
+  } else {
+    // CGImageCreate only supports 16- and 32-bit bit-depth
+    // Convert format to SurfaceFormat::B8G8R8A8
+    dataSurface =
+        gfxUtils::CopySurfaceToDataSourceSurfaceWithFormat(aSurface, SurfaceFormat::B8G8R8A8);
+  }
+
+  NS_ENSURE_TRUE(dataSurface, NS_ERROR_FAILURE);
+
+  int32_t width = dataSurface->GetSize().width;
+  int32_t height = dataSurface->GetSize().height;
+  if (height < 1 || width < 1) {
+    return NS_ERROR_FAILURE;
+  }
+
+  DataSourceSurface::MappedSurface map;
+  if (!dataSurface->Map(DataSourceSurface::MapType::READ, &map)) {
+    return NS_ERROR_FAILURE;
+  }
+  // The Unmap() call happens in data_ss_release_callback
+
+  if (aIsEntirelyBlack) {
+    *aIsEntirelyBlack = ComputeIsEntirelyBlack(map, dataSurface->GetSize());
+  }
+
+  // Create a CGImageRef with the bits from the image, taking into account
+  // the alpha ordering and endianness of the machine so we don't have to
+  // touch the bits ourselves.
+  CGDataProviderRef dataProvider = ::CGDataProviderCreateWithData(
+      dataSurface.forget().take(), map.mData, map.mStride * height, data_ss_release_callback);
+  CGColorSpaceRef colorSpace = ::CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
+  *aResult = ::CGImageCreate(width, height, 8, 32, map.mStride, colorSpace,
+                             kCGBitmapByteOrder32Host | kCGImageAlphaPremultipliedFirst,
+                             dataProvider, NULL, 0, kCGRenderingIntentDefault);
+  ::CGColorSpaceRelease(colorSpace);
+  ::CGDataProviderRelease(dataProvider);
+  return *aResult ? NS_OK : NS_ERROR_FAILURE;
+}
+
+nsresult nsCocoaUtils::CreateNSImageFromCGImage(CGImageRef aInputImage, NSImage** aResult) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // Be very careful when creating the NSImage that the backing NSImageRep is
+  // exactly 1:1 with the input image. On a retina display, both [NSImage
+  // lockFocus] and [NSImage initWithCGImage:size:] will create an image with a
+  // 2x backing NSImageRep. This prevents NSCursor from recognizing a retina
+  // cursor, which only occurs if pixelsWide and pixelsHigh are exactly 2x the
+  // size of the NSImage.
+  //
+  // For example, if a 32x32 SVG cursor is rendered on a retina display, then
+  // aInputImage will be 64x64. The resulting NSImage will be scaled back down
+  // to 32x32 so it stays the correct size on the screen by changing its size
+  // (resizing a NSImage only scales the image and doesn't resample the data).
+  // If aInputImage is converted using [NSImage initWithCGImage:size:] then the
+  // bitmap will be 128x128 and NSCursor won't recognize a retina cursor, since
+  // it will expect a 64x64 bitmap.
+
+  int32_t width = ::CGImageGetWidth(aInputImage);
+  int32_t height = ::CGImageGetHeight(aInputImage);
+  NSRect imageRect = ::NSMakeRect(0.0, 0.0, width, height);
+
+  NSBitmapImageRep* offscreenRep =
+      [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL
+                                              pixelsWide:width
+                                              pixelsHigh:height
+                                           bitsPerSample:8
+                                         samplesPerPixel:4
+                                                hasAlpha:YES
+                                                isPlanar:NO
+                                          colorSpaceName:NSDeviceRGBColorSpace
+                                            bitmapFormat:NSAlphaFirstBitmapFormat
+                                             bytesPerRow:0
+                                            bitsPerPixel:0];
+
+  NSGraphicsContext* context = [NSGraphicsContext graphicsContextWithBitmapImageRep:offscreenRep];
+  [NSGraphicsContext saveGraphicsState];
+  [NSGraphicsContext setCurrentContext:context];
+
+  // Get the Quartz context and draw.
+  CGContextRef imageContext = [[NSGraphicsContext currentContext] CGContext];
+  ::CGContextDrawImage(imageContext, *(CGRect*)&imageRect, aInputImage);
+
+  [NSGraphicsContext restoreGraphicsState];
+
+  *aResult = [[NSImage alloc] initWithSize:NSMakeSize(width, height)];
+  [*aResult addRepresentation:offscreenRep];
+  [offscreenRep release];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsCocoaUtils::CreateNSImageFromImageContainer(imgIContainer* aImage, uint32_t aWhichFrame,
+                                                       const nsPresContext* aPresContext,
+                                                       const ComputedStyle* aComputedStyle,
+                                                       NSImage** aResult, CGFloat scaleFactor,
+                                                       bool* aIsEntirelyBlack) {
+  RefPtr<SourceSurface> surface;
+  int32_t width = 0, height = 0;
+  aImage->GetWidth(&width);
+  aImage->GetHeight(&height);
+
+  // Render a vector image at the correct resolution on a retina display
+  if (aImage->GetType() == imgIContainer::TYPE_VECTOR) {
+    IntSize scaledSize = IntSize::Ceil(width * scaleFactor, height * scaleFactor);
+
+    RefPtr<DrawTarget> drawTarget = gfxPlatform::GetPlatform()->CreateOffscreenContentDrawTarget(
+        scaledSize, SurfaceFormat::B8G8R8A8);
+    if (!drawTarget || !drawTarget->IsValid()) {
+      NS_ERROR("Failed to create valid DrawTarget");
+      return NS_ERROR_FAILURE;
+    }
+
+    gfxContext context(drawTarget);
+
+    SVGImageContext svgContext;
+    if (aPresContext && aComputedStyle) {
+      SVGImageContext::MaybeStoreContextPaint(svgContext, *aPresContext, *aComputedStyle, aImage);
+    }
+    mozilla::image::ImgDrawResult res =
+        aImage->Draw(&context, scaledSize, ImageRegion::Create(scaledSize), aWhichFrame,
+                     SamplingFilter::POINT, svgContext, imgIContainer::FLAG_SYNC_DECODE, 1.0);
+
+    if (res != mozilla::image::ImgDrawResult::SUCCESS) {
+      return NS_ERROR_FAILURE;
+    }
+
+    surface = drawTarget->Snapshot();
+  } else {
+    surface = aImage->GetFrame(aWhichFrame,
+                               imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
+  }
+
+  NS_ENSURE_TRUE(surface, NS_ERROR_FAILURE);
+
+  CGImageRef imageRef = NULL;
+  nsresult rv = nsCocoaUtils::CreateCGImageFromSurface(surface, &imageRef, aIsEntirelyBlack);
+  if (NS_FAILED(rv) || !imageRef) {
+    return NS_ERROR_FAILURE;
+  }
+
+  rv = nsCocoaUtils::CreateNSImageFromCGImage(imageRef, aResult);
+  if (NS_FAILED(rv) || !aResult) {
+    return NS_ERROR_FAILURE;
+  }
+  ::CGImageRelease(imageRef);
+
+  // Ensure the image will be rendered the correct size on a retina display
+  NSSize size = NSMakeSize(width, height);
+  [*aResult setSize:size];
+  [[[*aResult representations] objectAtIndex:0] setSize:size];
+  return NS_OK;
+}
+
+nsresult nsCocoaUtils::CreateDualRepresentationNSImageFromImageContainer(
+    imgIContainer* aImage, uint32_t aWhichFrame, const nsPresContext* aPresContext,
+    const ComputedStyle* aComputedStyle, NSImage** aResult, bool* aIsEntirelyBlack) {
+  int32_t width = 0, height = 0;
+  aImage->GetWidth(&width);
+  aImage->GetHeight(&height);
+  NSSize size = NSMakeSize(width, height);
+  *aResult = [[NSImage alloc] init];
+  [*aResult setSize:size];
+
+  NSImage* newRepresentation = nil;
+  nsresult rv = CreateNSImageFromImageContainer(aImage, aWhichFrame, aPresContext, aComputedStyle,
+                                                &newRepresentation, 1.0f, aIsEntirelyBlack);
+  if (NS_FAILED(rv) || !newRepresentation) {
+    return NS_ERROR_FAILURE;
+  }
+
+  [[[newRepresentation representations] objectAtIndex:0] setSize:size];
+  [*aResult addRepresentation:[[newRepresentation representations] objectAtIndex:0]];
+  [newRepresentation release];
+  newRepresentation = nil;
+
+  rv = CreateNSImageFromImageContainer(aImage, aWhichFrame, aPresContext, aComputedStyle,
+                                       &newRepresentation, 2.0f, aIsEntirelyBlack);
+  if (NS_FAILED(rv) || !newRepresentation) {
+    return NS_ERROR_FAILURE;
+  }
+
+  [[[newRepresentation representations] objectAtIndex:0] setSize:size];
+  [*aResult addRepresentation:[[newRepresentation representations] objectAtIndex:0]];
+  [newRepresentation release];
+  return NS_OK;
+}
+
+// static
+void nsCocoaUtils::GetStringForNSString(const NSString* aSrc, nsAString& aDist) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!aSrc) {
+    aDist.Truncate();
+    return;
+  }
+
+  aDist.SetLength([aSrc length]);
+  [aSrc getCharacters:reinterpret_cast<unichar*>(aDist.BeginWriting())
+                range:NSMakeRange(0, [aSrc length])];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// static
+NSString* nsCocoaUtils::ToNSString(const nsAString& aString) {
+  if (aString.IsEmpty()) {
+    return [NSString string];
+  }
+  return [NSString stringWithCharacters:reinterpret_cast<const unichar*>(aString.BeginReading())
+                                 length:aString.Length()];
+}
+
+// static
+NSString* nsCocoaUtils::ToNSString(const nsACString& aCString) {
+  if (aCString.IsEmpty()) {
+    return [NSString string];
+  }
+  return [[[NSString alloc] initWithBytes:aCString.BeginReading()
+                                   length:aCString.Length()
+                                 encoding:NSUTF8StringEncoding] autorelease];
+}
+
+// static
+NSURL* nsCocoaUtils::ToNSURL(const nsAString& aURLString) {
+  nsAutoCString encodedURLString;
+  nsresult rv = NS_GetSpecWithNSURLEncoding(encodedURLString, NS_ConvertUTF16toUTF8(aURLString));
+  NS_ENSURE_SUCCESS(rv, nullptr);
+
+  NSString* encodedURLNSString = ToNSString(encodedURLString);
+  if (!encodedURLNSString) {
+    return nullptr;
+  }
+
+  return [NSURL URLWithString:encodedURLNSString];
+}
+
+// static
+void nsCocoaUtils::GeckoRectToNSRect(const nsIntRect& aGeckoRect, NSRect& aOutCocoaRect) {
+  aOutCocoaRect.origin.x = aGeckoRect.x;
+  aOutCocoaRect.origin.y = aGeckoRect.y;
+  aOutCocoaRect.size.width = aGeckoRect.width;
+  aOutCocoaRect.size.height = aGeckoRect.height;
+}
+
+// static
+void nsCocoaUtils::NSRectToGeckoRect(const NSRect& aCocoaRect, nsIntRect& aOutGeckoRect) {
+  aOutGeckoRect.x = NSToIntRound(aCocoaRect.origin.x);
+  aOutGeckoRect.y = NSToIntRound(aCocoaRect.origin.y);
+  aOutGeckoRect.width = NSToIntRound(aCocoaRect.origin.x + aCocoaRect.size.width) - aOutGeckoRect.x;
+  aOutGeckoRect.height =
+      NSToIntRound(aCocoaRect.origin.y + aCocoaRect.size.height) - aOutGeckoRect.y;
+}
+
+// static
+NSEvent* nsCocoaUtils::MakeNewCocoaEventWithType(NSEventType aEventType, NSEvent* aEvent) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSEvent* newEvent = [NSEvent keyEventWithType:aEventType
+                                       location:[aEvent locationInWindow]
+                                  modifierFlags:[aEvent modifierFlags]
+                                      timestamp:[aEvent timestamp]
+                                   windowNumber:[aEvent windowNumber]
+                                        context:nil
+                                     characters:[aEvent characters]
+                    charactersIgnoringModifiers:[aEvent charactersIgnoringModifiers]
+                                      isARepeat:[aEvent isARepeat]
+                                        keyCode:[aEvent keyCode]];
+  return newEvent;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+// static
+NSEvent* nsCocoaUtils::MakeNewCococaEventFromWidgetEvent(const WidgetKeyboardEvent& aKeyEvent,
+                                                         NSInteger aWindowNumber,
+                                                         NSGraphicsContext* aContext) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSEventType eventType;
+  if (aKeyEvent.mMessage == eKeyUp) {
+    eventType = NSEventTypeKeyUp;
+  } else {
+    eventType = NSEventTypeKeyDown;
+  }
+
+  static const uint32_t sModifierFlagMap[][2] = {{MODIFIER_SHIFT, NSEventModifierFlagShift},
+                                                 {MODIFIER_CONTROL, NSEventModifierFlagControl},
+                                                 {MODIFIER_ALT, NSEventModifierFlagOption},
+                                                 {MODIFIER_ALTGRAPH, NSEventModifierFlagOption},
+                                                 {MODIFIER_META, NSEventModifierFlagCommand},
+                                                 {MODIFIER_CAPSLOCK, NSEventModifierFlagCapsLock},
+                                                 {MODIFIER_NUMLOCK, NSEventModifierFlagNumericPad}};
+
+  NSUInteger modifierFlags = 0;
+  for (uint32_t i = 0; i < ArrayLength(sModifierFlagMap); ++i) {
+    if (aKeyEvent.mModifiers & sModifierFlagMap[i][0]) {
+      modifierFlags |= sModifierFlagMap[i][1];
+    }
+  }
+
+  NSString* characters;
+  if (aKeyEvent.mCharCode) {
+    characters =
+        [NSString stringWithCharacters:reinterpret_cast<const unichar*>(&(aKeyEvent.mCharCode))
+                                length:1];
+  } else {
+    uint32_t cocoaCharCode = nsCocoaUtils::ConvertGeckoKeyCodeToMacCharCode(aKeyEvent.mKeyCode);
+    characters = [NSString stringWithCharacters:reinterpret_cast<const unichar*>(&cocoaCharCode)
+                                         length:1];
+  }
+
+  return [NSEvent keyEventWithType:eventType
+                          location:NSMakePoint(0, 0)
+                     modifierFlags:modifierFlags
+                         timestamp:0
+                      windowNumber:aWindowNumber
+                           context:aContext
+                        characters:characters
+       charactersIgnoringModifiers:characters
+                         isARepeat:NO
+                           keyCode:0];  // Native key code not currently needed
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+// static
+void nsCocoaUtils::InitInputEvent(WidgetInputEvent& aInputEvent, NSEvent* aNativeEvent) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  aInputEvent.mModifiers = ModifiersForEvent(aNativeEvent);
+  aInputEvent.mTimeStamp = GetEventTimeStamp([aNativeEvent timestamp]);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// static
+Modifiers nsCocoaUtils::ModifiersForEvent(NSEvent* aNativeEvent) {
+  NSUInteger modifiers = aNativeEvent ? [aNativeEvent modifierFlags] : [NSEvent modifierFlags];
+  Modifiers result = 0;
+  if (modifiers & NSEventModifierFlagShift) {
+    result |= MODIFIER_SHIFT;
+  }
+  if (modifiers & NSEventModifierFlagControl) {
+    result |= MODIFIER_CONTROL;
+  }
+  if (modifiers & NSEventModifierFlagOption) {
+    result |= MODIFIER_ALT;
+    // Mac's option key is similar to other platforms' AltGr key.
+    // Let's set AltGr flag when option key is pressed for consistency with
+    // other platforms.
+    result |= MODIFIER_ALTGRAPH;
+  }
+  if (modifiers & NSEventModifierFlagCommand) {
+    result |= MODIFIER_META;
+  }
+
+  if (modifiers & NSEventModifierFlagCapsLock) {
+    result |= MODIFIER_CAPSLOCK;
+  }
+  // Mac doesn't have NumLock key.  We can assume that NumLock is always locked
+  // if user is using a keyboard which has numpad.  Otherwise, if user is using
+  // a keyboard which doesn't have numpad, e.g., MacBook's keyboard, we can
+  // assume that NumLock is always unlocked.
+  // Unfortunately, we cannot know whether current keyboard has numpad or not.
+  // We should notify locked state only when keys in numpad are pressed.
+  // By this, web applications may not be confused by unexpected numpad key's
+  // key event with unlocked state.
+  if (modifiers & NSEventModifierFlagNumericPad) {
+    result |= MODIFIER_NUMLOCK;
+  }
+
+  // Be aware, NSEventModifierFlagFunction is included when arrow keys, home key or some
+  // other keys are pressed. We cannot check whether 'fn' key is pressed or
+  // not by the flag.
+
+  return result;
+}
+
+// static
+UInt32 nsCocoaUtils::ConvertToCarbonModifier(NSUInteger aCocoaModifier) {
+  UInt32 carbonModifier = 0;
+  if (aCocoaModifier & NSEventModifierFlagCapsLock) {
+    carbonModifier |= alphaLock;
+  }
+  if (aCocoaModifier & NSEventModifierFlagControl) {
+    carbonModifier |= controlKey;
+  }
+  if (aCocoaModifier & NSEventModifierFlagOption) {
+    carbonModifier |= optionKey;
+  }
+  if (aCocoaModifier & NSEventModifierFlagShift) {
+    carbonModifier |= shiftKey;
+  }
+  if (aCocoaModifier & NSEventModifierFlagCommand) {
+    carbonModifier |= cmdKey;
+  }
+  if (aCocoaModifier & NSEventModifierFlagNumericPad) {
+    carbonModifier |= kEventKeyModifierNumLockMask;
+  }
+  if (aCocoaModifier & NSEventModifierFlagFunction) {
+    carbonModifier |= kEventKeyModifierFnMask;
+  }
+  return carbonModifier;
+}
+
+// While HiDPI support is not 100% complete and tested, we'll have a pref
+// to allow it to be turned off in case of problems (or for testing purposes).
+
+// gfx.hidpi.enabled is an integer with the meaning:
+//    <= 0 : HiDPI support is disabled
+//       1 : HiDPI enabled provided all screens have the same backing resolution
+//     > 1 : HiDPI enabled even if there are a mixture of screen modes
+
+// All the following code is to be removed once HiDPI work is more complete.
+
+static bool sHiDPIEnabled = false;
+static bool sHiDPIPrefInitialized = false;
+
+// static
+bool nsCocoaUtils::HiDPIEnabled() {
+  if (!sHiDPIPrefInitialized) {
+    sHiDPIPrefInitialized = true;
+
+    int prefSetting = Preferences::GetInt("gfx.hidpi.enabled", 1);
+    if (prefSetting <= 0) {
+      return false;
+    }
+
+    // prefSetting is at least 1, need to check attached screens...
+
+    int scaleFactors = 0;  // used as a bitset to track the screen types found
+    NSEnumerator* screenEnum = [[NSScreen screens] objectEnumerator];
+    while (NSScreen* screen = [screenEnum nextObject]) {
+      NSDictionary* desc = [screen deviceDescription];
+      if ([desc objectForKey:NSDeviceIsScreen] == nil) {
+        continue;
+      }
+      // Currently, we only care about differentiating "1.0" and "2.0",
+      // so we set one of the two low bits to record which.
+      if ([screen backingScaleFactor] > 1.0) {
+        scaleFactors |= 2;
+      } else {
+        scaleFactors |= 1;
+      }
+    }
+
+    // Now scaleFactors will be:
+    //   0 if no screens (supporting backingScaleFactor) found
+    //   1 if only lo-DPI screens
+    //   2 if only hi-DPI screens
+    //   3 if both lo- and hi-DPI screens
+    // We'll enable HiDPI support if there's only a single screen type,
+    // OR if the pref setting is explicitly greater than 1.
+    sHiDPIEnabled = (scaleFactors <= 2) || (prefSetting > 1);
+  }
+
+  return sHiDPIEnabled;
+}
+
+// static
+void nsCocoaUtils::InvalidateHiDPIState() { sHiDPIPrefInitialized = false; }
+
+void nsCocoaUtils::GetCommandsFromKeyEvent(NSEvent* aEvent,
+                                           nsTArray<KeyBindingsCommand>& aCommands) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  MOZ_ASSERT(aEvent);
+
+  static NativeKeyBindingsRecorder* sNativeKeyBindingsRecorder;
+  if (!sNativeKeyBindingsRecorder) {
+    sNativeKeyBindingsRecorder = [NativeKeyBindingsRecorder new];
+  }
+
+  [sNativeKeyBindingsRecorder startRecording:aCommands];
+
+  // This will trigger 0 - N calls to doCommandBySelector: and insertText:
+  [sNativeKeyBindingsRecorder interpretKeyEvents:[NSArray arrayWithObject:aEvent]];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+@implementation NativeKeyBindingsRecorder
+
+- (void)startRecording:(nsTArray<KeyBindingsCommand>&)aCommands {
+  mCommands = &aCommands;
+  mCommands->Clear();
+}
+
+- (void)doCommandBySelector:(SEL)aSelector {
+  KeyBindingsCommand command = {aSelector, nil};
+
+  mCommands->AppendElement(command);
+}
+
+- (void)insertText:(id)aString {
+  KeyBindingsCommand command = {@selector(insertText:), aString};
+
+  mCommands->AppendElement(command);
+}
+
+@end  // NativeKeyBindingsRecorder
+
+struct KeyConversionData {
+  const char* str;
+  size_t strLength;
+  uint32_t geckoKeyCode;
+  uint32_t charCode;
+};
+
+static const KeyConversionData gKeyConversions[] = {
+
+#define KEYCODE_ENTRY(aStr, aCode)             \
+  {                                            \
+#    aStr, sizeof(#aStr) - 1, NS_##aStr, aCode \
+  }
+
+// Some keycodes may have different name in KeyboardEvent from its key name.
+#define KEYCODE_ENTRY2(aStr, aNSName, aCode)      \
+  {                                               \
+#    aStr, sizeof(#aStr) - 1, NS_##aNSName, aCode \
+  }
+
+    KEYCODE_ENTRY(VK_CANCEL, 0x001B),
+    KEYCODE_ENTRY(VK_DELETE, NSDeleteFunctionKey),
+    KEYCODE_ENTRY(VK_BACK, NSBackspaceCharacter),
+    KEYCODE_ENTRY2(VK_BACK_SPACE, VK_BACK, NSBackspaceCharacter),
+    KEYCODE_ENTRY(VK_TAB, NSTabCharacter),
+    KEYCODE_ENTRY(VK_CLEAR, NSClearLineFunctionKey),
+    KEYCODE_ENTRY(VK_RETURN, NSEnterCharacter),
+    KEYCODE_ENTRY(VK_SHIFT, 0),
+    KEYCODE_ENTRY(VK_CONTROL, 0),
+    KEYCODE_ENTRY(VK_ALT, 0),
+    KEYCODE_ENTRY(VK_PAUSE, NSPauseFunctionKey),
+    KEYCODE_ENTRY(VK_CAPS_LOCK, 0),
+    KEYCODE_ENTRY(VK_ESCAPE, 0),
+    KEYCODE_ENTRY(VK_SPACE, ' '),
+    KEYCODE_ENTRY(VK_PAGE_UP, NSPageUpFunctionKey),
+    KEYCODE_ENTRY(VK_PAGE_DOWN, NSPageDownFunctionKey),
+    KEYCODE_ENTRY(VK_END, NSEndFunctionKey),
+    KEYCODE_ENTRY(VK_HOME, NSHomeFunctionKey),
+    KEYCODE_ENTRY(VK_LEFT, NSLeftArrowFunctionKey),
+    KEYCODE_ENTRY(VK_UP, NSUpArrowFunctionKey),
+    KEYCODE_ENTRY(VK_RIGHT, NSRightArrowFunctionKey),
+    KEYCODE_ENTRY(VK_DOWN, NSDownArrowFunctionKey),
+    KEYCODE_ENTRY(VK_PRINTSCREEN, NSPrintScreenFunctionKey),
+    KEYCODE_ENTRY(VK_INSERT, NSInsertFunctionKey),
+    KEYCODE_ENTRY(VK_HELP, NSHelpFunctionKey),
+    KEYCODE_ENTRY(VK_0, '0'),
+    KEYCODE_ENTRY(VK_1, '1'),
+    KEYCODE_ENTRY(VK_2, '2'),
+    KEYCODE_ENTRY(VK_3, '3'),
+    KEYCODE_ENTRY(VK_4, '4'),
+    KEYCODE_ENTRY(VK_5, '5'),
+    KEYCODE_ENTRY(VK_6, '6'),
+    KEYCODE_ENTRY(VK_7, '7'),
+    KEYCODE_ENTRY(VK_8, '8'),
+    KEYCODE_ENTRY(VK_9, '9'),
+    KEYCODE_ENTRY(VK_SEMICOLON, ':'),
+    KEYCODE_ENTRY(VK_EQUALS, '='),
+    KEYCODE_ENTRY(VK_A, 'A'),
+    KEYCODE_ENTRY(VK_B, 'B'),
+    KEYCODE_ENTRY(VK_C, 'C'),
+    KEYCODE_ENTRY(VK_D, 'D'),
+    KEYCODE_ENTRY(VK_E, 'E'),
+    KEYCODE_ENTRY(VK_F, 'F'),
+    KEYCODE_ENTRY(VK_G, 'G'),
+    KEYCODE_ENTRY(VK_H, 'H'),
+    KEYCODE_ENTRY(VK_I, 'I'),
+    KEYCODE_ENTRY(VK_J, 'J'),
+    KEYCODE_ENTRY(VK_K, 'K'),
+    KEYCODE_ENTRY(VK_L, 'L'),
+    KEYCODE_ENTRY(VK_M, 'M'),
+    KEYCODE_ENTRY(VK_N, 'N'),
+    KEYCODE_ENTRY(VK_O, 'O'),
+    KEYCODE_ENTRY(VK_P, 'P'),
+    KEYCODE_ENTRY(VK_Q, 'Q'),
+    KEYCODE_ENTRY(VK_R, 'R'),
+    KEYCODE_ENTRY(VK_S, 'S'),
+    KEYCODE_ENTRY(VK_T, 'T'),
+    KEYCODE_ENTRY(VK_U, 'U'),
+    KEYCODE_ENTRY(VK_V, 'V'),
+    KEYCODE_ENTRY(VK_W, 'W'),
+    KEYCODE_ENTRY(VK_X, 'X'),
+    KEYCODE_ENTRY(VK_Y, 'Y'),
+    KEYCODE_ENTRY(VK_Z, 'Z'),
+    KEYCODE_ENTRY(VK_CONTEXT_MENU, NSMenuFunctionKey),
+    KEYCODE_ENTRY(VK_NUMPAD0, '0'),
+    KEYCODE_ENTRY(VK_NUMPAD1, '1'),
+    KEYCODE_ENTRY(VK_NUMPAD2, '2'),
+    KEYCODE_ENTRY(VK_NUMPAD3, '3'),
+    KEYCODE_ENTRY(VK_NUMPAD4, '4'),
+    KEYCODE_ENTRY(VK_NUMPAD5, '5'),
+    KEYCODE_ENTRY(VK_NUMPAD6, '6'),
+    KEYCODE_ENTRY(VK_NUMPAD7, '7'),
+    KEYCODE_ENTRY(VK_NUMPAD8, '8'),
+    KEYCODE_ENTRY(VK_NUMPAD9, '9'),
+    KEYCODE_ENTRY(VK_MULTIPLY, '*'),
+    KEYCODE_ENTRY(VK_ADD, '+'),
+    KEYCODE_ENTRY(VK_SEPARATOR, 0),
+    KEYCODE_ENTRY(VK_SUBTRACT, '-'),
+    KEYCODE_ENTRY(VK_DECIMAL, '.'),
+    KEYCODE_ENTRY(VK_DIVIDE, '/'),
+    KEYCODE_ENTRY(VK_F1, NSF1FunctionKey),
+    KEYCODE_ENTRY(VK_F2, NSF2FunctionKey),
+    KEYCODE_ENTRY(VK_F3, NSF3FunctionKey),
+    KEYCODE_ENTRY(VK_F4, NSF4FunctionKey),
+    KEYCODE_ENTRY(VK_F5, NSF5FunctionKey),
+    KEYCODE_ENTRY(VK_F6, NSF6FunctionKey),
+    KEYCODE_ENTRY(VK_F7, NSF7FunctionKey),
+    KEYCODE_ENTRY(VK_F8, NSF8FunctionKey),
+    KEYCODE_ENTRY(VK_F9, NSF9FunctionKey),
+    KEYCODE_ENTRY(VK_F10, NSF10FunctionKey),
+    KEYCODE_ENTRY(VK_F11, NSF11FunctionKey),
+    KEYCODE_ENTRY(VK_F12, NSF12FunctionKey),
+    KEYCODE_ENTRY(VK_F13, NSF13FunctionKey),
+    KEYCODE_ENTRY(VK_F14, NSF14FunctionKey),
+    KEYCODE_ENTRY(VK_F15, NSF15FunctionKey),
+    KEYCODE_ENTRY(VK_F16, NSF16FunctionKey),
+    KEYCODE_ENTRY(VK_F17, NSF17FunctionKey),
+    KEYCODE_ENTRY(VK_F18, NSF18FunctionKey),
+    KEYCODE_ENTRY(VK_F19, NSF19FunctionKey),
+    KEYCODE_ENTRY(VK_F20, NSF20FunctionKey),
+    KEYCODE_ENTRY(VK_F21, NSF21FunctionKey),
+    KEYCODE_ENTRY(VK_F22, NSF22FunctionKey),
+    KEYCODE_ENTRY(VK_F23, NSF23FunctionKey),
+    KEYCODE_ENTRY(VK_F24, NSF24FunctionKey),
+    KEYCODE_ENTRY(VK_NUM_LOCK, NSClearLineFunctionKey),
+    KEYCODE_ENTRY(VK_SCROLL_LOCK, NSScrollLockFunctionKey),
+    KEYCODE_ENTRY(VK_COMMA, ','),
+    KEYCODE_ENTRY(VK_PERIOD, '.'),
+    KEYCODE_ENTRY(VK_SLASH, '/'),
+    KEYCODE_ENTRY(VK_BACK_QUOTE, '`'),
+    KEYCODE_ENTRY(VK_OPEN_BRACKET, '['),
+    KEYCODE_ENTRY(VK_BACK_SLASH, '\\'),
+    KEYCODE_ENTRY(VK_CLOSE_BRACKET, ']'),
+    KEYCODE_ENTRY(VK_QUOTE, '\'')
+
+#undef KEYCODE_ENTRY
+
+};
+
+uint32_t nsCocoaUtils::ConvertGeckoNameToMacCharCode(const nsAString& aKeyCodeName) {
+  if (aKeyCodeName.IsEmpty()) {
+    return 0;
+  }
+
+  nsAutoCString keyCodeName;
+  LossyCopyUTF16toASCII(aKeyCodeName, keyCodeName);
+  // We want case-insensitive comparison with data stored as uppercase.
+  ToUpperCase(keyCodeName);
+
+  uint32_t keyCodeNameLength = keyCodeName.Length();
+  const char* keyCodeNameStr = keyCodeName.get();
+  for (uint16_t i = 0; i < ArrayLength(gKeyConversions); ++i) {
+    if (keyCodeNameLength == gKeyConversions[i].strLength &&
+        nsCRT::strcmp(gKeyConversions[i].str, keyCodeNameStr) == 0) {
+      return gKeyConversions[i].charCode;
+    }
+  }
+
+  return 0;
+}
+
+uint32_t nsCocoaUtils::ConvertGeckoKeyCodeToMacCharCode(uint32_t aKeyCode) {
+  if (!aKeyCode) {
+    return 0;
+  }
+
+  for (uint16_t i = 0; i < ArrayLength(gKeyConversions); ++i) {
+    if (gKeyConversions[i].geckoKeyCode == aKeyCode) {
+      return gKeyConversions[i].charCode;
+    }
+  }
+
+  return 0;
+}
+
+NSEventModifierFlags nsCocoaUtils::ConvertWidgetModifiersToMacModifierFlags(
+    nsIWidget::Modifiers aNativeModifiers) {
+  if (!aNativeModifiers) {
+    return 0;
+  }
+  struct ModifierFlagMapEntry {
+    nsIWidget::Modifiers mWidgetModifier;
+    NSEventModifierFlags mModifierFlags;
+  };
+  static constexpr ModifierFlagMapEntry sModifierFlagMap[] = {
+      {nsIWidget::CAPS_LOCK, NSEventModifierFlagCapsLock},
+      {nsIWidget::SHIFT_L, NSEventModifierFlagShift | 0x0002},
+      {nsIWidget::SHIFT_R, NSEventModifierFlagShift | 0x0004},
+      {nsIWidget::CTRL_L, NSEventModifierFlagControl | 0x0001},
+      {nsIWidget::CTRL_R, NSEventModifierFlagControl | 0x2000},
+      {nsIWidget::ALT_L, NSEventModifierFlagOption | 0x0020},
+      {nsIWidget::ALT_R, NSEventModifierFlagOption | 0x0040},
+      {nsIWidget::COMMAND_L, NSEventModifierFlagCommand | 0x0008},
+      {nsIWidget::COMMAND_R, NSEventModifierFlagCommand | 0x0010},
+      {nsIWidget::NUMERIC_KEY_PAD, NSEventModifierFlagNumericPad},
+      {nsIWidget::HELP, NSEventModifierFlagHelp},
+      {nsIWidget::FUNCTION, NSEventModifierFlagFunction}};
+
+  NSEventModifierFlags modifierFlags = 0;
+  for (const ModifierFlagMapEntry& entry : sModifierFlagMap) {
+    if (aNativeModifiers & entry.mWidgetModifier) {
+      modifierFlags |= entry.mModifierFlags;
+    }
+  }
+  return modifierFlags;
+}
+
+mozilla::MouseButton nsCocoaUtils::ButtonForEvent(NSEvent* aEvent) {
+  switch (aEvent.type) {
+    case NSEventTypeLeftMouseDown:
+    case NSEventTypeLeftMouseDragged:
+    case NSEventTypeLeftMouseUp:
+      return MouseButton::ePrimary;
+    case NSEventTypeRightMouseDown:
+    case NSEventTypeRightMouseDragged:
+    case NSEventTypeRightMouseUp:
+      return MouseButton::eSecondary;
+    case NSEventTypeOtherMouseDown:
+    case NSEventTypeOtherMouseDragged:
+    case NSEventTypeOtherMouseUp:
+      switch (aEvent.buttonNumber) {
+        case 3:
+          return MouseButton::eX1;
+        case 4:
+          return MouseButton::eX2;
+        default:
+          // The middle button usually has button 2, but if this is a synthesized event (for which
+          // you cannot specify a buttonNumber), then the button will be 0. Treat all remaining
+          // OtherMouse events as the middle button.
+          return MouseButton::eMiddle;
+      }
+    default:
+      // Treat non-mouse events as the primary mouse button.
+      return MouseButton::ePrimary;
+  }
+}
+
+NSMutableAttributedString* nsCocoaUtils::GetNSMutableAttributedString(
+    const nsAString& aText, const nsTArray<mozilla::FontRange>& aFontRanges, const bool aIsVertical,
+    const CGFloat aBackingScaleFactor) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN
+
+  NSString* nsstr = nsCocoaUtils::ToNSString(aText);
+  NSMutableAttributedString* attrStr =
+      [[[NSMutableAttributedString alloc] initWithString:nsstr attributes:nil] autorelease];
+
+  int32_t lastOffset = aText.Length();
+  for (auto i = aFontRanges.Length(); i > 0; --i) {
+    const FontRange& fontRange = aFontRanges[i - 1];
+    NSString* fontName = nsCocoaUtils::ToNSString(fontRange.mFontName);
+    CGFloat fontSize = fontRange.mFontSize / aBackingScaleFactor;
+    NSFont* font = [NSFont fontWithName:fontName size:fontSize];
+    if (!font) {
+      font = [NSFont systemFontOfSize:fontSize];
+    }
+
+    NSDictionary* attrs = @{NSFontAttributeName : font};
+    NSRange range = NSMakeRange(fontRange.mStartOffset, lastOffset - fontRange.mStartOffset);
+    [attrStr setAttributes:attrs range:range];
+    lastOffset = fontRange.mStartOffset;
+  }
+
+  if (aIsVertical) {
+    [attrStr addAttribute:NSVerticalGlyphFormAttributeName
+                    value:[NSNumber numberWithInt:1]
+                    range:NSMakeRange(0, [attrStr length])];
+  }
+
+  return attrStr;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil)
+}
+
+TimeStamp nsCocoaUtils::GetEventTimeStamp(NSTimeInterval aEventTime) {
+  if (!aEventTime) {
+    // If the event is generated by a 3rd party application, its timestamp
+    // may be 0.  In this case, just return current timestamp.
+    // XXX Should we cache last event time?
+    return TimeStamp::Now();
+  }
+  // The internal value of the macOS implementation of TimeStamp is based on
+  // mach_absolute_time(), which measures "ticks" since boot.
+  // Event timestamps are NSTimeIntervals (seconds) since boot. So the two time
+  // representations already have the same base; we only need to convert
+  // seconds into ticks.
+  int64_t tick = BaseTimeDurationPlatformUtils::TicksFromMilliseconds(aEventTime * 1000.0);
+  return TimeStamp::FromSystemTime(tick);
+}
+
+static NSString* ActionOnDoubleClickSystemPref() {
+  NSUserDefaults* userDefaults = [NSUserDefaults standardUserDefaults];
+  NSString* kAppleActionOnDoubleClickKey = @"AppleActionOnDoubleClick";
+  id value = [userDefaults objectForKey:kAppleActionOnDoubleClickKey];
+  if ([value isKindOfClass:[NSString class]]) {
+    return value;
+  }
+  return nil;
+}
+
+@interface NSWindow (NSWindowShouldZoomOnDoubleClick)
++ (BOOL)_shouldZoomOnDoubleClick;  // present on 10.7 and above
+@end
+
+bool nsCocoaUtils::ShouldZoomOnTitlebarDoubleClick() {
+  if ([NSWindow respondsToSelector:@selector(_shouldZoomOnDoubleClick)]) {
+    return [NSWindow _shouldZoomOnDoubleClick];
+  }
+  return [ActionOnDoubleClickSystemPref() isEqualToString:@"Maximize"];
+}
+
+bool nsCocoaUtils::ShouldMinimizeOnTitlebarDoubleClick() {
+  // Check the system preferences.
+  // We could also check -[NSWindow _shouldMiniaturizeOnDoubleClick]. It's not clear to me which
+  // approach would be preferable; neither is public API.
+  return [ActionOnDoubleClickSystemPref() isEqualToString:@"Minimize"];
+}
+
+// AVAuthorizationStatus is not needed unless we are running on 10.14.
+// However, on pre-10.14 SDK's, AVAuthorizationStatus and its enum values
+// are both defined and prohibited from use by compile-time checks. We
+// define a copy of AVAuthorizationStatus to allow compilation on pre-10.14
+// SDK's. The enum values must match what is defined in the 10.14 SDK.
+// We use ASSERTS for 10.14 SDK builds to check the enum values match.
+enum GeckoAVAuthorizationStatus : NSInteger {
+  GeckoAVAuthorizationStatusNotDetermined = 0,
+  GeckoAVAuthorizationStatusRestricted = 1,
+  GeckoAVAuthorizationStatusDenied = 2,
+  GeckoAVAuthorizationStatusAuthorized = 3
+};
+
+#if !defined(MAC_OS_X_VERSION_10_14) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_14
+// Define authorizationStatusForMediaType: as returning
+// GeckoAVAuthorizationStatus instead of AVAuthorizationStatus to allow
+// compilation on pre-10.14 SDK's.
+@interface AVCaptureDevice (GeckoAVAuthorizationStatus)
++ (GeckoAVAuthorizationStatus)authorizationStatusForMediaType:(AVMediaType)mediaType;
+@end
+
+@interface AVCaptureDevice (WithCompletionHandler)
++ (void)requestAccessForMediaType:(AVMediaType)mediaType
+                completionHandler:(void (^)(BOOL granted))handler;
+@end
+#endif
+
+static const char* AVMediaTypeToString(AVMediaType aType) {
+  if (aType == AVMediaTypeVideo) {
+    return "video";
+  }
+
+  if (aType == AVMediaTypeAudio) {
+    return "audio";
+  }
+
+  return "unexpected type";
+}
+
+static void LogAuthorizationStatus(AVMediaType aType, int aState) {
+  const char* stateString;
+
+  switch (aState) {
+    case GeckoAVAuthorizationStatusAuthorized:
+      stateString = "AVAuthorizationStatusAuthorized";
+      break;
+    case GeckoAVAuthorizationStatusDenied:
+      stateString = "AVAuthorizationStatusDenied";
+      break;
+    case GeckoAVAuthorizationStatusNotDetermined:
+      stateString = "AVAuthorizationStatusNotDetermined";
+      break;
+    case GeckoAVAuthorizationStatusRestricted:
+      stateString = "AVAuthorizationStatusRestricted";
+      break;
+    default:
+      stateString = "Invalid state";
+  }
+
+  LOG("%s authorization status: %s\n", AVMediaTypeToString(aType), stateString);
+}
+
+static nsresult GetPermissionState(AVMediaType aMediaType, uint16_t& aState) {
+  MOZ_ASSERT(aMediaType == AVMediaTypeVideo || aMediaType == AVMediaTypeAudio);
+
+  // Only attempt to check authorization status on 10.14+.
+  if (@available(macOS 10.14, *)) {
+    GeckoAVAuthorizationStatus authStatus = static_cast<GeckoAVAuthorizationStatus>(
+        [AVCaptureDevice authorizationStatusForMediaType:aMediaType]);
+    LogAuthorizationStatus(aMediaType, authStatus);
+
+    // Convert GeckoAVAuthorizationStatus to nsIOSPermissionRequest const
+    switch (authStatus) {
+      case GeckoAVAuthorizationStatusAuthorized:
+        aState = nsIOSPermissionRequest::PERMISSION_STATE_AUTHORIZED;
+        return NS_OK;
+      case GeckoAVAuthorizationStatusDenied:
+        aState = nsIOSPermissionRequest::PERMISSION_STATE_DENIED;
+        return NS_OK;
+      case GeckoAVAuthorizationStatusNotDetermined:
+        aState = nsIOSPermissionRequest::PERMISSION_STATE_NOTDETERMINED;
+        return NS_OK;
+      case GeckoAVAuthorizationStatusRestricted:
+        aState = nsIOSPermissionRequest::PERMISSION_STATE_RESTRICTED;
+        return NS_OK;
+      default:
+        MOZ_ASSERT(false, "Invalid authorization status");
+        return NS_ERROR_UNEXPECTED;
+    }
+  }
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+nsresult nsCocoaUtils::GetVideoCapturePermissionState(uint16_t& aPermissionState) {
+  return GetPermissionState(AVMediaTypeVideo, aPermissionState);
+}
+
+nsresult nsCocoaUtils::GetAudioCapturePermissionState(uint16_t& aPermissionState) {
+  return GetPermissionState(AVMediaTypeAudio, aPermissionState);
+}
+
+// Set |aPermissionState| to PERMISSION_STATE_AUTHORIZED if this application
+// has already been granted permission to record the screen in macOS Security
+// and Privacy system settings. If we do not have permission (because the user
+// hasn't yet been asked yet or the user previously denied the prompt), use
+// PERMISSION_STATE_DENIED. Returns NS_ERROR_NOT_IMPLEMENTED on macOS 10.14
+// and earlier.
+nsresult nsCocoaUtils::GetScreenCapturePermissionState(uint16_t& aPermissionState) {
+  aPermissionState = nsIOSPermissionRequest::PERMISSION_STATE_NOTDETERMINED;
+
+  // Only attempt to check screen recording authorization status on 10.15+.
+  // On earlier macOS versions, screen recording is allowed by default.
+  if (@available(macOS 10.15, *)) {
+    if (!StaticPrefs::media_macos_screenrecording_oscheck_enabled()) {
+      aPermissionState = nsIOSPermissionRequest::PERMISSION_STATE_AUTHORIZED;
+      LOG("screen authorization status: authorized (test disabled via pref)");
+      return NS_OK;
+    }
+
+    // Unlike with camera and microphone capture, there is no support for
+    // checking the screen recording permission status. Instead, an application
+    // can use the presence of window names (which are privacy sensitive) in
+    // the window info list as an indication. The list only includes window
+    // names if the calling application has been authorized to record the
+    // screen. We use the window name, window level, and owning PID as
+    // heuristics to determine if we have screen recording permission.
+    AutoCFRelease<CFArrayRef> windowArray =
+        CGWindowListCopyWindowInfo(kCGWindowListOptionAll, kCGNullWindowID);
+    if (!windowArray) {
+      LOG("GetScreenCapturePermissionState() ERROR: got NULL window info list");
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    int32_t windowLevelDock = CGWindowLevelForKey(kCGDockWindowLevelKey);
+    int32_t windowLevelNormal = CGWindowLevelForKey(kCGNormalWindowLevelKey);
+    LOG("GetScreenCapturePermissionState(): DockWindowLevel: %d, "
+        "NormalWindowLevel: %d",
+        windowLevelDock, windowLevelNormal);
+
+    int32_t thisPid = [[NSProcessInfo processInfo] processIdentifier];
+
+    CFIndex windowCount = CFArrayGetCount(windowArray);
+    LOG("GetScreenCapturePermissionState() returned %ld windows", windowCount);
+    if (windowCount == 0) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    for (CFIndex i = 0; i < windowCount; i++) {
+      CFDictionaryRef windowDict =
+          reinterpret_cast<CFDictionaryRef>(CFArrayGetValueAtIndex(windowArray, i));
+
+      // Get the window owner's PID
+      int32_t windowOwnerPid = -1;
+      CFNumberRef windowPidRef =
+          reinterpret_cast<CFNumberRef>(CFDictionaryGetValue(windowDict, kCGWindowOwnerPID));
+      if (!windowPidRef || !CFNumberGetValue(windowPidRef, kCFNumberIntType, &windowOwnerPid)) {
+        LOG("GetScreenCapturePermissionState() ERROR: failed to get window owner");
+        continue;
+      }
+
+      // Our own window names are always readable and
+      // therefore not relevant to the heuristic.
+      if (thisPid == windowOwnerPid) {
+        continue;
+      }
+
+      CFStringRef windowName =
+          reinterpret_cast<CFStringRef>(CFDictionaryGetValue(windowDict, kCGWindowName));
+      if (!windowName) {
+        continue;
+      }
+
+      CFNumberRef windowLayerRef =
+          reinterpret_cast<CFNumberRef>(CFDictionaryGetValue(windowDict, kCGWindowLayer));
+      int32_t windowLayer;
+      if (!windowLayerRef || !CFNumberGetValue(windowLayerRef, kCFNumberIntType, &windowLayer)) {
+        LOG("GetScreenCapturePermissionState() ERROR: failed to get layer");
+        continue;
+      }
+
+      // If we have a window name and the window is in the dock or normal window
+      // level, and for another process, assume we have screen recording access.
+      LOG("GetScreenCapturePermissionState(): windowLayer: %d", windowLayer);
+      if (windowLayer == windowLevelDock || windowLayer == windowLevelNormal) {
+        aPermissionState = nsIOSPermissionRequest::PERMISSION_STATE_AUTHORIZED;
+        LOG("screen authorization status: authorized");
+        return NS_OK;
+      }
+    }
+
+    aPermissionState = nsIOSPermissionRequest::PERMISSION_STATE_DENIED;
+    LOG("screen authorization status: not authorized");
+    return NS_OK;
+  }
+
+  LOG("GetScreenCapturePermissionState(): nothing to do, not on 10.15+");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+nsresult nsCocoaUtils::RequestVideoCapturePermission(RefPtr<Promise>& aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+  return nsCocoaUtils::RequestCapturePermission(AVMediaTypeVideo, aPromise, sVideoCapturePromises,
+                                                VideoCompletionHandler);
+}
+
+nsresult nsCocoaUtils::RequestAudioCapturePermission(RefPtr<Promise>& aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+  return nsCocoaUtils::RequestCapturePermission(AVMediaTypeAudio, aPromise, sAudioCapturePromises,
+                                                AudioCompletionHandler);
+}
+
+//
+// Stores |aPromise| on |aPromiseList| and starts an asynchronous media
+// capture request for the given media type |aType|. If we are already
+// waiting for a capture request for this media type, don't start a new
+// request. |aHandler| is invoked on an arbitrary dispatch queue when the
+// request completes and must resolve any waiting Promises on the main
+// thread.
+//
+nsresult nsCocoaUtils::RequestCapturePermission(AVMediaType aType, RefPtr<Promise>& aPromise,
+                                                PromiseArray& aPromiseList,
+                                                void (^aHandler)(BOOL granted)) {
+  MOZ_ASSERT(aType == AVMediaTypeVideo || aType == AVMediaTypeAudio);
+#if defined(MAC_OS_X_VERSION_10_14)
+  // Ensure our enum constants match. We can only do this when
+  // compiling on 10.14+ because AVAuthorizationStatus is
+  // prohibited by preprocessor checks on earlier OS versions.
+  if (@available(macOS 10.14, *)) {
+    static_assert(
+        (int)GeckoAVAuthorizationStatusNotDetermined == (int)AVAuthorizationStatusNotDetermined,
+        "GeckoAVAuthorizationStatusNotDetermined  does not match");
+    static_assert((int)GeckoAVAuthorizationStatusRestricted == (int)AVAuthorizationStatusRestricted,
+                  "GeckoAVAuthorizationStatusRestricted does not match");
+    static_assert((int)GeckoAVAuthorizationStatusDenied == (int)AVAuthorizationStatusDenied,
+                  "GeckoAVAuthorizationStatusDenied does not match");
+    static_assert((int)GeckoAVAuthorizationStatusAuthorized == (int)AVAuthorizationStatusAuthorized,
+                  "GeckoAVAuthorizationStatusAuthorized does not match");
+  }
+#endif
+  LOG("RequestCapturePermission(%s)", AVMediaTypeToString(aType));
+
+  // Only attempt to request authorization on 10.14+.
+  if (@available(macOS 10.14, *)) {
+    sMediaCaptureMutex.Lock();
+
+    // Initialize our list of promises on first invocation
+    if (aPromiseList == nullptr) {
+      aPromiseList = new nsTArray<RefPtr<Promise>>;
+      ClearOnShutdown(&aPromiseList);
+    }
+
+    aPromiseList->AppendElement(aPromise);
+    size_t nPromises = aPromiseList->Length();
+
+    sMediaCaptureMutex.Unlock();
+
+    LOG("RequestCapturePermission(%s): %ld promise(s) unresolved", AVMediaTypeToString(aType),
+        nPromises);
+
+    // If we had one or more more existing promises waiting to be resolved
+    // by the completion handler, we don't need to start another request.
+    if (nPromises > 1) {
+      return NS_OK;
+    }
+
+    // Start the request
+    [AVCaptureDevice requestAccessForMediaType:aType completionHandler:aHandler];
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+//
+// Audio capture request completion handler. Called from an arbitrary
+// dispatch queue.
+//
+void (^nsCocoaUtils::AudioCompletionHandler)(BOOL) = ^void(BOOL granted) {
+  nsCocoaUtils::ResolveAudioCapturePromises(granted);
+};
+
+//
+// Video capture request completion handler. Called from an arbitrary
+// dispatch queue.
+//
+void (^nsCocoaUtils::VideoCompletionHandler)(BOOL) = ^void(BOOL granted) {
+  nsCocoaUtils::ResolveVideoCapturePromises(granted);
+};
+
+void nsCocoaUtils::ResolveMediaCapturePromises(bool aGranted, PromiseArray& aPromiseList) {
+  StaticMutexAutoLock lock(sMediaCaptureMutex);
+
+  // Remove each promise from the list and resolve it.
+  while (aPromiseList->Length() > 0) {
+    RefPtr<Promise> promise = aPromiseList->PopLastElement();
+
+    // Resolve on main thread
+    nsCOMPtr<nsIRunnable> runnable(NS_NewRunnableFunction(
+        "ResolveMediaAccessPromise",
+        [aGranted, aPromise = std::move(promise)]() { aPromise->MaybeResolve(aGranted); }));
+    NS_DispatchToMainThread(runnable.forget());
+  }
+}
+
+void nsCocoaUtils::ResolveAudioCapturePromises(bool aGranted) {
+  // Resolve on main thread
+  nsCOMPtr<nsIRunnable> runnable(NS_NewRunnableFunction("ResolveAudioCapturePromise", [aGranted]() {
+    ResolveMediaCapturePromises(aGranted, sAudioCapturePromises);
+  }));
+  NS_DispatchToMainThread(runnable.forget());
+}
+
+//
+// Attempt to trigger a dialog requesting permission to record the screen.
+// Unlike with the camera and microphone, there is no API to request permission
+// to record the screen or to receive a callback when permission is explicitly
+// allowed or denied. Here we attempt to trigger the dialog by attempting to
+// capture a 1x1 pixel section of the screen. The permission dialog is not
+// guaranteed to be displayed because the user may have already been prompted
+// in which case macOS does not display the dialog again.
+//
+nsresult nsCocoaUtils::MaybeRequestScreenCapturePermission() {
+  LOG("MaybeRequestScreenCapturePermission()");
+  AutoCFRelease<CGImageRef> image =
+      CGDisplayCreateImageForRect(kCGDirectMainDisplay, CGRectMake(0, 0, 1, 1));
+  return NS_OK;
+}
+
+void nsCocoaUtils::ResolveVideoCapturePromises(bool aGranted) {
+  // Resolve on main thread
+  nsCOMPtr<nsIRunnable> runnable(NS_NewRunnableFunction("ResolveVideoCapturePromise", [aGranted]() {
+    ResolveMediaCapturePromises(aGranted, sVideoCapturePromises);
+  }));
+  NS_DispatchToMainThread(runnable.forget());
+}
+
+static PanGestureInput::PanGestureType PanGestureTypeForEvent(NSEvent* aEvent) {
+  switch ([aEvent phase]) {
+    case NSEventPhaseMayBegin:
+      return PanGestureInput::PANGESTURE_MAYSTART;
+    case NSEventPhaseCancelled:
+      return PanGestureInput::PANGESTURE_CANCELLED;
+    case NSEventPhaseBegan:
+      return PanGestureInput::PANGESTURE_START;
+    case NSEventPhaseChanged:
+      return PanGestureInput::PANGESTURE_PAN;
+    case NSEventPhaseEnded:
+      return PanGestureInput::PANGESTURE_END;
+    case NSEventPhaseNone:
+      switch ([aEvent momentumPhase]) {
+        case NSEventPhaseBegan:
+          return PanGestureInput::PANGESTURE_MOMENTUMSTART;
+        case NSEventPhaseChanged:
+          return PanGestureInput::PANGESTURE_MOMENTUMPAN;
+        case NSEventPhaseEnded:
+          return PanGestureInput::PANGESTURE_MOMENTUMEND;
+        default:
+          NS_ERROR("unexpected event phase");
+          return PanGestureInput::PANGESTURE_PAN;
+      }
+    default:
+      NS_ERROR("unexpected event phase");
+      return PanGestureInput::PANGESTURE_PAN;
+  }
+}
+
+bool static ShouldConsiderStartingSwipeFromEvent(NSEvent* anEvent) {
+  // Only initiate horizontal tracking for gestures that have just begun --
+  // otherwise a scroll to one side of the page can have a swipe tacked on
+  // to it.
+  // [NSEvent isSwipeTrackingFromScrollEventsEnabled] checks whether the
+  // AppleEnableSwipeNavigateWithScrolls global preference is set.  If it isn't,
+  // fluid swipe tracking is disabled, and a horizontal two-finger gesture is
+  // always a scroll (even in Safari).  This preference can't (currently) be set
+  // from the Preferences UI -- only using 'defaults write'.
+  NSEventPhase eventPhase = [anEvent phase];
+  return [anEvent type] == NSEventTypeScrollWheel && eventPhase == NSEventPhaseBegan &&
+         [anEvent hasPreciseScrollingDeltas] && [NSEvent isSwipeTrackingFromScrollEventsEnabled];
+}
+
+PanGestureInput nsCocoaUtils::CreatePanGestureEvent(NSEvent* aNativeEvent, TimeStamp aTimeStamp,
+                                                    const ScreenPoint& aPanStartPoint,
+                                                    const ScreenPoint& aPreciseDelta,
+                                                    const gfx::IntPoint& aLineOrPageDelta,
+                                                    Modifiers aModifiers) {
+  PanGestureInput::PanGestureType type = PanGestureTypeForEvent(aNativeEvent);
+  // Always force zero deltas on event types that shouldn't cause any scrolling,
+  // so that we don't dispatch DOM wheel events for them.
+  bool shouldIgnoreDeltas =
+      type == PanGestureInput::PANGESTURE_MAYSTART || type == PanGestureInput::PANGESTURE_CANCELLED;
+
+  PanGestureInput panEvent(
+      type, aTimeStamp, aPanStartPoint, !shouldIgnoreDeltas ? aPreciseDelta : ScreenPoint(),
+      aModifiers,
+      PanGestureInput::IsEligibleForSwipe(ShouldConsiderStartingSwipeFromEvent(aNativeEvent)));
+
+  if (!shouldIgnoreDeltas) {
+    panEvent.SetLineOrPageDeltas(aLineOrPageDelta.x, aLineOrPageDelta.y);
+  }
+
+  return panEvent;
+}
+
+bool nsCocoaUtils::IsValidPasteboardType(NSString* aAvailableType, bool aAllowFileURL) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // Prevent exposing fileURL for non-fileURL type.
+  // We need URL provided by dropped webloc file, but don't need file's URL.
+  // kUTTypeFileURL is returned by [NSPasteboard availableTypeFromArray:] for
+  // kPublicUrlPboardType, since it conforms to kPublicUrlPboardType.
+  bool isValid = true;
+  if (!aAllowFileURL &&
+      [aAvailableType isEqualToString:[UTIHelper stringFromPboardType:(NSString*)kUTTypeFileURL]]) {
+    isValid = false;
+  }
+
+  return isValid;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+NSString* nsCocoaUtils::GetStringForTypeFromPasteboardItem(NSPasteboardItem* aItem,
+                                                           const NSString* aType,
+                                                           bool aAllowFileURL) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSString* availableType =
+      [aItem availableTypeFromArray:[NSArray arrayWithObjects:(id)aType, nil]];
+  if (availableType && IsValidPasteboardType(availableType, aAllowFileURL)) {
+    return [aItem stringForType:(id)availableType];
+  }
+
+  return nil;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+NSString* nsCocoaUtils::GetFilePathFromPasteboardItem(NSPasteboardItem* aItem) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSString* urlString = GetStringForTypeFromPasteboardItem(
+      aItem, [UTIHelper stringFromPboardType:(NSString*)kUTTypeFileURL], true);
+  if (urlString) {
+    NSURL* url = [NSURL URLWithString:urlString];
+    if (url) {
+      return [url path];
+    }
+  }
+
+  return nil;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+NSString* nsCocoaUtils::GetTitleForURLFromPasteboardItem(NSPasteboardItem* item) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSString* name = nsCocoaUtils::GetStringForTypeFromPasteboardItem(
+      item, [UTIHelper stringFromPboardType:kPublicUrlNamePboardType]);
+  if (name) {
+    return name;
+  }
+
+  NSString* filePath = nsCocoaUtils::GetFilePathFromPasteboardItem(item);
+  if (filePath) {
+    return [filePath lastPathComponent];
+  }
+
+  return nil;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+void nsCocoaUtils::SetTransferDataForTypeFromPasteboardItem(nsITransferable* aTransferable,
+                                                            const nsCString& aFlavor,
+                                                            NSPasteboardItem* aItem) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!aTransferable || !aItem) {
+    return;
+  }
+
+  MOZ_LOG(gCocoaUtilsLog, LogLevel::Info,
+          ("nsCocoaUtils::SetTransferDataForTypeFromPasteboardItem: looking for pasteboard data of "
+           "type %s\n",
+           aFlavor.get()));
+
+  if (aFlavor.EqualsLiteral(kFileMime)) {
+    NSString* filePath = nsCocoaUtils::GetFilePathFromPasteboardItem(aItem);
+    if (!filePath) {
+      return;
+    }
+
+    unsigned int stringLength = [filePath length];
+    unsigned int dataLength = (stringLength + 1) * sizeof(char16_t);  // in bytes
+    char16_t* clipboardDataPtr = (char16_t*)malloc(dataLength);
+    if (!clipboardDataPtr) {
+      return;
+    }
+
+    [filePath getCharacters:reinterpret_cast<unichar*>(clipboardDataPtr)];
+    clipboardDataPtr[stringLength] = 0;  // null terminate
+
+    nsCOMPtr<nsIFile> file;
+    nsresult rv = NS_NewLocalFile(nsDependentString(clipboardDataPtr), true, getter_AddRefs(file));
+    free(clipboardDataPtr);
+    if (NS_FAILED(rv)) {
+      return;
+    }
+
+    aTransferable->SetTransferData(aFlavor.get(), file);
+    return;
+  }
+
+  if (aFlavor.EqualsLiteral(kCustomTypesMime)) {
+    NSString* availableType =
+        [aItem availableTypeFromArray:[NSArray arrayWithObject:kMozCustomTypesPboardType]];
+    if (!availableType || !nsCocoaUtils::IsValidPasteboardType(availableType, false)) {
+      return;
+    }
+    NSData* pasteboardData = [aItem dataForType:availableType];
+    if (!pasteboardData) {
+      return;
+    }
+
+    unsigned int dataLength = [pasteboardData length];
+    void* clipboardDataPtr = malloc(dataLength);
+    if (!clipboardDataPtr) {
+      return;
+    }
+    [pasteboardData getBytes:clipboardDataPtr length:dataLength];
+
+    nsCOMPtr<nsISupports> genericDataWrapper;
+    nsPrimitiveHelpers::CreatePrimitiveForData(aFlavor, clipboardDataPtr, dataLength,
+                                               getter_AddRefs(genericDataWrapper));
+
+    aTransferable->SetTransferData(aFlavor.get(), genericDataWrapper);
+    free(clipboardDataPtr);
+    return;
+  }
+
+  NSString* pString = nil;
+  if (aFlavor.EqualsLiteral(kTextMime)) {
+    pString = nsCocoaUtils::GetStringForTypeFromPasteboardItem(
+        aItem, [UTIHelper stringFromPboardType:NSPasteboardTypeString]);
+  } else if (aFlavor.EqualsLiteral(kHTMLMime)) {
+    pString = nsCocoaUtils::GetStringForTypeFromPasteboardItem(
+        aItem, [UTIHelper stringFromPboardType:NSPasteboardTypeHTML]);
+  } else if (aFlavor.EqualsLiteral(kURLMime)) {
+    pString = nsCocoaUtils::GetStringForTypeFromPasteboardItem(
+        aItem, [UTIHelper stringFromPboardType:kPublicUrlPboardType]);
+    if (pString) {
+      NSString* title = GetTitleForURLFromPasteboardItem(aItem);
+      if (!title) {
+        title = pString;
+      }
+      pString = [NSString stringWithFormat:@"%@\n%@", pString, title];
+    }
+  } else if (aFlavor.EqualsLiteral(kURLDataMime)) {
+    pString = nsCocoaUtils::GetStringForTypeFromPasteboardItem(
+        aItem, [UTIHelper stringFromPboardType:kPublicUrlPboardType]);
+  } else if (aFlavor.EqualsLiteral(kURLDescriptionMime)) {
+    pString = GetTitleForURLFromPasteboardItem(aItem);
+  } else if (aFlavor.EqualsLiteral(kRTFMime)) {
+    pString = nsCocoaUtils::GetStringForTypeFromPasteboardItem(
+        aItem, [UTIHelper stringFromPboardType:NSPasteboardTypeRTF]);
+  }
+  if (pString) {
+    NSData* stringData;
+    bool isRTF = aFlavor.EqualsLiteral(kRTFMime);
+    if (isRTF) {
+      stringData = [pString dataUsingEncoding:NSASCIIStringEncoding];
+    } else {
+      stringData = [pString dataUsingEncoding:NSUnicodeStringEncoding];
+    }
+    unsigned int dataLength = [stringData length];
+    void* clipboardDataPtr = malloc(dataLength);
+    if (!clipboardDataPtr) {
+      return;
+    }
+    [stringData getBytes:clipboardDataPtr length:dataLength];
+
+    // The DOM only wants LF, so convert from MacOS line endings to DOM line endings.
+    int32_t signedDataLength = dataLength;
+    nsLinebreakHelpers::ConvertPlatformToDOMLinebreaks(isRTF, &clipboardDataPtr, &signedDataLength);
+    dataLength = signedDataLength;
+
+    // skip BOM (Byte Order Mark to distinguish little or big endian)
+    char16_t* clipboardDataPtrNoBOM = (char16_t*)clipboardDataPtr;
+    if ((dataLength > 2) &&
+        ((clipboardDataPtrNoBOM[0] == 0xFEFF) || (clipboardDataPtrNoBOM[0] == 0xFFFE))) {
+      dataLength -= sizeof(char16_t);
+      clipboardDataPtrNoBOM += 1;
+    }
+
+    nsCOMPtr<nsISupports> genericDataWrapper;
+    nsPrimitiveHelpers::CreatePrimitiveForData(aFlavor, clipboardDataPtrNoBOM, dataLength,
+                                               getter_AddRefs(genericDataWrapper));
+    aTransferable->SetTransferData(aFlavor.get(), genericDataWrapper);
+    free(clipboardDataPtr);
+    return;
+  }
+
+  // We have never supported this on Mac OS X, we should someday. Normally dragging images
+  // in is accomplished with a file path drag instead of the image data itself.
+  /*
+  if (aFlavor.EqualsLiteral(kPNGImageMime) || aFlavor.EqualsLiteral(kJPEGImageMime) ||
+      aFlavor.EqualsLiteral(kJPGImageMime) || aFlavor.EqualsLiteral(kGIFImageMime)) {
+
+  }
+  */
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
diff --git a/widget/cocoa/nsCocoaWindow.h b/widget/cocoa/nsCocoaWindow.h
new file mode 100644
index 0000000000..5c57fcea55
--- /dev/null
+++ b/widget/cocoa/nsCocoaWindow.h
@@ -0,0 +1,493 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCocoaWindow_h_
+#define nsCocoaWindow_h_
+
+#undef DARWIN
+
+#import <Cocoa/Cocoa.h>
+
+#include "mozilla/RefPtr.h"
+#include "nsBaseWidget.h"
+#include "nsPIWidgetCocoa.h"
+#include "nsCocoaUtils.h"
+#include "nsTouchBar.h"
+#include <dlfcn.h>
+#include <queue>
+
+class nsCocoaWindow;
+class nsChildView;
+class nsMenuBarX;
+@class ChildView;
+
+namespace mozilla {
+enum class NativeKeyBindingsType : uint8_t;
+}  // namespace mozilla
+
+typedef struct _nsCocoaWindowList {
+  _nsCocoaWindowList() : prev(nullptr), window(nullptr) {}
+  struct _nsCocoaWindowList* prev;
+  nsCocoaWindow* window;  // Weak
+} nsCocoaWindowList;
+
+// NSWindow subclass that is the base class for all of our own window classes.
+// Among other things, this class handles the storage of those settings that
+// need to be persisted across window destruction and reconstruction, i.e. when
+// switching to and from fullscreen mode.
+// We don't save shadow, transparency mode or background color because it's not
+// worth the hassle - Gecko will reset them anyway as soon as the window is
+// resized.
+@interface BaseWindow : NSWindow {
+  // Data Storage
+  NSMutableDictionary* mState;
+  BOOL mDrawsIntoWindowFrame;
+
+  // Invalidation disabling
+  BOOL mDisabledNeedsDisplay;
+
+  NSTrackingArea* mTrackingArea;
+
+  NSRect mDirtyRect;
+
+  BOOL mBeingShown;
+  BOOL mDrawTitle;
+  BOOL mUseMenuStyle;
+  BOOL mIsAnimationSuppressed;
+
+  nsTouchBar* mTouchBar;
+}
+
+- (void)importState:(NSDictionary*)aState;
+- (NSMutableDictionary*)exportState;
+- (void)setDrawsContentsIntoWindowFrame:(BOOL)aState;
+- (BOOL)drawsContentsIntoWindowFrame;
+
+// These two methods are like contentRectForFrameRect and frameRectForContentRect,
+// but they deal with the rect of the window's "main ChildView" instead of the
+// rect of the window's content view. The two are sometimes sized differently: The
+// window's content view always covers the entire window, whereas the ChildView
+// only covers the full window when drawsContentsIntoWindowFrame is YES. When
+// drawsContentsIntoWindowFrame is NO, there's a titlebar-sized gap above the
+// ChildView within the content view.
+- (NSRect)childViewRectForFrameRect:(NSRect)aFrameRect;
+- (NSRect)frameRectForChildViewRect:(NSRect)aChildViewRect;
+
+- (void)mouseEntered:(NSEvent*)aEvent;
+- (void)mouseExited:(NSEvent*)aEvent;
+- (void)mouseMoved:(NSEvent*)aEvent;
+- (void)updateTrackingArea;
+- (NSView*)trackingAreaView;
+
+- (void)setBeingShown:(BOOL)aValue;
+- (BOOL)isBeingShown;
+- (BOOL)isVisibleOrBeingShown;
+
+- (void)setIsAnimationSuppressed:(BOOL)aValue;
+- (BOOL)isAnimationSuppressed;
+
+// Returns an autoreleased NSArray containing the NSViews that we consider the
+// "contents" of this window. All views in the returned array are subviews of
+// this window's content view. However, the array may not include all of the
+// content view's subviews; concretely, the ToolbarWindow implementation will
+// exclude its MOZTitlebarView from the array that is returned here.
+// In the vast majority of cases, the array will only have a single element:
+// this window's mainChildView.
+- (NSArray<NSView*>*)contentViewContents;
+
+- (ChildView*)mainChildView;
+
+- (void)setWantsTitleDrawn:(BOOL)aDrawTitle;
+- (BOOL)wantsTitleDrawn;
+
+- (void)disableSetNeedsDisplay;
+- (void)enableSetNeedsDisplay;
+
+- (NSRect)getAndResetNativeDirtyRect;
+
+- (void)setUseMenuStyle:(BOOL)aValue;
+@property(nonatomic) mozilla::StyleWindowShadow shadowStyle;
+
+- (void)releaseJSObjects;
+
+@end
+
+@interface NSWindow (Undocumented)
+
+// If a window has been explicitly removed from the "window cache" (to
+// deactivate it), it's sometimes necessary to "reset" it to reactivate it
+// (and put it back in the "window cache").  One way to do this, which Apple
+// often uses, is to set the "window number" to '-1' and then back to its
+// original value.
+- (void)_setWindowNumber:(NSInteger)aNumber;
+
+- (BOOL)bottomCornerRounded;
+
+// Present in the same form on OS X since at least OS X 10.5.
+- (NSRect)contentRectForFrameRect:(NSRect)windowFrame styleMask:(NSUInteger)windowStyle;
+- (NSRect)frameRectForContentRect:(NSRect)windowContentRect styleMask:(NSUInteger)windowStyle;
+
+// Present since at least OS X 10.5.  The OS calls this method on NSWindow
+// (and its subclasses) to find out which NSFrameView subclass to instantiate
+// to create its "frame view".
++ (Class)frameViewClassForStyleMask:(NSUInteger)styleMask;
+
+@end
+
+@interface PopupWindow : BaseWindow {
+ @private
+  BOOL mIsContextMenu;
+}
+
+- (id)initWithContentRect:(NSRect)contentRect
+                styleMask:(NSUInteger)styleMask
+                  backing:(NSBackingStoreType)bufferingType
+                    defer:(BOOL)deferCreation;
+- (BOOL)isContextMenu;
+- (void)setIsContextMenu:(BOOL)flag;
+- (BOOL)canBecomeMainWindow;
+
+@end
+
+@interface BorderlessWindow : BaseWindow {
+}
+
+- (BOOL)canBecomeKeyWindow;
+- (BOOL)canBecomeMainWindow;
+
+@end
+
+@interface WindowDelegate : NSObject <NSWindowDelegate> {
+  nsCocoaWindow* mGeckoWindow;  // [WEAK] (we are owned by the window)
+  // Used to avoid duplication when we send NS_ACTIVATE and
+  // NS_DEACTIVATE to Gecko for toplevel widgets.  Starts out
+  // false.
+  bool mToplevelActiveState;
+  BOOL mHasEverBeenZoomed;
+}
++ (void)paintMenubarForWindow:(NSWindow*)aWindow;
+- (id)initWithGeckoWindow:(nsCocoaWindow*)geckoWind;
+- (void)windowDidResize:(NSNotification*)aNotification;
+- (nsCocoaWindow*)geckoWidget;
+- (bool)toplevelActiveState;
+- (void)sendToplevelActivateEvents;
+- (void)sendToplevelDeactivateEvents;
+@end
+
+@interface MOZTitlebarView : NSVisualEffectView
+@end
+
+@interface FullscreenTitlebarTracker : NSTitlebarAccessoryViewController
+- (FullscreenTitlebarTracker*)init;
+@end
+
+// NSWindow subclass for handling windows with toolbars.
+@interface ToolbarWindow : BaseWindow {
+  // This window's titlebar view, if present.
+  // Will be nil if the window has neither a titlebar nor a unified toolbar.
+  // This view is a subview of the window's content view and gets created and
+  // destroyed by updateTitlebarView.
+  MOZTitlebarView* mTitlebarView;  // [STRONG]
+  // mFullscreenTitlebarTracker attaches an invisible rectangle to the system
+  // title bar. This allows us to detect when the title bar is showing in
+  // fullscreen.
+  FullscreenTitlebarTracker* mFullscreenTitlebarTracker;
+
+  CGFloat mUnifiedToolbarHeight;
+  CGFloat mSheetAttachmentPosition;
+  CGFloat mMenuBarHeight;
+  /* Store the height of the titlebar when this window is initialized. The
+     titlebarHeight getter returns 0 when in fullscreen, which is not useful in
+     some cases. */
+  CGFloat mInitialTitlebarHeight;
+  NSRect mWindowButtonsRect;
+}
+- (void)setUnifiedToolbarHeight:(CGFloat)aHeight;
+- (CGFloat)unifiedToolbarHeight;
+- (CGFloat)titlebarHeight;
+- (NSRect)titlebarRect;
+- (void)setTitlebarNeedsDisplay;
+- (void)setDrawsContentsIntoWindowFrame:(BOOL)aState;
+- (void)setSheetAttachmentPosition:(CGFloat)aY;
+- (CGFloat)sheetAttachmentPosition;
+- (void)placeWindowButtons:(NSRect)aRect;
+- (NSRect)windowButtonsRect;
+- (void)windowMainStateChanged;
+@end
+
+class nsCocoaWindow final : public nsBaseWidget, public nsPIWidgetCocoa {
+ private:
+  typedef nsBaseWidget Inherited;
+
+ public:
+  nsCocoaWindow();
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSPIWIDGETCOCOA;  // semicolon for clang-format bug 1629756
+
+  [[nodiscard]] virtual nsresult Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
+                                        const DesktopIntRect& aRect, InitData* = nullptr) override;
+
+  [[nodiscard]] virtual nsresult Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
+                                        const LayoutDeviceIntRect& aRect,
+                                        InitData* = nullptr) override;
+
+  virtual void Destroy() override;
+
+  virtual void Show(bool aState) override;
+  virtual bool NeedsRecreateToReshow() override;
+
+  virtual nsIWidget* GetSheetWindowParent(void) override;
+  virtual void Enable(bool aState) override;
+  virtual bool IsEnabled() const override;
+  virtual void SetModal(bool aState) override;
+  virtual void SetFakeModal(bool aState) override;
+  virtual bool IsRunningAppModal() override;
+  virtual bool IsVisible() const override;
+  virtual void SetFocus(Raise, mozilla::dom::CallerType aCallerType) override;
+  virtual LayoutDeviceIntPoint WidgetToScreenOffset() override;
+  virtual LayoutDeviceIntPoint GetClientOffset() override;
+  virtual LayoutDeviceIntMargin ClientToWindowMargin() override;
+
+  virtual void* GetNativeData(uint32_t aDataType) override;
+
+  virtual void ConstrainPosition(DesktopIntPoint&) override;
+  virtual void SetSizeConstraints(const SizeConstraints& aConstraints) override;
+  virtual void Move(double aX, double aY) override;
+  virtual nsSizeMode SizeMode() override { return mSizeMode; }
+  virtual void SetSizeMode(nsSizeMode aMode) override;
+  virtual void GetWorkspaceID(nsAString& workspaceID) override;
+  virtual void MoveToWorkspace(const nsAString& workspaceID) override;
+  virtual void SuppressAnimation(bool aSuppress) override;
+  virtual void HideWindowChrome(bool aShouldHide) override;
+
+  virtual bool PrepareForFullscreenTransition(nsISupports** aData) override;
+  virtual void PerformFullscreenTransition(FullscreenTransitionStage aStage, uint16_t aDuration,
+                                           nsISupports* aData, nsIRunnable* aCallback) override;
+  virtual void CleanupFullscreenTransition() override;
+  nsresult MakeFullScreen(bool aFullScreen) final;
+  nsresult MakeFullScreenWithNativeTransition(bool aFullScreen) final;
+  NSAnimation* FullscreenTransitionAnimation() const { return mFullscreenTransitionAnimation; }
+  void ReleaseFullscreenTransitionAnimation() {
+    MOZ_ASSERT(mFullscreenTransitionAnimation, "Should only be called when there is animation");
+    [mFullscreenTransitionAnimation release];
+    mFullscreenTransitionAnimation = nil;
+  }
+
+  virtual void Resize(double aWidth, double aHeight, bool aRepaint) override;
+  virtual void Resize(double aX, double aY, double aWidth, double aHeight, bool aRepaint) override;
+  NSRect GetClientCocoaRect();
+  virtual LayoutDeviceIntRect GetClientBounds() override;
+  virtual LayoutDeviceIntRect GetScreenBounds() override;
+  void ReportMoveEvent();
+  void ReportSizeEvent();
+  virtual void SetCursor(const Cursor&) override;
+
+  CGFloat BackingScaleFactor();
+  void BackingScaleFactorChanged();
+  virtual double GetDefaultScaleInternal() override;
+  virtual int32_t RoundsWidgetCoordinatesTo() override;
+
+  mozilla::DesktopToLayoutDeviceScale GetDesktopToDeviceScale() final {
+    return mozilla::DesktopToLayoutDeviceScale(BackingScaleFactor());
+  }
+
+  virtual nsresult SetTitle(const nsAString& aTitle) override;
+
+  virtual void Invalidate(const LayoutDeviceIntRect& aRect) override;
+  virtual WindowRenderer* GetWindowRenderer() override;
+  virtual nsresult DispatchEvent(mozilla::WidgetGUIEvent* aEvent, nsEventStatus& aStatus) override;
+  virtual void CaptureRollupEvents(bool aDoCapture) override;
+  [[nodiscard]] virtual nsresult GetAttention(int32_t aCycleCount) override;
+  virtual bool HasPendingInputEvent() override;
+  virtual TransparencyMode GetTransparencyMode() override;
+  virtual void SetTransparencyMode(TransparencyMode aMode) override;
+  virtual void SetWindowShadowStyle(mozilla::StyleWindowShadow aStyle) override;
+  virtual void SetWindowOpacity(float aOpacity) override;
+  virtual void SetWindowTransform(const mozilla::gfx::Matrix& aTransform) override;
+  virtual void SetInputRegion(const InputRegion&) override;
+  virtual void SetColorScheme(const mozilla::Maybe<mozilla::ColorScheme>&) override;
+  virtual void SetShowsToolbarButton(bool aShow) override;
+  virtual void SetSupportsNativeFullscreen(bool aShow) override;
+  virtual void SetWindowAnimationType(WindowAnimationType aType) override;
+  virtual void SetDrawsTitle(bool aDrawTitle) override;
+  virtual nsresult SetNonClientMargins(const LayoutDeviceIntMargin&) override;
+  virtual void SetDrawsInTitlebar(bool aState) override;
+  virtual void UpdateThemeGeometries(const nsTArray<ThemeGeometry>& aThemeGeometries) override;
+  virtual nsresult SynthesizeNativeMouseEvent(LayoutDeviceIntPoint aPoint,
+                                              NativeMouseMessage aNativeMessage,
+                                              mozilla::MouseButton aButton,
+                                              nsIWidget::Modifiers aModifierFlags,
+                                              nsIObserver* aObserver) override;
+  virtual nsresult SynthesizeNativeMouseScrollEvent(LayoutDeviceIntPoint aPoint,
+                                                    uint32_t aNativeMessage, double aDeltaX,
+                                                    double aDeltaY, double aDeltaZ,
+                                                    uint32_t aModifierFlags,
+                                                    uint32_t aAdditionalFlags,
+                                                    nsIObserver* aObserver) override;
+  virtual void LockAspectRatio(bool aShouldLock) override;
+
+  void DispatchSizeModeEvent();
+  void DispatchOcclusionEvent();
+
+  // be notified that a some form of drag event needs to go into Gecko
+  virtual bool DragEvent(unsigned int aMessage, mozilla::gfx::Point aMouseGlobal,
+                         UInt16 aKeyModifiers);
+
+  bool HasModalDescendents() { return mNumModalDescendents > 0; }
+  NSWindow* GetCocoaWindow() { return mWindow; }
+
+  void SetMenuBar(RefPtr<nsMenuBarX>&& aMenuBar);
+  nsMenuBarX* GetMenuBar();
+
+  virtual void SetInputContext(const InputContext& aContext,
+                               const InputContextAction& aAction) override;
+  virtual InputContext GetInputContext() override { return mInputContext; }
+  MOZ_CAN_RUN_SCRIPT virtual bool GetEditCommands(
+      mozilla::NativeKeyBindingsType aType, const mozilla::WidgetKeyboardEvent& aEvent,
+      nsTArray<mozilla::CommandInt>& aCommands) override;
+
+  void SetPopupWindowLevel();
+
+  bool InFullScreenMode() const { return mInFullScreenMode; }
+
+  void PauseCompositor();
+  void ResumeCompositor();
+
+  bool AsyncPanZoomEnabled() const override;
+
+  bool StartAsyncAutoscroll(const ScreenPoint& aAnchorLocation,
+                            const ScrollableLayerGuid& aGuid) override;
+  void StopAsyncAutoscroll(const ScrollableLayerGuid& aGuid) override;
+
+  // Class method versions of NSWindow/Delegate callbacks which need to
+  // access object state.
+  void CocoaWindowWillEnterFullscreen(bool aFullscreen);
+  void CocoaWindowDidEnterFullscreen(bool aFullscreen);
+  void CocoaWindowDidFailFullscreen(bool aAttemptedFullscreen);
+  void CocoaWindowDidResize();
+  void CocoaSendToplevelActivateEvents();
+  void CocoaSendToplevelDeactivateEvents();
+
+  enum class TransitionType {
+    Windowed,
+    Fullscreen,
+    EmulatedFullscreen,
+    Miniaturize,
+    Deminiaturize,
+    Zoom,
+  };
+  void FinishCurrentTransition();
+  void FinishCurrentTransitionIfMatching(const TransitionType& aTransition);
+
+  // Called when something has happened that might cause us to update our
+  // fullscreen state. Returns true if we updated state. We'll call this
+  // on window resize, and we'll call it when we enter or exit fullscreen,
+  // since fullscreen to-and-from zoomed windows won't necessarily trigger
+  // a resize.
+  bool HandleUpdateFullscreenOnResize();
+
+ protected:
+  virtual ~nsCocoaWindow();
+
+  nsresult CreateNativeWindow(const NSRect& aRect, BorderStyle aBorderStyle, bool aRectIsFrameRect,
+                              bool aIsPrivateBrowsing);
+  nsresult CreatePopupContentView(const LayoutDeviceIntRect& aRect, InitData*);
+  void DestroyNativeWindow();
+  void UpdateBounds();
+  int32_t GetWorkspaceID();
+
+  void DoResize(double aX, double aY, double aWidth, double aHeight, bool aRepaint,
+                bool aConstrainToCurrentScreen);
+
+  void UpdateFullscreenState(bool aFullScreen, bool aNativeMode);
+  nsresult DoMakeFullScreen(bool aFullScreen, bool aUseSystemTransition);
+
+  virtual already_AddRefed<nsIWidget> AllocateChildPopupWidget() override {
+    return nsIWidget::CreateTopLevelWindow();
+  }
+
+  nsIWidget* mParent;         // if we're a popup, this is our parent [WEAK]
+  nsIWidget* mAncestorLink;   // link to traverse ancestors [WEAK]
+  BaseWindow* mWindow;        // our cocoa window [STRONG]
+  WindowDelegate* mDelegate;  // our delegate for processing window msgs [STRONG]
+  RefPtr<nsMenuBarX> mMenuBar;
+  NSWindow* mSheetWindowParent;    // if this is a sheet, this is the NSWindow it's attached to
+  nsChildView* mPopupContentView;  // if this is a popup, this is its content widget
+  // if this is a toplevel window, and there is any ongoing fullscreen
+  // transition, it is the animation object.
+  NSAnimation* mFullscreenTransitionAnimation;
+  mozilla::StyleWindowShadow mShadowStyle;
+
+  CGFloat mBackingScaleFactor;
+  CGFloat mAspectRatio;
+
+  WindowAnimationType mAnimationType;
+
+  bool mWindowMadeHere;  // true if we created the window, false for embedding
+  bool mSheetNeedsShow;  // if this is a sheet, are we waiting to be shown?
+                         // this is used for sibling sheet contention only
+  nsSizeMode mSizeMode;
+  bool mInFullScreenMode;
+  // Whether we are currently using native fullscreen. It could be false because
+  // we are in the emulated fullscreen where we do not use the native fullscreen.
+  bool mInNativeFullScreenMode;
+
+  mozilla::Maybe<TransitionType> mTransitionCurrent;
+  std::queue<TransitionType> mTransitionsPending;
+
+  // Sometimes we add a transition that wasn't requested by a caller. We do this
+  // to manage transitions between states that otherwise would be rejected by
+  // Cocoa. When we do this, it's useful to know when we are handling an added
+  // transition because we don't want to send size mode events when they execute.
+  bool mIsTransitionCurrentAdded = false;
+
+  // Whether we are treating the next resize as the start of a fullscreen transition.
+  // If we are, which direction are we going: Fullscreen or Windowed.
+  mozilla::Maybe<TransitionType> mUpdateFullscreenOnResize;
+
+  bool IsInTransition() { return mTransitionCurrent.isSome(); }
+  void QueueTransition(const TransitionType& aTransition);
+  void ProcessTransitions();
+
+  bool mInProcessTransitions = false;
+
+  // While running an emulated fullscreen transition, we want to suppress sending
+  // size mode events due to window resizing. We fix it up at the end when the
+  // transition is complete.
+  bool mSuppressSizeModeEvents = false;
+
+  // Ignore occlusion events caused by displaying the temporary fullscreen
+  // window during the fullscreen transition animation because only focused
+  // contexts are permitted to enter DOM fullscreen.
+  int mIgnoreOcclusionCount;
+
+  // Set to true when a native fullscreen transition is initiated -- either to
+  // or from fullscreen -- and set to false when it is complete. During this
+  // period, we presume the window is visible, which prevents us from sending
+  // unnecessary OcclusionStateChanged events.
+  bool mHasStartedNativeFullscreen;
+
+  bool mModal;
+  bool mFakeModal;
+
+  bool mIsAnimationSuppressed;
+
+  bool mInReportMoveEvent;  // true if in a call to ReportMoveEvent().
+  bool mInResize;           // true if in a call to DoResize().
+  bool mWindowTransformIsIdentity;
+  bool mAlwaysOnTop;
+  bool mAspectRatioLocked;
+
+  int32_t mNumModalDescendents;
+  InputContext mInputContext;
+  NSWindowAnimationBehavior mWindowAnimationBehavior;
+
+ private:
+  // true if Show() has been called.
+  bool mWasShown;
+};
+
+#endif  // nsCocoaWindow_h_
diff --git a/widget/cocoa/nsCocoaWindow.mm b/widget/cocoa/nsCocoaWindow.mm
new file mode 100644
index 0000000000..c3c246cc74
--- /dev/null
+++ b/widget/cocoa/nsCocoaWindow.mm
@@ -0,0 +1,4259 @@
+/* -*- Mode: Objective-C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCocoaWindow.h"
+
+#include "AppearanceOverride.h"
+#include "NativeKeyBindings.h"
+#include "ScreenHelperCocoa.h"
+#include "TextInputHandler.h"
+#include "nsCocoaUtils.h"
+#include "nsObjCExceptions.h"
+#include "nsCOMPtr.h"
+#include "nsWidgetsCID.h"
+#include "nsIRollupListener.h"
+#include "nsChildView.h"
+#include "nsWindowMap.h"
+#include "nsAppShell.h"
+#include "nsIAppShellService.h"
+#include "nsIBaseWindow.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIAppWindow.h"
+#include "nsToolkit.h"
+#include "nsTouchBarNativeAPIDefines.h"
+#include "nsPIDOMWindow.h"
+#include "nsThreadUtils.h"
+#include "nsMenuBarX.h"
+#include "nsMenuUtilsX.h"
+#include "nsStyleConsts.h"
+#include "nsNativeThemeColors.h"
+#include "nsNativeThemeCocoa.h"
+#include "nsChildView.h"
+#include "nsCocoaFeatures.h"
+#include "nsIScreenManager.h"
+#include "nsIWidgetListener.h"
+#include "SDKDeclarations.h"
+#include "VibrancyManager.h"
+#include "nsPresContext.h"
+#include "nsDocShell.h"
+
+#include "gfxPlatform.h"
+#include "qcms.h"
+
+#include "mozilla/AutoRestore.h"
+#include "mozilla/BasicEvents.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/NativeKeyBindingsType.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/StaticPrefs_widget.h"
+#include "mozilla/WritingModes.h"
+#include "mozilla/layers/CompositorBridgeChild.h"
+#include "mozilla/widget/Screen.h"
+#include <algorithm>
+
+namespace mozilla {
+namespace layers {
+class LayerManager;
+}  // namespace layers
+}  // namespace mozilla
+using namespace mozilla::layers;
+using namespace mozilla::widget;
+using namespace mozilla;
+
+int32_t gXULModalLevel = 0;
+
+// In principle there should be only one app-modal window at any given time.
+// But sometimes, despite our best efforts, another window appears above the
+// current app-modal window.  So we need to keep a linked list of app-modal
+// windows.  (A non-sheet window that appears above an app-modal window is
+// also made app-modal.)  See nsCocoaWindow::SetModal().
+nsCocoaWindowList* gGeckoAppModalWindowList = NULL;
+
+BOOL sTouchBarIsInitialized = NO;
+
+// defined in nsMenuBarX.mm
+extern NSMenu* sApplicationMenu;  // Application menu shared by all menubars
+
+// defined in nsChildView.mm
+extern BOOL gSomeMenuBarPainted;
+
+extern "C" {
+// CGSPrivate.h
+typedef NSInteger CGSConnection;
+typedef NSUInteger CGSSpaceID;
+typedef NSInteger CGSWindow;
+typedef enum {
+  kCGSSpaceIncludesCurrent = 1 << 0,
+  kCGSSpaceIncludesOthers = 1 << 1,
+  kCGSSpaceIncludesUser = 1 << 2,
+
+  kCGSAllSpacesMask = kCGSSpaceIncludesCurrent | kCGSSpaceIncludesOthers | kCGSSpaceIncludesUser
+} CGSSpaceMask;
+static NSString* const CGSSpaceIDKey = @"ManagedSpaceID";
+static NSString* const CGSSpacesKey = @"Spaces";
+extern CGSConnection _CGSDefaultConnection(void);
+extern CGError CGSSetWindowTransform(CGSConnection cid, CGSWindow wid, CGAffineTransform transform);
+}
+
+#define NS_APPSHELLSERVICE_CONTRACTID "@mozilla.org/appshell/appShellService;1"
+
+NS_IMPL_ISUPPORTS_INHERITED(nsCocoaWindow, Inherited, nsPIWidgetCocoa)
+
+// A note on testing to see if your object is a sheet...
+// |mWindowType == WindowType::Sheet| is true if your gecko nsIWidget is a sheet
+// widget - whether or not the sheet is showing. |[mWindow isSheet]| will return
+// true *only when the sheet is actually showing*. Choose your test wisely.
+
+static void RollUpPopups(
+    nsIRollupListener::AllowAnimations aAllowAnimations = nsIRollupListener::AllowAnimations::Yes) {
+  nsIRollupListener* rollupListener = nsBaseWidget::GetActiveRollupListener();
+  NS_ENSURE_TRUE_VOID(rollupListener);
+
+  if (rollupListener->RollupNativeMenu()) {
+    return;
+  }
+
+  nsCOMPtr<nsIWidget> rollupWidget = rollupListener->GetRollupWidget();
+  if (!rollupWidget) {
+    return;
+  }
+  nsIRollupListener::RollupOptions options{0, nsIRollupListener::FlushViews::Yes, nullptr,
+                                           aAllowAnimations};
+  rollupListener->Rollup(options);
+}
+
+nsCocoaWindow::nsCocoaWindow()
+    : mParent(nullptr),
+      mAncestorLink(nullptr),
+      mWindow(nil),
+      mDelegate(nil),
+      mSheetWindowParent(nil),
+      mPopupContentView(nil),
+      mFullscreenTransitionAnimation(nil),
+      mShadowStyle(StyleWindowShadow::Default),
+      mBackingScaleFactor(0.0),
+      mAnimationType(nsIWidget::eGenericWindowAnimation),
+      mWindowMadeHere(false),
+      mSheetNeedsShow(false),
+      mSizeMode(nsSizeMode_Normal),
+      mInFullScreenMode(false),
+      mInNativeFullScreenMode(false),
+      mIgnoreOcclusionCount(0),
+      mHasStartedNativeFullscreen(false),
+      mModal(false),
+      mFakeModal(false),
+      mIsAnimationSuppressed(false),
+      mInReportMoveEvent(false),
+      mInResize(false),
+      mWindowTransformIsIdentity(true),
+      mAlwaysOnTop(false),
+      mAspectRatioLocked(false),
+      mNumModalDescendents(0),
+      mWindowAnimationBehavior(NSWindowAnimationBehaviorDefault),
+      mWasShown(false) {
+  // Disable automatic tabbing. We need to do this before we
+  // orderFront any of our windows.
+  [NSWindow setAllowsAutomaticWindowTabbing:NO];
+}
+
+void nsCocoaWindow::DestroyNativeWindow() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) return;
+
+  [mWindow releaseJSObjects];
+  // We want to unhook the delegate here because we don't want events
+  // sent to it after this object has been destroyed.
+  [mWindow setDelegate:nil];
+  [mWindow close];
+  mWindow = nil;
+  [mDelegate autorelease];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsCocoaWindow::~nsCocoaWindow() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Notify the children that we're gone.  Popup windows (e.g. tooltips) can
+  // have nsChildView children.  'kid' is an nsChildView object if and only if
+  // its 'type' is 'WindowType::Child'.
+  // childView->ResetParent() can change our list of children while it's
+  // being iterated, so the way we iterate the list must allow for this.
+  for (nsIWidget* kid = mLastChild; kid;) {
+    WindowType kidType = kid->GetWindowType();
+    if (kidType == WindowType::Child) {
+      nsChildView* childView = static_cast<nsChildView*>(kid);
+      kid = kid->GetPrevSibling();
+      childView->ResetParent();
+    } else {
+      nsCocoaWindow* childWindow = static_cast<nsCocoaWindow*>(kid);
+      childWindow->mParent = nullptr;
+      childWindow->mAncestorLink = mAncestorLink;
+      kid = kid->GetPrevSibling();
+    }
+  }
+
+  if (mWindow && mWindowMadeHere) {
+    DestroyNativeWindow();
+  }
+
+  NS_IF_RELEASE(mPopupContentView);
+
+  // Deal with the possiblity that we're being destroyed while running modal.
+  if (mModal) {
+    NS_WARNING("Widget destroyed while running modal!");
+    --gXULModalLevel;
+    NS_ASSERTION(gXULModalLevel >= 0, "Weirdness setting modality!");
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Find the screen that overlaps aRect the most,
+// if none are found default to the mainScreen.
+static NSScreen* FindTargetScreenForRect(const DesktopIntRect& aRect) {
+  NSScreen* targetScreen = [NSScreen mainScreen];
+  NSEnumerator* screenEnum = [[NSScreen screens] objectEnumerator];
+  int largestIntersectArea = 0;
+  while (NSScreen* screen = [screenEnum nextObject]) {
+    DesktopIntRect screenRect = nsCocoaUtils::CocoaRectToGeckoRect([screen visibleFrame]);
+    screenRect = screenRect.Intersect(aRect);
+    int area = screenRect.width * screenRect.height;
+    if (area > largestIntersectArea) {
+      largestIntersectArea = area;
+      targetScreen = screen;
+    }
+  }
+  return targetScreen;
+}
+
+// fits the rect to the screen that contains the largest area of it,
+// or to aScreen if a screen is passed in
+// NB: this operates with aRect in desktop pixels
+static void FitRectToVisibleAreaForScreen(DesktopIntRect& aRect, NSScreen* aScreen) {
+  if (!aScreen) {
+    aScreen = FindTargetScreenForRect(aRect);
+  }
+
+  DesktopIntRect screenBounds = nsCocoaUtils::CocoaRectToGeckoRect([aScreen visibleFrame]);
+
+  if (aRect.width > screenBounds.width) {
+    aRect.width = screenBounds.width;
+  }
+  if (aRect.height > screenBounds.height) {
+    aRect.height = screenBounds.height;
+  }
+
+  if (aRect.x - screenBounds.x + aRect.width > screenBounds.width) {
+    aRect.x += screenBounds.width - (aRect.x - screenBounds.x + aRect.width);
+  }
+  if (aRect.y - screenBounds.y + aRect.height > screenBounds.height) {
+    aRect.y += screenBounds.height - (aRect.y - screenBounds.y + aRect.height);
+  }
+
+  // If the left/top edge of the window is off the screen in either direction,
+  // then set the window to start at the left/top edge of the screen.
+  if (aRect.x < screenBounds.x || aRect.x > (screenBounds.x + screenBounds.width)) {
+    aRect.x = screenBounds.x;
+  }
+  if (aRect.y < screenBounds.y || aRect.y > (screenBounds.y + screenBounds.height)) {
+    aRect.y = screenBounds.y;
+  }
+}
+
+DesktopToLayoutDeviceScale ParentBackingScaleFactor(nsIWidget* aParent, NSView* aParentView) {
+  if (aParent) {
+    return aParent->GetDesktopToDeviceScale();
+  }
+  NSWindow* parentWindow = [aParentView window];
+  if (parentWindow) {
+    return DesktopToLayoutDeviceScale([parentWindow backingScaleFactor]);
+  }
+  return DesktopToLayoutDeviceScale(1.0);
+}
+
+// Returns the screen rectangle for the given widget.
+// Child widgets are positioned relative to this rectangle.
+// Exactly one of the arguments must be non-null.
+static DesktopRect GetWidgetScreenRectForChildren(nsIWidget* aWidget, NSView* aView) {
+  if (aWidget) {
+    mozilla::DesktopToLayoutDeviceScale scale = aWidget->GetDesktopToDeviceScale();
+    if (aWidget->GetWindowType() == WindowType::Child) {
+      return aWidget->GetScreenBounds() / scale;
+    }
+    return aWidget->GetClientBounds() / scale;
+  }
+
+  MOZ_RELEASE_ASSERT(aView);
+
+  // 1. Transform the view rect into window coords.
+  // The returned rect is in "origin bottom-left" coordinates.
+  NSRect rectInWindowCoordinatesOBL = [aView convertRect:[aView bounds] toView:nil];
+
+  // 2. Turn the window-coord rect into screen coords, still origin bottom-left.
+  NSRect rectInScreenCoordinatesOBL =
+      [[aView window] convertRectToScreen:rectInWindowCoordinatesOBL];
+
+  // 3. Convert the NSRect to a DesktopRect. This will convert to coordinates
+  // with the origin in the top left corner of the primary screen.
+  return DesktopRect(nsCocoaUtils::CocoaRectToGeckoRect(rectInScreenCoordinatesOBL));
+}
+
+// aRect here is specified in desktop pixels
+//
+// For child windows (where either aParent or aNativeParent is non-null),
+// aRect.{x,y} are offsets from the origin of the parent window and not an
+// absolute position.
+nsresult nsCocoaWindow::Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
+                               const DesktopIntRect& aRect, widget::InitData* aInitData) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // Because the hidden window is created outside of an event loop,
+  // we have to provide an autorelease pool (see bug 559075).
+  nsAutoreleasePool localPool;
+
+  DesktopIntRect newBounds = aRect;
+  FitRectToVisibleAreaForScreen(newBounds, nullptr);
+
+  // Set defaults which can be overriden from aInitData in BaseCreate
+  mWindowType = WindowType::TopLevel;
+  mBorderStyle = BorderStyle::Default;
+
+  // Ensure that the toolkit is created.
+  nsToolkit::GetToolkit();
+
+  Inherited::BaseCreate(aParent, aInitData);
+
+  mParent = aParent;
+  mAncestorLink = aParent;
+  mAlwaysOnTop = aInitData->mAlwaysOnTop;
+
+  // If we have a parent widget, the new widget will be offset from the
+  // parent widget by aRect.{x,y}. Otherwise, we'll use aRect for the
+  // new widget coordinates.
+  DesktopIntPoint parentOrigin;
+
+  // Do we have a parent widget?
+  if (aParent || aNativeParent) {
+    DesktopRect parentDesktopRect = GetWidgetScreenRectForChildren(aParent, (NSView*)aNativeParent);
+    parentOrigin = gfx::RoundedToInt(parentDesktopRect.TopLeft());
+  }
+
+  DesktopIntRect widgetRect = aRect + parentOrigin;
+
+  nsresult rv = CreateNativeWindow(nsCocoaUtils::GeckoRectToCocoaRect(widgetRect), mBorderStyle,
+                                   false, aInitData->mIsPrivate);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (mWindowType == WindowType::Popup) {
+    // now we can convert widgetRect to device pixels for the window we created,
+    // as the child view expects a rect expressed in the dev pix of its parent
+    LayoutDeviceIntRect devRect = RoundedToInt(newBounds * GetDesktopToDeviceScale());
+    return CreatePopupContentView(devRect, aInitData);
+  }
+
+  mIsAnimationSuppressed = aInitData->mIsAnimationSuppressed;
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsCocoaWindow::Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
+                               const LayoutDeviceIntRect& aRect, widget::InitData* aInitData) {
+  DesktopIntRect desktopRect =
+      RoundedToInt(aRect / ParentBackingScaleFactor(aParent, (NSView*)aNativeParent));
+  return Create(aParent, aNativeParent, desktopRect, aInitData);
+}
+
+static unsigned int WindowMaskForBorderStyle(BorderStyle aBorderStyle) {
+  bool allOrDefault = (aBorderStyle == BorderStyle::All || aBorderStyle == BorderStyle::Default);
+
+  /* Apple's docs on NSWindow styles say that "a window's style mask should
+   * include NSWindowStyleMaskTitled if it includes any of the others [besides
+   * NSWindowStyleMaskBorderless]".  This implies that a borderless window
+   * shouldn't have any other styles than NSWindowStyleMaskBorderless.
+   */
+  if (!allOrDefault && !(aBorderStyle & BorderStyle::Title)) {
+    if (aBorderStyle & BorderStyle::Minimize) {
+      /* It appears that at a minimum, borderless windows can be miniaturizable,
+       * effectively contradicting some of Apple's documentation referenced
+       * above. One such exception is the screen share indicator, see
+       * bug 1742877.
+       */
+      return NSWindowStyleMaskBorderless | NSWindowStyleMaskMiniaturizable;
+    }
+    return NSWindowStyleMaskBorderless;
+  }
+
+  unsigned int mask = NSWindowStyleMaskTitled;
+  if (allOrDefault || aBorderStyle & BorderStyle::Close) {
+    mask |= NSWindowStyleMaskClosable;
+  }
+  if (allOrDefault || aBorderStyle & BorderStyle::Minimize) {
+    mask |= NSWindowStyleMaskMiniaturizable;
+  }
+  if (allOrDefault || aBorderStyle & BorderStyle::ResizeH) {
+    mask |= NSWindowStyleMaskResizable;
+  }
+
+  return mask;
+}
+
+// If aRectIsFrameRect, aRect specifies the frame rect of the new window.
+// Otherwise, aRect.x/y specify the position of the window's frame relative to
+// the bottom of the menubar and aRect.width/height specify the size of the
+// content rect.
+nsresult nsCocoaWindow::CreateNativeWindow(const NSRect& aRect, BorderStyle aBorderStyle,
+                                           bool aRectIsFrameRect, bool aIsPrivateBrowsing) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // We default to NSWindowStyleMaskBorderless, add features if needed.
+  unsigned int features = NSWindowStyleMaskBorderless;
+
+  // Configure the window we will create based on the window type.
+  switch (mWindowType) {
+    case WindowType::Invisible:
+    case WindowType::Child:
+      break;
+    case WindowType::Popup:
+      if (aBorderStyle != BorderStyle::Default && mBorderStyle & BorderStyle::Title) {
+        features |= NSWindowStyleMaskTitled;
+        if (aBorderStyle & BorderStyle::Close) {
+          features |= NSWindowStyleMaskClosable;
+        }
+      }
+      break;
+    case WindowType::TopLevel:
+    case WindowType::Dialog:
+      features = WindowMaskForBorderStyle(aBorderStyle);
+      break;
+    case WindowType::Sheet:
+      if (mParent->GetWindowType() != WindowType::Invisible &&
+          aBorderStyle & BorderStyle::ResizeH) {
+        features = NSWindowStyleMaskResizable;
+      } else {
+        features = NSWindowStyleMaskMiniaturizable;
+      }
+      features |= NSWindowStyleMaskTitled;
+      break;
+    default:
+      NS_ERROR("Unhandled window type!");
+      return NS_ERROR_FAILURE;
+  }
+
+  NSRect contentRect;
+
+  if (aRectIsFrameRect) {
+    contentRect = [NSWindow contentRectForFrameRect:aRect styleMask:features];
+  } else {
+    /*
+     * We pass a content area rect to initialize the native Cocoa window. The
+     * content rect we give is the same size as the size we're given by gecko.
+     * The origin we're given for non-popup windows is moved down by the height
+     * of the menu bar so that an origin of (0,100) from gecko puts the window
+     * 100 pixels below the top of the available desktop area. We also move the
+     * origin down by the height of a title bar if it exists. This is so the
+     * origin that gecko gives us for the top-left of  the window turns out to
+     * be the top-left of the window we create. This is how it was done in
+     * Carbon. If it ought to be different we'll probably need to look at all
+     * the callers.
+     *
+     * Note: This means that if you put a secondary screen on top of your main
+     * screen and open a window in the top screen, it'll be incorrectly shifted
+     * down by the height of the menu bar. Same thing would happen in Carbon.
+     *
+     * Note: If you pass a rect with 0,0 for an origin, the window ends up in a
+     * weird place for some reason. This stops that without breaking popups.
+     */
+    // Compensate for difference between frame and content area height (e.g. title bar).
+    NSRect newWindowFrame = [NSWindow frameRectForContentRect:aRect styleMask:features];
+
+    contentRect = aRect;
+    contentRect.origin.y -= (newWindowFrame.size.height - aRect.size.height);
+
+    if (mWindowType != WindowType::Popup) contentRect.origin.y -= [[NSApp mainMenu] menuBarHeight];
+  }
+
+  // NSLog(@"Top-level window being created at Cocoa rect: %f, %f, %f, %f\n",
+  //       rect.origin.x, rect.origin.y, rect.size.width, rect.size.height);
+
+  Class windowClass = [BaseWindow class];
+  // If we have a titlebar on a top-level window, we want to be able to control the
+  // titlebar color (for unified windows), so use the special ToolbarWindow class.
+  // Note that we need to check the window type because we mark sheets as
+  // having titlebars.
+  if ((mWindowType == WindowType::TopLevel || mWindowType == WindowType::Dialog) &&
+      (features & NSWindowStyleMaskTitled))
+    windowClass = [ToolbarWindow class];
+  // If we're a popup window we need to use the PopupWindow class.
+  else if (mWindowType == WindowType::Popup)
+    windowClass = [PopupWindow class];
+  // If we're a non-popup borderless window we need to use the
+  // BorderlessWindow class.
+  else if (features == NSWindowStyleMaskBorderless)
+    windowClass = [BorderlessWindow class];
+
+  // Create the window
+  mWindow = [[windowClass alloc] initWithContentRect:contentRect
+                                           styleMask:features
+                                             backing:NSBackingStoreBuffered
+                                               defer:YES];
+
+  // Make sure that window titles don't leak to disk in private browsing mode
+  // due to macOS' resume feature.
+  [mWindow setRestorable:!aIsPrivateBrowsing];
+  if (aIsPrivateBrowsing) {
+    [mWindow disableSnapshotRestoration];
+  }
+
+  // setup our notification delegate. Note that setDelegate: does NOT retain.
+  mDelegate = [[WindowDelegate alloc] initWithGeckoWindow:this];
+  [mWindow setDelegate:mDelegate];
+
+  // Make sure that the content rect we gave has been honored.
+  NSRect wantedFrame = [mWindow frameRectForChildViewRect:contentRect];
+  if (!NSEqualRects([mWindow frame], wantedFrame)) {
+    // This can happen when the window is not on the primary screen.
+    [mWindow setFrame:wantedFrame display:NO];
+  }
+  UpdateBounds();
+
+  if (mWindowType == WindowType::Invisible) {
+    [mWindow setLevel:kCGDesktopWindowLevelKey];
+  }
+
+  if (mWindowType == WindowType::Popup) {
+    SetPopupWindowLevel();
+    [mWindow setBackgroundColor:[NSColor clearColor]];
+    [mWindow setOpaque:NO];
+
+    // When multiple spaces are in use and the browser is assigned to a
+    // particular space, override the "Assign To" space and display popups on
+    // the active space. Does not work with multiple displays. See
+    // NeedsRecreateToReshow() for multi-display with multi-space workaround.
+    if (!mAlwaysOnTop) {
+      NSWindowCollectionBehavior behavior = [mWindow collectionBehavior];
+      behavior |= NSWindowCollectionBehaviorMoveToActiveSpace;
+      [mWindow setCollectionBehavior:behavior];
+    }
+  } else {
+    // Non-popup windows are always opaque.
+    [mWindow setOpaque:YES];
+  }
+
+  NSWindowCollectionBehavior newBehavior = [mWindow collectionBehavior];
+  if (mAlwaysOnTop) {
+    [mWindow setLevel:NSFloatingWindowLevel];
+    newBehavior |= NSWindowCollectionBehaviorCanJoinAllSpaces;
+  }
+  [mWindow setCollectionBehavior:newBehavior];
+
+  [mWindow setContentMinSize:NSMakeSize(60, 60)];
+  [mWindow disableCursorRects];
+
+  // Make the window use CoreAnimation from the start, so that we don't
+  // switch from a non-CA window to a CA-window in the middle.
+  [[mWindow contentView] setWantsLayer:YES];
+
+  // Make sure the window starts out not draggable by the background.
+  // We will turn it on as necessary.
+  [mWindow setMovableByWindowBackground:NO];
+
+  [[WindowDataMap sharedWindowDataMap] ensureDataForWindow:mWindow];
+  mWindowMadeHere = true;
+
+  if (@available(macOS 10.14, *)) {
+    // Make the window respect the global appearance, which follows the browser.theme.toolbar-theme
+    // pref.
+    mWindow.appearanceSource = MOZGlobalAppearance.sharedInstance;
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsCocoaWindow::CreatePopupContentView(const LayoutDeviceIntRect& aRect,
+                                               widget::InitData* aInitData) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // We need to make our content view a ChildView.
+  mPopupContentView = new nsChildView();
+  if (!mPopupContentView) return NS_ERROR_FAILURE;
+
+  NS_ADDREF(mPopupContentView);
+
+  nsIWidget* thisAsWidget = static_cast<nsIWidget*>(this);
+  nsresult rv = mPopupContentView->Create(thisAsWidget, nullptr, aRect, aInitData);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  NSView* contentView = [mWindow contentView];
+  ChildView* childView = (ChildView*)mPopupContentView->GetNativeData(NS_NATIVE_WIDGET);
+  [childView setFrame:[contentView bounds]];
+  [childView setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
+  [contentView addSubview:childView];
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsCocoaWindow::Destroy() {
+  if (mOnDestroyCalled) return;
+  mOnDestroyCalled = true;
+
+  // SetFakeModal(true) is called for non-modal window opened by modal window.
+  // On Cocoa, it needs corresponding SetFakeModal(false) on destroy to restore
+  // ancestor windows' state.
+  if (mFakeModal) {
+    SetFakeModal(false);
+  }
+
+  // If we don't hide here we run into problems with panels, this is not ideal.
+  // (Bug 891424)
+  Show(false);
+
+  if (mPopupContentView) mPopupContentView->Destroy();
+
+  if (mFullscreenTransitionAnimation) {
+    [mFullscreenTransitionAnimation stopAnimation];
+    ReleaseFullscreenTransitionAnimation();
+  }
+
+  nsBaseWidget::Destroy();
+  // nsBaseWidget::Destroy() calls GetParent()->RemoveChild(this). But we
+  // don't implement GetParent(), so we need to do the equivalent here.
+  if (mParent) {
+    mParent->RemoveChild(this);
+  }
+  nsBaseWidget::OnDestroy();
+
+  if (mInFullScreenMode) {
+    // On Lion we don't have to mess with the OS chrome when in Full Screen
+    // mode.  But we do have to destroy the native window here (and not wait
+    // for that to happen in our destructor).  We don't switch away from the
+    // native window's space until the window is destroyed, and otherwise this
+    // might not happen for several seconds (because at least one object
+    // holding a reference to ourselves is usually waiting to be garbage-
+    // collected).  See bug 757618.
+    if (mInNativeFullScreenMode) {
+      DestroyNativeWindow();
+    } else if (mWindow) {
+      nsCocoaUtils::HideOSChromeOnScreen(false);
+    }
+  }
+}
+
+nsIWidget* nsCocoaWindow::GetSheetWindowParent(void) {
+  if (mWindowType != WindowType::Sheet) return nullptr;
+  nsCocoaWindow* parent = static_cast<nsCocoaWindow*>(mParent);
+  while (parent && (parent->mWindowType == WindowType::Sheet))
+    parent = static_cast<nsCocoaWindow*>(parent->mParent);
+  return parent;
+}
+
+void* nsCocoaWindow::GetNativeData(uint32_t aDataType) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  void* retVal = nullptr;
+
+  switch (aDataType) {
+    // to emulate how windows works, we always have to return a NSView
+    // for NS_NATIVE_WIDGET
+    case NS_NATIVE_WIDGET:
+      retVal = [mWindow contentView];
+      break;
+
+    case NS_NATIVE_WINDOW:
+      retVal = mWindow;
+      break;
+
+    case NS_NATIVE_GRAPHIC:
+      // There isn't anything that makes sense to return here,
+      // and it doesn't matter so just return nullptr.
+      NS_ERROR("Requesting NS_NATIVE_GRAPHIC on a top-level window!");
+      break;
+    case NS_RAW_NATIVE_IME_CONTEXT: {
+      retVal = GetPseudoIMEContext();
+      if (retVal) {
+        break;
+      }
+      NSView* view = mWindow ? [mWindow contentView] : nil;
+      if (view) {
+        retVal = [view inputContext];
+      }
+      // If inputContext isn't available on this window, return this window's
+      // pointer instead of nullptr since if this returns nullptr,
+      // IMEStateManager cannot manage composition with TextComposition
+      // instance.  Although, this case shouldn't occur.
+      if (NS_WARN_IF(!retVal)) {
+        retVal = this;
+      }
+      break;
+    }
+  }
+
+  return retVal;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nullptr);
+}
+
+bool nsCocoaWindow::IsVisible() const {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return (mWindow && ([mWindow isVisibleOrBeingShown] || mSheetNeedsShow));
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+void nsCocoaWindow::SetModal(bool aState) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) return;
+
+  // This is used during startup (outside the event loop) when creating
+  // the add-ons compatibility checking dialog and the profile manager UI;
+  // therefore, it needs to provide an autorelease pool to avoid cocoa
+  // objects leaking.
+  nsAutoreleasePool localPool;
+
+  mModal = aState;
+  nsCocoaWindow* ancestor = static_cast<nsCocoaWindow*>(mAncestorLink);
+  if (aState) {
+    ++gXULModalLevel;
+    // When a non-sheet window gets "set modal", make the window(s) that it
+    // appears over behave as they should.  We can't rely on native methods to
+    // do this, for the following reason:  The OS runs modal non-sheet windows
+    // in an event loop (using [NSApplication runModalForWindow:] or similar
+    // methods) that's incompatible with the modal event loop in AppWindow::
+    // ShowModal() (each of these event loops is "exclusive", and can't run at
+    // the same time as other (similar) event loops).
+    if (mWindowType != WindowType::Sheet) {
+      while (ancestor) {
+        if (ancestor->mNumModalDescendents++ == 0) {
+          NSWindow* aWindow = ancestor->GetCocoaWindow();
+          if (ancestor->mWindowType != WindowType::Invisible) {
+            [[aWindow standardWindowButton:NSWindowCloseButton] setEnabled:NO];
+            [[aWindow standardWindowButton:NSWindowMiniaturizeButton] setEnabled:NO];
+            [[aWindow standardWindowButton:NSWindowZoomButton] setEnabled:NO];
+          }
+        }
+        ancestor = static_cast<nsCocoaWindow*>(ancestor->mParent);
+      }
+      [mWindow setLevel:NSModalPanelWindowLevel];
+      nsCocoaWindowList* windowList = new nsCocoaWindowList;
+      if (windowList) {
+        windowList->window = this;  // Don't ADDREF
+        windowList->prev = gGeckoAppModalWindowList;
+        gGeckoAppModalWindowList = windowList;
+      }
+    }
+  } else {
+    --gXULModalLevel;
+    NS_ASSERTION(gXULModalLevel >= 0, "Mismatched call to nsCocoaWindow::SetModal(false)!");
+    if (mWindowType != WindowType::Sheet) {
+      while (ancestor) {
+        if (--ancestor->mNumModalDescendents == 0) {
+          NSWindow* aWindow = ancestor->GetCocoaWindow();
+          if (ancestor->mWindowType != WindowType::Invisible) {
+            [[aWindow standardWindowButton:NSWindowCloseButton] setEnabled:YES];
+            [[aWindow standardWindowButton:NSWindowMiniaturizeButton] setEnabled:YES];
+            [[aWindow standardWindowButton:NSWindowZoomButton] setEnabled:YES];
+          }
+        }
+        NS_ASSERTION(ancestor->mNumModalDescendents >= 0, "Widget hierarchy changed while modal!");
+        ancestor = static_cast<nsCocoaWindow*>(ancestor->mParent);
+      }
+      if (gGeckoAppModalWindowList) {
+        NS_ASSERTION(gGeckoAppModalWindowList->window == this,
+                     "Widget hierarchy changed while modal!");
+        nsCocoaWindowList* saved = gGeckoAppModalWindowList;
+        gGeckoAppModalWindowList = gGeckoAppModalWindowList->prev;
+        delete saved;  // "window" not ADDREFed
+      }
+      if (mWindowType == WindowType::Popup)
+        SetPopupWindowLevel();
+      else
+        [mWindow setLevel:NSNormalWindowLevel];
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetFakeModal(bool aState) {
+  mFakeModal = aState;
+  SetModal(aState);
+}
+
+bool nsCocoaWindow::IsRunningAppModal() { return [NSApp _isRunningAppModal]; }
+
+// Hide or show this window
+void nsCocoaWindow::Show(bool bState) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) return;
+
+  if (!mSheetNeedsShow) {
+    // Early exit if our current visibility state is already the requested state.
+    if (bState == ([mWindow isVisible] || [mWindow isBeingShown])) {
+      return;
+    }
+  }
+
+  [mWindow setBeingShown:bState];
+  if (bState && !mWasShown) {
+    mWasShown = true;
+  }
+
+  nsIWidget* parentWidget = mParent;
+  nsCOMPtr<nsPIWidgetCocoa> piParentWidget(do_QueryInterface(parentWidget));
+  NSWindow* nativeParentWindow =
+      (parentWidget) ? (NSWindow*)parentWidget->GetNativeData(NS_NATIVE_WINDOW) : nil;
+
+  if (bState && !mBounds.IsEmpty()) {
+    // If we had set the activationPolicy to accessory, then right now we won't
+    // have a dock icon. Make sure that we undo that and show a dock icon now that
+    // we're going to show a window.
+    if ([NSApp activationPolicy] != NSApplicationActivationPolicyRegular) {
+      [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];
+      PR_SetEnv("MOZ_APP_NO_DOCK=");
+    }
+
+    // Don't try to show a popup when the parent isn't visible or is minimized.
+    if (mWindowType == WindowType::Popup && nativeParentWindow) {
+      if (![nativeParentWindow isVisible] || [nativeParentWindow isMiniaturized]) {
+        return;
+      }
+    }
+
+    if (mPopupContentView) {
+      // Ensure our content view is visible. We never need to hide it.
+      mPopupContentView->Show(true);
+    }
+
+    if (mWindowType == WindowType::Sheet) {
+      // bail if no parent window (its basically what we do in Carbon)
+      if (!nativeParentWindow || !piParentWidget) return;
+
+      NSWindow* topNonSheetWindow = nativeParentWindow;
+
+      // If this sheet is the child of another sheet, hide the parent so that
+      // this sheet can be displayed. Leave the parent mSheetNeedsShow alone,
+      // that is only used to handle sibling sheet contention. The parent will
+      // return once there are no more child sheets.
+      bool parentIsSheet = false;
+      if (NS_SUCCEEDED(piParentWidget->GetIsSheet(&parentIsSheet)) && parentIsSheet) {
+        piParentWidget->GetSheetWindowParent(&topNonSheetWindow);
+#ifdef MOZ_THUNDERBIRD
+        [NSApp endSheet:nativeParentWindow];
+#else
+        [nativeParentWindow.sheetParent endSheet:nativeParentWindow];
+#endif
+      }
+
+      nsCOMPtr<nsIWidget> sheetShown;
+      if (NS_SUCCEEDED(piParentWidget->GetChildSheet(true, getter_AddRefs(sheetShown))) &&
+          (!sheetShown || sheetShown == this)) {
+        // If this sheet is already the sheet actually being shown, don't
+        // tell it to show again. Otherwise the number of calls to
+#ifdef MOZ_THUNDERBIRD
+        // [NSApp beginSheet...] won't match up with [NSApp endSheet...].
+#else
+        // [NSWindow beginSheet...] won't match up with [NSWindow endSheet...].
+#endif
+        if (![mWindow isVisible]) {
+          mSheetNeedsShow = false;
+          mSheetWindowParent = topNonSheetWindow;
+#ifdef MOZ_THUNDERBIRD
+          // Only set contextInfo if our parent isn't a sheet.
+          NSWindow* contextInfo = parentIsSheet ? nil : mSheetWindowParent;
+          [TopLevelWindowData deactivateInWindow:mSheetWindowParent];
+          [NSApp beginSheet:mWindow
+              modalForWindow:mSheetWindowParent
+               modalDelegate:mDelegate
+              didEndSelector:@selector(didEndSheet:returnCode:contextInfo:)
+                 contextInfo:contextInfo];
+#else
+          NSWindow* sheet = mWindow;
+          NSWindow* nonSheetParent = parentIsSheet ? nil : mSheetWindowParent;
+          [TopLevelWindowData deactivateInWindow:mSheetWindowParent];
+          [mSheetWindowParent beginSheet:sheet
+                       completionHandler:^(NSModalResponse returnCode) {
+                         // Note: 'nonSheetParent' (if it is set) is the window that is the parent
+                         // of the sheet. If it's set, 'nonSheetParent' is always the top- level
+                         // window, not another sheet itself.  But 'nonSheetParent' is nil if our
+                         // parent window is also a sheet -- in that case we shouldn't send the
+                         // top-level window any activate events (because it's our parent window
+                         // that needs to get these events, not the top-level window).
+                         [TopLevelWindowData deactivateInWindow:sheet];
+                         [sheet orderOut:nil];
+                         if (nonSheetParent) {
+                           [TopLevelWindowData activateInWindow:nonSheetParent];
+                         }
+                       }];
+#endif
+          [TopLevelWindowData activateInWindow:mWindow];
+          SendSetZLevelEvent();
+        }
+      } else {
+        // A sibling of this sheet is active, don't show this sheet yet.
+        // When the active sheet hides, its brothers and sisters that have
+        // mSheetNeedsShow set will have their opportunities to display.
+        mSheetNeedsShow = true;
+      }
+    } else if (mWindowType == WindowType::Popup) {
+      // For reasons that aren't yet clear, calls to [NSWindow orderFront:] or
+      // [NSWindow makeKeyAndOrderFront:] can sometimes trigger "Error (1000)
+      // creating CGSWindow", which in turn triggers an internal inconsistency
+      // NSException.  These errors shouldn't be fatal.  So we need to wrap
+      // calls to ...orderFront: in TRY blocks.  See bmo bug 470864.
+      NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+      [[mWindow contentView] setNeedsDisplay:YES];
+      [mWindow orderFront:nil];
+      NS_OBJC_END_TRY_IGNORE_BLOCK;
+      SendSetZLevelEvent();
+      // If our popup window is a non-native context menu, tell the OS (and
+      // other programs) that a menu has opened.  This is how the OS knows to
+      // close other programs' context menus when ours open.
+      if ([mWindow isKindOfClass:[PopupWindow class]] && [(PopupWindow*)mWindow isContextMenu]) {
+        [[NSDistributedNotificationCenter defaultCenter]
+            postNotificationName:@"com.apple.HIToolbox.beginMenuTrackingNotification"
+                          object:@"org.mozilla.gecko.PopupWindow"];
+      }
+
+      // If a parent window was supplied and this is a popup at the parent
+      // level, set its child window. This will cause the child window to
+      // appear above the parent and move when the parent does. Setting this
+      // needs to happen after the _setWindowNumber calls above, otherwise the
+      // window doesn't focus properly.
+      if (nativeParentWindow && mPopupLevel == PopupLevel::Parent)
+        [nativeParentWindow addChildWindow:mWindow ordered:NSWindowAbove];
+    } else {
+      NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+      if (mWindowType == WindowType::TopLevel &&
+          [mWindow respondsToSelector:@selector(setAnimationBehavior:)]) {
+        NSWindowAnimationBehavior behavior;
+        if (mIsAnimationSuppressed) {
+          behavior = NSWindowAnimationBehaviorNone;
+        } else {
+          switch (mAnimationType) {
+            case nsIWidget::eDocumentWindowAnimation:
+              behavior = NSWindowAnimationBehaviorDocumentWindow;
+              break;
+            default:
+              MOZ_FALLTHROUGH_ASSERT("unexpected mAnimationType value");
+            case nsIWidget::eGenericWindowAnimation:
+              behavior = NSWindowAnimationBehaviorDefault;
+              break;
+          }
+        }
+        [mWindow setAnimationBehavior:behavior];
+        mWindowAnimationBehavior = behavior;
+      }
+
+      // We don't want alwaysontop windows to pull focus when they're opened,
+      // as these tend to be for peripheral indicators and displays.
+      if (mAlwaysOnTop) {
+        [mWindow orderFront:nil];
+      } else {
+        [mWindow makeKeyAndOrderFront:nil];
+      }
+      NS_OBJC_END_TRY_IGNORE_BLOCK;
+      SendSetZLevelEvent();
+    }
+  } else {
+    // roll up any popups if a top-level window is going away
+    if (mWindowType == WindowType::TopLevel || mWindowType == WindowType::Dialog) {
+      RollUpPopups();
+    }
+
+    // now get rid of the window/sheet
+    if (mWindowType == WindowType::Sheet) {
+      if (mSheetNeedsShow) {
+        // This is an attempt to hide a sheet that never had a chance to
+        // be shown. There's nothing to do other than make sure that it
+        // won't show.
+        mSheetNeedsShow = false;
+      } else {
+        // get sheet's parent *before* hiding the sheet (which breaks the linkage)
+        NSWindow* sheetParent = mSheetWindowParent;
+
+        // hide the sheet
+#ifdef MOZ_THUNDERBIRD
+        [NSApp endSheet:mWindow];
+#else
+        [mSheetWindowParent endSheet:mWindow];
+#endif
+        [TopLevelWindowData deactivateInWindow:mWindow];
+
+        nsCOMPtr<nsIWidget> siblingSheetToShow;
+        bool parentIsSheet = false;
+
+        if (nativeParentWindow && piParentWidget &&
+            NS_SUCCEEDED(
+                piParentWidget->GetChildSheet(false, getter_AddRefs(siblingSheetToShow))) &&
+            siblingSheetToShow) {
+          // First, give sibling sheets an opportunity to show.
+          siblingSheetToShow->Show(true);
+        } else if (nativeParentWindow && piParentWidget &&
+                   NS_SUCCEEDED(piParentWidget->GetIsSheet(&parentIsSheet)) && parentIsSheet) {
+#ifdef MOZ_THUNDERBIRD
+          // Only set contextInfo if the parent of the parent sheet we're about
+          // to restore isn't itself a sheet.
+          NSWindow* contextInfo = sheetParent;
+#else
+          // Only set nonSheetGrandparent if the parent of the parent sheet we're about
+          // to restore isn't itself a sheet.
+          NSWindow* nonSheetGrandparent = sheetParent;
+#endif
+          nsIWidget* grandparentWidget = nil;
+          if (NS_SUCCEEDED(piParentWidget->GetRealParent(&grandparentWidget)) &&
+              grandparentWidget) {
+            nsCOMPtr<nsPIWidgetCocoa> piGrandparentWidget(do_QueryInterface(grandparentWidget));
+            bool grandparentIsSheet = false;
+            if (piGrandparentWidget &&
+                NS_SUCCEEDED(piGrandparentWidget->GetIsSheet(&grandparentIsSheet)) &&
+                grandparentIsSheet) {
+#ifdef MOZ_THUNDERBIRD
+              contextInfo = nil;
+#else
+              nonSheetGrandparent = nil;
+#endif
+            }
+          }
+          // If there are no sibling sheets, but the parent is a sheet, restore
+          // it.  It wasn't sent any deactivate events when it was hidden, so
+          // don't call through Show, just let the OS put it back up.
+#ifdef MOZ_THUNDERBIRD
+          [NSApp beginSheet:nativeParentWindow
+              modalForWindow:sheetParent
+               modalDelegate:[nativeParentWindow delegate]
+              didEndSelector:@selector(didEndSheet:returnCode:contextInfo:)
+                 contextInfo:contextInfo];
+#else
+          [nativeParentWindow beginSheet:sheetParent
+                       completionHandler:^(NSModalResponse returnCode) {
+                         // Note: 'nonSheetGrandparent' (if it is set) is the window that is the
+                         // parent of sheetParent. If it's set, 'nonSheetGrandparent' is always the
+                         // top-level window, not another sheet itself.  But 'nonSheetGrandparent'
+                         // is nil if our parent window is also a sheet -- in that case we shouldn't
+                         // send the top-level window any activate events (because it's our parent
+                         // window that needs to get these events, not the top-level window).
+                         [TopLevelWindowData deactivateInWindow:sheetParent];
+                         [sheetParent orderOut:nil];
+                         if (nonSheetGrandparent) {
+                           [TopLevelWindowData activateInWindow:nonSheetGrandparent];
+                         }
+                       }];
+#endif
+        } else {
+          // Sheet, that was hard.  No more siblings or parents, going back
+          // to a real window.
+          NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+          [sheetParent makeKeyAndOrderFront:nil];
+          NS_OBJC_END_TRY_IGNORE_BLOCK;
+        }
+        SendSetZLevelEvent();
+      }
+    } else {
+      // If the window is a popup window with a parent window we need to
+      // unhook it here before ordering it out. When you order out the child
+      // of a window it hides the parent window.
+      if (mWindowType == WindowType::Popup && nativeParentWindow)
+        [nativeParentWindow removeChildWindow:mWindow];
+
+      [mWindow orderOut:nil];
+
+      // If our popup window is a non-native context menu, tell the OS (and
+      // other programs) that a menu has closed.
+      if ([mWindow isKindOfClass:[PopupWindow class]] && [(PopupWindow*)mWindow isContextMenu]) {
+        [[NSDistributedNotificationCenter defaultCenter]
+            postNotificationName:@"com.apple.HIToolbox.endMenuTrackingNotification"
+                          object:@"org.mozilla.gecko.PopupWindow"];
+      }
+    }
+  }
+
+  [mWindow setBeingShown:NO];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Work around a problem where with multiple displays and multiple spaces
+// enabled, where the browser is assigned to a single display or space, popup
+// windows that are reshown after being hidden with [NSWindow orderOut] show on
+// the assigned space even when opened from another display. Apply the
+// workaround whenever more than one display is enabled.
+bool nsCocoaWindow::NeedsRecreateToReshow() {
+  // Limit the workaround to popup windows because only they need to override
+  // the "Assign To" setting. i.e., to display where the parent window is.
+  return (mWindowType == WindowType::Popup) && mWasShown && ([[NSScreen screens] count] > 1);
+}
+
+WindowRenderer* nsCocoaWindow::GetWindowRenderer() {
+  if (mPopupContentView) {
+    return mPopupContentView->GetWindowRenderer();
+  }
+  return nullptr;
+}
+
+TransparencyMode nsCocoaWindow::GetTransparencyMode() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return (!mWindow || [mWindow isOpaque]) ? TransparencyMode::Opaque
+                                          : TransparencyMode::Transparent;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(TransparencyMode::Opaque);
+}
+
+// This is called from nsMenuPopupFrame when making a popup transparent.
+void nsCocoaWindow::SetTransparencyMode(TransparencyMode aMode) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Only respect calls for popup windows.
+  if (!mWindow || mWindowType != WindowType::Popup) {
+    return;
+  }
+
+  BOOL isTransparent = aMode == TransparencyMode::Transparent;
+  BOOL currentTransparency = ![mWindow isOpaque];
+  if (isTransparent != currentTransparency) {
+    [mWindow setOpaque:!isTransparent];
+    [mWindow setBackgroundColor:(isTransparent ? [NSColor clearColor] : [NSColor whiteColor])];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::Enable(bool aState) {}
+
+bool nsCocoaWindow::IsEnabled() const { return true; }
+
+void nsCocoaWindow::ConstrainPosition(DesktopIntPoint& aPoint) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow || ![mWindow screen]) {
+    return;
+  }
+
+  nsIntRect screenBounds;
+
+  int32_t width, height;
+
+  NSRect frame = [mWindow frame];
+
+  // zero size rects confuse the screen manager
+  width = std::max<int32_t>(frame.size.width, 1);
+  height = std::max<int32_t>(frame.size.height, 1);
+
+  nsCOMPtr<nsIScreenManager> screenMgr = do_GetService("@mozilla.org/gfx/screenmanager;1");
+  if (screenMgr) {
+    nsCOMPtr<nsIScreen> screen;
+    screenMgr->ScreenForRect(aPoint.x, aPoint.y, width, height, getter_AddRefs(screen));
+
+    if (screen) {
+      screen->GetRectDisplayPix(&(screenBounds.x), &(screenBounds.y), &(screenBounds.width),
+                                &(screenBounds.height));
+    }
+  }
+
+  if (aPoint.x < screenBounds.x) {
+    aPoint.x = screenBounds.x;
+  } else if (aPoint.x >= screenBounds.x + screenBounds.width - width) {
+    aPoint.x = screenBounds.x + screenBounds.width - width;
+  }
+
+  if (aPoint.y < screenBounds.y) {
+    aPoint.y = screenBounds.y;
+  } else if (aPoint.y >= screenBounds.y + screenBounds.height - height) {
+    aPoint.y = screenBounds.y + screenBounds.height - height;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetSizeConstraints(const SizeConstraints& aConstraints) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Popups can be smaller than (32, 32)
+  NSRect rect = (mWindowType == WindowType::Popup) ? NSZeroRect : NSMakeRect(0.0, 0.0, 32, 32);
+  rect = [mWindow frameRectForChildViewRect:rect];
+
+  SizeConstraints c = aConstraints;
+
+  if (c.mScale.scale == MOZ_WIDGET_INVALID_SCALE) {
+    c.mScale.scale = BackingScaleFactor();
+  }
+
+  c.mMinSize.width = std::max(nsCocoaUtils::CocoaPointsToDevPixels(rect.size.width, c.mScale.scale),
+                              c.mMinSize.width);
+  c.mMinSize.height = std::max(
+      nsCocoaUtils::CocoaPointsToDevPixels(rect.size.height, c.mScale.scale), c.mMinSize.height);
+
+  NSSize minSize = {nsCocoaUtils::DevPixelsToCocoaPoints(c.mMinSize.width, c.mScale.scale),
+                    nsCocoaUtils::DevPixelsToCocoaPoints(c.mMinSize.height, c.mScale.scale)};
+  [mWindow setMinSize:minSize];
+
+  c.mMaxSize.width = std::max(
+      nsCocoaUtils::CocoaPointsToDevPixels(c.mMaxSize.width, c.mScale.scale), c.mMaxSize.width);
+  c.mMaxSize.height = std::max(
+      nsCocoaUtils::CocoaPointsToDevPixels(c.mMaxSize.height, c.mScale.scale), c.mMaxSize.height);
+
+  NSSize maxSize = {c.mMaxSize.width == NS_MAXSIZE
+                        ? FLT_MAX
+                        : nsCocoaUtils::DevPixelsToCocoaPoints(c.mMaxSize.width, c.mScale.scale),
+                    c.mMaxSize.height == NS_MAXSIZE
+                        ? FLT_MAX
+                        : nsCocoaUtils::DevPixelsToCocoaPoints(c.mMaxSize.height, c.mScale.scale)};
+  [mWindow setMaxSize:maxSize];
+
+  nsBaseWidget::SetSizeConstraints(c);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Coordinates are desktop pixels
+void nsCocoaWindow::Move(double aX, double aY) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) {
+    return;
+  }
+
+  // The point we have is in Gecko coordinates (origin top-left). Convert
+  // it to Cocoa ones (origin bottom-left).
+  NSPoint coord = {static_cast<float>(aX),
+                   static_cast<float>(nsCocoaUtils::FlippedScreenY(NSToIntRound(aY)))};
+
+  NSRect frame = [mWindow frame];
+  if (frame.origin.x != coord.x || frame.origin.y + frame.size.height != coord.y) {
+    [mWindow setFrameTopLeftPoint:coord];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetSizeMode(nsSizeMode aMode) {
+  if (aMode == nsSizeMode_Normal) {
+    QueueTransition(TransitionType::Windowed);
+  } else if (aMode == nsSizeMode_Minimized) {
+    QueueTransition(TransitionType::Miniaturize);
+  } else if (aMode == nsSizeMode_Maximized) {
+    QueueTransition(TransitionType::Zoom);
+  } else if (aMode == nsSizeMode_Fullscreen) {
+    MakeFullScreen(true);
+  }
+}
+
+// The (work)space switching implementation below was inspired by Phoenix:
+// https://github.com/kasper/phoenix/tree/d6c877f62b30a060dff119d8416b0934f76af534
+// License: MIT.
+
+// Runtime `CGSGetActiveSpace` library function feature detection.
+typedef CGSSpaceID (*CGSGetActiveSpaceFunc)(CGSConnection cid);
+static CGSGetActiveSpaceFunc GetCGSGetActiveSpaceFunc() {
+  static CGSGetActiveSpaceFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSGetActiveSpaceFunc)dlsym(RTLD_DEFAULT, "CGSGetActiveSpace");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+// Runtime `CGSCopyManagedDisplaySpaces` library function feature detection.
+typedef CFArrayRef (*CGSCopyManagedDisplaySpacesFunc)(CGSConnection cid);
+static CGSCopyManagedDisplaySpacesFunc GetCGSCopyManagedDisplaySpacesFunc() {
+  static CGSCopyManagedDisplaySpacesFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSCopyManagedDisplaySpacesFunc)dlsym(RTLD_DEFAULT, "CGSCopyManagedDisplaySpaces");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+// Runtime `CGSCopySpacesForWindows` library function feature detection.
+typedef CFArrayRef (*CGSCopySpacesForWindowsFunc)(CGSConnection cid, CGSSpaceMask mask,
+                                                  CFArrayRef windowIDs);
+static CGSCopySpacesForWindowsFunc GetCGSCopySpacesForWindowsFunc() {
+  static CGSCopySpacesForWindowsFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSCopySpacesForWindowsFunc)dlsym(RTLD_DEFAULT, "CGSCopySpacesForWindows");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+// Runtime `CGSAddWindowsToSpaces` library function feature detection.
+typedef void (*CGSAddWindowsToSpacesFunc)(CGSConnection cid, CFArrayRef windowIDs,
+                                          CFArrayRef spaceIDs);
+static CGSAddWindowsToSpacesFunc GetCGSAddWindowsToSpacesFunc() {
+  static CGSAddWindowsToSpacesFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSAddWindowsToSpacesFunc)dlsym(RTLD_DEFAULT, "CGSAddWindowsToSpaces");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+// Runtime `CGSRemoveWindowsFromSpaces` library function feature detection.
+typedef void (*CGSRemoveWindowsFromSpacesFunc)(CGSConnection cid, CFArrayRef windowIDs,
+                                               CFArrayRef spaceIDs);
+static CGSRemoveWindowsFromSpacesFunc GetCGSRemoveWindowsFromSpacesFunc() {
+  static CGSRemoveWindowsFromSpacesFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSRemoveWindowsFromSpacesFunc)dlsym(RTLD_DEFAULT, "CGSRemoveWindowsFromSpaces");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+
+void nsCocoaWindow::GetWorkspaceID(nsAString& workspaceID) {
+  workspaceID.Truncate();
+  int32_t sid = GetWorkspaceID();
+  if (sid != 0) {
+    workspaceID.AppendInt(sid);
+  }
+}
+
+int32_t nsCocoaWindow::GetWorkspaceID() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Mac OSX space IDs start at '1' (default space), so '0' means 'unknown',
+  // effectively.
+  CGSSpaceID sid = 0;
+
+  CGSCopySpacesForWindowsFunc CopySpacesForWindows = GetCGSCopySpacesForWindowsFunc();
+  if (!CopySpacesForWindows) {
+    return sid;
+  }
+
+  CGSConnection cid = _CGSDefaultConnection();
+  // Fetch all spaces that this window belongs to (in order).
+  NSArray<NSNumber*>* spaceIDs = CFBridgingRelease(CopySpacesForWindows(
+      cid, kCGSAllSpacesMask, (__bridge CFArrayRef) @[ @([mWindow windowNumber]) ]));
+  if ([spaceIDs count]) {
+    // When spaces are found, return the first one.
+    // We don't support a single window painted across multiple places for now.
+    sid = [spaceIDs[0] integerValue];
+  } else {
+    // Fall back to the workspace that's currently active, which is '1' in the
+    // common case.
+    CGSGetActiveSpaceFunc GetActiveSpace = GetCGSGetActiveSpaceFunc();
+    if (GetActiveSpace) {
+      sid = GetActiveSpace(cid);
+    }
+  }
+
+  return sid;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::MoveToWorkspace(const nsAString& workspaceIDStr) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if ([NSScreen screensHaveSeparateSpaces] && [[NSScreen screens] count] > 1) {
+    // We don't support moving to a workspace when the user has this option
+    // enabled in Mission Control.
+    return;
+  }
+
+  nsresult rv = NS_OK;
+  int32_t workspaceID = workspaceIDStr.ToInteger(&rv);
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  CGSConnection cid = _CGSDefaultConnection();
+  int32_t currentSpace = GetWorkspaceID();
+  // If an empty workspace ID is passed in (not valid on OSX), or when the
+  // window is already on this workspace, we don't need to do anything.
+  if (!workspaceID || workspaceID == currentSpace) {
+    return;
+  }
+
+  CGSCopyManagedDisplaySpacesFunc CopyManagedDisplaySpaces = GetCGSCopyManagedDisplaySpacesFunc();
+  CGSAddWindowsToSpacesFunc AddWindowsToSpaces = GetCGSAddWindowsToSpacesFunc();
+  CGSRemoveWindowsFromSpacesFunc RemoveWindowsFromSpaces = GetCGSRemoveWindowsFromSpacesFunc();
+  if (!CopyManagedDisplaySpaces || !AddWindowsToSpaces || !RemoveWindowsFromSpaces) {
+    return;
+  }
+
+  // Fetch an ordered list of all known spaces.
+  NSArray* displaySpacesInfo = CFBridgingRelease(CopyManagedDisplaySpaces(cid));
+  // When we found the space we're looking for, we can bail out of the loop
+  // early, which this local variable is used for.
+  BOOL found = false;
+  for (NSDictionary<NSString*, id>* spacesInfo in displaySpacesInfo) {
+    NSArray<NSNumber*>* sids = [spacesInfo[CGSSpacesKey] valueForKey:CGSSpaceIDKey];
+    for (NSNumber* sid in sids) {
+      // If we found our space in the list, we're good to go and can jump out of
+      // this loop.
+      if ((int)[sid integerValue] == workspaceID) {
+        found = true;
+        break;
+      }
+    }
+    if (found) {
+      break;
+    }
+  }
+
+  // We were unable to find the space to correspond with the workspaceID as
+  // requested, so let's bail out.
+  if (!found) {
+    return;
+  }
+
+  // First we add the window to the appropriate space.
+  AddWindowsToSpaces(cid, (__bridge CFArrayRef) @[ @([mWindow windowNumber]) ],
+                     (__bridge CFArrayRef) @[ @(workspaceID) ]);
+  // Then we remove the window from the active space.
+  RemoveWindowsFromSpaces(cid, (__bridge CFArrayRef) @[ @([mWindow windowNumber]) ],
+                          (__bridge CFArrayRef) @[ @(currentSpace) ]);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SuppressAnimation(bool aSuppress) {
+  if ([mWindow respondsToSelector:@selector(setAnimationBehavior:)]) {
+    if (aSuppress) {
+      [mWindow setIsAnimationSuppressed:YES];
+      [mWindow setAnimationBehavior:NSWindowAnimationBehaviorNone];
+    } else {
+      [mWindow setIsAnimationSuppressed:NO];
+      [mWindow setAnimationBehavior:mWindowAnimationBehavior];
+    }
+  }
+}
+
+// This has to preserve the window's frame bounds.
+// This method requires (as does the Windows impl.) that you call Resize shortly
+// after calling HideWindowChrome. See bug 498835 for fixing this.
+void nsCocoaWindow::HideWindowChrome(bool aShouldHide) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow || !mWindowMadeHere ||
+      (mWindowType != WindowType::TopLevel && mWindowType != WindowType::Dialog))
+    return;
+
+  BOOL isVisible = [mWindow isVisible];
+
+  // Remove child windows.
+  NSArray* childWindows = [mWindow childWindows];
+  NSEnumerator* enumerator = [childWindows objectEnumerator];
+  NSWindow* child = nil;
+  while ((child = [enumerator nextObject])) {
+    [mWindow removeChildWindow:child];
+  }
+
+  // Remove the views in the old window's content view.
+  // The NSArray is autoreleased and retains its NSViews.
+  NSArray<NSView*>* contentViewContents = [mWindow contentViewContents];
+  for (NSView* view in contentViewContents) {
+    [view removeFromSuperviewWithoutNeedingDisplay];
+  }
+
+  // Save state (like window title).
+  NSMutableDictionary* state = [mWindow exportState];
+
+  // Recreate the window with the right border style.
+  NSRect frameRect = [mWindow frame];
+  DestroyNativeWindow();
+  nsresult rv = CreateNativeWindow(frameRect, aShouldHide ? BorderStyle::None : mBorderStyle, true,
+                                   mWindow.restorable);
+  NS_ENSURE_SUCCESS_VOID(rv);
+
+  // Re-import state.
+  [mWindow importState:state];
+
+  // Add the old content view subviews to the new window's content view.
+  for (NSView* view in contentViewContents) {
+    [[mWindow contentView] addSubview:view];
+  }
+
+  // Reparent child windows.
+  enumerator = [childWindows objectEnumerator];
+  while ((child = [enumerator nextObject])) {
+    [mWindow addChildWindow:child ordered:NSWindowAbove];
+  }
+
+  // Show the new window.
+  if (isVisible) {
+    bool wasAnimationSuppressed = mIsAnimationSuppressed;
+    mIsAnimationSuppressed = true;
+    Show(true);
+    mIsAnimationSuppressed = wasAnimationSuppressed;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+class FullscreenTransitionData : public nsISupports {
+ public:
+  NS_DECL_ISUPPORTS
+
+  explicit FullscreenTransitionData(NSWindow* aWindow) : mTransitionWindow(aWindow) {}
+
+  NSWindow* mTransitionWindow;
+
+ private:
+  virtual ~FullscreenTransitionData() { [mTransitionWindow close]; }
+};
+
+NS_IMPL_ISUPPORTS0(FullscreenTransitionData)
+
+@interface FullscreenTransitionDelegate : NSObject <NSAnimationDelegate> {
+ @public
+  nsCocoaWindow* mWindow;
+  nsIRunnable* mCallback;
+}
+@end
+
+@implementation FullscreenTransitionDelegate
+- (void)cleanupAndDispatch:(NSAnimation*)animation {
+  [animation setDelegate:nil];
+  [self autorelease];
+  // The caller should have added ref for us.
+  NS_DispatchToMainThread(already_AddRefed<nsIRunnable>(mCallback));
+}
+
+- (void)animationDidEnd:(NSAnimation*)animation {
+  MOZ_ASSERT(animation == mWindow->FullscreenTransitionAnimation(),
+             "Should be handling the only animation on the window");
+  mWindow->ReleaseFullscreenTransitionAnimation();
+  [self cleanupAndDispatch:animation];
+}
+
+- (void)animationDidStop:(NSAnimation*)animation {
+  [self cleanupAndDispatch:animation];
+}
+@end
+
+static bool AlwaysUsesNativeFullScreen() {
+  return Preferences::GetBool("full-screen-api.macos-native-full-screen", false);
+}
+
+/* virtual */ bool nsCocoaWindow::PrepareForFullscreenTransition(nsISupports** aData) {
+  if (AlwaysUsesNativeFullScreen()) {
+    return false;
+  }
+
+  // Our fullscreen transition creates a new window occluding this window.
+  // That triggers an occlusion event which can cause DOM fullscreen requests
+  // to fail due to the context not being focused at the time the focus check
+  // is performed in the child process. Until the transition is cleaned up in
+  // CleanupFullscreenTransition(), ignore occlusion events for this window.
+  // If this method is changed to return false, the transition will not be
+  // performed and mIgnoreOcclusionCount should not be incremented.
+  MOZ_ASSERT(mIgnoreOcclusionCount >= 0);
+  mIgnoreOcclusionCount++;
+
+  nsCOMPtr<nsIScreen> widgetScreen = GetWidgetScreen();
+  NSScreen* cocoaScreen = ScreenHelperCocoa::CocoaScreenForScreen(widgetScreen);
+
+  NSWindow* win = [[NSWindow alloc] initWithContentRect:[cocoaScreen frame]
+                                              styleMask:NSWindowStyleMaskBorderless
+                                                backing:NSBackingStoreBuffered
+                                                  defer:YES];
+  [win setBackgroundColor:[NSColor blackColor]];
+  [win setAlphaValue:0];
+  [win setIgnoresMouseEvents:YES];
+  [win setLevel:NSScreenSaverWindowLevel];
+  [win makeKeyAndOrderFront:nil];
+
+  auto data = new FullscreenTransitionData(win);
+  *aData = data;
+  NS_ADDREF(data);
+  return true;
+}
+
+/* virtual */ void nsCocoaWindow::CleanupFullscreenTransition() {
+  MOZ_ASSERT(mIgnoreOcclusionCount > 0);
+  mIgnoreOcclusionCount--;
+}
+
+/* virtual */ void nsCocoaWindow::PerformFullscreenTransition(FullscreenTransitionStage aStage,
+                                                              uint16_t aDuration,
+                                                              nsISupports* aData,
+                                                              nsIRunnable* aCallback) {
+  auto data = static_cast<FullscreenTransitionData*>(aData);
+  FullscreenTransitionDelegate* delegate = [[FullscreenTransitionDelegate alloc] init];
+  delegate->mWindow = this;
+  // Storing already_AddRefed directly could cause static checking fail.
+  delegate->mCallback = nsCOMPtr<nsIRunnable>(aCallback).forget().take();
+
+  if (mFullscreenTransitionAnimation) {
+    [mFullscreenTransitionAnimation stopAnimation];
+    ReleaseFullscreenTransitionAnimation();
+  }
+
+  NSDictionary* dict = @{
+    NSViewAnimationTargetKey : data->mTransitionWindow,
+    NSViewAnimationEffectKey : aStage == eBeforeFullscreenToggle ? NSViewAnimationFadeInEffect
+                                                                 : NSViewAnimationFadeOutEffect
+  };
+  mFullscreenTransitionAnimation = [[NSViewAnimation alloc] initWithViewAnimations:@[ dict ]];
+  [mFullscreenTransitionAnimation setDelegate:delegate];
+  [mFullscreenTransitionAnimation setDuration:aDuration / 1000.0];
+  [mFullscreenTransitionAnimation startAnimation];
+}
+
+void nsCocoaWindow::CocoaWindowWillEnterFullscreen(bool aFullscreen) {
+  MOZ_ASSERT(mUpdateFullscreenOnResize.isNothing());
+
+  mHasStartedNativeFullscreen = true;
+
+  // Ensure that we update our fullscreen state as early as possible, when the resize
+  // happens.
+  mUpdateFullscreenOnResize =
+      Some(aFullscreen ? TransitionType::Fullscreen : TransitionType::Windowed);
+}
+
+void nsCocoaWindow::CocoaWindowDidEnterFullscreen(bool aFullscreen) {
+  mHasStartedNativeFullscreen = false;
+  DispatchOcclusionEvent();
+  HandleUpdateFullscreenOnResize();
+  FinishCurrentTransitionIfMatching(aFullscreen ? TransitionType::Fullscreen
+                                                : TransitionType::Windowed);
+}
+
+void nsCocoaWindow::CocoaWindowDidFailFullscreen(bool aAttemptedFullscreen) {
+  mHasStartedNativeFullscreen = false;
+  DispatchOcclusionEvent();
+
+  // If we already updated our fullscreen state due to a resize, we need to update it again.
+  if (mUpdateFullscreenOnResize.isNothing()) {
+    UpdateFullscreenState(!aAttemptedFullscreen, true);
+    ReportSizeEvent();
+  }
+
+  TransitionType transition =
+      aAttemptedFullscreen ? TransitionType::Fullscreen : TransitionType::Windowed;
+  FinishCurrentTransitionIfMatching(transition);
+}
+
+void nsCocoaWindow::UpdateFullscreenState(bool aFullScreen, bool aNativeMode) {
+  bool wasInFullscreen = mInFullScreenMode;
+  mInFullScreenMode = aFullScreen;
+  if (aNativeMode || mInNativeFullScreenMode) {
+    mInNativeFullScreenMode = aFullScreen;
+  }
+
+  if (aFullScreen == wasInFullscreen) {
+    return;
+  }
+
+  DispatchSizeModeEvent();
+
+  // Notify the mainChildView with our new fullscreen state.
+  nsChildView* mainChildView = static_cast<nsChildView*>([[mWindow mainChildView] widget]);
+  if (mainChildView) {
+    mainChildView->UpdateFullscreen(aFullScreen);
+  }
+}
+
+nsresult nsCocoaWindow::MakeFullScreen(bool aFullScreen) {
+  return DoMakeFullScreen(aFullScreen, AlwaysUsesNativeFullScreen());
+}
+
+nsresult nsCocoaWindow::MakeFullScreenWithNativeTransition(bool aFullScreen) {
+  return DoMakeFullScreen(aFullScreen, true);
+}
+
+nsresult nsCocoaWindow::DoMakeFullScreen(bool aFullScreen, bool aUseSystemTransition) {
+  if (!mWindow) {
+    return NS_OK;
+  }
+
+  // Figure out what type of transition is being requested.
+  TransitionType transition = TransitionType::Windowed;
+  if (aFullScreen) {
+    // Decide whether to use fullscreen or emulated fullscreen.
+    transition = (aUseSystemTransition &&
+                  (mWindow.collectionBehavior & NSWindowCollectionBehaviorFullScreenPrimary))
+                     ? TransitionType::Fullscreen
+                     : TransitionType::EmulatedFullscreen;
+  }
+
+  QueueTransition(transition);
+  return NS_OK;
+}
+
+void nsCocoaWindow::QueueTransition(const TransitionType& aTransition) {
+  mTransitionsPending.push(aTransition);
+  ProcessTransitions();
+}
+
+void nsCocoaWindow::ProcessTransitions() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK
+
+  if (mInProcessTransitions) {
+    return;
+  }
+
+  mInProcessTransitions = true;
+
+  // Start a loop that will continue as long as we have transitions to process
+  // and we aren't waiting on an asynchronous transition to complete. Any
+  // transition that starts something async will `continue` this loop to exit.
+  while (!mTransitionsPending.empty() && !IsInTransition()) {
+    TransitionType nextTransition = mTransitionsPending.front();
+
+    // We have to check for some incompatible transition states, and if we find one,
+    // instead perform an alternative transition and leave the queue untouched. If
+    // we add one of these transitions, we set mIsTransitionCurrentAdded because we
+    // don't want to confuse listeners who are expecting to receive exactly one
+    // event when the requested transition has completed.
+    switch (nextTransition) {
+      case TransitionType::Fullscreen:
+      case TransitionType::EmulatedFullscreen:
+      case TransitionType::Windowed:
+      case TransitionType::Zoom:
+        // These can't handle miniaturized windows, so deminiaturize first.
+        if (mWindow.miniaturized) {
+          mTransitionCurrent = Some(TransitionType::Deminiaturize);
+          mIsTransitionCurrentAdded = true;
+        }
+        break;
+      case TransitionType::Miniaturize:
+        // This can't handle fullscreen, so go to windowed first.
+        if (mInFullScreenMode) {
+          mTransitionCurrent = Some(TransitionType::Windowed);
+          mIsTransitionCurrentAdded = true;
+        }
+        break;
+      default:
+        break;
+    }
+
+    // If mTransitionCurrent is still empty, then we use the nextTransition and pop
+    // the queue.
+    if (mTransitionCurrent.isNothing()) {
+      mTransitionCurrent = Some(nextTransition);
+      mTransitionsPending.pop();
+    }
+
+    switch (*mTransitionCurrent) {
+      case TransitionType::Fullscreen: {
+        if (!mInFullScreenMode) {
+          // This triggers an async animation, so continue.
+          [mWindow toggleFullScreen:nil];
+          continue;
+        }
+        break;
+      }
+
+      case TransitionType::EmulatedFullscreen: {
+        if (!mInFullScreenMode) {
+          NSDisableScreenUpdates();
+          mSuppressSizeModeEvents = true;
+          // The order here matters. When we exit full screen mode, we need to show the
+          // Dock first, otherwise the newly-created window won't have its minimize
+          // button enabled. See bug 526282.
+          nsCocoaUtils::HideOSChromeOnScreen(true);
+          nsBaseWidget::InfallibleMakeFullScreen(true);
+          mSuppressSizeModeEvents = false;
+          NSEnableScreenUpdates();
+          UpdateFullscreenState(true, false);
+        }
+        break;
+      }
+
+      case TransitionType::Windowed: {
+        if (mInFullScreenMode) {
+          if (mInNativeFullScreenMode) {
+            // This triggers an async animation, so continue.
+            [mWindow toggleFullScreen:nil];
+            continue;
+          } else {
+            NSDisableScreenUpdates();
+            mSuppressSizeModeEvents = true;
+            // The order here matters. When we exit full screen mode, we need to show the
+            // Dock first, otherwise the newly-created window won't have its minimize
+            // button enabled. See bug 526282.
+            nsCocoaUtils::HideOSChromeOnScreen(false);
+            nsBaseWidget::InfallibleMakeFullScreen(false);
+            mSuppressSizeModeEvents = false;
+            NSEnableScreenUpdates();
+            UpdateFullscreenState(false, false);
+          }
+        } else if (mWindow.zoomed) {
+          [mWindow zoom:nil];
+
+          // Check if we're still zoomed. If we are, we need to do *something* to make the
+          // window smaller than the zoom size so Cocoa will treat us as being out of the
+          // zoomed state. Otherwise, we could stay zoomed and never be able to be "normal"
+          // from calls to SetSizeMode.
+          if (mWindow.zoomed) {
+            NSRect maximumFrame = mWindow.frame;
+            const CGFloat INSET_OUT_OF_ZOOM = 20.0f;
+            [mWindow setFrame:NSInsetRect(maximumFrame, INSET_OUT_OF_ZOOM, INSET_OUT_OF_ZOOM)
+                      display:YES];
+            MOZ_ASSERT(!mWindow.zoomed,
+                       "We should be able to unzoom by shrinking the frame a bit.");
+          }
+        }
+        break;
+      }
+
+      case TransitionType::Miniaturize:
+        if (!mWindow.miniaturized) {
+          // This triggers an async animation, so continue.
+          [mWindow miniaturize:nil];
+          continue;
+        }
+        break;
+
+      case TransitionType::Deminiaturize:
+        if (mWindow.miniaturized) {
+          // This triggers an async animation, so continue.
+          [mWindow deminiaturize:nil];
+          continue;
+        }
+        break;
+
+      case TransitionType::Zoom:
+        if (!mWindow.zoomed) {
+          [mWindow zoom:nil];
+        }
+        break;
+
+      default:
+        break;
+    }
+
+    mTransitionCurrent.reset();
+    mIsTransitionCurrentAdded = false;
+  }
+
+  mInProcessTransitions = false;
+
+  // When we finish processing transitions, dispatch a size mode event to cover the
+  // cases where an inserted transition suppressed one, and the original transition
+  // never sent one because it detected it was at the desired state when it ran. If
+  // we've already sent a size mode event, then this will be a no-op.
+  if (!IsInTransition()) {
+    DispatchSizeModeEvent();
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::FinishCurrentTransition() {
+  mTransitionCurrent.reset();
+  mIsTransitionCurrentAdded = false;
+  ProcessTransitions();
+}
+
+void nsCocoaWindow::FinishCurrentTransitionIfMatching(const TransitionType& aTransition) {
+  // We've just finished some transition activity, and we're not sure whether it was
+  // triggered programmatically, or by the user. If it matches our current transition,
+  // then assume it was triggered programmatically and we can clean up that transition
+  // and start processing transitions again.
+
+  // Whether programmatic or user-initiated, we send out a size mode event.
+  DispatchSizeModeEvent();
+
+  if (mTransitionCurrent.isSome() && (*mTransitionCurrent == aTransition)) {
+    // This matches our current transition. Since this function is called from
+    // nsWindowDelegate transition callbacks, we want to make sure those callbacks are
+    // all the way done before we start processing more transitions. To accomplish this,
+    // we dispatch our cleanup to happen on the next event loop. Doing this will ensure
+    // that any async native transition methods we call (like toggleFullscreen) will
+    // succeed.
+    NS_DispatchToCurrentThread(NewRunnableMethod("FinishCurrentTransition", this,
+                                                 &nsCocoaWindow::FinishCurrentTransition));
+  }
+}
+
+bool nsCocoaWindow::HandleUpdateFullscreenOnResize() {
+  if (mUpdateFullscreenOnResize.isNothing()) {
+    return false;
+  }
+
+  bool toFullscreen = (*mUpdateFullscreenOnResize == TransitionType::Fullscreen);
+  mUpdateFullscreenOnResize.reset();
+  UpdateFullscreenState(toFullscreen, true);
+
+  return true;
+}
+
+// Coordinates are desktop pixels
+void nsCocoaWindow::DoResize(double aX, double aY, double aWidth, double aHeight, bool aRepaint,
+                             bool aConstrainToCurrentScreen) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow || mInResize) {
+    return;
+  }
+
+  // We are able to resize a window outside of any aspect ratio contraints
+  // applied to it, but in order to "update" the aspect ratio contraint to the
+  // new window dimensions, we must re-lock the aspect ratio.
+  auto relockAspectRatio = MakeScopeExit([&]() {
+    if (mAspectRatioLocked) {
+      LockAspectRatio(true);
+    }
+  });
+
+  AutoRestore<bool> reentrantResizeGuard(mInResize);
+  mInResize = true;
+
+  CGFloat scale = mSizeConstraints.mScale.scale;
+  if (scale == MOZ_WIDGET_INVALID_SCALE) {
+    scale = BackingScaleFactor();
+  }
+
+  // mSizeConstraints is in device pixels.
+  int32_t width = NSToIntRound(aWidth * scale);
+  int32_t height = NSToIntRound(aHeight * scale);
+
+  width =
+      std::max(mSizeConstraints.mMinSize.width, std::min(mSizeConstraints.mMaxSize.width, width));
+  height = std::max(mSizeConstraints.mMinSize.height,
+                    std::min(mSizeConstraints.mMaxSize.height, height));
+
+  DesktopIntRect newBounds(NSToIntRound(aX), NSToIntRound(aY), NSToIntRound(width / scale),
+                           NSToIntRound(height / scale));
+
+  // constrain to the screen that contains the largest area of the new rect
+  FitRectToVisibleAreaForScreen(newBounds, aConstrainToCurrentScreen ? [mWindow screen] : nullptr);
+
+  // convert requested bounds into Cocoa coordinate system
+  NSRect newFrame = nsCocoaUtils::GeckoRectToCocoaRect(newBounds);
+
+  NSRect frame = [mWindow frame];
+  BOOL isMoving = newFrame.origin.x != frame.origin.x || newFrame.origin.y != frame.origin.y;
+  BOOL isResizing =
+      newFrame.size.width != frame.size.width || newFrame.size.height != frame.size.height;
+
+  if (!isMoving && !isResizing) {
+    return;
+  }
+
+  // We ignore aRepaint -- we have to call display:YES, otherwise the
+  // title bar doesn't immediately get repainted and is displayed in
+  // the wrong place, leading to a visual jump.
+  [mWindow setFrame:newFrame display:YES];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Coordinates are desktop pixels
+void nsCocoaWindow::Resize(double aX, double aY, double aWidth, double aHeight, bool aRepaint) {
+  DoResize(aX, aY, aWidth, aHeight, aRepaint, false);
+}
+
+// Coordinates are desktop pixels
+void nsCocoaWindow::Resize(double aWidth, double aHeight, bool aRepaint) {
+  double invScale = 1.0 / BackingScaleFactor();
+  DoResize(mBounds.x * invScale, mBounds.y * invScale, aWidth, aHeight, aRepaint, true);
+}
+
+// Return the area that the Gecko ChildView in our window should cover, as an
+// NSRect in screen coordinates (with 0,0 being the bottom left corner of the
+// primary screen).
+NSRect nsCocoaWindow::GetClientCocoaRect() {
+  if (!mWindow) {
+    return NSZeroRect;
+  }
+
+  return [mWindow childViewRectForFrameRect:[mWindow frame]];
+}
+
+LayoutDeviceIntRect nsCocoaWindow::GetClientBounds() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  CGFloat scaleFactor = BackingScaleFactor();
+  return nsCocoaUtils::CocoaRectToGeckoRectDevPix(GetClientCocoaRect(), scaleFactor);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntRect(0, 0, 0, 0));
+}
+
+void nsCocoaWindow::UpdateBounds() {
+  NSRect frame = NSZeroRect;
+  if (mWindow) {
+    frame = [mWindow frame];
+  }
+  mBounds = nsCocoaUtils::CocoaRectToGeckoRectDevPix(frame, BackingScaleFactor());
+
+  if (mPopupContentView) {
+    mPopupContentView->UpdateBoundsFromView();
+  }
+}
+
+LayoutDeviceIntRect nsCocoaWindow::GetScreenBounds() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+#ifdef DEBUG
+  LayoutDeviceIntRect r =
+      nsCocoaUtils::CocoaRectToGeckoRectDevPix([mWindow frame], BackingScaleFactor());
+  NS_ASSERTION(mWindow && mBounds == r, "mBounds out of sync!");
+#endif
+
+  return mBounds;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntRect(0, 0, 0, 0));
+}
+
+double nsCocoaWindow::GetDefaultScaleInternal() { return BackingScaleFactor(); }
+
+static CGFloat GetBackingScaleFactor(NSWindow* aWindow) {
+  NSRect frame = [aWindow frame];
+  if (frame.size.width > 0 && frame.size.height > 0) {
+    return nsCocoaUtils::GetBackingScaleFactor(aWindow);
+  }
+
+  // For windows with zero width or height, the backingScaleFactor method
+  // is broken - it will always return 2 on a retina macbook, even when
+  // the window position implies it's on a non-hidpi external display
+  // (to the extent that a zero-area window can be said to be "on" a
+  // display at all!)
+  // And to make matters worse, Cocoa even fires a
+  // windowDidChangeBackingProperties notification with the
+  // NSBackingPropertyOldScaleFactorKey key when a window on an
+  // external display is resized to/from zero height, even though it hasn't
+  // really changed screens.
+
+  // This causes us to handle popup window sizing incorrectly when the
+  // popup is resized to zero height (bug 820327) - nsXULPopupManager
+  // becomes (incorrectly) convinced the popup has been explicitly forced
+  // to a non-default size and needs to have size attributes attached.
+
+  // Workaround: instead of asking the window, we'll find the screen it is on
+  // and ask that for *its* backing scale factor.
+
+  // (See bug 853252 and additional comments in windowDidChangeScreen: below
+  // for further complications this causes.)
+
+  // First, expand the rect so that it actually has a measurable area,
+  // for FindTargetScreenForRect to use.
+  if (frame.size.width == 0) {
+    frame.size.width = 1;
+  }
+  if (frame.size.height == 0) {
+    frame.size.height = 1;
+  }
+
+  // Then identify the screen it belongs to, and return its scale factor.
+  NSScreen* screen = FindTargetScreenForRect(nsCocoaUtils::CocoaRectToGeckoRect(frame));
+  return nsCocoaUtils::GetBackingScaleFactor(screen);
+}
+
+CGFloat nsCocoaWindow::BackingScaleFactor() {
+  if (mBackingScaleFactor > 0.0) {
+    return mBackingScaleFactor;
+  }
+  if (!mWindow) {
+    return 1.0;
+  }
+  mBackingScaleFactor = GetBackingScaleFactor(mWindow);
+  return mBackingScaleFactor;
+}
+
+void nsCocoaWindow::BackingScaleFactorChanged() {
+  CGFloat newScale = GetBackingScaleFactor(mWindow);
+
+  // ignore notification if it hasn't really changed (or maybe we have
+  // disabled HiDPI mode via prefs)
+  if (mBackingScaleFactor == newScale) {
+    return;
+  }
+
+  mBackingScaleFactor = newScale;
+
+  if (!mWidgetListener || mWidgetListener->GetAppWindow()) {
+    return;
+  }
+
+  if (PresShell* presShell = mWidgetListener->GetPresShell()) {
+    presShell->BackingScaleFactorChanged();
+  }
+  mWidgetListener->UIResolutionChanged();
+}
+
+int32_t nsCocoaWindow::RoundsWidgetCoordinatesTo() {
+  if (BackingScaleFactor() == 2.0) {
+    return 2;
+  }
+  return 1;
+}
+
+void nsCocoaWindow::SetCursor(const Cursor& aCursor) {
+  if (mPopupContentView) {
+    mPopupContentView->SetCursor(aCursor);
+  }
+}
+
+nsresult nsCocoaWindow::SetTitle(const nsAString& aTitle) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mWindow) {
+    return NS_OK;
+  }
+
+  const nsString& strTitle = PromiseFlatString(aTitle);
+  const unichar* uniTitle = reinterpret_cast<const unichar*>(strTitle.get());
+  NSString* title = [NSString stringWithCharacters:uniTitle length:strTitle.Length()];
+  if ([mWindow drawsContentsIntoWindowFrame] && ![mWindow wantsTitleDrawn]) {
+    // Don't cause invalidations when the title isn't displayed.
+    [mWindow disableSetNeedsDisplay];
+    [mWindow setTitle:title];
+    [mWindow enableSetNeedsDisplay];
+  } else {
+    [mWindow setTitle:title];
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsCocoaWindow::Invalidate(const LayoutDeviceIntRect& aRect) {
+  if (mPopupContentView) {
+    mPopupContentView->Invalidate(aRect);
+  }
+}
+
+// Pass notification of some drag event to Gecko
+//
+// The drag manager has let us know that something related to a drag has
+// occurred in this window. It could be any number of things, ranging from
+// a drop, to a drag enter/leave, or a drag over event. The actual event
+// is passed in |aMessage| and is passed along to our event hanlder so Gecko
+// knows about it.
+bool nsCocoaWindow::DragEvent(unsigned int aMessage, mozilla::gfx::Point aMouseGlobal,
+                              UInt16 aKeyModifiers) {
+  return false;
+}
+
+NS_IMETHODIMP nsCocoaWindow::SendSetZLevelEvent() {
+  nsWindowZ placement = nsWindowZTop;
+  nsCOMPtr<nsIWidget> actualBelow;
+  if (mWidgetListener)
+    mWidgetListener->ZLevelChanged(true, &placement, nullptr, getter_AddRefs(actualBelow));
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::GetChildSheet(bool aShown, nsIWidget** _retval) {
+  nsIWidget* child = GetFirstChild();
+
+  while (child) {
+    if (child->GetWindowType() == WindowType::Sheet) {
+      // if it's a sheet, it must be an nsCocoaWindow
+      nsCocoaWindow* cocoaWindow = static_cast<nsCocoaWindow*>(child);
+      if (cocoaWindow->mWindow && ((aShown && [cocoaWindow->mWindow isVisible]) ||
+                                   (!aShown && cocoaWindow->mSheetNeedsShow))) {
+        nsCOMPtr<nsIWidget> widget = cocoaWindow;
+        widget.forget(_retval);
+        return NS_OK;
+      }
+    }
+    child = child->GetNextSibling();
+  }
+
+  *_retval = nullptr;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::GetRealParent(nsIWidget** parent) {
+  *parent = mParent;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::GetIsSheet(bool* isSheet) {
+  mWindowType == WindowType::Sheet ? * isSheet = true : * isSheet = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::GetSheetWindowParent(NSWindow** sheetWindowParent) {
+  *sheetWindowParent = mSheetWindowParent;
+  return NS_OK;
+}
+
+// Invokes callback and ProcessEvent methods on Event Listener object
+nsresult nsCocoaWindow::DispatchEvent(WidgetGUIEvent* event, nsEventStatus& aStatus) {
+  aStatus = nsEventStatus_eIgnore;
+
+  nsCOMPtr<nsIWidget> kungFuDeathGrip(event->mWidget);
+  mozilla::Unused << kungFuDeathGrip;  // Not used within this function
+
+  if (mWidgetListener) aStatus = mWidgetListener->HandleEvent(event, mUseAttachedEvents);
+
+  return NS_OK;
+}
+
+// aFullScreen should be the window's mInFullScreenMode. We don't have access to that
+// from here, so we need to pass it in. mInFullScreenMode should be the canonical
+// indicator that a window is currently full screen and it makes sense to keep
+// all sizemode logic here.
+static nsSizeMode GetWindowSizeMode(NSWindow* aWindow, bool aFullScreen) {
+  if (aFullScreen) return nsSizeMode_Fullscreen;
+  if ([aWindow isMiniaturized]) return nsSizeMode_Minimized;
+  if (([aWindow styleMask] & NSWindowStyleMaskResizable) && [aWindow isZoomed])
+    return nsSizeMode_Maximized;
+  return nsSizeMode_Normal;
+}
+
+void nsCocoaWindow::ReportMoveEvent() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Prevent recursion, which can become infinite (see bug 708278).  This
+  // can happen when the call to [NSWindow setFrameTopLeftPoint:] in
+  // nsCocoaWindow::Move() triggers an immediate NSWindowDidMove notification
+  // (and a call to [WindowDelegate windowDidMove:]).
+  if (mInReportMoveEvent) {
+    return;
+  }
+  mInReportMoveEvent = true;
+
+  UpdateBounds();
+
+  // The zoomed state can change when we're moving, in which case we need to
+  // update our internal mSizeMode. This can happen either if we're maximized
+  // and then moved, or if we're not maximized and moved back to zoomed state.
+  if (mWindow && ((mSizeMode == nsSizeMode_Maximized) ^ [mWindow isZoomed])) {
+    DispatchSizeModeEvent();
+  }
+
+  // Dispatch the move event to Gecko
+  NotifyWindowMoved(mBounds.x, mBounds.y);
+
+  mInReportMoveEvent = false;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::DispatchSizeModeEvent() {
+  if (!mWindow) {
+    return;
+  }
+
+  if (mSuppressSizeModeEvents || mIsTransitionCurrentAdded) {
+    return;
+  }
+
+  nsSizeMode newMode = GetWindowSizeMode(mWindow, mInFullScreenMode);
+  if (mSizeMode == newMode) {
+    return;
+  }
+
+  mSizeMode = newMode;
+  if (mWidgetListener) {
+    mWidgetListener->SizeModeChanged(newMode);
+  }
+
+  if (StaticPrefs::widget_pause_compositor_when_minimized()) {
+    if (newMode == nsSizeMode_Minimized) {
+      PauseCompositor();
+    } else {
+      ResumeCompositor();
+    }
+  }
+}
+
+void nsCocoaWindow::DispatchOcclusionEvent() {
+  if (!mWindow) {
+    return;
+  }
+
+  // Our new occlusion state is true if the window is not visible.
+  bool newOcclusionState =
+      !(mHasStartedNativeFullscreen || ([mWindow occlusionState] & NSWindowOcclusionStateVisible));
+
+  // Don't dispatch if the new occlustion state is the same as the current state.
+  if (mIsFullyOccluded == newOcclusionState) {
+    return;
+  }
+
+  MOZ_ASSERT(mIgnoreOcclusionCount >= 0);
+  if (newOcclusionState && mIgnoreOcclusionCount > 0) {
+    return;
+  }
+
+  mIsFullyOccluded = newOcclusionState;
+  if (mWidgetListener) {
+    mWidgetListener->OcclusionStateChanged(mIsFullyOccluded);
+  }
+}
+
+void nsCocoaWindow::ReportSizeEvent() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  UpdateBounds();
+  if (mWidgetListener) {
+    LayoutDeviceIntRect innerBounds = GetClientBounds();
+    mWidgetListener->WindowResized(this, innerBounds.width, innerBounds.height);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::PauseCompositor() {
+  nsIWidget* mainChildView = static_cast<nsIWidget*>([[mWindow mainChildView] widget]);
+  if (!mainChildView) {
+    return;
+  }
+  CompositorBridgeChild* remoteRenderer = mainChildView->GetRemoteRenderer();
+  if (!remoteRenderer) {
+    return;
+  }
+  remoteRenderer->SendPause();
+}
+
+void nsCocoaWindow::ResumeCompositor() {
+  nsIWidget* mainChildView = static_cast<nsIWidget*>([[mWindow mainChildView] widget]);
+  if (!mainChildView) {
+    return;
+  }
+  CompositorBridgeChild* remoteRenderer = mainChildView->GetRemoteRenderer();
+  if (!remoteRenderer) {
+    return;
+  }
+  remoteRenderer->SendResume();
+}
+
+void nsCocoaWindow::SetMenuBar(RefPtr<nsMenuBarX>&& aMenuBar) {
+  if (!mWindow) {
+    mMenuBar = nullptr;
+    return;
+  }
+  mMenuBar = std::move(aMenuBar);
+
+  // Only paint for active windows, or paint the hidden window menu bar if no
+  // other menu bar has been painted yet so that some reasonable menu bar is
+  // displayed when the app starts up.
+  if (mMenuBar && ((!gSomeMenuBarPainted && nsMenuUtilsX::GetHiddenWindowMenuBar() == mMenuBar) ||
+                   [mWindow isMainWindow]))
+    mMenuBar->Paint();
+}
+
+void nsCocoaWindow::SetFocus(Raise aRaise, mozilla::dom::CallerType aCallerType) {
+  if (!mWindow) return;
+
+  if (mPopupContentView) {
+    return mPopupContentView->SetFocus(aRaise, aCallerType);
+  }
+
+  if (aRaise == Raise::Yes && ([mWindow isVisible] || [mWindow isMiniaturized])) {
+    if ([mWindow isMiniaturized]) {
+      [mWindow deminiaturize:nil];
+    }
+
+    [mWindow makeKeyAndOrderFront:nil];
+    SendSetZLevelEvent();
+  }
+}
+
+LayoutDeviceIntPoint nsCocoaWindow::WidgetToScreenOffset() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return nsCocoaUtils::CocoaRectToGeckoRectDevPix(GetClientCocoaRect(), BackingScaleFactor())
+      .TopLeft();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntPoint(0, 0));
+}
+
+LayoutDeviceIntPoint nsCocoaWindow::GetClientOffset() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  LayoutDeviceIntRect clientRect = GetClientBounds();
+
+  return clientRect.TopLeft() - mBounds.TopLeft();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntPoint(0, 0));
+}
+
+LayoutDeviceIntMargin nsCocoaWindow::ClientToWindowMargin() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mWindow || mWindow.drawsContentsIntoWindowFrame || mWindowType == WindowType::Popup) {
+    return {};
+  }
+
+  NSRect clientNSRect = mWindow.contentLayoutRect;
+  NSRect frameNSRect = [mWindow frameRectForChildViewRect:clientNSRect];
+
+  CGFloat backingScale = BackingScaleFactor();
+  const auto clientRect = nsCocoaUtils::CocoaRectToGeckoRectDevPix(clientNSRect, backingScale);
+  const auto frameRect = nsCocoaUtils::CocoaRectToGeckoRectDevPix(frameNSRect, backingScale);
+
+  return frameRect - clientRect;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN({});
+}
+
+nsMenuBarX* nsCocoaWindow::GetMenuBar() { return mMenuBar; }
+
+void nsCocoaWindow::CaptureRollupEvents(bool aDoCapture) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (aDoCapture) {
+    if (![NSApp isActive]) {
+      // We need to capture mouse event if we aren't
+      // the active application. We only set this up when needed
+      // because they cause spurious mouse event after crash
+      // and gdb sessions. See bug 699538.
+      nsToolkit::GetToolkit()->MonitorAllProcessMouseEvents();
+    }
+
+    // Sometimes more than one popup window can be visible at the same time
+    // (e.g. nested non-native context menus, or the test case (attachment
+    // 276885) for bmo bug 392389, which displays a non-native combo-box in a
+    // non-native popup window).  In these cases the "active" popup window should
+    // be the topmost -- the (nested) context menu the mouse is currently over,
+    // or the combo-box's drop-down list (when it's displayed).  But (among
+    // windows that have the same "level") OS X makes topmost the window that
+    // last received a mouse-down event, which may be incorrect (in the combo-
+    // box case, it makes topmost the window containing the combo-box).  So
+    // here we fiddle with a non-native popup window's level to make sure the
+    // "active" one is always above any other non-native popup windows that
+    // may be visible.
+    if (mWindow && (mWindowType == WindowType::Popup)) SetPopupWindowLevel();
+  } else {
+    nsToolkit::GetToolkit()->StopMonitoringAllProcessMouseEvents();
+
+    // XXXndeakin this doesn't make sense.
+    // Why is the new window assumed to be a modal panel?
+    if (mWindow && (mWindowType == WindowType::Popup)) [mWindow setLevel:NSModalPanelWindowLevel];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsresult nsCocoaWindow::GetAttention(int32_t aCycleCount) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  [NSApp requestUserAttention:NSInformationalRequest];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+bool nsCocoaWindow::HasPendingInputEvent() { return nsChildView::DoHasPendingInputEvent(); }
+
+void nsCocoaWindow::SetWindowShadowStyle(StyleWindowShadow aStyle) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  mShadowStyle = aStyle;
+
+  if (!mWindow || mWindowType != WindowType::Popup) {
+    return;
+  }
+
+  mWindow.shadowStyle = mShadowStyle;
+  [mWindow setUseMenuStyle:mShadowStyle == StyleWindowShadow::Menu];
+  [mWindow setHasShadow:aStyle != StyleWindowShadow::None];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetWindowOpacity(float aOpacity) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) {
+    return;
+  }
+
+  [mWindow setAlphaValue:(CGFloat)aOpacity];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetColorScheme(const Maybe<ColorScheme>& aScheme) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) {
+    return;
+  }
+
+  mWindow.appearance = aScheme ? NSAppearanceForColorScheme(*aScheme) : nil;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static inline CGAffineTransform GfxMatrixToCGAffineTransform(const gfx::Matrix& m) {
+  CGAffineTransform t;
+  t.a = m._11;
+  t.b = m._12;
+  t.c = m._21;
+  t.d = m._22;
+  t.tx = m._31;
+  t.ty = m._32;
+  return t;
+}
+
+void nsCocoaWindow::SetWindowTransform(const gfx::Matrix& aTransform) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) {
+    return;
+  }
+
+  // Calling CGSSetWindowTransform when the window is not visible results in
+  // misplacing the window into doubled x,y coordinates (see bug 1448132).
+  if (![mWindow isVisible] || NSIsEmptyRect([mWindow frame])) {
+    return;
+  }
+
+  if (StaticPrefs::widget_window_transforms_disabled()) {
+    // CGSSetWindowTransform is a private API. In case calling it causes
+    // problems either now or in the future, we'll want to have an easy kill
+    // switch. So we allow disabling it with a pref.
+    return;
+  }
+
+  gfx::Matrix transform = aTransform;
+
+  // aTransform is a transform that should be applied to the window relative
+  // to its regular position: If aTransform._31 is 100, then we want the
+  // window to be displayed 100 pixels to the right of its regular position.
+  // The transform that CGSSetWindowTransform accepts has a different meaning:
+  // It's used to answer the question "For the screen pixel at x,y (with the
+  // origin at the top left), what pixel in the window's buffer (again with
+  // origin top left) should be displayed at that position?"
+  // In the example above, this means that we need to call
+  // CGSSetWindowTransform with a horizontal translation of -windowPos.x - 100.
+  // So we need to invert the transform and adjust it by the window's position.
+  if (!transform.Invert()) {
+    // Treat non-invertible transforms as the identity transform.
+    transform = gfx::Matrix();
+  }
+
+  bool isIdentity = transform.IsIdentity();
+  if (isIdentity && mWindowTransformIsIdentity) {
+    return;
+  }
+
+  transform.PreTranslate(-mBounds.x, -mBounds.y);
+
+  // Snap translations to device pixels, to match what we do for CSS transforms
+  // and because the window server rounds down instead of to nearest.
+  if (!transform.HasNonTranslation() && transform.HasNonIntegerTranslation()) {
+    auto snappedTranslation = gfx::IntPoint::Round(transform.GetTranslation());
+    transform = gfx::Matrix::Translation(snappedTranslation.x, snappedTranslation.y);
+  }
+
+  // We also need to account for the backing scale factor: aTransform is given
+  // in device pixels, but CGSSetWindowTransform works with logical display
+  // pixels.
+  CGFloat backingScale = BackingScaleFactor();
+  transform.PreScale(backingScale, backingScale);
+  transform.PostScale(1 / backingScale, 1 / backingScale);
+
+  CGSConnection cid = _CGSDefaultConnection();
+  CGSSetWindowTransform(cid, [mWindow windowNumber], GfxMatrixToCGAffineTransform(transform));
+
+  mWindowTransformIsIdentity = isIdentity;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetInputRegion(const InputRegion& aInputRegion) {
+  MOZ_ASSERT(mWindowType == WindowType::Popup, "This should only be called on popup windows.");
+  // TODO: Somehow support aInputRegion.mMargin? Though maybe not.
+  if (aInputRegion.mFullyTransparent) {
+    [mWindow setIgnoresMouseEvents:YES];
+  } else {
+    [mWindow setIgnoresMouseEvents:NO];
+  }
+}
+
+void nsCocoaWindow::SetShowsToolbarButton(bool aShow) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mWindow) [mWindow setShowsToolbarButton:aShow];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetSupportsNativeFullscreen(bool aSupportsNativeFullscreen) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mWindow) {
+    // This determines whether we tell cocoa that the window supports native
+    // full screen. If we do so, and another window is in native full screen,
+    // this window will also appear in native full screen. We generally only
+    // want to do this for primary application windows. We'll set the
+    // relevant macnativefullscreen attribute on those, which will lead to us
+    // being called with aSupportsNativeFullscreen set to `true` here.
+    NSWindowCollectionBehavior newBehavior = [mWindow collectionBehavior];
+    if (aSupportsNativeFullscreen) {
+      newBehavior |= NSWindowCollectionBehaviorFullScreenPrimary;
+    } else {
+      newBehavior &= ~NSWindowCollectionBehaviorFullScreenPrimary;
+    }
+    [mWindow setCollectionBehavior:newBehavior];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetWindowAnimationType(nsIWidget::WindowAnimationType aType) {
+  mAnimationType = aType;
+}
+
+void nsCocoaWindow::SetDrawsTitle(bool aDrawTitle) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (![mWindow drawsContentsIntoWindowFrame]) {
+    // If we don't draw into the window frame, we always want to display window
+    // titles.
+    [mWindow setWantsTitleDrawn:YES];
+  } else {
+    [mWindow setWantsTitleDrawn:aDrawTitle];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsresult nsCocoaWindow::SetNonClientMargins(const LayoutDeviceIntMargin& margins) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  SetDrawsInTitlebar(margins.top == 0);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsCocoaWindow::SetDrawsInTitlebar(bool aState) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mWindow) {
+    [mWindow setDrawsContentsIntoWindowFrame:aState];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::SynthesizeNativeMouseEvent(LayoutDeviceIntPoint aPoint,
+                                                        NativeMouseMessage aNativeMessage,
+                                                        MouseButton aButton,
+                                                        nsIWidget::Modifiers aModifierFlags,
+                                                        nsIObserver* aObserver) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  AutoObserverNotifier notifier(aObserver, "mouseevent");
+  if (mPopupContentView) {
+    return mPopupContentView->SynthesizeNativeMouseEvent(aPoint, aNativeMessage, aButton,
+                                                         aModifierFlags, nullptr);
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP nsCocoaWindow::SynthesizeNativeMouseScrollEvent(
+    LayoutDeviceIntPoint aPoint, uint32_t aNativeMessage, double aDeltaX, double aDeltaY,
+    double aDeltaZ, uint32_t aModifierFlags, uint32_t aAdditionalFlags, nsIObserver* aObserver) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  AutoObserverNotifier notifier(aObserver, "mousescrollevent");
+  if (mPopupContentView) {
+    // Pass nullptr as the observer so that the AutoObserverNotification in
+    // nsChildView::SynthesizeNativeMouseScrollEvent will be ignored.
+    return mPopupContentView->SynthesizeNativeMouseScrollEvent(aPoint, aNativeMessage, aDeltaX,
+                                                               aDeltaY, aDeltaZ, aModifierFlags,
+                                                               aAdditionalFlags, nullptr);
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsCocoaWindow::LockAspectRatio(bool aShouldLock) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (aShouldLock) {
+    [mWindow setContentAspectRatio:mWindow.frame.size];
+    mAspectRatioLocked = true;
+  } else {
+    // According to https://developer.apple.com/documentation/appkit/nswindow/1419507-aspectratio,
+    // aspect ratios and resize increments are mutually exclusive, and the accepted way of
+    // cancelling an established aspect ratio is to set the resize increments to 1.0, 1.0
+    [mWindow setResizeIncrements:NSMakeSize(1.0, 1.0)];
+    mAspectRatioLocked = false;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::UpdateThemeGeometries(const nsTArray<ThemeGeometry>& aThemeGeometries) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mPopupContentView) {
+    return mPopupContentView->UpdateThemeGeometries(aThemeGeometries);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetPopupWindowLevel() {
+  if (!mWindow) return;
+
+  // Floating popups are at the floating level and hide when the window is
+  // deactivated.
+  if (mPopupLevel == PopupLevel::Floating) {
+    [mWindow setLevel:NSFloatingWindowLevel];
+    [mWindow setHidesOnDeactivate:YES];
+  } else {
+    // Otherwise, this is a top-level or parent popup. Parent popups always
+    // appear just above their parent and essentially ignore the level.
+    [mWindow setLevel:NSPopUpMenuWindowLevel];
+    [mWindow setHidesOnDeactivate:NO];
+  }
+}
+
+void nsCocoaWindow::SetInputContext(const InputContext& aContext,
+                                    const InputContextAction& aAction) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  mInputContext = aContext;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+bool nsCocoaWindow::GetEditCommands(NativeKeyBindingsType aType, const WidgetKeyboardEvent& aEvent,
+                                    nsTArray<CommandInt>& aCommands) {
+  // Validate the arguments.
+  if (NS_WARN_IF(!nsIWidget::GetEditCommands(aType, aEvent, aCommands))) {
+    return false;
+  }
+
+  NativeKeyBindings* keyBindings = NativeKeyBindings::GetInstance(aType);
+  // When the keyboard event is fired from this widget, it must mean that no web content has focus
+  // because any web contents should be on `nsChildView`.  And in any locales, the system UI is
+  // always horizontal layout.  So, let's pass `Nothing()` for the writing mode here, it won't be
+  // treated as in a vertical content.
+  keyBindings->GetEditCommands(aEvent, Nothing(), aCommands);
+  return true;
+}
+
+bool nsCocoaWindow::AsyncPanZoomEnabled() const {
+  if (mPopupContentView) {
+    return mPopupContentView->AsyncPanZoomEnabled();
+  }
+  return nsBaseWidget::AsyncPanZoomEnabled();
+}
+
+bool nsCocoaWindow::StartAsyncAutoscroll(const ScreenPoint& aAnchorLocation,
+                                         const ScrollableLayerGuid& aGuid) {
+  if (mPopupContentView) {
+    return mPopupContentView->StartAsyncAutoscroll(aAnchorLocation, aGuid);
+  }
+  return nsBaseWidget::StartAsyncAutoscroll(aAnchorLocation, aGuid);
+}
+
+void nsCocoaWindow::StopAsyncAutoscroll(const ScrollableLayerGuid& aGuid) {
+  if (mPopupContentView) {
+    mPopupContentView->StopAsyncAutoscroll(aGuid);
+    return;
+  }
+  nsBaseWidget::StopAsyncAutoscroll(aGuid);
+}
+
+already_AddRefed<nsIWidget> nsIWidget::CreateTopLevelWindow() {
+  nsCOMPtr<nsIWidget> window = new nsCocoaWindow();
+  return window.forget();
+}
+
+already_AddRefed<nsIWidget> nsIWidget::CreateChildWindow() {
+  nsCOMPtr<nsIWidget> window = new nsChildView();
+  return window.forget();
+}
+
+@implementation WindowDelegate
+
+// We try to find a gecko menu bar to paint. If one does not exist, just paint
+// the application menu by itself so that a window doesn't have some other
+// window's menu bar.
++ (void)paintMenubarForWindow:(NSWindow*)aWindow {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // make sure we only act on windows that have this kind of
+  // object as a delegate
+  id windowDelegate = [aWindow delegate];
+  if ([windowDelegate class] != [self class]) return;
+
+  nsCocoaWindow* geckoWidget = [windowDelegate geckoWidget];
+  NS_ASSERTION(geckoWidget, "Window delegate not returning a gecko widget!");
+
+  nsMenuBarX* geckoMenuBar = geckoWidget->GetMenuBar();
+  if (geckoMenuBar) {
+    geckoMenuBar->Paint();
+  } else {
+    // sometimes we don't have a native application menu early in launching
+    if (!sApplicationMenu) return;
+
+    NSMenu* mainMenu = [NSApp mainMenu];
+    NS_ASSERTION([mainMenu numberOfItems] > 0,
+                 "Main menu does not have any items, something is terribly wrong!");
+
+    // Create a new menu bar.
+    // We create a GeckoNSMenu because all menu bar NSMenu objects should use that subclass for
+    // key handling reasons.
+    GeckoNSMenu* newMenuBar = [[GeckoNSMenu alloc] initWithTitle:@"MainMenuBar"];
+
+    // move the application menu from the existing menu bar to the new one
+    NSMenuItem* firstMenuItem = [[mainMenu itemAtIndex:0] retain];
+    [mainMenu removeItemAtIndex:0];
+    [newMenuBar insertItem:firstMenuItem atIndex:0];
+    [firstMenuItem release];
+
+    // set our new menu bar as the main menu
+    [NSApp setMainMenu:newMenuBar];
+    [newMenuBar release];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (id)initWithGeckoWindow:(nsCocoaWindow*)geckoWind {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  [super init];
+  mGeckoWindow = geckoWind;
+  mToplevelActiveState = false;
+  mHasEverBeenZoomed = false;
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (NSSize)windowWillResize:(NSWindow*)sender toSize:(NSSize)proposedFrameSize {
+  RollUpPopups();
+  return proposedFrameSize;
+}
+
+- (NSRect)windowWillUseStandardFrame:(NSWindow*)window defaultFrame:(NSRect)newFrame {
+  // This function needs to return a rect representing the frame a window would
+  // have if it is in its "maximized" size mode. The parameter newFrame is supposed
+  // to be a frame representing the maximum window size on the screen where the
+  // window currently appears. However, in practice, newFrame can be a much smaller
+  // size. So, we ignore newframe and instead return the frame of the entire screen
+  // associated with the window. That frame is bigger than the window could actually
+  // be, due to the presence of the menubar and possibly the dock, but we never call
+  // this function directly, and Cocoa callers will shrink it to its true maximum
+  // size.
+  return window.screen.frame;
+}
+
+void nsCocoaWindow::CocoaSendToplevelActivateEvents() {
+  if (mWidgetListener) {
+    mWidgetListener->WindowActivated();
+  }
+}
+
+void nsCocoaWindow::CocoaSendToplevelDeactivateEvents() {
+  if (mWidgetListener) {
+    mWidgetListener->WindowDeactivated();
+  }
+}
+
+void nsCocoaWindow::CocoaWindowDidResize() {
+  // It's important to update our bounds before we trigger any listeners. This
+  // ensures that our bounds are correct when GetScreenBounds is called.
+  UpdateBounds();
+
+  if (HandleUpdateFullscreenOnResize()) {
+    ReportSizeEvent();
+    return;
+  }
+
+  // Resizing might have changed our zoom state.
+  DispatchSizeModeEvent();
+  ReportSizeEvent();
+}
+
+- (void)windowDidResize:(NSNotification*)aNotification {
+  BaseWindow* window = [aNotification object];
+  [window updateTrackingArea];
+
+  if (!mGeckoWindow) return;
+
+  mGeckoWindow->CocoaWindowDidResize();
+}
+
+- (void)windowDidChangeScreen:(NSNotification*)aNotification {
+  if (!mGeckoWindow) return;
+
+  // Because of Cocoa's peculiar treatment of zero-size windows (see comments
+  // at GetBackingScaleFactor() above), we sometimes have a situation where
+  // our concept of backing scale (based on the screen where the zero-sized
+  // window is positioned) differs from Cocoa's idea (always based on the
+  // Retina screen, AFAICT, even when an external non-Retina screen is the
+  // primary display).
+  //
+  // As a result, if the window was created with zero size on an external
+  // display, but then made visible on the (secondary) Retina screen, we
+  // will *not* get a windowDidChangeBackingProperties notification for it.
+  // This leads to an incorrect GetDefaultScale(), and widget coordinate
+  // confusion, as per bug 853252.
+  //
+  // To work around this, we check for a backing scale mismatch when we
+  // receive a windowDidChangeScreen notification, as we will receive this
+  // even if Cocoa was already treating the zero-size window as having
+  // Retina backing scale.
+  NSWindow* window = (NSWindow*)[aNotification object];
+  if ([window respondsToSelector:@selector(backingScaleFactor)]) {
+    if (GetBackingScaleFactor(window) != mGeckoWindow->BackingScaleFactor()) {
+      mGeckoWindow->BackingScaleFactorChanged();
+    }
+  }
+
+  mGeckoWindow->ReportMoveEvent();
+}
+
+- (void)windowWillEnterFullScreen:(NSNotification*)notification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowWillEnterFullscreen(true);
+}
+
+// Lion's full screen mode will bypass our internal fullscreen tracking, so
+// we need to catch it when we transition and call our own methods, which in
+// turn will fire "fullscreen" events.
+- (void)windowDidEnterFullScreen:(NSNotification*)notification {
+  // On Yosemite, the NSThemeFrame class has two new properties --
+  // titlebarView (an NSTitlebarView object) and titlebarContainerView (an
+  // NSTitlebarContainerView object).  These are used to display the titlebar
+  // in fullscreen mode.  In Safari they're not transparent.  But in Firefox
+  // for some reason they are, which causes bug 1069658.  The following code
+  // works around this Apple bug or design flaw.
+  NSWindow* window = (NSWindow*)[notification object];
+  NSView* frameView = [[window contentView] superview];
+  NSView* titlebarView = nil;
+  NSView* titlebarContainerView = nil;
+  if ([frameView respondsToSelector:@selector(titlebarView)]) {
+    titlebarView = [frameView titlebarView];
+  }
+  if ([frameView respondsToSelector:@selector(titlebarContainerView)]) {
+    titlebarContainerView = [frameView titlebarContainerView];
+  }
+  if ([titlebarView respondsToSelector:@selector(setTransparent:)]) {
+    [titlebarView setTransparent:NO];
+  }
+  if ([titlebarContainerView respondsToSelector:@selector(setTransparent:)]) {
+    [titlebarContainerView setTransparent:NO];
+  }
+
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowDidEnterFullscreen(true);
+}
+
+- (void)windowWillExitFullScreen:(NSNotification*)notification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowWillEnterFullscreen(false);
+}
+
+- (void)windowDidExitFullScreen:(NSNotification*)notification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowDidEnterFullscreen(false);
+}
+
+- (void)windowDidFailToEnterFullScreen:(NSWindow*)window {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowDidFailFullscreen(true);
+}
+
+- (void)windowDidFailToExitFullScreen:(NSWindow*)window {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowDidFailFullscreen(false);
+}
+
+- (void)windowDidBecomeMain:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  RollUpPopups();
+  ChildViewMouseTracker::ReEvaluateMouseEnterState();
+
+  // [NSApp _isRunningAppModal] will return true if we're running an OS dialog
+  // app modally. If one of those is up then we want it to retain its menu bar.
+  if ([NSApp _isRunningAppModal]) return;
+  NSWindow* window = [aNotification object];
+  if (window) [WindowDelegate paintMenubarForWindow:window];
+
+  if ([window isKindOfClass:[ToolbarWindow class]]) {
+    [(ToolbarWindow*)window windowMainStateChanged];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)windowDidResignMain:(NSNotification*)aNotification {
+  RollUpPopups();
+  ChildViewMouseTracker::ReEvaluateMouseEnterState();
+
+  // [NSApp _isRunningAppModal] will return true if we're running an OS dialog
+  // app modally. If one of those is up then we want it to retain its menu bar.
+  if ([NSApp _isRunningAppModal]) return;
+  RefPtr<nsMenuBarX> hiddenWindowMenuBar = nsMenuUtilsX::GetHiddenWindowMenuBar();
+  if (hiddenWindowMenuBar) {
+    // printf("painting hidden window menu bar due to window losing main status\n");
+    hiddenWindowMenuBar->Paint();
+  }
+
+  NSWindow* window = [aNotification object];
+  if ([window isKindOfClass:[ToolbarWindow class]]) {
+    [(ToolbarWindow*)window windowMainStateChanged];
+  }
+}
+
+- (void)windowDidBecomeKey:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  RollUpPopups();
+  ChildViewMouseTracker::ReEvaluateMouseEnterState();
+
+  NSWindow* window = [aNotification object];
+  if ([window isSheet]) [WindowDelegate paintMenubarForWindow:window];
+
+  nsChildView* mainChildView =
+      static_cast<nsChildView*>([[(BaseWindow*)window mainChildView] widget]);
+  if (mainChildView) {
+    if (mainChildView->GetInputContext().IsPasswordEditor()) {
+      TextInputHandler::EnableSecureEventInput();
+    } else {
+      TextInputHandler::EnsureSecureEventInputDisabled();
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)windowDidResignKey:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  RollUpPopups(nsIRollupListener::AllowAnimations::No);
+
+  ChildViewMouseTracker::ReEvaluateMouseEnterState();
+
+  // If a sheet just resigned key then we should paint the menu bar
+  // for whatever window is now main.
+  NSWindow* window = [aNotification object];
+  if ([window isSheet]) [WindowDelegate paintMenubarForWindow:[NSApp mainWindow]];
+
+  TextInputHandler::EnsureSecureEventInputDisabled();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)windowWillMove:(NSNotification*)aNotification {
+  RollUpPopups();
+}
+
+- (void)windowDidMove:(NSNotification*)aNotification {
+  if (mGeckoWindow) mGeckoWindow->ReportMoveEvent();
+}
+
+- (BOOL)windowShouldClose:(id)sender {
+  nsIWidgetListener* listener = mGeckoWindow ? mGeckoWindow->GetWidgetListener() : nullptr;
+  if (listener) listener->RequestWindowClose(mGeckoWindow);
+  return NO;  // gecko will do it
+}
+
+- (void)windowWillClose:(NSNotification*)aNotification {
+  RollUpPopups();
+}
+
+- (void)windowWillMiniaturize:(NSNotification*)aNotification {
+  RollUpPopups();
+}
+
+- (void)windowDidMiniaturize:(NSNotification*)aNotification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->FinishCurrentTransitionIfMatching(nsCocoaWindow::TransitionType::Miniaturize);
+}
+
+- (void)windowDidDeminiaturize:(NSNotification*)aNotification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->FinishCurrentTransitionIfMatching(nsCocoaWindow::TransitionType::Deminiaturize);
+}
+
+- (BOOL)windowShouldZoom:(NSWindow*)window toFrame:(NSRect)proposedFrame {
+  if (!mHasEverBeenZoomed && [window isZoomed]) return NO;  // See bug 429954.
+
+  mHasEverBeenZoomed = YES;
+  return YES;
+}
+
+- (NSRect)window:(NSWindow*)window willPositionSheet:(NSWindow*)sheet usingRect:(NSRect)rect {
+  if ([window isKindOfClass:[ToolbarWindow class]]) {
+    rect.origin.y = [(ToolbarWindow*)window sheetAttachmentPosition];
+  }
+  return rect;
+}
+
+#ifdef MOZ_THUNDERBIRD
+- (void)didEndSheet:(NSWindow*)sheet returnCode:(int)returnCode contextInfo:(void*)contextInfo {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // Note: 'contextInfo' (if it is set) is the window that is the parent of
+  // the sheet.  The value of contextInfo is determined in
+  // nsCocoaWindow::Show().  If it's set, 'contextInfo' is always the top-
+  // level window, not another sheet itself.  But 'contextInfo' is nil if
+  // our parent window is also a sheet -- in that case we shouldn't send
+  // the top-level window any activate events (because it's our parent
+  // window that needs to get these events, not the top-level window).
+  [TopLevelWindowData deactivateInWindow:sheet];
+  [sheet orderOut:self];
+  if (contextInfo) [TopLevelWindowData activateInWindow:(NSWindow*)contextInfo];
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+#endif
+
+- (void)windowDidChangeBackingProperties:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NSWindow* window = (NSWindow*)[aNotification object];
+
+  if ([window respondsToSelector:@selector(backingScaleFactor)]) {
+    CGFloat oldFactor =
+        [[[aNotification userInfo] objectForKey:@"NSBackingPropertyOldScaleFactorKey"] doubleValue];
+    if ([window backingScaleFactor] != oldFactor) {
+      mGeckoWindow->BackingScaleFactorChanged();
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// This method is on NSWindowDelegate starting with 10.9
+- (void)windowDidChangeOcclusionState:(NSNotification*)aNotification {
+  if (mGeckoWindow) {
+    mGeckoWindow->DispatchOcclusionEvent();
+  }
+}
+
+- (nsCocoaWindow*)geckoWidget {
+  return mGeckoWindow;
+}
+
+- (bool)toplevelActiveState {
+  return mToplevelActiveState;
+}
+
+- (void)sendToplevelActivateEvents {
+  if (!mToplevelActiveState && mGeckoWindow) {
+    mGeckoWindow->CocoaSendToplevelActivateEvents();
+
+    mToplevelActiveState = true;
+  }
+}
+
+- (void)sendToplevelDeactivateEvents {
+  if (mToplevelActiveState && mGeckoWindow) {
+    mGeckoWindow->CocoaSendToplevelDeactivateEvents();
+    mToplevelActiveState = false;
+  }
+}
+
+@end
+
+@interface NSView (FrameViewMethodSwizzling)
+- (NSPoint)FrameView__closeButtonOrigin;
+- (CGFloat)FrameView__titlebarHeight;
+@end
+
+@implementation NSView (FrameViewMethodSwizzling)
+
+- (NSPoint)FrameView__closeButtonOrigin {
+  if (![self.window isKindOfClass:[ToolbarWindow class]]) {
+    return self.FrameView__closeButtonOrigin;
+  }
+  ToolbarWindow* win = (ToolbarWindow*)[self window];
+  if (win.drawsContentsIntoWindowFrame && !(win.styleMask & NSWindowStyleMaskFullScreen) &&
+      (win.styleMask & NSWindowStyleMaskTitled)) {
+    const NSRect buttonsRect = win.windowButtonsRect;
+    if (NSIsEmptyRect(buttonsRect)) {
+      // Empty rect. Let's hide the buttons.
+      // Position is in non-flipped window coordinates. Using frame's height
+      // for the vertical coordinate will move the buttons above the window,
+      // making them invisible.
+      return NSMakePoint(buttonsRect.origin.x, win.frame.size.height);
+    } else if (win.windowTitlebarLayoutDirection == NSUserInterfaceLayoutDirectionRightToLeft) {
+      // We're in RTL mode, which means that the close button is the rightmost
+      // button of the three window buttons. and buttonsRect.origin is the
+      // bottom left corner of the green (zoom) button. The close button is 40px
+      // to the right of the zoom button. This is confirmed to be the same on
+      // all macOS versions between 10.12 - 12.0.
+      return NSMakePoint(buttonsRect.origin.x + 40.0f, buttonsRect.origin.y);
+    }
+    return buttonsRect.origin;
+  }
+  return self.FrameView__closeButtonOrigin;
+}
+
+- (CGFloat)FrameView__titlebarHeight {
+  CGFloat height = [self FrameView__titlebarHeight];
+  if ([[self window] isKindOfClass:[ToolbarWindow class]]) {
+    // Make sure that the titlebar height includes our shifted buttons.
+    // The following coordinates are in window space, with the origin being at the bottom left
+    // corner of the window.
+    ToolbarWindow* win = (ToolbarWindow*)[self window];
+    CGFloat frameHeight = [self frame].size.height;
+    CGFloat windowButtonY = frameHeight;
+    if (!NSIsEmptyRect(win.windowButtonsRect) && win.drawsContentsIntoWindowFrame &&
+        !(win.styleMask & NSWindowStyleMaskFullScreen) &&
+        (win.styleMask & NSWindowStyleMaskTitled)) {
+      windowButtonY = win.windowButtonsRect.origin.y;
+    }
+    height = std::max(height, frameHeight - windowButtonY);
+  }
+  return height;
+}
+
+@end
+
+static NSMutableSet* gSwizzledFrameViewClasses = nil;
+
+@interface NSWindow (PrivateSetNeedsDisplayInRectMethod)
+- (void)_setNeedsDisplayInRect:(NSRect)aRect;
+@end
+
+@interface NSView (NSVisualEffectViewSetMaskImage)
+- (void)setMaskImage:(NSImage*)image;
+@end
+
+@interface BaseWindow (Private)
+- (void)removeTrackingArea;
+- (void)cursorUpdated:(NSEvent*)aEvent;
+- (void)reflowTitlebarElements;
+@end
+
+@implementation BaseWindow
+
+// The frame of a window is implemented using undocumented NSView subclasses.
+// We offset the window buttons by overriding the method _closeButtonOrigin on
+// these frame view classes. The class which is
+// used for a window is determined in the window's frameViewClassForStyleMask:
+// method, so this is where we make sure that we have swizzled the method on
+// all encountered classes.
++ (Class)frameViewClassForStyleMask:(NSUInteger)styleMask {
+  Class frameViewClass = [super frameViewClassForStyleMask:styleMask];
+
+  if (!gSwizzledFrameViewClasses) {
+    gSwizzledFrameViewClasses = [[NSMutableSet setWithCapacity:3] retain];
+    if (!gSwizzledFrameViewClasses) {
+      return frameViewClass;
+    }
+  }
+
+  static IMP our_closeButtonOrigin =
+      class_getMethodImplementation([NSView class], @selector(FrameView__closeButtonOrigin));
+  static IMP our_titlebarHeight =
+      class_getMethodImplementation([NSView class], @selector(FrameView__titlebarHeight));
+
+  if (![gSwizzledFrameViewClasses containsObject:frameViewClass]) {
+    // Either of these methods might be implemented in both a subclass of
+    // NSFrameView and one of its own subclasses.  Which means that if we
+    // aren't careful we might end up swizzling the same method twice.
+    // Since method swizzling involves swapping pointers, this would break
+    // things.
+    IMP _closeButtonOrigin =
+        class_getMethodImplementation(frameViewClass, @selector(_closeButtonOrigin));
+    if (_closeButtonOrigin && _closeButtonOrigin != our_closeButtonOrigin) {
+      nsToolkit::SwizzleMethods(frameViewClass, @selector(_closeButtonOrigin),
+                                @selector(FrameView__closeButtonOrigin));
+    }
+
+    // Override _titlebarHeight so that the floating titlebar doesn't clip the bottom of the
+    // window buttons which we move down with our override of _closeButtonOrigin.
+    IMP _titlebarHeight = class_getMethodImplementation(frameViewClass, @selector(_titlebarHeight));
+    if (_titlebarHeight && _titlebarHeight != our_titlebarHeight) {
+      nsToolkit::SwizzleMethods(frameViewClass, @selector(_titlebarHeight),
+                                @selector(FrameView__titlebarHeight));
+    }
+
+    [gSwizzledFrameViewClasses addObject:frameViewClass];
+  }
+
+  return frameViewClass;
+}
+
+- (id)initWithContentRect:(NSRect)aContentRect
+                styleMask:(NSUInteger)aStyle
+                  backing:(NSBackingStoreType)aBufferingType
+                    defer:(BOOL)aFlag {
+  mDrawsIntoWindowFrame = NO;
+  [super initWithContentRect:aContentRect styleMask:aStyle backing:aBufferingType defer:aFlag];
+  mState = nil;
+  mDisabledNeedsDisplay = NO;
+  mTrackingArea = nil;
+  mDirtyRect = NSZeroRect;
+  mBeingShown = NO;
+  mDrawTitle = NO;
+  mUseMenuStyle = NO;
+  mTouchBar = nil;
+  mIsAnimationSuppressed = NO;
+  [self updateTrackingArea];
+
+  return self;
+}
+
+// Returns an autoreleased NSImage.
+static NSImage* GetMenuMaskImage() {
+  CGFloat radius = 4.0f;
+  NSEdgeInsets insets = {5, 5, 5, 5};
+  NSSize maskSize = {12, 12};
+  NSImage* maskImage = [NSImage imageWithSize:maskSize
+                                      flipped:YES
+                               drawingHandler:^BOOL(NSRect dstRect) {
+                                 NSBezierPath* path =
+                                     [NSBezierPath bezierPathWithRoundedRect:dstRect
+                                                                     xRadius:radius
+                                                                     yRadius:radius];
+                                 [[NSColor colorWithDeviceWhite:1.0 alpha:1.0] set];
+                                 [path fill];
+                                 return YES;
+                               }];
+  [maskImage setCapInsets:insets];
+  return maskImage;
+}
+
+- (void)swapOutChildViewWrapper:(NSView*)aNewWrapper {
+  [aNewWrapper setFrame:[[self contentView] frame]];
+  NSView* childView = [[self mainChildView] retain];
+  [childView removeFromSuperview];
+  [aNewWrapper addSubview:childView];
+  [childView release];
+  [super setContentView:aNewWrapper];
+}
+
+- (void)setUseMenuStyle:(BOOL)aValue {
+  if (aValue && !mUseMenuStyle) {
+    // Turn on rounded corner masking.
+    NSView* effectView = VibrancyManager::CreateEffectView(VibrancyType::MENU, YES);
+    [effectView setMaskImage:GetMenuMaskImage()];
+    [self swapOutChildViewWrapper:effectView];
+    [effectView release];
+  } else if (mUseMenuStyle && !aValue) {
+    // Turn off rounded corner masking.
+    NSView* wrapper = [[NSView alloc] initWithFrame:NSZeroRect];
+    [wrapper setWantsLayer:YES];
+    [self swapOutChildViewWrapper:wrapper];
+    [wrapper release];
+  }
+  mUseMenuStyle = aValue;
+}
+
+- (NSTouchBar*)makeTouchBar {
+  mTouchBar = [[nsTouchBar alloc] init];
+  if (mTouchBar) {
+    sTouchBarIsInitialized = YES;
+  }
+  return mTouchBar;
+}
+
+- (void)setBeingShown:(BOOL)aValue {
+  mBeingShown = aValue;
+}
+
+- (BOOL)isBeingShown {
+  return mBeingShown;
+}
+
+- (BOOL)isVisibleOrBeingShown {
+  return [super isVisible] || mBeingShown;
+}
+
+- (void)setIsAnimationSuppressed:(BOOL)aValue {
+  mIsAnimationSuppressed = aValue;
+}
+
+- (BOOL)isAnimationSuppressed {
+  return mIsAnimationSuppressed;
+}
+
+- (void)disableSetNeedsDisplay {
+  mDisabledNeedsDisplay = YES;
+}
+
+- (void)enableSetNeedsDisplay {
+  mDisabledNeedsDisplay = NO;
+}
+
+- (void)dealloc {
+  [mTouchBar release];
+  [self removeTrackingArea];
+  ChildViewMouseTracker::OnDestroyWindow(self);
+  [super dealloc];
+}
+
+static const NSString* kStateTitleKey = @"title";
+static const NSString* kStateDrawsContentsIntoWindowFrameKey = @"drawsContentsIntoWindowFrame";
+static const NSString* kStateShowsToolbarButton = @"showsToolbarButton";
+static const NSString* kStateCollectionBehavior = @"collectionBehavior";
+static const NSString* kStateWantsTitleDrawn = @"wantsTitleDrawn";
+
+- (void)importState:(NSDictionary*)aState {
+  if (NSString* title = [aState objectForKey:kStateTitleKey]) {
+    [self setTitle:title];
+  }
+  [self setDrawsContentsIntoWindowFrame:[[aState objectForKey:kStateDrawsContentsIntoWindowFrameKey]
+                                            boolValue]];
+  [self setShowsToolbarButton:[[aState objectForKey:kStateShowsToolbarButton] boolValue]];
+  [self setCollectionBehavior:[[aState objectForKey:kStateCollectionBehavior] unsignedIntValue]];
+  [self setWantsTitleDrawn:[[aState objectForKey:kStateWantsTitleDrawn] boolValue]];
+}
+
+- (NSMutableDictionary*)exportState {
+  NSMutableDictionary* state = [NSMutableDictionary dictionaryWithCapacity:10];
+  if (NSString* title = [self title]) {
+    [state setObject:title forKey:kStateTitleKey];
+  }
+  [state setObject:[NSNumber numberWithBool:[self drawsContentsIntoWindowFrame]]
+            forKey:kStateDrawsContentsIntoWindowFrameKey];
+  [state setObject:[NSNumber numberWithBool:[self showsToolbarButton]]
+            forKey:kStateShowsToolbarButton];
+  [state setObject:[NSNumber numberWithUnsignedInt:[self collectionBehavior]]
+            forKey:kStateCollectionBehavior];
+  [state setObject:[NSNumber numberWithBool:[self wantsTitleDrawn]] forKey:kStateWantsTitleDrawn];
+  return state;
+}
+
+- (void)setDrawsContentsIntoWindowFrame:(BOOL)aState {
+  bool changed = (aState != mDrawsIntoWindowFrame);
+  mDrawsIntoWindowFrame = aState;
+  if (changed) {
+    [self reflowTitlebarElements];
+  }
+}
+
+- (BOOL)drawsContentsIntoWindowFrame {
+  return mDrawsIntoWindowFrame;
+}
+
+- (NSRect)childViewRectForFrameRect:(NSRect)aFrameRect {
+  if (mDrawsIntoWindowFrame) {
+    return aFrameRect;
+  }
+  NSUInteger styleMask = [self styleMask];
+  styleMask &= ~NSWindowStyleMaskFullSizeContentView;
+  return [NSWindow contentRectForFrameRect:aFrameRect styleMask:styleMask];
+}
+
+- (NSRect)frameRectForChildViewRect:(NSRect)aChildViewRect {
+  if (mDrawsIntoWindowFrame) {
+    return aChildViewRect;
+  }
+  NSUInteger styleMask = [self styleMask];
+  styleMask &= ~NSWindowStyleMaskFullSizeContentView;
+  return [NSWindow frameRectForContentRect:aChildViewRect styleMask:styleMask];
+}
+
+- (NSTimeInterval)animationResizeTime:(NSRect)newFrame {
+  if (mIsAnimationSuppressed) {
+    // Should not animate the initial session-restore size change
+    return 0.0;
+  }
+
+  return [super animationResizeTime:newFrame];
+}
+
+- (void)setWantsTitleDrawn:(BOOL)aDrawTitle {
+  mDrawTitle = aDrawTitle;
+  [self setTitleVisibility:mDrawTitle ? NSWindowTitleVisible : NSWindowTitleHidden];
+}
+
+- (BOOL)wantsTitleDrawn {
+  return mDrawTitle;
+}
+
+- (NSView*)trackingAreaView {
+  NSView* contentView = [self contentView];
+  return [contentView superview] ? [contentView superview] : contentView;
+}
+
+- (NSArray<NSView*>*)contentViewContents {
+  return [[[[self contentView] subviews] copy] autorelease];
+}
+
+- (ChildView*)mainChildView {
+  NSView* contentView = [self contentView];
+  NSView* lastView = [[contentView subviews] lastObject];
+  if ([lastView isKindOfClass:[ChildView class]]) {
+    return (ChildView*)lastView;
+  }
+  return nil;
+}
+
+- (void)removeTrackingArea {
+  if (mTrackingArea) {
+    [[self trackingAreaView] removeTrackingArea:mTrackingArea];
+    [mTrackingArea release];
+    mTrackingArea = nil;
+  }
+}
+
+- (void)updateTrackingArea {
+  [self removeTrackingArea];
+
+  NSView* view = [self trackingAreaView];
+  const NSTrackingAreaOptions options =
+      NSTrackingMouseEnteredAndExited | NSTrackingMouseMoved | NSTrackingActiveAlways;
+  mTrackingArea = [[NSTrackingArea alloc] initWithRect:[view bounds]
+                                               options:options
+                                                 owner:self
+                                              userInfo:nil];
+  [view addTrackingArea:mTrackingArea];
+}
+
+- (void)mouseEntered:(NSEvent*)aEvent {
+  ChildViewMouseTracker::MouseEnteredWindow(aEvent);
+}
+
+- (void)mouseExited:(NSEvent*)aEvent {
+  ChildViewMouseTracker::MouseExitedWindow(aEvent);
+}
+
+- (void)mouseMoved:(NSEvent*)aEvent {
+  ChildViewMouseTracker::MouseMoved(aEvent);
+}
+
+- (void)cursorUpdated:(NSEvent*)aEvent {
+  // Nothing to do here, but NSTrackingArea wants us to implement this method.
+}
+
+- (void)_setNeedsDisplayInRect:(NSRect)aRect {
+  // Prevent unnecessary invalidations due to moving NSViews (e.g. for plugins)
+  if (!mDisabledNeedsDisplay) {
+    // This method is only called by Cocoa, so when we're here, we know that
+    // it's available and don't need to check whether our superclass responds
+    // to the selector.
+    [super _setNeedsDisplayInRect:aRect];
+    mDirtyRect = NSUnionRect(mDirtyRect, aRect);
+  }
+}
+
+- (NSRect)getAndResetNativeDirtyRect {
+  NSRect dirtyRect = mDirtyRect;
+  mDirtyRect = NSZeroRect;
+  return dirtyRect;
+}
+
+// Possibly move the titlebar buttons.
+- (void)reflowTitlebarElements {
+  NSView* frameView = [[self contentView] superview];
+  if ([frameView respondsToSelector:@selector(_tileTitlebarAndRedisplay:)]) {
+    [frameView _tileTitlebarAndRedisplay:NO];
+  }
+}
+
+- (BOOL)respondsToSelector:(SEL)aSelector {
+  // Claim the window doesn't respond to this so that the system
+  // doesn't steal keyboard equivalents for it. Bug 613710.
+  if (aSelector == @selector(cancelOperation:)) {
+    return NO;
+  }
+
+  return [super respondsToSelector:aSelector];
+}
+
+- (void)doCommandBySelector:(SEL)aSelector {
+  // We override this so that it won't beep if it can't act.
+  // We want to control the beeping for missing or disabled
+  // commands ourselves.
+  [self tryToPerform:aSelector with:nil];
+}
+
+- (id)accessibilityAttributeValue:(NSString*)attribute {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  id retval = [super accessibilityAttributeValue:attribute];
+
+  // The following works around a problem with Text-to-Speech on OS X 10.7.
+  // See bug 674612 for more info.
+  //
+  // When accessibility is off, AXUIElementCopyAttributeValue(), when called
+  // on an AXApplication object to get its AXFocusedUIElement attribute,
+  // always returns an AXWindow object (the actual browser window -- never a
+  // mozAccessible object).  This also happens with accessibility turned on,
+  // if no other object in the browser window has yet been focused.  But if
+  // the browser window has a title bar (as it currently always does), the
+  // AXWindow object will always have four "accessible" children, one of which
+  // is an AXStaticText object (the title bar's "title"; the other three are
+  // the close, minimize and zoom buttons).  This means that (for complicated
+  // reasons, for which see bug 674612) Text-to-Speech on OS X 10.7 will often
+  // "speak" the window title, no matter what text is selected, or even if no
+  // text at all is selected.  (This always happens when accessibility is off.
+  // It doesn't happen in Firefox releases because Apple has (on OS X 10.7)
+  // special-cased the handling of apps whose CFBundleIdentifier is
+  // org.mozilla.firefox.)
+  //
+  // We work around this problem by only returning AXChildren that are
+  // mozAccessible object or are one of the titlebar's buttons (which
+  // instantiate subclasses of NSButtonCell).
+  if ([retval isKindOfClass:[NSArray class]] && [attribute isEqualToString:@"AXChildren"]) {
+    NSMutableArray* holder = [NSMutableArray arrayWithCapacity:10];
+    [holder addObjectsFromArray:(NSArray*)retval];
+    NSUInteger count = [holder count];
+    for (NSInteger i = count - 1; i >= 0; --i) {
+      id item = [holder objectAtIndex:i];
+      // Remove anything from holder that isn't one of the titlebar's buttons
+      // (which instantiate subclasses of NSButtonCell) or a mozAccessible
+      // object (or one of its subclasses).
+      if (![item isKindOfClass:[NSButtonCell class]] &&
+          ![item respondsToSelector:@selector(hasRepresentedView)]) {
+        [holder removeObjectAtIndex:i];
+      }
+    }
+    retval = [NSArray arrayWithArray:holder];
+  }
+
+  return retval;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)releaseJSObjects {
+  [mTouchBar releaseJSObjects];
+}
+
+@end
+
+@interface NSView (NSThemeFrame)
+- (void)_drawTitleStringInClip:(NSRect)aRect;
+- (void)_maskCorners:(NSUInteger)aFlags clipRect:(NSRect)aRect;
+@end
+
+@implementation MOZTitlebarView
+
+- (instancetype)initWithFrame:(NSRect)aFrame {
+  self = [super initWithFrame:aFrame];
+
+  self.material = NSVisualEffectMaterialTitlebar;
+  self.blendingMode = NSVisualEffectBlendingModeWithinWindow;
+
+  // Add a separator line at the bottom of the titlebar. NSBoxSeparator isn't a perfect match for
+  // a native titlebar separator, but it's better than nothing.
+  // We really want the appearance that _NSTitlebarDecorationView creates with the help of CoreUI,
+  // but there's no public API for that.
+  NSBox* separatorLine = [[NSBox alloc] initWithFrame:NSMakeRect(0, 0, aFrame.size.width, 1)];
+  separatorLine.autoresizingMask = NSViewWidthSizable | NSViewMaxYMargin;
+  separatorLine.boxType = NSBoxSeparator;
+  [self addSubview:separatorLine];
+  [separatorLine release];
+
+  return self;
+}
+
+- (BOOL)mouseDownCanMoveWindow {
+  return YES;
+}
+
+- (void)mouseUp:(NSEvent*)event {
+  if ([event clickCount] == 2) {
+    // Handle titlebar double click. We don't get the window's default behavior here because the
+    // window uses NSWindowStyleMaskFullSizeContentView, and this view (the titlebar gradient view)
+    // is technically part of the window "contents" (it's a subview of the content view).
+    if (nsCocoaUtils::ShouldZoomOnTitlebarDoubleClick()) {
+      [[self window] performZoom:nil];
+    } else if (nsCocoaUtils::ShouldMinimizeOnTitlebarDoubleClick()) {
+      [[self window] performMiniaturize:nil];
+    }
+  }
+}
+
+@end
+
+@interface MOZTitlebarAccessoryView : NSView
+@end
+
+@implementation MOZTitlebarAccessoryView : NSView
+- (void)viewWillMoveToWindow:(NSWindow*)aWindow {
+  if (aWindow) {
+    // When entering full screen mode, titlebar accessory views are inserted
+    // into a floating NSWindow which houses the window titlebar and toolbars.
+    // In order to work around a drawing bug with titlebarAppearsTransparent
+    // windows in full screen mode, disable titlebar separators for all
+    // NSWindows that this view is used in, including the floating full screen
+    // toolbar window. The drawing bug was filed as FB9056136. See bug 1700211
+    // for more details.
+#if !defined(MAC_OS_VERSION_11_0) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_11_0
+    if (nsCocoaFeatures::OnBigSurOrLater()) {
+#else
+    if (@available(macOS 11.0, *)) {
+#endif
+      aWindow.titlebarSeparatorStyle = NSTitlebarSeparatorStyleNone;
+    }
+  }
+}
+@end
+
+@implementation FullscreenTitlebarTracker
+- (FullscreenTitlebarTracker*)init {
+  [super init];
+  self.view = [[[MOZTitlebarAccessoryView alloc] initWithFrame:NSZeroRect] autorelease];
+  self.hidden = YES;
+  return self;
+}
+@end
+
+// This class allows us to exercise control over the window's title bar. It is
+// used for all windows with titlebars.
+//
+// ToolbarWindow supports two modes:
+//  - drawsContentsIntoWindowFrame mode: In this mode, the Gecko ChildView is
+//    sized to cover the entire window frame and manages titlebar drawing.
+//  - separate titlebar mode, with support for unified toolbars: In this mode,
+//    the Gecko ChildView does not extend into the titlebar. However, this
+//    window's content view (which is the ChildView's superview) *does* extend
+//    into the titlebar. Moreover, in this mode, we place a MOZTitlebarView
+//    in the content view, as a sibling of the ChildView.
+//
+// The "separate titlebar mode" supports the "unified toolbar" look:
+// If there's a toolbar right below the titlebar, the two can "connect" and
+// form a single gradient without a separator line in between.
+//
+// The following mechanism communicates the height of the unified toolbar to
+// the ToolbarWindow:
+//
+// 1) In the style sheet we set the toolbar's -moz-appearance to toolbar.
+// 2) When the toolbar is visible and we paint the application chrome
+//    window, the array that Gecko passes nsChildView::UpdateThemeGeometries
+//    will contain an entry for the widget type StyleAppearance::Toolbar.
+// 3) nsChildView::UpdateThemeGeometries passes the toolbar's height, plus the
+//    titlebar height, to -[ToolbarWindow setUnifiedToolbarHeight:].
+//
+// The actual drawing of the gradient happens in two parts: The titlebar part
+// (i.e. the top 22 pixels of the gradient) is drawn by the MOZTitlebarView,
+// which is a subview of the window's content view and a sibling of the ChildView.
+// The rest of the gradient is drawn by Gecko into the ChildView, as part of the
+// -moz-appearance rendering of the toolbar.
+@implementation ToolbarWindow
+
+- (id)initWithContentRect:(NSRect)aChildViewRect
+                styleMask:(NSUInteger)aStyle
+                  backing:(NSBackingStoreType)aBufferingType
+                    defer:(BOOL)aFlag {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // We treat aChildViewRect as the rectangle that the window's main ChildView
+  // should be sized to. Get the right frameRect for the requested child view
+  // rect.
+  NSRect frameRect = [NSWindow frameRectForContentRect:aChildViewRect styleMask:aStyle];
+
+  // Always size the content view to the full frame size of the window.
+  // We do this even if we want this window to have a titlebar; in that case, the window's content
+  // view covers the entire window but the ChildView inside it will only cover the content area. We
+  // do this so that we can render the titlebar gradient manually, with a subview of our content
+  // view that's positioned in the titlebar area. This lets us have a smooth connection between
+  // titlebar and toolbar gradient in case the window has a "unified toolbar + titlebar" look.
+  // Moreover, always using a full size content view lets us toggle the titlebar on and off without
+  // changing the window's style mask (which would have other subtle effects, for example on
+  // keyboard focus).
+  aStyle |= NSWindowStyleMaskFullSizeContentView;
+
+  // -[NSWindow initWithContentRect:styleMask:backing:defer:] calls
+  // [self frameRectForContentRect:styleMask:] to convert the supplied content
+  // rect to the window's frame rect. We've overridden that method to be a
+  // pass-through function. So, in order to get the intended frameRect, we need
+  // to supply frameRect itself as the "content rect".
+  NSRect contentRect = frameRect;
+
+  if ((self = [super initWithContentRect:contentRect
+                               styleMask:aStyle
+                                 backing:aBufferingType
+                                   defer:aFlag])) {
+    mTitlebarView = nil;
+    mUnifiedToolbarHeight = 22.0f;
+    mSheetAttachmentPosition = aChildViewRect.size.height;
+    mWindowButtonsRect = NSZeroRect;
+    mInitialTitlebarHeight = [self titlebarHeight];
+
+    [self setTitlebarAppearsTransparent:YES];
+#if !defined(MAC_OS_VERSION_11_0) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_11_0
+    if (nsCocoaFeatures::OnBigSurOrLater()) {
+#else
+    if (@available(macOS 11.0, *)) {
+#endif
+      self.titlebarSeparatorStyle = NSTitlebarSeparatorStyleNone;
+    }
+    [self updateTitlebarView];
+
+    mFullscreenTitlebarTracker = [[FullscreenTitlebarTracker alloc] init];
+    // revealAmount is an undocumented property of
+    // NSTitlebarAccessoryViewController that updates whenever the menubar
+    // slides down in fullscreen mode.
+    [mFullscreenTitlebarTracker addObserver:self
+                                 forKeyPath:@"revealAmount"
+                                    options:NSKeyValueObservingOptionNew
+                                    context:nil];
+    // Adding this accessory view controller allows us to shift the toolbar down
+    // when the user mouses to the top of the screen in fullscreen.
+    [(NSWindow*)self addTitlebarAccessoryViewController:mFullscreenTitlebarTracker];
+  }
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)observeValueForKeyPath:(NSString*)keyPath
+                      ofObject:(id)object
+                        change:(NSDictionary<NSKeyValueChangeKey, id>*)change
+                       context:(void*)context {
+  if ([keyPath isEqualToString:@"revealAmount"]) {
+    [[self mainChildView] ensureNextCompositeIsAtomicWithMainThreadPaint];
+    NSNumber* revealAmount = (change[NSKeyValueChangeNewKey]);
+    [self updateTitlebarShownAmount:[revealAmount doubleValue]];
+  } else {
+    [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
+  }
+}
+
+static bool ScreenHasNotch(nsCocoaWindow* aGeckoWindow) {
+  if (@available(macOS 12.0, *)) {
+    nsCOMPtr<nsIScreen> widgetScreen = aGeckoWindow->GetWidgetScreen();
+    NSScreen* cocoaScreen = ScreenHelperCocoa::CocoaScreenForScreen(widgetScreen);
+    return cocoaScreen.safeAreaInsets.top != 0.0f;
+  }
+  return false;
+}
+
+static bool ShouldShiftByMenubarHeightInFullscreen(nsCocoaWindow* aWindow) {
+  switch (StaticPrefs::widget_macos_shift_by_menubar_on_fullscreen()) {
+    case 0:
+      return false;
+    case 1:
+      return true;
+    default:
+      break;
+  }
+  // TODO: On notch-less macbooks, this creates extra space when the
+  // "automatically show and hide the menubar on fullscreen" option is unchecked
+  // (default checked). We tried to detect that in bug 1737831 but it wasn't
+  // reliable enough, see the regressions from that bug. For now, stick to the
+  // good behavior for default configurations (that is, shift by menubar height
+  // on notch-less macbooks, and don't for devices that have a notch). This will
+  // need refinement in the future.
+  return !ScreenHasNotch(aWindow);
+}
+
+- (void)updateTitlebarShownAmount:(CGFloat)aShownAmount {
+  NSInteger styleMask = [self styleMask];
+  if (!(styleMask & NSWindowStyleMaskFullScreen)) {
+    // We are not interested in the size of the titlebar unless we are in
+    // fullscreen.
+    return;
+  }
+
+  // [NSApp mainMenu] menuBarHeight] returns one of two values: the full height
+  // if the menubar is shown or is in the process of being shown, and 0
+  // otherwise. Since we are multiplying the menubar height by aShownAmount, we
+  // always want the full height.
+  CGFloat menuBarHeight = NSApp.mainMenu.menuBarHeight;
+  if (menuBarHeight > 0.0f) {
+    mMenuBarHeight = menuBarHeight;
+  }
+  if ([[self delegate] isKindOfClass:[WindowDelegate class]]) {
+    WindowDelegate* windowDelegate = (WindowDelegate*)[self delegate];
+    nsCocoaWindow* geckoWindow = [windowDelegate geckoWidget];
+    if (!geckoWindow) {
+      return;
+    }
+
+    if (nsIWidgetListener* listener = geckoWindow->GetWidgetListener()) {
+      // Use the titlebar height cached in our frame rather than
+      // [ToolbarWindow titlebarHeight]. titlebarHeight returns 0 when we're in
+      // fullscreen.
+      CGFloat shiftByPixels = mInitialTitlebarHeight * aShownAmount;
+      if (ShouldShiftByMenubarHeightInFullscreen(geckoWindow)) {
+        shiftByPixels += mMenuBarHeight * aShownAmount;
+      }
+      // Use mozilla::DesktopToLayoutDeviceScale rather than the
+      // DesktopToLayoutDeviceScale in nsCocoaWindow. The latter accounts for
+      // screen DPI. We don't want that because the revealAmount property
+      // already accounts for it, so we'd be compounding DPI scales > 1.
+      mozilla::DesktopCoord coord =
+          LayoutDeviceCoord(shiftByPixels) / mozilla::DesktopToLayoutDeviceScale();
+
+      listener->MacFullscreenMenubarOverlapChanged(coord);
+    }
+  }
+}
+
+- (void)dealloc {
+  [mTitlebarView release];
+  [mFullscreenTitlebarTracker removeObserver:self forKeyPath:@"revealAmount"];
+  [mFullscreenTitlebarTracker removeFromParentViewController];
+  [mFullscreenTitlebarTracker release];
+
+  [super dealloc];
+}
+
+- (NSArray<NSView*>*)contentViewContents {
+  NSMutableArray<NSView*>* contents = [[[self contentView] subviews] mutableCopy];
+  if (mTitlebarView) {
+    // Do not include the titlebar gradient view in the returned array.
+    [contents removeObject:mTitlebarView];
+  }
+  return [contents autorelease];
+}
+
+- (void)updateTitlebarView {
+  BOOL needTitlebarView = ![self drawsContentsIntoWindowFrame] || mUnifiedToolbarHeight > 0;
+  if (needTitlebarView && !mTitlebarView) {
+    mTitlebarView = [[MOZTitlebarView alloc] initWithFrame:[self unifiedToolbarRect]];
+    mTitlebarView.autoresizingMask = NSViewWidthSizable | NSViewMinYMargin;
+    [self.contentView addSubview:mTitlebarView positioned:NSWindowBelow relativeTo:nil];
+  } else if (needTitlebarView && mTitlebarView) {
+    mTitlebarView.frame = [self unifiedToolbarRect];
+  } else if (!needTitlebarView && mTitlebarView) {
+    [mTitlebarView removeFromSuperview];
+    [mTitlebarView release];
+    mTitlebarView = nil;
+  }
+}
+
+- (void)windowMainStateChanged {
+  [self setTitlebarNeedsDisplay];
+  [[self mainChildView] ensureNextCompositeIsAtomicWithMainThreadPaint];
+}
+
+- (void)setTitlebarNeedsDisplay {
+  [mTitlebarView setNeedsDisplay:YES];
+}
+
+- (NSRect)titlebarRect {
+  CGFloat titlebarHeight = [self titlebarHeight];
+  return NSMakeRect(0, [self frame].size.height - titlebarHeight, [self frame].size.width,
+                    titlebarHeight);
+}
+
+// In window contentView coordinates (origin bottom left)
+- (NSRect)unifiedToolbarRect {
+  return NSMakeRect(0, [self frame].size.height - mUnifiedToolbarHeight, [self frame].size.width,
+                    mUnifiedToolbarHeight);
+}
+
+// Returns the unified height of titlebar + toolbar.
+- (CGFloat)unifiedToolbarHeight {
+  return mUnifiedToolbarHeight;
+}
+
+- (CGFloat)titlebarHeight {
+  // We use the original content rect here, not what we return from
+  // [self contentRectForFrameRect:], because that would give us a
+  // titlebarHeight of zero.
+  NSRect frameRect = [self frame];
+  NSUInteger styleMask = [self styleMask];
+  styleMask &= ~NSWindowStyleMaskFullSizeContentView;
+  NSRect originalContentRect = [NSWindow contentRectForFrameRect:frameRect styleMask:styleMask];
+  return NSMaxY(frameRect) - NSMaxY(originalContentRect);
+}
+
+// Stores the complete height of titlebar + toolbar.
+- (void)setUnifiedToolbarHeight:(CGFloat)aHeight {
+  if (aHeight == mUnifiedToolbarHeight) return;
+
+  mUnifiedToolbarHeight = aHeight;
+
+  [self updateTitlebarView];
+}
+
+// Extending the content area into the title bar works by resizing the
+// mainChildView so that it covers the titlebar.
+- (void)setDrawsContentsIntoWindowFrame:(BOOL)aState {
+  BOOL stateChanged = ([self drawsContentsIntoWindowFrame] != aState);
+  [super setDrawsContentsIntoWindowFrame:aState];
+  if (stateChanged && [[self delegate] isKindOfClass:[WindowDelegate class]]) {
+    // Here we extend / shrink our mainChildView. We do that by firing a resize
+    // event which will cause the ChildView to be resized to the rect returned
+    // by nsCocoaWindow::GetClientBounds. GetClientBounds bases its return
+    // value on what we return from drawsContentsIntoWindowFrame.
+    WindowDelegate* windowDelegate = (WindowDelegate*)[self delegate];
+    nsCocoaWindow* geckoWindow = [windowDelegate geckoWidget];
+    if (geckoWindow) {
+      // Re-layout our contents.
+      geckoWindow->ReportSizeEvent();
+    }
+
+    // Resizing the content area causes a reflow which would send a synthesized
+    // mousemove event to the old mouse position relative to the top left
+    // corner of the content area. But the mouse has shifted relative to the
+    // content area, so that event would have wrong position information. So
+    // we'll send a mouse move event with the correct new position.
+    ChildViewMouseTracker::ResendLastMouseMoveEvent();
+  }
+
+  [self updateTitlebarView];
+}
+
+- (void)setWantsTitleDrawn:(BOOL)aDrawTitle {
+  [super setWantsTitleDrawn:aDrawTitle];
+  [self setTitlebarNeedsDisplay];
+}
+
+- (void)setSheetAttachmentPosition:(CGFloat)aY {
+  mSheetAttachmentPosition = aY;
+}
+
+- (CGFloat)sheetAttachmentPosition {
+  return mSheetAttachmentPosition;
+}
+
+- (void)placeWindowButtons:(NSRect)aRect {
+  if (!NSEqualRects(mWindowButtonsRect, aRect)) {
+    mWindowButtonsRect = aRect;
+    [self reflowTitlebarElements];
+  }
+}
+
+- (NSRect)windowButtonsRect {
+  return mWindowButtonsRect;
+}
+
+// Returning YES here makes the setShowsToolbarButton method work even though
+// the window doesn't contain an NSToolbar.
+- (BOOL)_hasToolbar {
+  return YES;
+}
+
+// Dispatch a toolbar pill button clicked message to Gecko.
+- (void)_toolbarPillButtonClicked:(id)sender {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  RollUpPopups();
+
+  if ([[self delegate] isKindOfClass:[WindowDelegate class]]) {
+    WindowDelegate* windowDelegate = (WindowDelegate*)[self delegate];
+    nsCocoaWindow* geckoWindow = [windowDelegate geckoWidget];
+    if (!geckoWindow) return;
+
+    nsIWidgetListener* listener = geckoWindow->GetWidgetListener();
+    if (listener) listener->OSToolbarButtonPressed();
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Retain and release "self" to avoid crashes when our widget (and its native
+// window) is closed as a result of processing a key equivalent (e.g.
+// Command+w or Command+q).  This workaround is only needed for a window
+// that can become key.
+- (BOOL)performKeyEquivalent:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSWindow* nativeWindow = [self retain];
+  BOOL retval = [super performKeyEquivalent:theEvent];
+  [nativeWindow release];
+  return retval;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+- (void)sendEvent:(NSEvent*)anEvent {
+  NSEventType type = [anEvent type];
+
+  switch (type) {
+    case NSEventTypeScrollWheel:
+    case NSEventTypeLeftMouseDown:
+    case NSEventTypeLeftMouseUp:
+    case NSEventTypeRightMouseDown:
+    case NSEventTypeRightMouseUp:
+    case NSEventTypeOtherMouseDown:
+    case NSEventTypeOtherMouseUp:
+    case NSEventTypeMouseMoved:
+    case NSEventTypeLeftMouseDragged:
+    case NSEventTypeRightMouseDragged:
+    case NSEventTypeOtherMouseDragged: {
+      // Drop all mouse events if a modal window has appeared above us.
+      // This helps make us behave as if the OS were running a "real" modal
+      // event loop.
+      id delegate = [self delegate];
+      if (delegate && [delegate isKindOfClass:[WindowDelegate class]]) {
+        nsCocoaWindow* widget = [(WindowDelegate*)delegate geckoWidget];
+        if (widget) {
+          if (gGeckoAppModalWindowList && (widget != gGeckoAppModalWindowList->window)) return;
+          if (widget->HasModalDescendents()) return;
+        }
+      }
+      break;
+    }
+    default:
+      break;
+  }
+
+  [super sendEvent:anEvent];
+}
+
+@end
+
+@implementation PopupWindow
+
+- (id)initWithContentRect:(NSRect)contentRect
+                styleMask:(NSUInteger)styleMask
+                  backing:(NSBackingStoreType)bufferingType
+                    defer:(BOOL)deferCreation {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  mIsContextMenu = false;
+  return [super initWithContentRect:contentRect
+                          styleMask:styleMask
+                            backing:bufferingType
+                              defer:deferCreation];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+// Override the private API _backdropBleedAmount. This determines how much the
+// desktop wallpaper contributes to the vibrancy backdrop.
+// Return 0 in order to match what the system does for sheet windows and
+// _NSPopoverWindows.
+- (CGFloat)_backdropBleedAmount {
+  return 0.0;
+}
+
+// Override the private API shadowOptions.
+// The constants below were found in AppKit's implementations of the
+// shadowOptions method on the various window types.
+static const NSUInteger kWindowShadowOptionsNoShadow = 0;
+static const NSUInteger kWindowShadowOptionsMenu = 2;
+static const NSUInteger kWindowShadowOptionsTooltipMojaveOrLater = 4;
+- (NSUInteger)shadowOptions {
+  if (!self.hasShadow) {
+    return kWindowShadowOptionsNoShadow;
+  }
+
+  switch (self.shadowStyle) {
+    case StyleWindowShadow::None:
+      return kWindowShadowOptionsNoShadow;
+
+    case StyleWindowShadow::Default:  // we treat "default" as "default panel"
+    case StyleWindowShadow::Menu:
+      return kWindowShadowOptionsMenu;
+
+    case StyleWindowShadow::Tooltip:
+      if (nsCocoaFeatures::OnMojaveOrLater()) {
+        return kWindowShadowOptionsTooltipMojaveOrLater;
+      }
+      return kWindowShadowOptionsMenu;
+  }
+}
+
+- (BOOL)isContextMenu {
+  return mIsContextMenu;
+}
+
+- (void)setIsContextMenu:(BOOL)flag {
+  mIsContextMenu = flag;
+}
+
+- (BOOL)canBecomeMainWindow {
+  // This is overriden because the default is 'yes' when a titlebar is present.
+  return NO;
+}
+
+@end
+
+// According to Apple's docs on [NSWindow canBecomeKeyWindow] and [NSWindow
+// canBecomeMainWindow], windows without a title bar or resize bar can't (by
+// default) become key or main.  But if a window can't become key, it can't
+// accept keyboard input (bmo bug 393250).  And it should also be possible for
+// an otherwise "ordinary" window to become main.  We need to override these
+// two methods to make this happen.
+@implementation BorderlessWindow
+
+- (BOOL)canBecomeKeyWindow {
+  return YES;
+}
+
+- (void)sendEvent:(NSEvent*)anEvent {
+  NSEventType type = [anEvent type];
+
+  switch (type) {
+    case NSEventTypeScrollWheel:
+    case NSEventTypeLeftMouseDown:
+    case NSEventTypeLeftMouseUp:
+    case NSEventTypeRightMouseDown:
+    case NSEventTypeRightMouseUp:
+    case NSEventTypeOtherMouseDown:
+    case NSEventTypeOtherMouseUp:
+    case NSEventTypeMouseMoved:
+    case NSEventTypeLeftMouseDragged:
+    case NSEventTypeRightMouseDragged:
+    case NSEventTypeOtherMouseDragged: {
+      // Drop all mouse events if a modal window has appeared above us.
+      // This helps make us behave as if the OS were running a "real" modal
+      // event loop.
+      id delegate = [self delegate];
+      if (delegate && [delegate isKindOfClass:[WindowDelegate class]]) {
+        nsCocoaWindow* widget = [(WindowDelegate*)delegate geckoWidget];
+        if (widget) {
+          if (gGeckoAppModalWindowList && (widget != gGeckoAppModalWindowList->window)) return;
+          if (widget->HasModalDescendents()) return;
+        }
+      }
+      break;
+    }
+    default:
+      break;
+  }
+
+  [super sendEvent:anEvent];
+}
+
+// Apple's doc on this method says that the NSWindow class's default is not to
+// become main if the window isn't "visible" -- so we should replicate that
+// behavior here.  As best I can tell, the [NSWindow isVisible] method is an
+// accurate test of what Apple means by "visibility".
+- (BOOL)canBecomeMainWindow {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (![self isVisible]) return NO;
+  return YES;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+// Retain and release "self" to avoid crashes when our widget (and its native
+// window) is closed as a result of processing a key equivalent (e.g.
+// Command+w or Command+q).  This workaround is only needed for a window
+// that can become key.
+- (BOOL)performKeyEquivalent:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSWindow* nativeWindow = [self retain];
+  BOOL retval = [super performKeyEquivalent:theEvent];
+  [nativeWindow release];
+  return retval;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+@end
diff --git a/widget/cocoa/nsColorPicker.h b/widget/cocoa/nsColorPicker.h
new file mode 100644
index 0000000000..325f159fde
--- /dev/null
+++ b/widget/cocoa/nsColorPicker.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsColorPicker_h_
+#define nsColorPicker_h_
+
+#include "nsIColorPicker.h"
+#include "nsString.h"
+#include "nsCOMPtr.h"
+
+class nsIColorPickerShownCallback;
+class mozIDOMWindowProxy;
+@class NSColorPanelWrapper;
+@class NSColor;
+
+class nsColorPicker final : public nsIColorPicker {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSICOLORPICKER
+
+  // For NSColorPanelWrapper.
+  void Update(NSColor* aColor);
+  void Done();
+
+ private:
+  ~nsColorPicker();
+
+  static NSColor* GetNSColorFromHexString(const nsAString& aColor);
+  static void GetHexStringFromNSColor(NSColor* aColor, nsAString& aResult);
+
+  NSColorPanelWrapper* mColorPanelWrapper;
+
+  nsString mTitle;
+  nsString mColor;
+  nsCOMPtr<nsIColorPickerShownCallback> mCallback;
+};
+
+#endif  // nsColorPicker_h_
diff --git a/widget/cocoa/nsColorPicker.mm b/widget/cocoa/nsColorPicker.mm
new file mode 100644
index 0000000000..255610b27c
--- /dev/null
+++ b/widget/cocoa/nsColorPicker.mm
@@ -0,0 +1,158 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsColorPicker.h"
+#include "nsCocoaUtils.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla;
+
+static unsigned int HexStrToInt(NSString* str) {
+  unsigned int result = 0;
+
+  for (unsigned int i = 0; i < [str length]; ++i) {
+    char c = [str characterAtIndex:i];
+    result *= 16;
+    if (c >= '0' && c <= '9') {
+      result += c - '0';
+    } else if (c >= 'A' && c <= 'F') {
+      result += 10 + (c - 'A');
+    } else {
+      result += 10 + (c - 'a');
+    }
+  }
+
+  return result;
+}
+
+@interface NSColorPanelWrapper : NSObject <NSWindowDelegate> {
+  NSColorPanel* mColorPanel;
+  nsColorPicker* mColorPicker;
+}
+- (id)initWithPicker:(nsColorPicker*)aPicker;
+- (void)open:(NSColor*)aInitialColor title:(NSString*)aTitle;
+- (void)colorChanged:(NSColorPanel*)aPanel;
+- (void)windowWillClose:(NSNotification*)aNotification;
+- (void)close;
+@end
+
+@implementation NSColorPanelWrapper
+- (id)initWithPicker:(nsColorPicker*)aPicker {
+  mColorPicker = aPicker;
+  mColorPanel = [NSColorPanel sharedColorPanel];
+
+  self = [super init];
+  return self;
+}
+
+- (void)open:(NSColor*)aInitialColor title:(NSString*)aTitle {
+  [mColorPanel setTarget:self];
+  [mColorPanel setAction:@selector(colorChanged:)];
+  [mColorPanel setDelegate:self];
+  [mColorPanel setTitle:aTitle];
+  [mColorPanel setColor:aInitialColor];
+  [mColorPanel setFrameOrigin:[NSEvent mouseLocation]];
+  [mColorPanel makeKeyAndOrderFront:nil];
+}
+
+- (void)colorChanged:(NSColorPanel*)aPanel {
+  if (!mColorPicker) {
+    return;
+  }
+  mColorPicker->Update([mColorPanel color]);
+}
+
+- (void)windowWillClose:(NSNotification*)aNotification {
+  if (!mColorPicker) {
+    return;
+  }
+  mColorPicker->Done();
+}
+
+- (void)close {
+  [mColorPanel setTarget:nil];
+  [mColorPanel setAction:nil];
+  [mColorPanel setDelegate:nil];
+
+  mColorPanel = nil;
+  mColorPicker = nullptr;
+}
+@end
+
+NS_IMPL_ISUPPORTS(nsColorPicker, nsIColorPicker)
+
+nsColorPicker::~nsColorPicker() {
+  if (mColorPanelWrapper) {
+    [mColorPanelWrapper close];
+    [mColorPanelWrapper release];
+    mColorPanelWrapper = nullptr;
+  }
+}
+
+// TODO(bug 1805397): Implement default colors
+NS_IMETHODIMP
+nsColorPicker::Init(mozIDOMWindowProxy* aParent, const nsAString& aTitle,
+                    const nsAString& aInitialColor, const nsTArray<nsString>& aDefaultColors) {
+  MOZ_ASSERT(NS_IsMainThread(), "Color pickers can only be opened from main thread currently");
+  mTitle = aTitle;
+  mColor = aInitialColor;
+  mColorPanelWrapper = [[NSColorPanelWrapper alloc] initWithPicker:this];
+  return NS_OK;
+}
+
+/* static */ NSColor* nsColorPicker::GetNSColorFromHexString(const nsAString& aColor) {
+  NSString* str = nsCocoaUtils::ToNSString(aColor);
+
+  double red = HexStrToInt([str substringWithRange:NSMakeRange(1, 2)]) / 255.0;
+  double green = HexStrToInt([str substringWithRange:NSMakeRange(3, 2)]) / 255.0;
+  double blue = HexStrToInt([str substringWithRange:NSMakeRange(5, 2)]) / 255.0;
+
+  return [NSColor colorWithDeviceRed:red green:green blue:blue alpha:1.0];
+}
+
+/* static */ void nsColorPicker::GetHexStringFromNSColor(NSColor* aColor, nsAString& aResult) {
+  CGFloat redFloat, greenFloat, blueFloat;
+
+  NSColor* color = aColor;
+  @try {
+    [color getRed:&redFloat green:&greenFloat blue:&blueFloat alpha:nil];
+  } @catch (NSException* e) {
+    color = [color colorUsingColorSpace:[NSColorSpace genericRGBColorSpace]];
+    [color getRed:&redFloat green:&greenFloat blue:&blueFloat alpha:nil];
+  }
+
+  nsCocoaUtils::GetStringForNSString(
+      [NSString stringWithFormat:@"#%02x%02x%02x", (int)(redFloat * 255), (int)(greenFloat * 255),
+                                 (int)(blueFloat * 255)],
+      aResult);
+}
+
+NS_IMETHODIMP
+nsColorPicker::Open(nsIColorPickerShownCallback* aCallback) {
+  MOZ_ASSERT(aCallback);
+  mCallback = aCallback;
+
+  [mColorPanelWrapper open:GetNSColorFromHexString(mColor) title:nsCocoaUtils::ToNSString(mTitle)];
+
+  NS_ADDREF_THIS();
+
+  return NS_OK;
+}
+
+void nsColorPicker::Update(NSColor* aColor) {
+  GetHexStringFromNSColor(aColor, mColor);
+  mCallback->Update(mColor);
+}
+
+void nsColorPicker::Done() {
+  [mColorPanelWrapper close];
+  [mColorPanelWrapper release];
+  mColorPanelWrapper = nullptr;
+  mCallback->Done(u""_ns);
+  mCallback = nullptr;
+  NS_RELEASE_THIS();
+}
diff --git a/widget/cocoa/nsCursorManager.h b/widget/cocoa/nsCursorManager.h
new file mode 100644
index 0000000000..c36d8962fb
--- /dev/null
+++ b/widget/cocoa/nsCursorManager.h
@@ -0,0 +1,60 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCursorManager_h_
+#define nsCursorManager_h_
+
+#import <Foundation/Foundation.h>
+#include "nsIWidget.h"
+#include "nsMacCursor.h"
+
+/*! @class      nsCursorManager
+    @abstract   Singleton service provides access to all cursors available in the application.
+    @discussion Use <code>nsCusorManager</code> to set the current cursor using
+                an XP <code>nsCusor</code> enum value.
+                <code>nsCursorManager</code> encapsulates the details of
+                setting different types of cursors, animating cursors and
+                cleaning up cursors when they are no longer in use.
+ */
+@interface nsCursorManager : NSObject {
+ @private
+  NSMutableDictionary* mCursors;
+  nsMacCursor* mCurrentMacCursor;
+}
+
+/*! @method     setCursor:
+    @abstract   Sets the current cursor.
+    @discussion Sets the current cursor to the cursor indicated by the XP
+                cursor given in the argument. Resources associated with the
+                previous cursor are cleaned up.
+    @param aCursor the cursor to use
+*/
+- (nsresult)setNonCustomCursor:(const nsIWidget::Cursor&)aCursor;
+
+// As above, but returns an error if the cursor isn't custom or we couldn't set
+// it for some reason.
+- (nsresult)setCustomCursor:(const nsIWidget::Cursor&)aCursor
+          widgetScaleFactor:(CGFloat)aWidgetScaleFactor;
+
+/*! @method     sharedInstance
+    @abstract   Get the Singleton instance of the cursor manager.
+    @discussion Use this method to obtain a reference to the cursor manager.
+    @result a reference to the cursor manager
+*/
++ (nsCursorManager*)sharedInstance;
+
+/*! @method     dispose
+    @abstract   Releases the shared instance of the cursor manager.
+    @discussion Use dispose to clean up the cursor manager and associated cursors.
+*/
++ (void)dispose;
+@end
+
+@interface NSCursor (Undocumented)
+// busyButClickableCursor is an undocumented NSCursor API, but has been in use since
+// at least OS X 10.4 and through 10.9.
++ (NSCursor*)busyButClickableCursor;
+@end
+
+#endif  // nsCursorManager_h_
diff --git a/widget/cocoa/nsCursorManager.mm b/widget/cocoa/nsCursorManager.mm
new file mode 100644
index 0000000000..6596df25a3
--- /dev/null
+++ b/widget/cocoa/nsCursorManager.mm
@@ -0,0 +1,317 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "imgIContainer.h"
+#include "nsCocoaUtils.h"
+#include "nsCursorManager.h"
+#include "nsObjCExceptions.h"
+#include <math.h>
+
+static nsCursorManager* gInstance;
+static CGFloat sCurrentCursorScaleFactor = 0.0f;
+static nsIWidget::Cursor sCurrentCursor;
+static constexpr nsCursor kCustomCursor = eCursorCount;
+
+/*! @category nsCursorManager(PrivateMethods)
+    Private methods for the cursor manager class.
+*/
+@interface nsCursorManager (PrivateMethods)
+/*! @method     getCursor:
+    @abstract   Get a reference to the native Mac representation of a cursor.
+    @discussion Gets a reference to the Mac native implementation of a cursor.
+                If the cursor has been requested before, it is retreived from the cursor cache,
+                otherwise it is created and cached.
+    @param      aCursor the cursor to get
+    @result     the Mac native implementation of the cursor
+*/
+- (nsMacCursor*)getCursor:(nsCursor)aCursor;
+
+/*! @method     setMacCursor:
+ @abstract   Set the current Mac native cursor
+ @discussion Sets the current cursor - this routine is what actually causes the cursor to change.
+ The argument is retained and the old cursor is released.
+ @param      aMacCursor the cursor to set
+ @result     NS_OK
+ */
+- (nsresult)setMacCursor:(nsMacCursor*)aMacCursor;
+
+/*! @method     createCursor:
+    @abstract   Create a Mac native representation of a cursor.
+    @discussion Creates a version of the Mac native representation of this cursor
+    @param      aCursor the cursor to create
+    @result     the Mac native implementation of the cursor
+*/
++ (nsMacCursor*)createCursor:(enum nsCursor)aCursor;
+
+@end
+
+@implementation nsCursorManager
+
++ (nsCursorManager*)sharedInstance {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!gInstance) {
+    gInstance = [[nsCursorManager alloc] init];
+  }
+  return gInstance;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
++ (void)dispose {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [gInstance release];
+  gInstance = nil;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
++ (nsMacCursor*)createCursor:(enum nsCursor)aCursor {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  switch (aCursor) {
+    case eCursor_standard:
+      return [nsMacCursor cursorWithCursor:[NSCursor arrowCursor] type:aCursor];
+    case eCursor_wait:
+    case eCursor_spinning: {
+      return [nsMacCursor cursorWithCursor:[NSCursor busyButClickableCursor] type:aCursor];
+    }
+    case eCursor_select:
+      return [nsMacCursor cursorWithCursor:[NSCursor IBeamCursor] type:aCursor];
+    case eCursor_hyperlink:
+      return [nsMacCursor cursorWithCursor:[NSCursor pointingHandCursor] type:aCursor];
+    case eCursor_crosshair:
+      return [nsMacCursor cursorWithCursor:[NSCursor crosshairCursor] type:aCursor];
+    case eCursor_move:
+      return [nsMacCursor cursorWithImageNamed:@"move" hotSpot:NSMakePoint(12, 12) type:aCursor];
+    case eCursor_help:
+      return [nsMacCursor cursorWithImageNamed:@"help" hotSpot:NSMakePoint(12, 12) type:aCursor];
+    case eCursor_copy: {
+      SEL cursorSelector = @selector(dragCopyCursor);
+      return [nsMacCursor cursorWithCursor:[NSCursor respondsToSelector:cursorSelector]
+                                               ? [NSCursor performSelector:cursorSelector]
+                                               : [NSCursor arrowCursor]
+                                      type:aCursor];
+    }
+    case eCursor_alias: {
+      SEL cursorSelector = @selector(dragLinkCursor);
+      return [nsMacCursor cursorWithCursor:[NSCursor respondsToSelector:cursorSelector]
+                                               ? [NSCursor performSelector:cursorSelector]
+                                               : [NSCursor arrowCursor]
+                                      type:aCursor];
+    }
+    case eCursor_context_menu: {
+      SEL cursorSelector = @selector(contextualMenuCursor);
+      return [nsMacCursor cursorWithCursor:[NSCursor respondsToSelector:cursorSelector]
+                                               ? [NSCursor performSelector:cursorSelector]
+                                               : [NSCursor arrowCursor]
+                                      type:aCursor];
+    }
+    case eCursor_cell:
+      return [nsMacCursor cursorWithImageNamed:@"cell" hotSpot:NSMakePoint(12, 12) type:aCursor];
+    case eCursor_grab:
+      return [nsMacCursor cursorWithCursor:[NSCursor openHandCursor] type:aCursor];
+    case eCursor_grabbing:
+      return [nsMacCursor cursorWithCursor:[NSCursor closedHandCursor] type:aCursor];
+    case eCursor_zoom_in:
+      return [nsMacCursor cursorWithImageNamed:@"zoomIn" hotSpot:NSMakePoint(10, 10) type:aCursor];
+    case eCursor_zoom_out:
+      return [nsMacCursor cursorWithImageNamed:@"zoomOut" hotSpot:NSMakePoint(10, 10) type:aCursor];
+    case eCursor_vertical_text:
+      return [nsMacCursor cursorWithImageNamed:@"vtIBeam" hotSpot:NSMakePoint(12, 11) type:aCursor];
+    case eCursor_all_scroll:
+      return [nsMacCursor cursorWithCursor:[NSCursor openHandCursor] type:aCursor];
+    case eCursor_not_allowed:
+    case eCursor_no_drop: {
+      SEL cursorSelector = @selector(operationNotAllowedCursor);
+      return [nsMacCursor cursorWithCursor:[NSCursor respondsToSelector:cursorSelector]
+                                               ? [NSCursor performSelector:cursorSelector]
+                                               : [NSCursor arrowCursor]
+                                      type:aCursor];
+    }
+    // Resize Cursors:
+    // North
+    case eCursor_n_resize:
+      return [nsMacCursor cursorWithCursor:[NSCursor resizeUpCursor] type:aCursor];
+    // North East
+    case eCursor_ne_resize:
+      return [nsMacCursor cursorWithImageNamed:@"sizeNE" hotSpot:NSMakePoint(12, 11) type:aCursor];
+    // East
+    case eCursor_e_resize:
+      return [nsMacCursor cursorWithCursor:[NSCursor resizeRightCursor] type:aCursor];
+    // South East
+    case eCursor_se_resize:
+      return [nsMacCursor cursorWithImageNamed:@"sizeSE" hotSpot:NSMakePoint(12, 12) type:aCursor];
+    // South
+    case eCursor_s_resize:
+      return [nsMacCursor cursorWithCursor:[NSCursor resizeDownCursor] type:aCursor];
+    // South West
+    case eCursor_sw_resize:
+      return [nsMacCursor cursorWithImageNamed:@"sizeSW" hotSpot:NSMakePoint(10, 12) type:aCursor];
+    // West
+    case eCursor_w_resize:
+      return [nsMacCursor cursorWithCursor:[NSCursor resizeLeftCursor] type:aCursor];
+    // North West
+    case eCursor_nw_resize:
+      return [nsMacCursor cursorWithImageNamed:@"sizeNW" hotSpot:NSMakePoint(11, 11) type:aCursor];
+    // North & South
+    case eCursor_ns_resize:
+      return [nsMacCursor cursorWithCursor:[NSCursor resizeUpDownCursor] type:aCursor];
+    // East & West
+    case eCursor_ew_resize:
+      return [nsMacCursor cursorWithCursor:[NSCursor resizeLeftRightCursor] type:aCursor];
+    // North East & South West
+    case eCursor_nesw_resize:
+      return [nsMacCursor cursorWithImageNamed:@"sizeNESW"
+                                       hotSpot:NSMakePoint(12, 12)
+                                          type:aCursor];
+    // North West & South East
+    case eCursor_nwse_resize:
+      return [nsMacCursor cursorWithImageNamed:@"sizeNWSE"
+                                       hotSpot:NSMakePoint(12, 12)
+                                          type:aCursor];
+    // Column Resize
+    case eCursor_col_resize:
+      return [nsMacCursor cursorWithImageNamed:@"colResize"
+                                       hotSpot:NSMakePoint(12, 12)
+                                          type:aCursor];
+    // Row Resize
+    case eCursor_row_resize:
+      return [nsMacCursor cursorWithImageNamed:@"rowResize"
+                                       hotSpot:NSMakePoint(12, 12)
+                                          type:aCursor];
+    default:
+      return [nsMacCursor cursorWithCursor:[NSCursor arrowCursor] type:aCursor];
+  }
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (id)init {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if ((self = [super init])) {
+    mCursors = [[NSMutableDictionary alloc] initWithCapacity:25];
+  }
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (nsresult)setNonCustomCursor:(const nsIWidget::Cursor&)aCursor {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  [self setMacCursor:[self getCursor:aCursor.mDefaultCursor]];
+
+  sCurrentCursor = aCursor;
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+- (nsresult)setMacCursor:(nsMacCursor*)aMacCursor {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsCursor oldType = [mCurrentMacCursor type];
+  nsCursor newType = [aMacCursor type];
+  if (oldType != newType) {
+    if (newType == eCursor_none) {
+      [NSCursor hide];
+    } else if (oldType == eCursor_none) {
+      [NSCursor unhide];
+    }
+  }
+
+  if (mCurrentMacCursor != aMacCursor || ![mCurrentMacCursor isSet]) {
+    [aMacCursor retain];
+    [mCurrentMacCursor unset];
+    [aMacCursor set];
+    [mCurrentMacCursor release];
+    mCurrentMacCursor = aMacCursor;
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+- (nsresult)setCustomCursor:(const nsIWidget::Cursor&)aCursor
+          widgetScaleFactor:(CGFloat)scaleFactor {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // As the user moves the mouse, this gets called repeatedly with the same aCursorImage
+  if (sCurrentCursor == aCursor && sCurrentCursorScaleFactor == scaleFactor && mCurrentMacCursor) {
+    // Native dragging can unset our cursor apparently (see bug 1739352).
+    if (MOZ_UNLIKELY(![mCurrentMacCursor isSet])) {
+      [mCurrentMacCursor set];
+    }
+    return NS_OK;
+  }
+
+  sCurrentCursor = aCursor;
+  sCurrentCursorScaleFactor = scaleFactor;
+
+  if (!aCursor.IsCustom()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIntSize size = nsIWidget::CustomCursorSize(aCursor);
+  // prevent DoS attacks
+  if (size.width > 128 || size.height > 128) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSImage* cursorImage;
+  nsresult rv = nsCocoaUtils::CreateNSImageFromImageContainer(
+      aCursor.mContainer, imgIContainer::FRAME_FIRST, nullptr, nullptr, &cursorImage, scaleFactor);
+  if (NS_FAILED(rv) || !cursorImage) {
+    return NS_ERROR_FAILURE;
+  }
+
+  {
+    NSSize cocoaSize = NSMakeSize(size.width, size.height);
+    [cursorImage setSize:cocoaSize];
+    [[[cursorImage representations] objectAtIndex:0] setSize:cocoaSize];
+  }
+
+  // if the hotspot is nonsensical, make it 0,0
+  uint32_t hotspotX = aCursor.mHotspotX > (uint32_t(size.width) - 1) ? 0 : aCursor.mHotspotX;
+  uint32_t hotspotY = aCursor.mHotspotY > (uint32_t(size.height) - 1) ? 0 : aCursor.mHotspotY;
+  NSPoint hotSpot = ::NSMakePoint(hotspotX, hotspotY);
+  [self setMacCursor:[nsMacCursor cursorWithCursor:[[NSCursor alloc] initWithImage:cursorImage
+                                                                           hotSpot:hotSpot]
+                                              type:kCustomCursor]];
+  [cursorImage release];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+- (nsMacCursor*)getCursor:(enum nsCursor)aCursor {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsMacCursor* result = [mCursors objectForKey:[NSNumber numberWithInt:aCursor]];
+  if (!result) {
+    result = [nsCursorManager createCursor:aCursor];
+    [mCursors setObject:result forKey:[NSNumber numberWithInt:aCursor]];
+  }
+  return result;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)dealloc {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mCurrentMacCursor unset];
+  [mCurrentMacCursor release];
+  [mCursors release];
+  sCurrentCursor = {};
+  [super dealloc];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+@end
diff --git a/widget/cocoa/nsDeviceContextSpecX.h b/widget/cocoa/nsDeviceContextSpecX.h
new file mode 100644
index 0000000000..9f44446c7d
--- /dev/null
+++ b/widget/cocoa/nsDeviceContextSpecX.h
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDeviceContextSpecX_h_
+#define nsDeviceContextSpecX_h_
+
+#include "nsIDeviceContextSpec.h"
+#include "nsIPrinter.h"
+#include "nsIPrinterList.h"
+
+#include "nsCOMPtr.h"
+
+#include "mozilla/gfx/PrintPromise.h"
+
+#include <ApplicationServices/ApplicationServices.h>
+
+class nsDeviceContextSpecX : public nsIDeviceContextSpec {
+ public:
+  NS_DECL_ISUPPORTS
+
+  nsDeviceContextSpecX();
+
+  NS_IMETHOD Init(nsIPrintSettings* aPS, bool aIsPrintPreview) override;
+  already_AddRefed<PrintTarget> MakePrintTarget() final;
+  NS_IMETHOD BeginDocument(const nsAString& aTitle,
+                           const nsAString& aPrintToFileName,
+                           int32_t aStartPage, int32_t aEndPage) override;
+  RefPtr<mozilla::gfx::PrintEndDocumentPromise> EndDocument() override;
+  NS_IMETHOD BeginPage() override { return NS_OK; };
+  NS_IMETHOD EndPage() override { return NS_OK; };
+
+  void GetPaperRect(double* aTop, double* aLeft, double* aBottom,
+                    double* aRight);
+
+ protected:
+  virtual ~nsDeviceContextSpecX();
+
+ protected:
+  PMPrintSession mPrintSession = nullptr;
+  PMPageFormat mPageFormat = nullptr;
+  PMPrintSettings mPMPrintSettings = nullptr;
+  nsCOMPtr<nsIOutputStream> mOutputStream;  // Output stream from settings.
+#ifdef MOZ_ENABLE_SKIA_PDF
+  // file "print" output generated if printing via PDF
+  nsCOMPtr<nsIFile> mTempFile;
+#endif
+ private:
+  nsresult DoEndDocument();
+};
+
+#endif  // nsDeviceContextSpecX_h_
diff --git a/widget/cocoa/nsDeviceContextSpecX.mm b/widget/cocoa/nsDeviceContextSpecX.mm
new file mode 100644
index 0000000000..568eec44dc
--- /dev/null
+++ b/widget/cocoa/nsDeviceContextSpecX.mm
@@ -0,0 +1,303 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsDeviceContextSpecX.h"
+
+#import <Cocoa/Cocoa.h>
+#include "mozilla/gfx/PrintPromise.h"
+#include <CoreFoundation/CoreFoundation.h>
+#include <unistd.h>
+
+#ifdef MOZ_ENABLE_SKIA_PDF
+#  include "mozilla/gfx/PrintTargetSkPDF.h"
+#endif
+#include "mozilla/gfx/PrintTargetCG.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/Telemetry.h"
+
+#include "AppleUtils.h"
+#include "nsCocoaUtils.h"
+#include "nsCRT.h"
+#include "nsCUPSShim.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsILocalFileMac.h"
+#include "nsIOutputStream.h"
+#include "nsPaper.h"
+#include "nsPrinterListCUPS.h"
+#include "nsPrintSettingsX.h"
+#include "nsQueryObject.h"
+#include "prenv.h"
+
+// This must be the last include:
+#include "nsObjCExceptions.h"
+
+using namespace mozilla;
+using mozilla::gfx::IntSize;
+using mozilla::gfx::PrintEndDocumentPromise;
+using mozilla::gfx::PrintTarget;
+using mozilla::gfx::PrintTargetCG;
+#ifdef MOZ_ENABLE_SKIA_PDF
+using mozilla::gfx::PrintTargetSkPDF;
+#endif
+
+//----------------------------------------------------------------------
+// nsDeviceContentSpecX
+
+nsDeviceContextSpecX::nsDeviceContextSpecX() = default;
+
+nsDeviceContextSpecX::~nsDeviceContextSpecX() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mPrintSession) {
+    ::PMRelease(mPrintSession);
+  }
+  if (mPageFormat) {
+    ::PMRelease(mPageFormat);
+  }
+  if (mPMPrintSettings) {
+    ::PMRelease(mPMPrintSettings);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+NS_IMPL_ISUPPORTS(nsDeviceContextSpecX, nsIDeviceContextSpec)
+
+NS_IMETHODIMP nsDeviceContextSpecX::Init(nsIPrintSettings* aPS, bool aIsPrintPreview) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  RefPtr<nsPrintSettingsX> settings(do_QueryObject(aPS));
+  if (!settings) {
+    return NS_ERROR_NO_INTERFACE;
+  }
+  // Note: unlike other platforms, we don't set our base class's mPrintSettings
+  // here since we don't need it currently (we do set mPMPrintSettings below).
+
+  NSPrintInfo* printInfo = settings->CreateOrCopyPrintInfo();
+  if (!printInfo) {
+    return NS_ERROR_FAILURE;
+  }
+  if (aPS->GetOutputDestination() == nsIPrintSettings::kOutputDestinationStream) {
+    aPS->GetOutputStream(getter_AddRefs(mOutputStream));
+    if (!mOutputStream) {
+      return NS_ERROR_FAILURE;
+    }
+  }
+  mPrintSession = static_cast<PMPrintSession>([printInfo PMPrintSession]);
+  mPageFormat = static_cast<PMPageFormat>([printInfo PMPageFormat]);
+  mPMPrintSettings = static_cast<PMPrintSettings>([printInfo PMPrintSettings]);
+  MOZ_ASSERT(mPrintSession && mPageFormat && mPMPrintSettings);
+  ::PMRetain(mPrintSession);
+  ::PMRetain(mPageFormat);
+  ::PMRetain(mPMPrintSettings);
+  [printInfo release];
+
+#ifdef MOZ_ENABLE_SKIA_PDF
+  nsAutoString printViaPdf;
+  mozilla::Preferences::GetString("print.print_via_pdf_encoder", printViaPdf);
+  if (printViaPdf.EqualsLiteral("skia-pdf")) {
+    // Annoyingly, PMPrinterPrintWithFile does not pay attention to the
+    // kPMDestination* value set in the PMPrintSession; it always sends the PDF
+    // to the specified printer.  This means that if we create the PDF using
+    // SkPDF then we need to manually handle user actions like "Open PDF in
+    // Preview" and "Save as PDF...".
+    // TODO: Currently we do not support using SkPDF for kPMDestinationFax or
+    // kPMDestinationProcessPDF ("Add PDF to iBooks, etc.), and we only support
+    // it for kPMDestinationFile if the destination file is a PDF.
+    // XXX Could PMWorkflowSubmitPDFWithSettings/PMPrinterPrintWithProvider help?
+    OSStatus status = noErr;
+    PMDestinationType destination;
+    status = ::PMSessionGetDestinationType(mPrintSession, mPMPrintSettings, &destination);
+    if (status == noErr) {
+      if (destination == kPMDestinationPrinter || destination == kPMDestinationPreview) {
+        mPrintViaSkPDF = true;
+      } else if (destination == kPMDestinationFile) {
+        AutoCFRelease<CFURLRef> destURL(nullptr);
+        status =
+            ::PMSessionCopyDestinationLocation(mPrintSession, mPMPrintSettings, destURL.receive());
+        if (status == noErr) {
+          AutoCFRelease<CFStringRef> destPathRef =
+              CFURLCopyFileSystemPath(destURL, kCFURLPOSIXPathStyle);
+          NSString* destPath = (NSString*)CFStringRef(destPathRef);
+          NSString* destPathExt = [destPath pathExtension];
+          if ([destPathExt isEqualToString:@"pdf"]) {
+            mPrintViaSkPDF = true;
+          }
+        }
+      }
+    }
+  }
+#endif
+
+  int16_t outputFormat = aPS->GetOutputFormat();
+
+  if (outputFormat == nsIPrintSettings::kOutputFormatPDF) {
+    // We don't actually currently support/use kOutputFormatPDF on mac, but
+    // this is for completeness in case we add that (we probably need to in
+    // order to support adding links into saved PDFs, for example).
+    Telemetry::ScalarAdd(Telemetry::ScalarID::PRINTING_TARGET_TYPE, u"pdf_file"_ns, 1);
+  } else {
+    PMDestinationType destination;
+    OSStatus status = ::PMSessionGetDestinationType(mPrintSession, mPMPrintSettings, &destination);
+    if (status == noErr &&
+        (destination == kPMDestinationFile || destination == kPMDestinationPreview ||
+         destination == kPMDestinationProcessPDF)) {
+      Telemetry::ScalarAdd(Telemetry::ScalarID::PRINTING_TARGET_TYPE, u"pdf_file"_ns, 1);
+    } else {
+      Telemetry::ScalarAdd(Telemetry::ScalarID::PRINTING_TARGET_TYPE, u"unknown"_ns, 1);
+    }
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP nsDeviceContextSpecX::BeginDocument(const nsAString& aTitle,
+                                                  const nsAString& aPrintToFileName,
+                                                  int32_t aStartPage, int32_t aEndPage) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+RefPtr<PrintEndDocumentPromise> nsDeviceContextSpecX::EndDocument() {
+  return nsIDeviceContextSpec::EndDocumentPromiseFromResult(DoEndDocument(), __func__);
+}
+
+nsresult nsDeviceContextSpecX::DoEndDocument() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+#ifdef MOZ_ENABLE_SKIA_PDF
+  if (mPrintViaSkPDF) {
+    OSStatus status = noErr;
+
+    nsCOMPtr<nsILocalFileMac> tmpPDFFile = do_QueryInterface(mTempFile);
+    if (!tmpPDFFile) {
+      return NS_ERROR_FAILURE;
+    }
+    AutoCFRelease<CFURLRef> pdfURL(nullptr);
+    // Note that the caller is responsible to release pdfURL according to nsILocalFileMac.idl,
+    // even though we didn't follow the Core Foundation naming conventions here (the method
+    // should've been called CopyCFURL).
+    nsresult rv = tmpPDFFile->GetCFURL(pdfURL.receive());
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    PMDestinationType destination;
+    status = ::PMSessionGetDestinationType(mPrintSession, mPMPrintSettings, &destination);
+
+    switch (destination) {
+      case kPMDestinationPrinter: {
+        PMPrinter currentPrinter = NULL;
+        status = ::PMSessionGetCurrentPrinter(mPrintSession, &currentPrinter);
+        if (status != noErr) {
+          return NS_ERROR_FAILURE;
+        }
+        CFStringRef mimeType = CFSTR("application/pdf");
+        status = ::PMPrinterPrintWithFile(currentPrinter, mPMPrintSettings, mPageFormat, mimeType,
+                                          pdfURL);
+        break;
+      }
+      case kPMDestinationPreview: {
+        // XXXjwatt Or should we use CocoaFileUtils::RevealFileInFinder(pdfURL);
+        AutoCFRelease<CFStringRef> pdfPath = CFURLCopyFileSystemPath(pdfURL, kCFURLPOSIXPathStyle);
+        NSString* path = (NSString*)CFStringRef(pdfPath);
+        NSWorkspace* ws = [NSWorkspace sharedWorkspace];
+        [ws openFile:path];
+        break;
+      }
+      case kPMDestinationFile: {
+        AutoCFRelease<CFURLRef> destURL(nullptr);
+        status =
+            ::PMSessionCopyDestinationLocation(mPrintSession, mPMPrintSettings, destURL.receive());
+        if (status == noErr) {
+          AutoCFRelease<CFStringRef> sourcePathRef =
+              CFURLCopyFileSystemPath(pdfURL, kCFURLPOSIXPathStyle);
+          NSString* sourcePath = (NSString*)CFStringRef(sourcePathRef);
+#  ifdef DEBUG
+          AutoCFRelease<CFStringRef> destPathRef =
+              CFURLCopyFileSystemPath(destURL, kCFURLPOSIXPathStyle);
+          NSString* destPath = (NSString*)CFStringRef(destPathRef);
+          NSString* destPathExt = [destPath pathExtension];
+          MOZ_ASSERT([destPathExt isEqualToString:@"pdf"],
+                     "nsDeviceContextSpecX::Init only allows '.pdf' for now");
+          // We could use /usr/sbin/cupsfilter to convert the PDF to PS, but
+          // currently we don't.
+#  endif
+          NSFileManager* fileManager = [NSFileManager defaultManager];
+          if ([fileManager fileExistsAtPath:sourcePath]) {
+            NSURL* src = static_cast<NSURL*>(CFURLRef(pdfURL));
+            NSURL* dest = static_cast<NSURL*>(CFURLRef(destURL));
+            bool ok = [fileManager replaceItemAtURL:dest
+                                      withItemAtURL:src
+                                     backupItemName:nil
+                                            options:NSFileManagerItemReplacementUsingNewMetadataOnly
+                                   resultingItemURL:nil
+                                              error:nil];
+            if (!ok) {
+              return NS_ERROR_FAILURE;
+            }
+          }
+        }
+        break;
+      }
+      default:
+        MOZ_ASSERT_UNREACHABLE("nsDeviceContextSpecX::Init doesn't set "
+                               "mPrintViaSkPDF for other values");
+    }
+
+    return (status == noErr) ? NS_OK : NS_ERROR_FAILURE;
+  }
+#endif
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsDeviceContextSpecX::GetPaperRect(double* aTop, double* aLeft, double* aBottom,
+                                        double* aRight) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  PMRect paperRect;
+  ::PMGetAdjustedPaperRect(mPageFormat, &paperRect);
+
+  *aTop = paperRect.top;
+  *aLeft = paperRect.left;
+  *aBottom = paperRect.bottom;
+  *aRight = paperRect.right;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+already_AddRefed<PrintTarget> nsDeviceContextSpecX::MakePrintTarget() {
+  double top, left, bottom, right;
+  GetPaperRect(&top, &left, &bottom, &right);
+  const double width = right - left;
+  const double height = bottom - top;
+  IntSize size = IntSize::Ceil(width, height);
+
+#ifdef MOZ_ENABLE_SKIA_PDF
+  if (mPrintViaSkPDF) {
+    // TODO: Add support for stream printing via SkPDF if we enable that again.
+    nsresult rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(mTempFile));
+    NS_ENSURE_SUCCESS(rv, nullptr);
+    nsAutoCString tempPath("tmp-printing.pdf");
+    mTempFile->AppendNative(tempPath);
+    rv = mTempFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);
+    NS_ENSURE_SUCCESS(rv, nullptr);
+    mTempFile->GetNativePath(tempPath);
+    auto stream = MakeUnique<SkFILEWStream>(tempPath.get());
+    return PrintTargetSkPDF::CreateOrNull(std::move(stream), size);
+  }
+#endif
+
+  return PrintTargetCG::CreateOrNull(mOutputStream, mPrintSession, mPageFormat, mPMPrintSettings,
+                                     size);
+}
diff --git a/widget/cocoa/nsDragService.h b/widget/cocoa/nsDragService.h
new file mode 100644
index 0000000000..da5211fbab
--- /dev/null
+++ b/widget/cocoa/nsDragService.h
@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDragService_h_
+#define nsDragService_h_
+
+#include "nsBaseDragService.h"
+#include "nsChildView.h"
+
+#include <Cocoa/Cocoa.h>
+
+class nsDragService : public nsBaseDragService {
+ public:
+  nsDragService();
+
+  // nsBaseDragService
+  MOZ_CAN_RUN_SCRIPT virtual nsresult InvokeDragSessionImpl(
+      nsIArray* anArrayTransferables, const mozilla::Maybe<mozilla::CSSIntRegion>& aRegion,
+      uint32_t aActionType) override;
+  // nsIDragService
+  MOZ_CAN_RUN_SCRIPT NS_IMETHOD EndDragSession(bool aDoneDrag, uint32_t aKeyModifiers) override;
+  NS_IMETHOD UpdateDragImage(nsINode* aImage, int32_t aImageX, int32_t aImageY) override;
+
+  // nsIDragSession
+  NS_IMETHOD GetData(nsITransferable* aTransferable, uint32_t aItemIndex) override;
+  NS_IMETHOD IsDataFlavorSupported(const char* aDataFlavor, bool* _retval) override;
+  NS_IMETHOD GetNumDropItems(uint32_t* aNumItems) override;
+
+  void DragMovedWithView(NSDraggingSession* aSession, NSPoint aPoint);
+
+ protected:
+  virtual ~nsDragService();
+
+ private:
+  // Creates and returns the drag image for a drag. aImagePoint will be set to
+  // the origin of the drag relative to mNativeDragView.
+  NSImage* ConstructDragImage(nsINode* aDOMNode,
+                              const mozilla::Maybe<mozilla::CSSIntRegion>& aRegion,
+                              NSPoint* aImagePoint);
+
+  // Creates and returns the drag image for a drag. aPoint should be the origin
+  // of the drag, for example the mouse coordinate of the mousedown event.
+  // aDragRect will be set the area of the drag relative to this.
+  NSImage* ConstructDragImage(nsINode* aDOMNode,
+                              const mozilla::Maybe<mozilla::CSSIntRegion>& aRegion,
+                              mozilla::CSSIntPoint aPoint, mozilla::LayoutDeviceIntRect* aDragRect);
+
+  nsCOMPtr<nsIArray> mDataItems;  // only valid for a drag started within gecko
+  ChildView* mNativeDragView;
+  NSEvent* mNativeDragEvent;
+
+  bool mDragImageChanged;
+};
+
+#endif  // nsDragService_h_
diff --git a/widget/cocoa/nsDragService.mm b/widget/cocoa/nsDragService.mm
new file mode 100644
index 0000000000..4ac5c3cbc0
--- /dev/null
+++ b/widget/cocoa/nsDragService.mm
@@ -0,0 +1,477 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Logging.h"
+
+#include "gfxContext.h"
+#include "nsArrayUtils.h"
+#include "nsDragService.h"
+#include "nsArrayUtils.h"
+#include "nsObjCExceptions.h"
+#include "nsITransferable.h"
+#include "nsString.h"
+#include "nsClipboard.h"
+#include "nsXPCOM.h"
+#include "nsCOMPtr.h"
+#include "nsPrimitiveHelpers.h"
+#include "nsLinebreakConverter.h"
+#include "nsINode.h"
+#include "nsRect.h"
+#include "nsPoint.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include "nsIContent.h"
+#include "nsView.h"
+#include "nsCocoaUtils.h"
+#include "mozilla/gfx/2D.h"
+#include "gfxPlatform.h"
+#include "nsDeviceContext.h"
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+
+extern mozilla::LazyLogModule sCocoaLog;
+
+extern NSPasteboard* globalDragPboard;
+extern ChildView* gLastDragView;
+extern NSEvent* gLastDragMouseDownEvent;
+extern bool gUserCancelledDrag;
+
+// This global makes the transferable array available to Cocoa's promised
+// file destination callback.
+mozilla::StaticRefPtr<nsIArray> gDraggedTransferables;
+
+nsDragService::nsDragService()
+    : mNativeDragView(nil), mNativeDragEvent(nil), mDragImageChanged(false) {}
+
+nsDragService::~nsDragService() {}
+
+NSImage* nsDragService::ConstructDragImage(nsINode* aDOMNode, const Maybe<CSSIntRegion>& aRegion,
+                                           NSPoint* aDragPoint) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  CGFloat scaleFactor = nsCocoaUtils::GetBackingScaleFactor(mNativeDragView);
+
+  LayoutDeviceIntRect dragRect(0, 0, 20, 20);
+  NSImage* image = ConstructDragImage(mSourceNode, aRegion, mScreenPosition, &dragRect);
+  if (!image) {
+    // if no image was returned, just draw a rectangle
+    NSSize size;
+    size.width = nsCocoaUtils::DevPixelsToCocoaPoints(dragRect.width, scaleFactor);
+    size.height = nsCocoaUtils::DevPixelsToCocoaPoints(dragRect.height, scaleFactor);
+    image = [NSImage imageWithSize:size
+                           flipped:YES
+                    drawingHandler:^BOOL(NSRect dstRect) {
+                      [[NSColor grayColor] set];
+                      NSBezierPath* path = [NSBezierPath bezierPathWithRect:dstRect];
+                      [path setLineWidth:2.0];
+                      [path stroke];
+                      return YES;
+                    }];
+  }
+
+  LayoutDeviceIntPoint pt(dragRect.x, dragRect.YMost());
+  NSPoint point = nsCocoaUtils::DevPixelsToCocoaPoints(pt, scaleFactor);
+  point.y = nsCocoaUtils::FlippedScreenY(point.y);
+
+  point = nsCocoaUtils::ConvertPointFromScreen([mNativeDragView window], point);
+  *aDragPoint = [mNativeDragView convertPoint:point fromView:nil];
+
+  return image;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+NSImage* nsDragService::ConstructDragImage(nsINode* aDOMNode, const Maybe<CSSIntRegion>& aRegion,
+                                           CSSIntPoint aPoint, LayoutDeviceIntRect* aDragRect) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  CGFloat scaleFactor = nsCocoaUtils::GetBackingScaleFactor(mNativeDragView);
+
+  RefPtr<SourceSurface> surface;
+  nsPresContext* pc;
+  nsresult rv = DrawDrag(aDOMNode, aRegion, aPoint, aDragRect, &surface, &pc);
+  if (pc && (!aDragRect->width || !aDragRect->height)) {
+    // just use some suitable defaults
+    int32_t size = nsCocoaUtils::CocoaPointsToDevPixels(20, scaleFactor);
+    aDragRect->SetRect(pc->CSSPixelsToDevPixels(aPoint.x), pc->CSSPixelsToDevPixels(aPoint.y), size,
+                       size);
+  }
+
+  if (NS_FAILED(rv) || !surface) return nil;
+
+  uint32_t width = aDragRect->width;
+  uint32_t height = aDragRect->height;
+
+  RefPtr<DataSourceSurface> dataSurface =
+      Factory::CreateDataSourceSurface(IntSize(width, height), SurfaceFormat::B8G8R8A8);
+  DataSourceSurface::MappedSurface map;
+  if (!dataSurface->Map(DataSourceSurface::MapType::READ_WRITE, &map)) {
+    return nil;
+  }
+
+  RefPtr<DrawTarget> dt = Factory::CreateDrawTargetForData(
+      BackendType::CAIRO, map.mData, dataSurface->GetSize(), map.mStride, dataSurface->GetFormat());
+  if (!dt) {
+    dataSurface->Unmap();
+    return nil;
+  }
+
+  dt->FillRect(gfx::Rect(0, 0, width, height), SurfacePattern(surface, ExtendMode::CLAMP),
+               DrawOptions(1.0f, CompositionOp::OP_SOURCE));
+
+  NSBitmapImageRep* imageRep =
+      [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL
+                                              pixelsWide:width
+                                              pixelsHigh:height
+                                           bitsPerSample:8
+                                         samplesPerPixel:4
+                                                hasAlpha:YES
+                                                isPlanar:NO
+                                          colorSpaceName:NSDeviceRGBColorSpace
+                                             bytesPerRow:width * 4
+                                            bitsPerPixel:32];
+
+  uint8_t* dest = [imageRep bitmapData];
+  for (uint32_t i = 0; i < height; ++i) {
+    uint8_t* src = map.mData + i * map.mStride;
+    for (uint32_t j = 0; j < width; ++j) {
+      // Reduce transparency overall by multipying by a factor. Remember, Alpha
+      // is premultipled here. Also, Quartz likes RGBA, so do that translation as well.
+#ifdef IS_BIG_ENDIAN
+      dest[0] = uint8_t(src[1] * DRAG_TRANSLUCENCY);
+      dest[1] = uint8_t(src[2] * DRAG_TRANSLUCENCY);
+      dest[2] = uint8_t(src[3] * DRAG_TRANSLUCENCY);
+      dest[3] = uint8_t(src[0] * DRAG_TRANSLUCENCY);
+#else
+      dest[0] = uint8_t(src[2] * DRAG_TRANSLUCENCY);
+      dest[1] = uint8_t(src[1] * DRAG_TRANSLUCENCY);
+      dest[2] = uint8_t(src[0] * DRAG_TRANSLUCENCY);
+      dest[3] = uint8_t(src[3] * DRAG_TRANSLUCENCY);
+#endif
+      src += 4;
+      dest += 4;
+    }
+  }
+  dataSurface->Unmap();
+
+  NSImage* image =
+      [[NSImage alloc] initWithSize:NSMakeSize(width / scaleFactor, height / scaleFactor)];
+  [image addRepresentation:imageRep];
+  [imageRep release];
+
+  return [image autorelease];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+nsresult nsDragService::InvokeDragSessionImpl(nsIArray* aTransferableArray,
+                                              const Maybe<CSSIntRegion>& aRegion,
+                                              uint32_t aActionType) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+#ifdef NIGHTLY_BUILD
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+#endif
+
+  if (!gLastDragView) {
+    // gLastDragView is non-null between -[ChildView mouseDown:] and -[ChildView mouseUp:].
+    // If we get here with gLastDragView being null, that means that the mouse button has already
+    // been released. In that case we need to abort the drag because the OS won't know where to drop
+    // whatever's being dragged, and we might end up with a stuck drag & drop session.
+    return NS_ERROR_FAILURE;
+  }
+
+  mDataItems = aTransferableArray;
+
+  // Save the transferables away in case a promised file callback is invoked.
+  gDraggedTransferables = aTransferableArray;
+
+  // We need to retain the view and the event during the drag in case either
+  // gets destroyed.
+  mNativeDragView = [gLastDragView retain];
+  mNativeDragEvent = [gLastDragMouseDownEvent retain];
+
+  gUserCancelledDrag = false;
+
+  NSPasteboardItem* pbItem = [NSPasteboardItem new];
+  NSMutableArray* types = [NSMutableArray arrayWithCapacity:5];
+
+  if (gDraggedTransferables) {
+    uint32_t count = 0;
+    gDraggedTransferables->GetLength(&count);
+
+    for (uint32_t j = 0; j < count; j++) {
+      nsCOMPtr<nsITransferable> currentTransferable = do_QueryElementAt(aTransferableArray, j);
+      if (!currentTransferable) {
+        return NS_ERROR_FAILURE;
+      }
+
+      // Transform the transferable to an NSDictionary
+      NSDictionary* pasteboardOutputDict =
+          nsClipboard::PasteboardDictFromTransferable(currentTransferable);
+      if (!pasteboardOutputDict) {
+        return NS_ERROR_FAILURE;
+      }
+
+      // write everything out to the general pasteboard
+      [types addObjectsFromArray:[pasteboardOutputDict allKeys]];
+      // Gecko is initiating this drag so we always want its own views to
+      // consider it. Add our wildcard type to the pasteboard to accomplish
+      // this.
+      [types addObject:[UTIHelper stringFromPboardType:kMozWildcardPboardType]];
+    }
+  }
+  [pbItem setDataProvider:mNativeDragView forTypes:types];
+
+  NSPoint draggingPoint;
+  NSImage* image = ConstructDragImage(mSourceNode, aRegion, &draggingPoint);
+
+  NSRect localDragRect = image.alignmentRect;
+  localDragRect.origin.x = draggingPoint.x;
+  localDragRect.origin.y = draggingPoint.y - localDragRect.size.height;
+
+  NSDraggingItem* dragItem = [[NSDraggingItem alloc] initWithPasteboardWriter:pbItem];
+  [pbItem release];
+  [dragItem setDraggingFrame:localDragRect contents:image];
+
+  nsBaseDragService::StartDragSession();
+  nsBaseDragService::OpenDragPopup();
+
+  NSDraggingSession* draggingSession = [mNativeDragView
+      beginDraggingSessionWithItems:[NSArray arrayWithObject:[dragItem autorelease]]
+                              event:mNativeDragEvent
+                             source:mNativeDragView];
+  draggingSession.animatesToStartingPositionsOnCancelOrFail =
+      !mDataTransfer || mDataTransfer->MozShowFailAnimation();
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsDragService::GetData(nsITransferable* aTransferable, uint32_t aItemIndex) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!aTransferable) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // get flavor list that includes all acceptable flavors (including ones obtained through
+  // conversion)
+  nsTArray<nsCString> flavors;
+  nsresult rv = aTransferable->FlavorsTransferableCanImport(flavors);
+  if (NS_FAILED(rv)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // if this drag originated within Mozilla we should just use the cached data from
+  // when the drag started if possible
+  if (mDataItems) {
+    nsCOMPtr<nsITransferable> currentTransferable = do_QueryElementAt(mDataItems, aItemIndex);
+    if (currentTransferable) {
+      for (uint32_t i = 0; i < flavors.Length(); i++) {
+        nsCString& flavorStr = flavors[i];
+
+        nsCOMPtr<nsISupports> dataSupports;
+        rv = currentTransferable->GetTransferData(flavorStr.get(), getter_AddRefs(dataSupports));
+        if (NS_SUCCEEDED(rv)) {
+          aTransferable->SetTransferData(flavorStr.get(), dataSupports);
+          return NS_OK;  // maybe try to fill in more types? Is there a point?
+        }
+      }
+    }
+  }
+
+  NSArray* droppedItems = [globalDragPboard pasteboardItems];
+  if (!droppedItems) {
+    return NS_ERROR_FAILURE;
+  }
+
+  uint32_t itemCount = [droppedItems count];
+  if (aItemIndex >= itemCount) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSPasteboardItem* item = [droppedItems objectAtIndex:aItemIndex];
+  if (!item) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // now check the actual clipboard for data
+  for (uint32_t i = 0; i < flavors.Length(); i++) {
+    nsCocoaUtils::SetTransferDataForTypeFromPasteboardItem(aTransferable, flavors[i], item);
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsDragService::IsDataFlavorSupported(const char* aDataFlavor, bool* _retval) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  *_retval = false;
+
+  if (!globalDragPboard) return NS_ERROR_FAILURE;
+
+  nsDependentCString dataFlavor(aDataFlavor);
+
+  // first see if we have data for this in our cached transferable
+  if (mDataItems) {
+    uint32_t dataItemsCount;
+    mDataItems->GetLength(&dataItemsCount);
+    for (unsigned int i = 0; i < dataItemsCount; i++) {
+      nsCOMPtr<nsITransferable> currentTransferable = do_QueryElementAt(mDataItems, i);
+      if (!currentTransferable) continue;
+
+      nsTArray<nsCString> flavors;
+      nsresult rv = currentTransferable->FlavorsTransferableCanImport(flavors);
+      if (NS_FAILED(rv)) continue;
+
+      for (uint32_t j = 0; j < flavors.Length(); j++) {
+        if (dataFlavor.Equals(flavors[j])) {
+          *_retval = true;
+          return NS_OK;
+        }
+      }
+    }
+  }
+
+  const NSString* type = nil;
+  bool allowFileURL = false;
+  if (dataFlavor.EqualsLiteral(kFileMime)) {
+    type = [UTIHelper stringFromPboardType:(NSString*)kUTTypeFileURL];
+    allowFileURL = true;
+  } else if (dataFlavor.EqualsLiteral(kTextMime)) {
+    type = [UTIHelper stringFromPboardType:NSPasteboardTypeString];
+  } else if (dataFlavor.EqualsLiteral(kHTMLMime)) {
+    type = [UTIHelper stringFromPboardType:NSPasteboardTypeHTML];
+  } else if (dataFlavor.EqualsLiteral(kURLMime) || dataFlavor.EqualsLiteral(kURLDataMime)) {
+    type = [UTIHelper stringFromPboardType:kPublicUrlPboardType];
+  } else if (dataFlavor.EqualsLiteral(kURLDescriptionMime)) {
+    type = [UTIHelper stringFromPboardType:kPublicUrlNamePboardType];
+  } else if (dataFlavor.EqualsLiteral(kRTFMime)) {
+    type = [UTIHelper stringFromPboardType:NSPasteboardTypeRTF];
+  } else if (dataFlavor.EqualsLiteral(kCustomTypesMime)) {
+    type = [UTIHelper stringFromPboardType:kMozCustomTypesPboardType];
+  }
+
+  NSString* availableType =
+      [globalDragPboard availableTypeFromArray:[NSArray arrayWithObjects:(id)type, nil]];
+  if (availableType && nsCocoaUtils::IsValidPasteboardType(availableType, allowFileURL)) {
+    *_retval = true;
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsDragService::GetNumDropItems(uint32_t* aNumItems) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  *aNumItems = 0;
+
+  // first check to see if we have a number of items cached
+  if (mDataItems) {
+    mDataItems->GetLength(aNumItems);
+    return NS_OK;
+  }
+
+  NSArray* droppedItems = [globalDragPboard pasteboardItems];
+  if (droppedItems) {
+    *aNumItems = [droppedItems count];
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsDragService::UpdateDragImage(nsINode* aImage, int32_t aImageX, int32_t aImageY) {
+  nsBaseDragService::UpdateDragImage(aImage, aImageX, aImageY);
+  mDragImageChanged = true;
+  return NS_OK;
+}
+
+void nsDragService::DragMovedWithView(NSDraggingSession* aSession, NSPoint aPoint) {
+  aPoint.y = nsCocoaUtils::FlippedScreenY(aPoint.y);
+
+  // XXX It feels like we should be using the backing scale factor at aPoint
+  // rather than the initial drag view, but I've seen no ill effects of this.
+  CGFloat scaleFactor = nsCocoaUtils::GetBackingScaleFactor(mNativeDragView);
+  LayoutDeviceIntPoint devPoint = nsCocoaUtils::CocoaPointsToDevPixels(aPoint, scaleFactor);
+
+  // If the image has changed, call enumerateDraggingItemsWithOptions to get
+  // the item being dragged and update its image.
+  if (mDragImageChanged && mNativeDragView) {
+    mDragImageChanged = false;
+
+    nsPresContext* pc = nullptr;
+    nsCOMPtr<nsIContent> content = do_QueryInterface(mImage);
+    if (content) {
+      pc = content->OwnerDoc()->GetPresContext();
+    }
+
+    if (pc) {
+      void (^changeImageBlock)(NSDraggingItem*, NSInteger, BOOL*) =
+          ^(NSDraggingItem* draggingItem, NSInteger idx, BOOL* stop) {
+            // We never add more than one item right now, but check just in case.
+            if (idx > 0) {
+              return;
+            }
+
+            nsPoint pt =
+                LayoutDevicePixel::ToAppUnits(devPoint, pc->DeviceContext()->AppUnitsPerDevPixel());
+            CSSIntPoint screenPoint = CSSIntPoint(nsPresContext::AppUnitsToIntCSSPixels(pt.x),
+                                                  nsPresContext::AppUnitsToIntCSSPixels(pt.y));
+
+            // Create a new image; if one isn't returned don't change the current one.
+            LayoutDeviceIntRect newRect;
+            NSImage* image = ConstructDragImage(mSourceNode, Nothing(), screenPoint, &newRect);
+            if (image) {
+              NSRect draggingRect = nsCocoaUtils::GeckoRectToCocoaRectDevPix(newRect, scaleFactor);
+              [draggingItem setDraggingFrame:draggingRect contents:image];
+            }
+          };
+
+      [aSession enumerateDraggingItemsWithOptions:NSDraggingItemEnumerationConcurrent
+                                          forView:nil
+                                          classes:[NSArray arrayWithObject:[NSPasteboardItem class]]
+                                    searchOptions:@{}
+                                       usingBlock:changeImageBlock];
+    }
+  }
+
+  DragMoved(devPoint.x, devPoint.y);
+}
+
+NS_IMETHODIMP
+nsDragService::EndDragSession(bool aDoneDrag, uint32_t aKeyModifiers) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (mNativeDragView) {
+    [mNativeDragView release];
+    mNativeDragView = nil;
+  }
+  if (mNativeDragEvent) {
+    [mNativeDragEvent release];
+    mNativeDragEvent = nil;
+  }
+
+  mUserCancelled = gUserCancelledDrag;
+
+  nsresult rv = nsBaseDragService::EndDragSession(aDoneDrag, aKeyModifiers);
+  mDataItems = nullptr;
+  return rv;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
diff --git a/widget/cocoa/nsFilePicker.h b/widget/cocoa/nsFilePicker.h
new file mode 100644
index 0000000000..cdc17f8646
--- /dev/null
+++ b/widget/cocoa/nsFilePicker.h
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsFilePicker_h_
+#define nsFilePicker_h_
+
+#include "nsBaseFilePicker.h"
+#include "nsString.h"
+#include "nsIFile.h"
+#include "nsCOMArray.h"
+#include "nsTArray.h"
+
+class nsILocalFileMac;
+@class NSArray;
+
+class nsFilePicker : public nsBaseFilePicker {
+ public:
+  nsFilePicker();
+  using nsIFilePicker::ResultCode;
+
+  NS_DECL_ISUPPORTS
+
+  // nsIFilePicker (less what's in nsBaseFilePicker)
+  NS_IMETHOD GetDefaultString(nsAString& aDefaultString) override;
+  NS_IMETHOD SetDefaultString(const nsAString& aDefaultString) override;
+  NS_IMETHOD GetDefaultExtension(nsAString& aDefaultExtension) override;
+  NS_IMETHOD GetFilterIndex(int32_t* aFilterIndex) override;
+  NS_IMETHOD SetFilterIndex(int32_t aFilterIndex) override;
+  NS_IMETHOD SetDefaultExtension(const nsAString& aDefaultExtension) override;
+  NS_IMETHOD GetFile(nsIFile** aFile) override;
+  NS_IMETHOD GetFileURL(nsIURI** aFileURL) override;
+  NS_IMETHOD GetFiles(nsISimpleEnumerator** aFiles) override;
+  NS_IMETHOD AppendFilter(const nsAString& aTitle, const nsAString& aFilter) override;
+
+  /**
+   * Returns the current filter list in the format used by Cocoa's NSSavePanel
+   * and NSOpenPanel.
+   * Returns nil if no filter currently apply.
+   */
+  NSArray* GetFilterList();
+
+ protected:
+  virtual ~nsFilePicker();
+
+  virtual void InitNative(nsIWidget* aParent, const nsAString& aTitle) override;
+  nsresult Show(ResultCode* _retval) override;
+
+  // actual implementations of get/put dialogs using NSOpenPanel & NSSavePanel
+  // aFile is an existing but unspecified file. These functions must specify it.
+  //
+  // will return |returnCancel| or |returnOK| as result.
+  ResultCode GetLocalFiles(bool inAllowMultiple, nsCOMArray<nsIFile>& outFiles);
+  ResultCode GetLocalFolder(nsIFile** outFile);
+  ResultCode PutLocalFile(nsIFile** outFile);
+
+  void SetDialogTitle(const nsString& inTitle, id aDialog);
+  NSString* PanelDefaultDirectory();
+  NSView* GetAccessoryView();
+
+  nsString mTitle;
+  nsCOMArray<nsIFile> mFiles;
+  nsString mDefaultFilename;
+
+  nsTArray<nsString> mFilters;
+  nsTArray<nsString> mTitles;
+
+  int32_t mSelectedTypeIndex;
+};
+
+#endif  // nsFilePicker_h_
diff --git a/widget/cocoa/nsFilePicker.mm b/widget/cocoa/nsFilePicker.mm
new file mode 100644
index 0000000000..ec0100e569
--- /dev/null
+++ b/widget/cocoa/nsFilePicker.mm
@@ -0,0 +1,639 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsFilePicker.h"
+#include "nsCOMPtr.h"
+#include "nsReadableUtils.h"
+#include "nsNetUtil.h"
+#include "nsIFile.h"
+#include "nsILocalFileMac.h"
+#include "nsArrayEnumerator.h"
+#include "nsIStringBundle.h"
+#include "nsCocoaUtils.h"
+#include "mozilla/Preferences.h"
+
+// This must be included last:
+#include "nsObjCExceptions.h"
+
+using namespace mozilla;
+
+const float kAccessoryViewPadding = 5;
+const int kSaveTypeControlTag = 1;
+
+static bool gCallSecretHiddenFileAPI = false;
+const char kShowHiddenFilesPref[] = "filepicker.showHiddenFiles";
+
+/**
+ * This class is an observer of NSPopUpButton selection change.
+ */
+@interface NSPopUpButtonObserver : NSObject {
+  NSPopUpButton* mPopUpButton;
+  NSOpenPanel* mOpenPanel;
+  nsFilePicker* mFilePicker;
+}
+- (void)setPopUpButton:(NSPopUpButton*)aPopUpButton;
+- (void)setOpenPanel:(NSOpenPanel*)aOpenPanel;
+- (void)setFilePicker:(nsFilePicker*)aFilePicker;
+- (void)menuChangedItem:(NSNotification*)aSender;
+@end
+
+NS_IMPL_ISUPPORTS(nsFilePicker, nsIFilePicker)
+
+// We never want to call the secret show hidden files API unless the pref
+// has been set. Once the pref has been set we always need to call it even
+// if it disappears so that we stop showing hidden files if a user deletes
+// the pref. If the secret API was used once and things worked out it should
+// continue working for subsequent calls so the user is at no more risk.
+static void SetShowHiddenFileState(NSSavePanel* panel) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  bool show = false;
+  if (NS_SUCCEEDED(Preferences::GetBool(kShowHiddenFilesPref, &show))) {
+    gCallSecretHiddenFileAPI = true;
+  }
+
+  if (gCallSecretHiddenFileAPI) {
+    // invoke a method to get a Cocoa-internal nav view
+    SEL navViewSelector = @selector(_navView);
+    NSMethodSignature* navViewSignature = [panel methodSignatureForSelector:navViewSelector];
+    if (!navViewSignature) return;
+    NSInvocation* navViewInvocation = [NSInvocation invocationWithMethodSignature:navViewSignature];
+    [navViewInvocation setSelector:navViewSelector];
+    [navViewInvocation setTarget:panel];
+    [navViewInvocation invoke];
+
+    // get the returned nav view
+    id navView = nil;
+    [navViewInvocation getReturnValue:&navView];
+
+    // invoke the secret show hidden file state method on the nav view
+    SEL showHiddenFilesSelector = @selector(setShowsHiddenFiles:);
+    NSMethodSignature* showHiddenFilesSignature =
+        [navView methodSignatureForSelector:showHiddenFilesSelector];
+    if (!showHiddenFilesSignature) return;
+    NSInvocation* showHiddenFilesInvocation =
+        [NSInvocation invocationWithMethodSignature:showHiddenFilesSignature];
+    [showHiddenFilesInvocation setSelector:showHiddenFilesSelector];
+    [showHiddenFilesInvocation setTarget:navView];
+    [showHiddenFilesInvocation setArgument:&show atIndex:2];
+    [showHiddenFilesInvocation invoke];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsFilePicker::nsFilePicker() : mSelectedTypeIndex(0) {}
+
+nsFilePicker::~nsFilePicker() {}
+
+void nsFilePicker::InitNative(nsIWidget* aParent, const nsAString& aTitle) { mTitle = aTitle; }
+
+NSView* nsFilePicker::GetAccessoryView() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSView* accessoryView = [[[NSView alloc] initWithFrame:NSMakeRect(0, 0, 0, 0)] autorelease];
+
+  // Set a label's default value.
+  NSString* label = @"Format:";
+
+  // Try to get the localized string.
+  nsCOMPtr<nsIStringBundleService> sbs = do_GetService(NS_STRINGBUNDLE_CONTRACTID);
+  nsCOMPtr<nsIStringBundle> bundle;
+  nsresult rv =
+      sbs->CreateBundle("chrome://global/locale/filepicker.properties", getter_AddRefs(bundle));
+  if (NS_SUCCEEDED(rv)) {
+    nsAutoString locaLabel;
+    rv = bundle->GetStringFromName("formatLabel", locaLabel);
+    if (NS_SUCCEEDED(rv)) {
+      label = [NSString stringWithCharacters:reinterpret_cast<const unichar*>(locaLabel.get())
+                                      length:locaLabel.Length()];
+    }
+  }
+
+  // set up label text field
+  NSTextField* textField = [[[NSTextField alloc] init] autorelease];
+  [textField setEditable:NO];
+  [textField setSelectable:NO];
+  [textField setDrawsBackground:NO];
+  [textField setBezeled:NO];
+  [textField setBordered:NO];
+  [textField setFont:[NSFont labelFontOfSize:13.0]];
+  [textField setStringValue:label];
+  [textField setTag:0];
+  [textField sizeToFit];
+
+  // set up popup button
+  NSPopUpButton* popupButton = [[[NSPopUpButton alloc] initWithFrame:NSMakeRect(0, 0, 0, 0)
+                                                           pullsDown:NO] autorelease];
+  uint32_t numMenuItems = mTitles.Length();
+  for (uint32_t i = 0; i < numMenuItems; i++) {
+    const nsString& currentTitle = mTitles[i];
+    NSString* titleString;
+    if (currentTitle.IsEmpty()) {
+      const nsString& currentFilter = mFilters[i];
+      titleString =
+          [[NSString alloc] initWithCharacters:reinterpret_cast<const unichar*>(currentFilter.get())
+                                        length:currentFilter.Length()];
+    } else {
+      titleString =
+          [[NSString alloc] initWithCharacters:reinterpret_cast<const unichar*>(currentTitle.get())
+                                        length:currentTitle.Length()];
+    }
+    [popupButton addItemWithTitle:titleString];
+    [titleString release];
+  }
+  if (mSelectedTypeIndex >= 0 && (uint32_t)mSelectedTypeIndex < numMenuItems)
+    [popupButton selectItemAtIndex:mSelectedTypeIndex];
+  [popupButton setTag:kSaveTypeControlTag];
+  [popupButton sizeToFit];  // we have to do sizeToFit to get the height calculated for us
+  // This is just a default width that works well, doesn't truncate the vast majority of
+  // things that might end up in the menu.
+  [popupButton setFrameSize:NSMakeSize(180, [popupButton frame].size.height)];
+
+  // position everything based on control sizes with kAccessoryViewPadding pix padding
+  // on each side kAccessoryViewPadding pix horizontal padding between controls
+  float greatestHeight = [textField frame].size.height;
+  if ([popupButton frame].size.height > greatestHeight)
+    greatestHeight = [popupButton frame].size.height;
+  float totalViewHeight = greatestHeight + kAccessoryViewPadding * 2;
+  float totalViewWidth =
+      [textField frame].size.width + [popupButton frame].size.width + kAccessoryViewPadding * 3;
+  [accessoryView setFrameSize:NSMakeSize(totalViewWidth, totalViewHeight)];
+
+  float textFieldOriginY =
+      ((greatestHeight - [textField frame].size.height) / 2 + 1) + kAccessoryViewPadding;
+  [textField setFrameOrigin:NSMakePoint(kAccessoryViewPadding, textFieldOriginY)];
+
+  float popupOriginX = [textField frame].size.width + kAccessoryViewPadding * 2;
+  float popupOriginY =
+      ((greatestHeight - [popupButton frame].size.height) / 2) + kAccessoryViewPadding;
+  [popupButton setFrameOrigin:NSMakePoint(popupOriginX, popupOriginY)];
+
+  [accessoryView addSubview:textField];
+  [accessoryView addSubview:popupButton];
+  return accessoryView;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+// Display the file dialog
+nsresult nsFilePicker::Show(ResultCode* retval) {
+  NS_ENSURE_ARG_POINTER(retval);
+
+  *retval = returnCancel;
+
+  ResultCode userClicksOK = returnCancel;
+
+  mFiles.Clear();
+  nsCOMPtr<nsIFile> theFile;
+
+  // Note that GetLocalFolder shares a lot of code with GetLocalFiles.
+  // Could combine the functions and just pass the mode in.
+  switch (mMode) {
+    case modeOpen:
+      userClicksOK = GetLocalFiles(false, mFiles);
+      break;
+
+    case modeOpenMultiple:
+      userClicksOK = GetLocalFiles(true, mFiles);
+      break;
+
+    case modeSave:
+      userClicksOK = PutLocalFile(getter_AddRefs(theFile));
+      break;
+
+    case modeGetFolder:
+      userClicksOK = GetLocalFolder(getter_AddRefs(theFile));
+      break;
+
+    default:
+      NS_ERROR("Unknown file picker mode");
+      break;
+  }
+
+  if (theFile) mFiles.AppendObject(theFile);
+
+  *retval = userClicksOK;
+  return NS_OK;
+}
+
+static void UpdatePanelFileTypes(NSOpenPanel* aPanel, NSArray* aFilters) {
+  // If we show all file types, also "expose" bundles' contents.
+  [aPanel setTreatsFilePackagesAsDirectories:!aFilters];
+
+  [aPanel setAllowedFileTypes:aFilters];
+}
+
+@implementation NSPopUpButtonObserver
+- (void)setPopUpButton:(NSPopUpButton*)aPopUpButton {
+  mPopUpButton = aPopUpButton;
+}
+
+- (void)setOpenPanel:(NSOpenPanel*)aOpenPanel {
+  mOpenPanel = aOpenPanel;
+}
+
+- (void)setFilePicker:(nsFilePicker*)aFilePicker {
+  mFilePicker = aFilePicker;
+}
+
+- (void)menuChangedItem:(NSNotification*)aSender {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+  int32_t selectedItem = [mPopUpButton indexOfSelectedItem];
+  if (selectedItem < 0) {
+    return;
+  }
+
+  mFilePicker->SetFilterIndex(selectedItem);
+  UpdatePanelFileTypes(mOpenPanel, mFilePicker->GetFilterList());
+
+  NS_OBJC_END_TRY_BLOCK_RETURN();
+}
+@end
+
+// Use OpenPanel to do a GetFile. Returns |returnOK| if the user presses OK in the dialog.
+nsIFilePicker::ResultCode nsFilePicker::GetLocalFiles(bool inAllowMultiple,
+                                                      nsCOMArray<nsIFile>& outFiles) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  ResultCode retVal = nsIFilePicker::returnCancel;
+  NSOpenPanel* thePanel = [NSOpenPanel openPanel];
+
+  SetShowHiddenFileState(thePanel);
+
+  // Set the options for how the get file dialog will appear
+  SetDialogTitle(mTitle, thePanel);
+  [thePanel setAllowsMultipleSelection:inAllowMultiple];
+  [thePanel setCanSelectHiddenExtension:YES];
+  [thePanel setCanChooseDirectories:NO];
+  [thePanel setCanChooseFiles:YES];
+  [thePanel setResolvesAliases:YES];
+
+  // Get filters
+  // filters may be null, if we should allow all file types.
+  NSArray* filters = GetFilterList();
+
+  // set up default directory
+  NSString* theDir = PanelDefaultDirectory();
+
+  // if this is the "Choose application..." dialog, and no other start
+  // dir has been set, then use the Applications folder.
+  if (!theDir) {
+    if (filters && [filters count] == 1 &&
+        [(NSString*)[filters objectAtIndex:0] isEqualToString:@"app"])
+      theDir = @"/Applications/";
+    else
+      theDir = @"";
+  }
+
+  if (theDir) {
+    [thePanel setDirectoryURL:[NSURL fileURLWithPath:theDir isDirectory:YES]];
+  }
+
+  int result;
+  nsCocoaUtils::PrepareForNativeAppModalDialog();
+  if (mFilters.Length() > 1) {
+    // [NSURL initWithString:] (below) throws an exception if URLString is nil.
+
+    NSPopUpButtonObserver* observer = [[NSPopUpButtonObserver alloc] init];
+
+    NSView* accessoryView = GetAccessoryView();
+    [thePanel setAccessoryView:accessoryView];
+
+    [observer setPopUpButton:[accessoryView viewWithTag:kSaveTypeControlTag]];
+    [observer setOpenPanel:thePanel];
+    [observer setFilePicker:this];
+
+    [[NSNotificationCenter defaultCenter] addObserver:observer
+                                             selector:@selector(menuChangedItem:)
+                                                 name:NSMenuWillSendActionNotification
+                                               object:nil];
+
+    UpdatePanelFileTypes(thePanel, filters);
+    result = [thePanel runModal];
+
+    [[NSNotificationCenter defaultCenter] removeObserver:observer];
+    [observer release];
+  } else {
+    // If we show all file types, also "expose" bundles' contents.
+    if (!filters) {
+      [thePanel setTreatsFilePackagesAsDirectories:YES];
+    }
+    [thePanel setAllowedFileTypes:filters];
+    result = [thePanel runModal];
+  }
+  nsCocoaUtils::CleanUpAfterNativeAppModalDialog();
+
+  if (result == NSFileHandlingPanelCancelButton) return retVal;
+
+  // Converts data from a NSArray of NSURL to the returned format.
+  // We should be careful to not call [thePanel URLs] more than once given that
+  // it creates a new array each time.
+  // We are using Fast Enumeration, thus the NSURL array is created once then
+  // iterated.
+  for (NSURL* url in [thePanel URLs]) {
+    if (!url) {
+      continue;
+    }
+
+    nsCOMPtr<nsIFile> localFile;
+    NS_NewLocalFile(u""_ns, true, getter_AddRefs(localFile));
+    nsCOMPtr<nsILocalFileMac> macLocalFile = do_QueryInterface(localFile);
+    if (macLocalFile && NS_SUCCEEDED(macLocalFile->InitWithCFURL((CFURLRef)url))) {
+      outFiles.AppendObject(localFile);
+    }
+  }
+
+  if (outFiles.Count() > 0) retVal = returnOK;
+
+  return retVal;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nsIFilePicker::returnOK);
+}
+
+// Use OpenPanel to do a GetFolder. Returns |returnOK| if the user presses OK in the dialog.
+nsIFilePicker::ResultCode nsFilePicker::GetLocalFolder(nsIFile** outFile) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+  NS_ASSERTION(outFile, "this protected member function expects a null initialized out pointer");
+
+  ResultCode retVal = nsIFilePicker::returnCancel;
+  NSOpenPanel* thePanel = [NSOpenPanel openPanel];
+
+  SetShowHiddenFileState(thePanel);
+
+  // Set the options for how the get file dialog will appear
+  SetDialogTitle(mTitle, thePanel);
+  [thePanel setAllowsMultipleSelection:NO];
+  [thePanel setCanSelectHiddenExtension:YES];
+  [thePanel setCanChooseDirectories:YES];
+  [thePanel setCanChooseFiles:NO];
+  [thePanel setResolvesAliases:YES];
+  [thePanel setCanCreateDirectories:YES];
+
+  // packages != folders
+  [thePanel setTreatsFilePackagesAsDirectories:NO];
+
+  // set up default directory
+  NSString* theDir = PanelDefaultDirectory();
+  if (theDir) {
+    [thePanel setDirectoryURL:[NSURL fileURLWithPath:theDir isDirectory:YES]];
+  }
+  nsCocoaUtils::PrepareForNativeAppModalDialog();
+  int result = [thePanel runModal];
+  nsCocoaUtils::CleanUpAfterNativeAppModalDialog();
+
+  if (result == NSFileHandlingPanelCancelButton) return retVal;
+
+  // get the path for the folder (we allow just 1, so that's all we get)
+  NSURL* theURL = [[thePanel URLs] objectAtIndex:0];
+  if (theURL) {
+    nsCOMPtr<nsIFile> localFile;
+    NS_NewLocalFile(u""_ns, true, getter_AddRefs(localFile));
+    nsCOMPtr<nsILocalFileMac> macLocalFile = do_QueryInterface(localFile);
+    if (macLocalFile && NS_SUCCEEDED(macLocalFile->InitWithCFURL((CFURLRef)theURL))) {
+      *outFile = localFile;
+      NS_ADDREF(*outFile);
+      retVal = returnOK;
+    }
+  }
+
+  return retVal;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nsIFilePicker::returnOK);
+}
+
+// Returns |returnOK| if the user presses OK in the dialog.
+nsIFilePicker::ResultCode nsFilePicker::PutLocalFile(nsIFile** outFile) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+  NS_ASSERTION(outFile, "this protected member function expects a null initialized out pointer");
+
+  ResultCode retVal = nsIFilePicker::returnCancel;
+  NSSavePanel* thePanel = [NSSavePanel savePanel];
+
+  SetShowHiddenFileState(thePanel);
+
+  SetDialogTitle(mTitle, thePanel);
+
+  // set up accessory view for file format options
+  NSView* accessoryView = GetAccessoryView();
+  [thePanel setAccessoryView:accessoryView];
+
+  // set up default file name
+  NSString* defaultFilename = [NSString stringWithCharacters:(const unichar*)mDefaultFilename.get()
+                                                      length:mDefaultFilename.Length()];
+
+  // Set up the allowed type. This prevents the extension from being selected.
+  NSString* extension = defaultFilename.pathExtension;
+  if (extension.length != 0) {
+    thePanel.allowedFileTypes = @[ extension ];
+  }
+  // Allow users to change the extension.
+  thePanel.allowsOtherFileTypes = YES;
+
+  // If extensions are hidden and we’re saving a file with multiple extensions,
+  // only the last extension will be hidden in the panel (".tar.gz" will become
+  // ".tar"). If the remaining extension is known, the OS will think that we're
+  // trying to add a non-default extension. To avoid the confusion, we ensure
+  // that all extensions are shown in the panel if the remaining extension is
+  // known by the OS.
+  NSString* fileName = [[defaultFilename lastPathComponent] stringByDeletingPathExtension];
+  NSString* otherExtension = fileName.pathExtension;
+  if (otherExtension.length != 0) {
+    // There's another extension here. Get the UTI.
+    CFStringRef type = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension,
+                                                             (CFStringRef)otherExtension, NULL);
+    if (type) {
+      if (!CFStringHasPrefix(type, CFSTR("dyn."))) {
+        // We have a UTI, otherwise the type would have a "dyn." prefix. Ensure
+        // extensions are shown in the panel.
+        [thePanel setExtensionHidden:NO];
+      }
+      CFRelease(type);
+    }
+  }
+
+  // set up default directory
+  NSString* theDir = PanelDefaultDirectory();
+  if (theDir) {
+    [thePanel setDirectoryURL:[NSURL fileURLWithPath:theDir isDirectory:YES]];
+  }
+
+  // load the panel
+  nsCocoaUtils::PrepareForNativeAppModalDialog();
+  [thePanel setNameFieldStringValue:defaultFilename];
+  int result = [thePanel runModal];
+  nsCocoaUtils::CleanUpAfterNativeAppModalDialog();
+  if (result == NSFileHandlingPanelCancelButton) return retVal;
+
+  // get the save type
+  NSPopUpButton* popupButton = [accessoryView viewWithTag:kSaveTypeControlTag];
+  if (popupButton) {
+    mSelectedTypeIndex = [popupButton indexOfSelectedItem];
+  }
+
+  NSURL* fileURL = [thePanel URL];
+  if (fileURL) {
+    nsCOMPtr<nsIFile> localFile;
+    NS_NewLocalFile(u""_ns, true, getter_AddRefs(localFile));
+    nsCOMPtr<nsILocalFileMac> macLocalFile = do_QueryInterface(localFile);
+    if (macLocalFile && NS_SUCCEEDED(macLocalFile->InitWithCFURL((CFURLRef)fileURL))) {
+      *outFile = localFile;
+      NS_ADDREF(*outFile);
+      // We tell if we are replacing or not by just looking to see if the file exists.
+      // The user could not have hit OK and not meant to replace the file.
+      if ([[NSFileManager defaultManager] fileExistsAtPath:[fileURL path]])
+        retVal = returnReplace;
+      else
+        retVal = returnOK;
+    }
+  }
+
+  return retVal;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nsIFilePicker::returnCancel);
+}
+
+NSArray* nsFilePicker::GetFilterList() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mFilters.Length()) {
+    return nil;
+  }
+
+  if (mFilters.Length() <= (uint32_t)mSelectedTypeIndex) {
+    NS_WARNING("An out of range index has been selected. Using the first index instead.");
+    mSelectedTypeIndex = 0;
+  }
+
+  const nsString& filterWide = mFilters[mSelectedTypeIndex];
+  if (!filterWide.Length()) {
+    return nil;
+  }
+
+  if (filterWide.Equals(u"*"_ns)) {
+    return nil;
+  }
+
+  // The extensions in filterWide are in the format "*.ext" but are expected
+  // in the format "ext" by NSOpenPanel. So we need to filter some characters.
+  NSMutableString* filterString = [[[NSMutableString alloc]
+      initWithString:[NSString
+                         stringWithCharacters:reinterpret_cast<const unichar*>(filterWide.get())
+                                       length:filterWide.Length()]] autorelease];
+  NSCharacterSet* set = [NSCharacterSet characterSetWithCharactersInString:@". *"];
+  NSRange range = [filterString rangeOfCharacterFromSet:set];
+  while (range.length) {
+    [filterString replaceCharactersInRange:range withString:@""];
+    range = [filterString rangeOfCharacterFromSet:set];
+  }
+
+  return
+      [[[NSArray alloc] initWithArray:[filterString componentsSeparatedByString:@";"]] autorelease];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+// Sets the dialog title to whatever it should be.  If it fails, eh,
+// the OS will provide a sensible default.
+void nsFilePicker::SetDialogTitle(const nsString& inTitle, id aPanel) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [aPanel setTitle:[NSString stringWithCharacters:(const unichar*)inTitle.get()
+                                           length:inTitle.Length()]];
+
+  if (!mOkButtonLabel.IsEmpty()) {
+    [aPanel setPrompt:[NSString stringWithCharacters:(const unichar*)mOkButtonLabel.get()
+                                              length:mOkButtonLabel.Length()]];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Converts path from an nsIFile into a NSString path
+// If it fails, returns an empty string.
+NSString* nsFilePicker::PanelDefaultDirectory() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSString* directory = nil;
+  if (mDisplayDirectory) {
+    nsAutoString pathStr;
+    mDisplayDirectory->GetPath(pathStr);
+    directory =
+        [[[NSString alloc] initWithCharacters:reinterpret_cast<const unichar*>(pathStr.get())
+                                       length:pathStr.Length()] autorelease];
+  }
+  return directory;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+NS_IMETHODIMP nsFilePicker::GetFile(nsIFile** aFile) {
+  NS_ENSURE_ARG_POINTER(aFile);
+  *aFile = nullptr;
+
+  // just return the first file
+  if (mFiles.Count() > 0) {
+    *aFile = mFiles.ObjectAt(0);
+    NS_IF_ADDREF(*aFile);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFilePicker::GetFileURL(nsIURI** aFileURL) {
+  NS_ENSURE_ARG_POINTER(aFileURL);
+  *aFileURL = nullptr;
+
+  if (mFiles.Count() == 0) return NS_OK;
+
+  return NS_NewFileURI(aFileURL, mFiles.ObjectAt(0));
+}
+
+NS_IMETHODIMP nsFilePicker::GetFiles(nsISimpleEnumerator** aFiles) {
+  return NS_NewArrayEnumerator(aFiles, mFiles, NS_GET_IID(nsIFile));
+}
+
+NS_IMETHODIMP nsFilePicker::SetDefaultString(const nsAString& aString) {
+  mDefaultFilename = aString;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFilePicker::GetDefaultString(nsAString& aString) { return NS_ERROR_FAILURE; }
+
+// The default extension to use for files
+NS_IMETHODIMP nsFilePicker::GetDefaultExtension(nsAString& aExtension) {
+  aExtension.Truncate();
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFilePicker::SetDefaultExtension(const nsAString& aExtension) { return NS_OK; }
+
+// Append an entry to the filters array
+NS_IMETHODIMP
+nsFilePicker::AppendFilter(const nsAString& aTitle, const nsAString& aFilter) {
+  // "..apps" has to be translated with native executable extensions.
+  if (aFilter.EqualsLiteral("..apps")) {
+    mFilters.AppendElement(u"*.app"_ns);
+  } else {
+    mFilters.AppendElement(aFilter);
+  }
+  mTitles.AppendElement(aTitle);
+
+  return NS_OK;
+}
+
+// Get the filter index - do we still need this?
+NS_IMETHODIMP nsFilePicker::GetFilterIndex(int32_t* aFilterIndex) {
+  *aFilterIndex = mSelectedTypeIndex;
+  return NS_OK;
+}
+
+// Set the filter index - do we still need this?
+NS_IMETHODIMP nsFilePicker::SetFilterIndex(int32_t aFilterIndex) {
+  mSelectedTypeIndex = aFilterIndex;
+  return NS_OK;
+}
diff --git a/widget/cocoa/nsLookAndFeel.h b/widget/cocoa/nsLookAndFeel.h
new file mode 100644
index 0000000000..adce685a4e
--- /dev/null
+++ b/widget/cocoa/nsLookAndFeel.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsLookAndFeel_h_
+#define nsLookAndFeel_h_
+#include "nsXPLookAndFeel.h"
+
+class nsLookAndFeel final : public nsXPLookAndFeel {
+ public:
+  nsLookAndFeel();
+  virtual ~nsLookAndFeel();
+
+  void NativeInit() final;
+  nsresult NativeGetColor(ColorID, ColorScheme, nscolor& aColor) override;
+  nsresult NativeGetInt(IntID, int32_t& aResult) override;
+  nsresult NativeGetFloat(FloatID, float& aResult) override;
+  bool NativeGetFont(FontID aID, nsString& aFontName,
+                     gfxFontStyle& aFontStyle) override;
+
+  virtual char16_t GetPasswordCharacterImpl() override {
+    // unicode value for the bullet character, used for password textfields.
+    return 0x2022;
+  }
+
+  void RecordLookAndFeelSpecificTelemetry() override {
+    RecordAccessibilityTelemetry();
+  }
+
+  // Having a separate, static method allows us to rely on the same
+  // chunk of telemetry logging code at initialization and when we
+  // recieve an event that changes the value of our telemetry probe.
+  static void RecordAccessibilityTelemetry();
+
+ protected:
+  static bool SystemWantsDarkTheme();
+  static bool IsSystemOrientationRTL();
+  static nscolor ProcessSelectionBackground(nscolor aColor,
+                                            ColorScheme aScheme);
+};
+
+#endif  // nsLookAndFeel_h_
diff --git a/widget/cocoa/nsLookAndFeel.mm b/widget/cocoa/nsLookAndFeel.mm
new file mode 100644
index 0000000000..65e852b38e
--- /dev/null
+++ b/widget/cocoa/nsLookAndFeel.mm
@@ -0,0 +1,691 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "AppearanceOverride.h"
+#include "mozilla/widget/ThemeChangeKind.h"
+#include "nsLookAndFeel.h"
+#include "nsCocoaFeatures.h"
+#include "nsNativeThemeColors.h"
+#include "nsStyleConsts.h"
+#include "nsCocoaFeatures.h"
+#include "nsIContent.h"
+#include "gfxFont.h"
+#include "gfxFontConstants.h"
+#include "gfxPlatformMac.h"
+#include "nsCSSColorUtils.h"
+#include "mozilla/FontPropertyTypes.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/StaticPrefs_widget.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/widget/WidgetMessageUtils.h"
+#include "SDKDeclarations.h"
+
+#import <Cocoa/Cocoa.h>
+#import <AppKit/NSColor.h>
+
+// This must be included last:
+#include "nsObjCExceptions.h"
+
+using namespace mozilla;
+
+@interface MOZLookAndFeelDynamicChangeObserver : NSObject
++ (void)startObserving;
+@end
+
+nsLookAndFeel::nsLookAndFeel() = default;
+
+nsLookAndFeel::~nsLookAndFeel() = default;
+
+void nsLookAndFeel::NativeInit() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK
+
+  [MOZLookAndFeelDynamicChangeObserver startObserving];
+  RecordTelemetry();
+
+  NS_OBJC_END_TRY_ABORT_BLOCK
+}
+
+static nscolor GetColorFromNSColor(NSColor* aColor) {
+  NSColor* deviceColor = [aColor colorUsingColorSpaceName:NSDeviceRGBColorSpace];
+  return NS_RGBA((unsigned int)(deviceColor.redComponent * 255.0),
+                 (unsigned int)(deviceColor.greenComponent * 255.0),
+                 (unsigned int)(deviceColor.blueComponent * 255.0),
+                 (unsigned int)(deviceColor.alphaComponent * 255.0));
+}
+
+static nscolor GetColorFromNSColorWithCustomAlpha(NSColor* aColor, float alpha) {
+  NSColor* deviceColor = [aColor colorUsingColorSpaceName:NSDeviceRGBColorSpace];
+  return NS_RGBA((unsigned int)(deviceColor.redComponent * 255.0),
+                 (unsigned int)(deviceColor.greenComponent * 255.0),
+                 (unsigned int)(deviceColor.blueComponent * 255.0), (unsigned int)(alpha * 255.0));
+}
+
+// Turns an opaque selection color into a partially transparent selection color,
+// which usually leads to better contrast with the text color and which should
+// look more visually appealing in most contexts.
+// The idea is that the text and its regular, non-selected background are
+// usually chosen in such a way that they contrast well. Making the selection
+// color partially transparent causes the selection color to mix with the text's
+// regular background, so the end result will often have better contrast with
+// the text than an arbitrary opaque selection color.
+// The motivating example for this is the light selection color on dark web
+// pages: White text on a light blue selection color has very bad contrast,
+// whereas white text on dark blue (which what you get if you mix
+// partially-transparent light blue with the black textbox background) has much
+// better contrast.
+nscolor nsLookAndFeel::ProcessSelectionBackground(nscolor aColor, ColorScheme aScheme) {
+  if (aScheme == ColorScheme::Dark) {
+    // When we use a dark selection color, we do not change alpha because we do
+    // not use dark selection in content. The dark system color is appropriate for
+    // Firefox UI without needing to adjust its alpha.
+    return aColor;
+  }
+  uint16_t hue, sat, value;
+  uint8_t alpha;
+  nscolor resultColor = aColor;
+  NS_RGB2HSV(resultColor, hue, sat, value, alpha);
+  int factor = 2;
+  alpha = alpha / factor;
+  if (sat > 0) {
+    // The color is not a shade of grey, restore the saturation taken away by
+    // the transparency.
+    sat = mozilla::clamped(sat * factor, 0, 255);
+  } else {
+    // The color is a shade of grey, find the value that looks equivalent
+    // on a white background with the given opacity.
+    value = mozilla::clamped(255 - (255 - value) * factor, 0, 255);
+  }
+  NS_HSV2RGB(resultColor, hue, sat, value, alpha);
+  return resultColor;
+}
+
+nsresult nsLookAndFeel::NativeGetColor(ColorID aID, ColorScheme aScheme, nscolor& aColor) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK
+
+  if (@available(macOS 10.14, *)) {
+    // No-op. macOS 10.14+ supports dark mode, so currentAppearance can be set
+    // to either Light or Dark.
+  } else {
+    // System colors before 10.14 are always Light.
+    aScheme = ColorScheme::Light;
+  }
+
+  NSAppearance.currentAppearance = NSAppearanceForColorScheme(aScheme);
+
+  nscolor color = 0;
+  switch (aID) {
+    case ColorID::Infobackground:
+      color = aScheme == ColorScheme::Light ? NS_RGB(0xdd, 0xdd, 0xdd)
+                                            : GetColorFromNSColor(NSColor.windowBackgroundColor);
+      break;
+    case ColorID::Highlight:
+      color = ProcessSelectionBackground(GetColorFromNSColor(NSColor.selectedTextBackgroundColor),
+                                         aScheme);
+      break;
+    // This is used to gray out the selection when it's not focused. Used with
+    // nsISelectionController::SELECTION_DISABLED.
+    case ColorID::TextSelectDisabledBackground:
+      color = ProcessSelectionBackground(GetColorFromNSColor(NSColor.secondarySelectedControlColor),
+                                         aScheme);
+      break;
+    case ColorID::MozMenuhoverdisabled:
+      aColor = NS_TRANSPARENT;
+      break;
+    case ColorID::MozMenuhover:
+    case ColorID::Selecteditem:
+      color = GetColorFromNSColor(NSColor.alternateSelectedControlColor);
+      break;
+    case ColorID::Accentcolortext:
+    case ColorID::MozMenuhovertext:
+    case ColorID::Selecteditemtext:
+      color = GetColorFromNSColor(NSColor.alternateSelectedControlTextColor);
+      break;
+    case ColorID::IMESelectedRawTextBackground:
+    case ColorID::IMESelectedConvertedTextBackground:
+    case ColorID::IMERawInputBackground:
+    case ColorID::IMEConvertedTextBackground:
+      color = NS_TRANSPARENT;
+      break;
+    case ColorID::IMESelectedRawTextForeground:
+    case ColorID::IMESelectedConvertedTextForeground:
+    case ColorID::IMERawInputForeground:
+    case ColorID::IMEConvertedTextForeground:
+    case ColorID::Highlighttext:
+      color = NS_SAME_AS_FOREGROUND_COLOR;
+      break;
+    case ColorID::IMERawInputUnderline:
+    case ColorID::IMEConvertedTextUnderline:
+      color = NS_40PERCENT_FOREGROUND_COLOR;
+      break;
+    case ColorID::IMESelectedRawTextUnderline:
+    case ColorID::IMESelectedConvertedTextUnderline:
+      color = NS_SAME_AS_FOREGROUND_COLOR;
+      break;
+
+      //
+      // css2 system colors http://www.w3.org/TR/REC-CSS2/ui.html#system-colors
+      //
+      // It's really hard to effectively map these to the Appearance Manager properly,
+      // since they are modeled word for word after the win32 system colors and don't have any
+      // real counterparts in the Mac world. I'm sure we'll be tweaking these for
+      // years to come.
+      //
+      // Thanks to mpt26@student.canterbury.ac.nz for the hardcoded values that form the defaults
+      //  if querying the Appearance Manager fails ;)
+      //
+    case ColorID::MozMacDefaultbuttontext:
+      color = NS_RGB(0xFF, 0xFF, 0xFF);
+      break;
+    case ColorID::MozButtonactivetext:
+      // Pre-macOS 12, pressed buttons were filled with the highlight color and the text was white.
+      // Starting with macOS 12, pressed (non-default) buttons are filled with medium gray and the
+      // text color is the same as in the non-pressed state.
+      color = nsCocoaFeatures::OnMontereyOrLater() ? GetColorFromNSColor(NSColor.controlTextColor)
+                                                   : NS_RGB(0xFF, 0xFF, 0xFF);
+      break;
+    case ColorID::Captiontext:
+    case ColorID::Menutext:
+    case ColorID::Infotext:
+    case ColorID::MozMenubartext:
+      color = GetColorFromNSColor(NSColor.textColor);
+      break;
+    case ColorID::Windowtext:
+      color = GetColorFromNSColor(NSColor.windowFrameTextColor);
+      break;
+    case ColorID::Activecaption:
+      color = GetColorFromNSColor(NSColor.gridColor);
+      break;
+    case ColorID::Activeborder:
+      color = GetColorFromNSColor(NSColor.keyboardFocusIndicatorColor);
+      break;
+    case ColorID::Appworkspace:
+      color = NS_RGB(0xFF, 0xFF, 0xFF);
+      break;
+    case ColorID::Background:
+      color = NS_RGB(0x63, 0x63, 0xCE);
+      break;
+    case ColorID::Buttonface:
+    case ColorID::MozButtonhoverface:
+    case ColorID::MozButtonactiveface:
+    case ColorID::MozButtondisabledface:
+      color = GetColorFromNSColor(NSColor.controlColor);
+      if (!NS_GET_A(color)) {
+        color = GetColorFromNSColor(NSColor.controlBackgroundColor);
+      }
+      break;
+    case ColorID::Buttonhighlight:
+      color = GetColorFromNSColor(NSColor.selectedControlColor);
+      break;
+    case ColorID::Inactivecaptiontext:
+      color = NS_RGB(0x45, 0x45, 0x45);
+      break;
+    case ColorID::Scrollbar:
+      color = GetColorFromNSColor(NSColor.scrollBarColor);
+      break;
+    case ColorID::Threedhighlight:
+      color = GetColorFromNSColor(NSColor.highlightColor);
+      break;
+    case ColorID::Buttonshadow:
+    case ColorID::Threeddarkshadow:
+      color = aScheme == ColorScheme::Dark ? *GenericDarkColor(aID) : NS_RGB(0xDC, 0xDC, 0xDC);
+      break;
+    case ColorID::Threedshadow:
+      color = aScheme == ColorScheme::Dark ? *GenericDarkColor(aID) : NS_RGB(0xE0, 0xE0, 0xE0);
+      break;
+    case ColorID::Threedface:
+      color = aScheme == ColorScheme::Dark ? *GenericDarkColor(aID) : NS_RGB(0xF0, 0xF0, 0xF0);
+      break;
+    case ColorID::Threedlightshadow:
+    case ColorID::Buttonborder:
+    case ColorID::MozDisabledfield:
+      color = aScheme == ColorScheme::Dark ? *GenericDarkColor(aID) : NS_RGB(0xDA, 0xDA, 0xDA);
+      break;
+    case ColorID::Menu:
+      color = GetColorFromNSColor(NSColor.textBackgroundColor);
+      break;
+    case ColorID::Windowframe:
+      color = GetColorFromNSColor(NSColor.windowFrameColor);
+      break;
+    case ColorID::Window: {
+      if (@available(macOS 10.14, *)) {
+        color = GetColorFromNSColor(NSColor.windowBackgroundColor);
+      } else {
+        // On 10.13 and below, NSColor.windowBackgroundColor is transparent black.
+        // Use a light grey instead (taken from macOS 11.5).
+        color = NS_RGB(0xF6, 0xF6, 0xF6);
+      }
+      break;
+    }
+    case ColorID::Field:
+    case ColorID::MozCombobox:
+    case ColorID::Inactiveborder:
+    case ColorID::Inactivecaption:
+    case ColorID::MozDialog:
+      color = GetColorFromNSColor(NSColor.controlBackgroundColor);
+      break;
+    case ColorID::Fieldtext:
+    case ColorID::MozComboboxtext:
+    case ColorID::Buttontext:
+    case ColorID::MozButtonhovertext:
+    case ColorID::MozDialogtext:
+    case ColorID::MozCellhighlighttext:
+    case ColorID::MozColheadertext:
+    case ColorID::MozColheaderhovertext:
+      color = GetColorFromNSColor(NSColor.controlTextColor);
+      break;
+    case ColorID::MozDragtargetzone:
+      color = GetColorFromNSColor(NSColor.selectedControlColor);
+      break;
+    case ColorID::MozMacChromeActive: {
+      int grey = NativeGreyColorAsInt(toolbarFillGrey, true);
+      color = NS_RGB(grey, grey, grey);
+      break;
+    }
+    case ColorID::MozMacChromeInactive: {
+      int grey = NativeGreyColorAsInt(toolbarFillGrey, false);
+      color = NS_RGB(grey, grey, grey);
+      break;
+    }
+    case ColorID::MozMacFocusring:
+      color = GetColorFromNSColorWithCustomAlpha(NSColor.keyboardFocusIndicatorColor, 0.48);
+      break;
+    case ColorID::MozMacMenushadow:
+      color = NS_RGB(0xA3, 0xA3, 0xA3);
+      break;
+    case ColorID::MozMacMenutextdisable:
+      color = NS_RGB(0x98, 0x98, 0x98);
+      break;
+    case ColorID::MozMacMenutextselect:
+      color = GetColorFromNSColor(NSColor.selectedMenuItemTextColor);
+      break;
+    case ColorID::MozMacDisabledtoolbartext:
+    case ColorID::Graytext:
+      color = GetColorFromNSColor(NSColor.disabledControlTextColor);
+      break;
+    case ColorID::MozMacMenuselect:
+      color = GetColorFromNSColor(NSColor.alternateSelectedControlColor);
+      break;
+    case ColorID::MozButtondefault:
+      color = NS_RGB(0xDC, 0xDC, 0xDC);
+      break;
+    case ColorID::MozCellhighlight:
+    case ColorID::MozMacSecondaryhighlight:
+      // For inactive list selection
+      color = GetColorFromNSColor(NSColor.secondarySelectedControlColor);
+      break;
+    case ColorID::MozEventreerow:
+      // Background color of even list rows.
+      color = GetColorFromNSColor(NSColor.controlAlternatingRowBackgroundColors[0]);
+      break;
+    case ColorID::MozOddtreerow:
+      // Background color of odd list rows.
+      color = GetColorFromNSColor(NSColor.controlAlternatingRowBackgroundColors[1]);
+      break;
+    case ColorID::MozNativehyperlinktext:
+      color = GetColorFromNSColor(NSColor.linkColor);
+      break;
+    case ColorID::MozNativevisitedhyperlinktext:
+      color = GetColorFromNSColor(NSColor.systemPurpleColor);
+      break;
+    case ColorID::MozMacTooltip:
+    case ColorID::MozMacMenupopup:
+    case ColorID::MozMacMenuitem:
+      color = aScheme == ColorScheme::Light ? NS_RGB(0xf6, 0xf6, 0xf6) : NS_RGB(0x28, 0x28, 0x28);
+      break;
+    case ColorID::MozMacSourceList:
+      color = aScheme == ColorScheme::Light ? NS_RGB(0xf6, 0xf6, 0xf6) : NS_RGB(0x2d, 0x2d, 0x2d);
+      break;
+    case ColorID::MozMacSourceListSelection:
+      color = aScheme == ColorScheme::Light ? NS_RGB(0xd3, 0xd3, 0xd3) : NS_RGB(0x2d, 0x2d, 0x2d);
+      break;
+    case ColorID::MozMacActiveMenuitem:
+    case ColorID::MozMacActiveSourceListSelection:
+    case ColorID::Accentcolor:
+      color = GetColorFromNSColor(ControlAccentColor());
+      break;
+    case ColorID::Marktext:
+    case ColorID::Mark:
+    case ColorID::SpellCheckerUnderline:
+      aColor = GetStandinForNativeColor(aID, aScheme);
+      return NS_OK;
+    default:
+      aColor = NS_RGB(0xff, 0xff, 0xff);
+      return NS_ERROR_FAILURE;
+  }
+
+  aColor = color;
+  return NS_OK;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK
+}
+
+nsresult nsLookAndFeel::NativeGetInt(IntID aID, int32_t& aResult) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsresult res = NS_OK;
+
+  switch (aID) {
+    case IntID::ScrollButtonLeftMouseButtonAction:
+      aResult = 0;
+      break;
+    case IntID::ScrollButtonMiddleMouseButtonAction:
+    case IntID::ScrollButtonRightMouseButtonAction:
+      aResult = 3;
+      break;
+    case IntID::CaretBlinkTime:
+      aResult = 567;
+      break;
+    case IntID::CaretWidth:
+      aResult = 1;
+      break;
+    case IntID::ShowCaretDuringSelection:
+      aResult = 0;
+      break;
+    case IntID::SelectTextfieldsOnKeyFocus:
+      // Select textfield content when focused by kbd
+      // used by EventStateManager::sTextfieldSelectModel
+      aResult = 1;
+      break;
+    case IntID::SubmenuDelay:
+      aResult = 200;
+      break;
+    case IntID::TooltipDelay:
+      aResult = 500;
+      break;
+    case IntID::MenusCanOverlapOSBar:
+      // xul popups are not allowed to overlap the menubar.
+      aResult = 0;
+      break;
+    case IntID::SkipNavigatingDisabledMenuItem:
+      aResult = 1;
+      break;
+    case IntID::DragThresholdX:
+    case IntID::DragThresholdY:
+      aResult = 4;
+      break;
+    case IntID::ScrollArrowStyle:
+      aResult = eScrollArrow_None;
+      break;
+    case IntID::UseOverlayScrollbars:
+    case IntID::AllowOverlayScrollbarsOverlap:
+      aResult = NSScroller.preferredScrollerStyle == NSScrollerStyleOverlay;
+      break;
+    case IntID::ScrollbarDisplayOnMouseMove:
+      aResult = 0;
+      break;
+    case IntID::ScrollbarFadeBeginDelay:
+      aResult = 450;
+      break;
+    case IntID::ScrollbarFadeDuration:
+      aResult = 200;
+      break;
+    case IntID::TreeOpenDelay:
+      aResult = 1000;
+      break;
+    case IntID::TreeCloseDelay:
+      aResult = 1000;
+      break;
+    case IntID::TreeLazyScrollDelay:
+      aResult = 150;
+      break;
+    case IntID::TreeScrollDelay:
+      aResult = 100;
+      break;
+    case IntID::TreeScrollLinesMax:
+      aResult = 3;
+      break;
+    case IntID::MacGraphiteTheme:
+      aResult = NSColor.currentControlTint == NSGraphiteControlTint;
+      break;
+    case IntID::MacBigSurTheme:
+      aResult = nsCocoaFeatures::OnBigSurOrLater();
+      break;
+    case IntID::MacRTL:
+      aResult = IsSystemOrientationRTL();
+      break;
+    case IntID::AlertNotificationOrigin:
+      aResult = NS_ALERT_TOP;
+      break;
+    case IntID::TabFocusModel:
+      aResult = [NSApp isFullKeyboardAccessEnabled] ? nsIContent::eTabFocus_any
+                                                    : nsIContent::eTabFocus_textControlsMask;
+      break;
+    case IntID::ScrollToClick: {
+      aResult = [[NSUserDefaults standardUserDefaults] boolForKey:@"AppleScrollerPagingBehavior"];
+    } break;
+    case IntID::ChosenMenuItemsShouldBlink:
+      aResult = 1;
+      break;
+    case IntID::IMERawInputUnderlineStyle:
+    case IntID::IMEConvertedTextUnderlineStyle:
+    case IntID::IMESelectedRawTextUnderlineStyle:
+    case IntID::IMESelectedConvertedTextUnderline:
+      aResult = static_cast<int32_t>(StyleTextDecorationStyle::Solid);
+      break;
+    case IntID::SpellCheckerUnderlineStyle:
+      aResult = static_cast<int32_t>(StyleTextDecorationStyle::Dotted);
+      break;
+    case IntID::ScrollbarButtonAutoRepeatBehavior:
+      aResult = 0;
+      break;
+    case IntID::SwipeAnimationEnabled:
+      aResult = NSEvent.isSwipeTrackingFromScrollEventsEnabled;
+      break;
+    case IntID::ContextMenuOffsetVertical:
+      aResult = -6;
+      break;
+    case IntID::ContextMenuOffsetHorizontal:
+      aResult = 1;
+      break;
+    case IntID::SystemUsesDarkTheme:
+      aResult = SystemWantsDarkTheme();
+      break;
+    case IntID::PrefersReducedMotion:
+      aResult = NSWorkspace.sharedWorkspace.accessibilityDisplayShouldReduceMotion;
+      break;
+    case IntID::PrefersReducedTransparency:
+      aResult = NSWorkspace.sharedWorkspace.accessibilityDisplayShouldReduceTransparency;
+      break;
+    case IntID::InvertedColors:
+      aResult = NSWorkspace.sharedWorkspace.accessibilityDisplayShouldInvertColors;
+      break;
+    case IntID::UseAccessibilityTheme:
+      aResult = NSWorkspace.sharedWorkspace.accessibilityDisplayShouldIncreaseContrast;
+      break;
+    case IntID::VideoDynamicRange: {
+      // If the platform says it supports HDR, then we claim to support video-dynamic-range.
+      gfxPlatform* platform = gfxPlatform::GetPlatform();
+      MOZ_ASSERT(platform);
+      aResult = platform->SupportsHDR();
+      break;
+    }
+    case IntID::PanelAnimations:
+      aResult = 1;
+      break;
+    default:
+      aResult = 0;
+      res = NS_ERROR_FAILURE;
+  }
+  return res;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsLookAndFeel::NativeGetFloat(FloatID aID, float& aResult) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsresult res = NS_OK;
+
+  switch (aID) {
+    case FloatID::IMEUnderlineRelativeSize:
+      aResult = 2.0f;
+      break;
+    case FloatID::SpellCheckerUnderlineRelativeSize:
+      aResult = 2.0f;
+      break;
+    case FloatID::CursorScale: {
+      id uaDefaults = [[NSUserDefaults alloc] initWithSuiteName:@"com.apple.universalaccess"];
+      float f = [uaDefaults floatForKey:@"mouseDriverCursorSize"];
+      [uaDefaults release];
+      aResult = f > 0.0 ? f : 1.0;  // default to 1.0 if value not available
+      break;
+    }
+    default:
+      aResult = -1.0;
+      res = NS_ERROR_FAILURE;
+  }
+
+  return res;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+bool nsLookAndFeel::SystemWantsDarkTheme() {
+  // This returns true if the macOS system appearance is set to dark mode on
+  // 10.14+, false otherwise.
+  if (@available(macOS 10.14, *)) {
+    NSAppearanceName aquaOrDarkAqua = [NSApp.effectiveAppearance
+        bestMatchFromAppearancesWithNames:@[ NSAppearanceNameAqua, NSAppearanceNameDarkAqua ]];
+    return [aquaOrDarkAqua isEqualToString:NSAppearanceNameDarkAqua];
+  }
+  return false;
+}
+
+/*static*/
+bool nsLookAndFeel::IsSystemOrientationRTL() {
+  NSWindow* window = [[NSWindow alloc] initWithContentRect:NSZeroRect
+                                                 styleMask:NSWindowStyleMaskBorderless
+                                                   backing:NSBackingStoreBuffered
+                                                     defer:NO];
+  auto direction = window.windowTitlebarLayoutDirection;
+  [window release];
+  return direction == NSUserInterfaceLayoutDirectionRightToLeft;
+}
+
+bool nsLookAndFeel::NativeGetFont(FontID aID, nsString& aFontName, gfxFontStyle& aFontStyle) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsAutoCString name;
+  gfxPlatformMac::LookupSystemFont(aID, name, aFontStyle);
+  aFontName.Append(NS_ConvertUTF8toUTF16(name));
+
+  return true;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+void nsLookAndFeel::RecordAccessibilityTelemetry() {
+  if ([[NSWorkspace sharedWorkspace]
+          respondsToSelector:@selector(accessibilityDisplayShouldInvertColors)]) {
+    bool val = [[NSWorkspace sharedWorkspace] accessibilityDisplayShouldInvertColors];
+    Telemetry::ScalarSet(Telemetry::ScalarID::A11Y_INVERT_COLORS, val);
+  }
+}
+
+@implementation MOZLookAndFeelDynamicChangeObserver
+
++ (void)startObserving {
+  static MOZLookAndFeelDynamicChangeObserver* gInstance = nil;
+  if (!gInstance) {
+    gInstance = [[MOZLookAndFeelDynamicChangeObserver alloc] init];  // leaked
+  }
+}
+
+- (instancetype)init {
+  self = [super init];
+
+  [NSNotificationCenter.defaultCenter addObserver:self
+                                         selector:@selector(colorsChanged)
+                                             name:NSControlTintDidChangeNotification
+                                           object:nil];
+  [NSNotificationCenter.defaultCenter addObserver:self
+                                         selector:@selector(colorsChanged)
+                                             name:NSSystemColorsDidChangeNotification
+                                           object:nil];
+
+  if (@available(macOS 10.14, *)) {
+    [NSWorkspace.sharedWorkspace.notificationCenter
+        addObserver:self
+           selector:@selector(mediaQueriesChanged)
+               name:NSWorkspaceAccessibilityDisplayOptionsDidChangeNotification
+             object:nil];
+  } else {
+    [NSNotificationCenter.defaultCenter
+        addObserver:self
+           selector:@selector(mediaQueriesChanged)
+               name:NSWorkspaceAccessibilityDisplayOptionsDidChangeNotification
+             object:nil];
+  }
+
+  [NSNotificationCenter.defaultCenter addObserver:self
+                                         selector:@selector(scrollbarsChanged)
+                                             name:NSPreferredScrollerStyleDidChangeNotification
+                                           object:nil];
+  [NSDistributedNotificationCenter.defaultCenter
+             addObserver:self
+                selector:@selector(scrollbarsChanged)
+                    name:@"AppleAquaScrollBarVariantChanged"
+                  object:nil
+      suspensionBehavior:NSNotificationSuspensionBehaviorDeliverImmediately];
+  [NSDistributedNotificationCenter.defaultCenter
+             addObserver:self
+                selector:@selector(cachedValuesChanged)
+                    name:@"AppleNoRedisplayAppearancePreferenceChanged"
+                  object:nil
+      suspensionBehavior:NSNotificationSuspensionBehaviorCoalesce];
+  [NSDistributedNotificationCenter.defaultCenter
+             addObserver:self
+                selector:@selector(cachedValuesChanged)
+                    name:@"com.apple.KeyboardUIModeDidChange"
+                  object:nil
+      suspensionBehavior:NSNotificationSuspensionBehaviorDeliverImmediately];
+
+  [MOZGlobalAppearance.sharedInstance addObserver:self
+                                       forKeyPath:@"effectiveAppearance"
+                                          options:0
+                                          context:nil];
+  [NSApp addObserver:self forKeyPath:@"effectiveAppearance" options:0 context:nil];
+
+  return self;
+}
+
+- (void)observeValueForKeyPath:(NSString*)keyPath
+                      ofObject:(id)object
+                        change:(NSDictionary<NSKeyValueChangeKey, id>*)change
+                       context:(void*)context {
+  if ([keyPath isEqualToString:@"effectiveAppearance"]) {
+    [self entireThemeChanged];
+  } else {
+    [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
+  }
+}
+
+- (void)entireThemeChanged {
+  LookAndFeel::NotifyChangedAllWindows(widget::ThemeChangeKind::StyleAndLayout);
+}
+
+- (void)scrollbarsChanged {
+  LookAndFeel::NotifyChangedAllWindows(widget::ThemeChangeKind::StyleAndLayout);
+}
+
+- (void)mediaQueriesChanged {
+  // Changing`Invert Colors` sends AccessibilityDisplayOptionsDidChangeNotifications.
+  // We monitor that setting via telemetry, so call into that
+  // recording method here.
+  nsLookAndFeel::RecordAccessibilityTelemetry();
+  LookAndFeel::NotifyChangedAllWindows(widget::ThemeChangeKind::MediaQueriesOnly);
+}
+
+- (void)colorsChanged {
+  LookAndFeel::NotifyChangedAllWindows(widget::ThemeChangeKind::Style);
+}
+
+- (void)cachedValuesChanged {
+  // We only need to re-cache (and broadcast) updated LookAndFeel values, so that they're
+  // up-to-date the next time they're queried. No further change handling is needed.
+  // TODO: Add a change hint for this which avoids the unnecessary media query invalidation.
+  LookAndFeel::NotifyChangedAllWindows(widget::ThemeChangeKind::MediaQueriesOnly);
+}
+@end
diff --git a/widget/cocoa/nsMacCursor.h b/widget/cocoa/nsMacCursor.h
new file mode 100644
index 0000000000..fc97728da5
--- /dev/null
+++ b/widget/cocoa/nsMacCursor.h
@@ -0,0 +1,128 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMacCursor_h_
+#define nsMacCursor_h_
+
+#import <Cocoa/Cocoa.h>
+#import "nsIWidget.h"
+
+/*! @class      nsMacCursor
+    @abstract   Represents a native Mac cursor.
+    @discussion <code>nsMacCursor</code> provides a simple API for creating and
+                working with native Macintosh cursors.  Cursors can be created
+                used without needing to be aware of the way different cursors
+                are implemented, in particular the details of managing an
+                animated cursor are hidden.
+*/
+@interface nsMacCursor : NSObject {
+ @private
+  NSTimer* mTimer;
+ @protected
+  nsCursor mType;
+  int mFrameCounter;
+}
+
+/*! @method     cursorWithCursor:
+    @abstract   Create a cursor by specifying a Cocoa <code>NSCursor</code>.
+    @discussion Creates a cursor representing the given Cocoa built-in cursor.
+    @param      aCursor the <code>NSCursor</code> to use
+    @param      aType the corresponding <code>nsCursor</code> constant
+    @result     an autoreleased instance of <code>nsMacCursor</code>
+                representing the given <code>NSCursor</code>
+ */
++ (nsMacCursor*)cursorWithCursor:(NSCursor*)aCursor type:(nsCursor)aType;
+
+/*! @method     cursorWithImageNamed:hotSpot:type:
+    @abstract   Create a cursor by specifying the name of an image resource to
+                use for the cursor and a hotspot.
+    @discussion Creates a cursor by loading the named image using the
+                <code>+[NSImage imageNamed:]</code> method.
+                <p>The image must be compatible with any restrictions laid down
+                by <code>NSCursor</code>. These vary by operating system
+                version.</p>
+                <p>The hotspot precisely determines the point where the user
+                clicks when using the cursor.</p>
+    @param      aCursor the name of the image to use for the cursor
+    @param      aPoint the point within the cursor to use as the hotspot
+    @param      aType the corresponding <code>nsCursor</code> constant
+    @result     an autoreleased instance of <code>nsMacCursor</code> that uses the given image and
+   hotspot
+ */
++ (nsMacCursor*)cursorWithImageNamed:(NSString*)aCursorImage
+                             hotSpot:(NSPoint)aPoint
+                                type:(nsCursor)aType;
+
+/*! @method     cursorWithFrames:type:
+    @abstract   Create an animated cursor by specifying the frames to use for
+                the animation.
+    @discussion Creates a cursor that will animate by cycling through the given
+                frames. Each element of the array must be an instance of
+                <code>NSCursor</code>
+    @param      aCursorFrames an array of <code>NSCursor</code>, representing
+                the frames of an animated cursor, in the order they should be
+                played.
+    @param      aType the corresponding <code>nsCursor</code> constant
+    @result     an autoreleased instance of <code>nsMacCursor</code> that will
+                animate the given cursor frames
+ */
++ (nsMacCursor*)cursorWithFrames:(NSArray*)aCursorFrames type:(nsCursor)aType;
+
+/*! @method     cocoaCursorWithImageNamed:hotSpot:
+    @abstract   Create a Cocoa NSCursor object with a Gecko image resource name
+                and a hotspot point.
+    @discussion Create a Cocoa NSCursor object with a Gecko image resource name
+                and a hotspot point.
+    @param      imageName the name of the gecko image resource, "tiff"
+                extension is assumed, do not append.
+    @param      aPoint the point within the cursor to use as the hotspot
+    @result     an autoreleased instance of <code>nsMacCursor</code> that will
+                animate the given cursor frames
+ */
++ (NSCursor*)cocoaCursorWithImageNamed:(NSString*)imageName hotSpot:(NSPoint)aPoint;
+
+/*! @method     isSet
+    @abstract   Determines whether this cursor is currently active.
+    @discussion This can be helpful when the Cocoa NSCursor state can be
+                influenced without going through nsCursorManager.
+    @result     whether the cursor is currently set
+ */
+- (BOOL)isSet;
+
+/*! @method     set
+    @abstract   Set the cursor.
+    @discussion Makes this cursor the current cursor. If the cursor is
+                animated, the animation is started.
+ */
+- (void)set;
+
+/*! @method     unset
+    @abstract   Unset the cursor. The cursor will return to the default
+                (usually the arrow cursor).
+    @discussion Unsets the cursor. If the cursor is animated, the animation is
+                stopped.
+ */
+- (void)unset;
+
+/*! @method     isAnimated
+    @abstract   Tests whether this cursor is animated.
+    @discussion Use this method to determine whether a cursor is animated
+    @result     YES if the cursor is animated (has more than one frame), NO if
+                it is a simple static cursor.
+ */
+- (BOOL)isAnimated;
+
+/** @method     cursorType
+    @abstract   Get the cursor type for this cursor
+    @discussion This method returns the <code>nsCursor</code> constant that
+                corresponds to this cursor, which is  equivalent to the CSS
+                name for the cursor.
+    @result     The nsCursor constant corresponding to this cursor, or
+                nsCursor's 'eCursorCount' if the cursor is a custom cursor
+                loaded from a URI
+ */
+- (nsCursor)type;
+@end
+
+#endif  // nsMacCursor_h_
diff --git a/widget/cocoa/nsMacCursor.mm b/widget/cocoa/nsMacCursor.mm
new file mode 100644
index 0000000000..0f56cf9a27
--- /dev/null
+++ b/widget/cocoa/nsMacCursor.mm
@@ -0,0 +1,367 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMacCursor.h"
+#include "nsObjCExceptions.h"
+#include "nsDebug.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsCOMPtr.h"
+#include "nsIFile.h"
+#include "nsString.h"
+
+/*! @category   nsMacCursor (PrivateMethods)
+    @abstract   Private methods internal to the nsMacCursor class.
+    @discussion <code>nsMacCursor</code> is effectively an abstract class. It does not define
+   complete behaviour in and of itself, the subclasses defined in this file provide the useful
+   implementations.
+*/
+@interface nsMacCursor (PrivateMethods)
+
+/*! @method     getNextCursorFrame
+    @abstract   get the index of the next cursor frame to display.
+    @discussion Increments and returns the frame counter of an animated cursor.
+    @result     The index of the next frame to display in the cursor animation
+*/
+- (int)getNextCursorFrame;
+
+/*! @method     numFrames
+    @abstract   Query the number of frames in this cursor's animation.
+    @discussion Returns the number of frames in this cursor's animation. Static cursors return 1.
+*/
+- (int)numFrames;
+
+/*! @method     createTimer
+    @abstract   Create a Timer to use to animate the cursor.
+    @discussion Creates an instance of <code>NSTimer</code> which is used to drive the cursor
+   animation. This method should only be called for cursors that are animated.
+*/
+- (void)createTimer;
+
+/*! @method     destroyTimer
+    @abstract   Destroy any timer instance associated with this cursor.
+    @discussion Invalidates and releases any <code>NSTimer</code> instance associated with this
+   cursor.
+ */
+- (void)destroyTimer;
+/*! @method     destroyTimer
+    @abstract   Destroy any timer instance associated with this cursor.
+    @discussion Invalidates and releases any <code>NSTimer</code> instance associated with this
+   cursor.
+*/
+
+/*! @method     advanceAnimatedCursor:
+    @abstract   Method called by animation timer to perform animation.
+    @discussion Called by an animated cursor's associated timer to advance the animation to the next
+   frame. Determines which frame should occur next and sets the cursor to that frame.
+    @param      aTimer the timer causing the animation
+*/
+- (void)advanceAnimatedCursor:(NSTimer*)aTimer;
+
+/*! @method     setFrame:
+    @abstract   Sets the current cursor, using an index to determine which frame in the animation to
+   display.
+    @discussion Sets the current cursor. The frame index determines which frame is shown if the
+   cursor is animated. Frames and numbered from <code>0</code> to <code>-[nsMacCursor numFrames] -
+   1</code>. A static cursor has a single frame, numbered 0.
+    @param      aFrameIndex the index indicating which frame from the animation to display
+*/
+- (void)setFrame:(int)aFrameIndex;
+
+@end
+
+/*! @class      nsCocoaCursor
+    @abstract   Implementation of <code>nsMacCursor</code> that uses Cocoa <code>NSCursor</code>
+   instances.
+    @discussion Displays a static or animated cursor, using Cocoa <code>NSCursor</code> instances.
+   These can be either built-in <code>NSCursor</code> instances, or custom <code>NSCursor</code>s
+   created from images. When more than one <code>NSCursor</code> is provided, the cursor will use
+   these as animation frames.
+*/
+@interface nsCocoaCursor : nsMacCursor {
+ @private
+  NSArray* mFrames;
+  NSCursor* mLastSetCocoaCursor;
+}
+
+/*! @method     initWithFrames:
+    @abstract   Create an animated cursor by specifying the frames to use for the animation.
+    @discussion Creates a cursor that will animate by cycling through the given frames. Each element
+   of the array must be an instance of <code>NSCursor</code>
+    @param      aCursorFrames an array of <code>NSCursor</code>, representing the frames of an
+   animated cursor, in the order they should be played.
+    @param      aType the corresponding <code>nsCursor</code> constant
+    @result     an instance of <code>nsCocoaCursor</code> that will animate the given cursor frames
+ */
+- (id)initWithFrames:(NSArray*)aCursorFrames type:(nsCursor)aType;
+
+/*! @method     initWithCursor:
+    @abstract   Create a cursor by specifying a Cocoa <code>NSCursor</code>.
+    @discussion Creates a cursor representing the given Cocoa built-in cursor.
+    @param      aCursor the <code>NSCursor</code> to use
+    @param      aType the corresponding <code>nsCursor</code> constant
+    @result     an instance of <code>nsCocoaCursor</code> representing the given
+   <code>NSCursor</code>
+*/
+- (id)initWithCursor:(NSCursor*)aCursor type:(nsCursor)aType;
+
+/*! @method     initWithImageNamed:hotSpot:
+    @abstract   Create a cursor by specifying the name of an image resource to use for the cursor
+   and a hotspot.
+    @discussion Creates a cursor by loading the named image using the <code>+[NSImage
+   imageNamed:]</code> method. <p>The image must be compatible with any restrictions laid down by
+   <code>NSCursor</code>. These vary by operating system version.</p> <p>The hotspot precisely
+   determines the point where the user clicks when using the cursor.</p>
+    @param      aCursor the name of the image to use for the cursor
+    @param      aPoint the point within the cursor to use as the hotspot
+    @param      aType the corresponding <code>nsCursor</code> constant
+    @result     an instance of <code>nsCocoaCursor</code> that uses the given image and hotspot
+*/
+- (id)initWithImageNamed:(NSString*)aCursorImage hotSpot:(NSPoint)aPoint type:(nsCursor)aType;
+
+@end
+
+@implementation nsMacCursor
+
++ (nsMacCursor*)cursorWithCursor:(NSCursor*)aCursor type:(nsCursor)aType {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [[[nsCocoaCursor alloc] initWithCursor:aCursor type:aType] autorelease];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
++ (nsMacCursor*)cursorWithImageNamed:(NSString*)aCursorImage
+                             hotSpot:(NSPoint)aPoint
+                                type:(nsCursor)aType {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [[[nsCocoaCursor alloc] initWithImageNamed:aCursorImage hotSpot:aPoint
+                                               type:aType] autorelease];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
++ (nsMacCursor*)cursorWithFrames:(NSArray*)aCursorFrames type:(nsCursor)aType {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [[[nsCocoaCursor alloc] initWithFrames:aCursorFrames type:aType] autorelease];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
++ (NSCursor*)cocoaCursorWithImageNamed:(NSString*)imageName hotSpot:(NSPoint)aPoint {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsCOMPtr<nsIFile> resDir;
+  nsAutoCString resPath;
+  NSString *pathToImage, *pathToHiDpiImage;
+  NSImage *cursorImage, *hiDpiCursorImage;
+
+  nsresult rv = NS_GetSpecialDirectory(NS_GRE_DIR, getter_AddRefs(resDir));
+  if (NS_FAILED(rv)) goto INIT_FAILURE;
+  resDir->AppendNative("res"_ns);
+  resDir->AppendNative("cursors"_ns);
+
+  rv = resDir->GetNativePath(resPath);
+  if (NS_FAILED(rv)) goto INIT_FAILURE;
+
+  pathToImage = [NSString stringWithUTF8String:(const char*)resPath.get()];
+  if (!pathToImage) goto INIT_FAILURE;
+  pathToImage = [pathToImage stringByAppendingPathComponent:imageName];
+  pathToHiDpiImage = [pathToImage stringByAppendingString:@"@2x"];
+  // Add same extension to both image paths.
+  pathToImage = [pathToImage stringByAppendingPathExtension:@"png"];
+  pathToHiDpiImage = [pathToHiDpiImage stringByAppendingPathExtension:@"png"];
+
+  cursorImage = [[[NSImage alloc] initWithContentsOfFile:pathToImage] autorelease];
+  if (!cursorImage) goto INIT_FAILURE;
+
+  // Note 1: There are a few different ways to get a hidpi image via
+  // initWithContentsOfFile. We let the OS handle this here: when the
+  // file basename ends in "@2x", it will be displayed at native resolution
+  // instead of being pixel-doubled. See bug 784909 comment 7 for alternates ways.
+  //
+  // Note 2: The OS is picky, and will ignore the hidpi representation
+  // unless it is exactly twice the size of the lowdpi image.
+  hiDpiCursorImage = [[[NSImage alloc] initWithContentsOfFile:pathToHiDpiImage] autorelease];
+  if (hiDpiCursorImage) {
+    NSImageRep* imageRep = [[hiDpiCursorImage representations] objectAtIndex:0];
+    [cursorImage addRepresentation:imageRep];
+  }
+  return [[[NSCursor alloc] initWithImage:cursorImage hotSpot:aPoint] autorelease];
+
+INIT_FAILURE:
+  NS_WARNING("Problem getting path to cursor image file!");
+  [self release];
+  return nil;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (BOOL)isSet {
+  // implemented by subclasses
+  return NO;
+}
+
+- (void)set {
+  if ([self isAnimated]) {
+    [self createTimer];
+  }
+  // if the cursor isn't animated or the timer creation fails for any reason...
+  if (!mTimer) {
+    [self setFrame:0];
+  }
+}
+
+- (void)unset {
+  [self destroyTimer];
+}
+
+- (BOOL)isAnimated {
+  return [self numFrames] > 1;
+}
+
+- (int)numFrames {
+  // subclasses need to override this to support animation
+  return 1;
+}
+
+- (int)getNextCursorFrame {
+  mFrameCounter = (mFrameCounter + 1) % [self numFrames];
+  return mFrameCounter;
+}
+
+- (void)createTimer {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mTimer) {
+    mTimer = [[NSTimer scheduledTimerWithTimeInterval:0.25
+                                               target:self
+                                             selector:@selector(advanceAnimatedCursor:)
+                                             userInfo:nil
+                                              repeats:YES] retain];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)destroyTimer {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mTimer) {
+    [mTimer invalidate];
+    [mTimer release];
+    mTimer = nil;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)advanceAnimatedCursor:(NSTimer*)aTimer {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if ([aTimer isValid]) {
+    [self setFrame:[self getNextCursorFrame]];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)setFrame:(int)aFrameIndex {
+  // subclasses need to do something useful here
+}
+
+- (nsCursor)type {
+  return mType;
+}
+
+- (void)dealloc {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [self destroyTimer];
+  [super dealloc];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+@end
+
+@implementation nsCocoaCursor
+
+- (id)initWithFrames:(NSArray*)aCursorFrames type:(nsCursor)aType {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  self = [super init];
+  NSEnumerator* it = [aCursorFrames objectEnumerator];
+  NSObject* frame = nil;
+  while ((frame = [it nextObject])) {
+    NS_ASSERTION([frame isKindOfClass:[NSCursor class]],
+                 "Invalid argument: All frames must be of type NSCursor");
+  }
+  mFrames = [aCursorFrames retain];
+  mFrameCounter = 0;
+  mType = aType;
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (id)initWithCursor:(NSCursor*)aCursor type:(nsCursor)aType {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSArray* frame = [NSArray arrayWithObjects:aCursor, nil];
+  return [self initWithFrames:frame type:aType];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (id)initWithImageNamed:(NSString*)aCursorImage hotSpot:(NSPoint)aPoint type:(nsCursor)aType {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [self initWithCursor:[nsMacCursor cocoaCursorWithImageNamed:aCursorImage hotSpot:aPoint]
+                         type:aType];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (BOOL)isSet {
+  return [NSCursor currentCursor] == mLastSetCocoaCursor;
+}
+
+- (void)setFrame:(int)aFrameIndex {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NSCursor* newCursor = [mFrames objectAtIndex:aFrameIndex];
+  [newCursor set];
+  mLastSetCocoaCursor = newCursor;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (int)numFrames {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [mFrames count];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(0);
+}
+
+- (NSString*)description {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [mFrames description];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)dealloc {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mFrames release];
+  [super dealloc];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+@end
diff --git a/widget/cocoa/nsMacDockSupport.h b/widget/cocoa/nsMacDockSupport.h
new file mode 100644
index 0000000000..f3a12485b3
--- /dev/null
+++ b/widget/cocoa/nsMacDockSupport.h
@@ -0,0 +1,35 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIMacDockSupport.h"
+#include "nsIStandaloneNativeMenu.h"
+#include "nsITaskbarProgress.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+
+@class MOZProgressDockOverlayView;
+
+class nsMacDockSupport : public nsIMacDockSupport, public nsITaskbarProgress {
+ public:
+  nsMacDockSupport();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMACDOCKSUPPORT
+  NS_DECL_NSITASKBARPROGRESS
+
+ protected:
+  virtual ~nsMacDockSupport();
+
+  nsCOMPtr<nsIStandaloneNativeMenu> mDockMenu;
+  nsString mBadgeText;
+
+  NSView* mDockTileWrapperView;
+  MOZProgressDockOverlayView* mProgressDockOverlayView;
+
+  nsTaskbarProgressState mProgressState;
+  double mProgressFraction;
+
+  nsresult UpdateDockTile();
+};
diff --git a/widget/cocoa/nsMacDockSupport.mm b/widget/cocoa/nsMacDockSupport.mm
new file mode 100644
index 0000000000..e69c0b6259
--- /dev/null
+++ b/widget/cocoa/nsMacDockSupport.mm
@@ -0,0 +1,419 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+#include <CoreFoundation/CoreFoundation.h>
+#include <signal.h>
+
+#include "nsCocoaUtils.h"
+#include "nsComponentManagerUtils.h"
+#include "nsMacDockSupport.h"
+#include "nsObjCExceptions.h"
+#include "nsNativeThemeColors.h"
+#include "nsString.h"
+
+NS_IMPL_ISUPPORTS(nsMacDockSupport, nsIMacDockSupport, nsITaskbarProgress)
+
+// This view is used in the dock tile when we're downloading a file.
+// It draws a progress bar that looks similar to the native progress bar on
+// 10.12. This style of progress bar is not animated, unlike the pre-10.10
+// progress bar look which had to redrawn multiple times per second.
+@interface MOZProgressDockOverlayView : NSView {
+  double mFractionValue;
+}
+@property double fractionValue;
+
+@end
+
+@implementation MOZProgressDockOverlayView
+
+@synthesize fractionValue = mFractionValue;
+
+- (void)drawRect:(NSRect)aRect {
+  // Erase the background behind this view, i.e. cut a rectangle hole in the icon.
+  [[NSColor clearColor] set];
+  NSRectFill(self.bounds);
+
+  // Split the height of this view into four quarters. The middle two quarters
+  // will be covered by the actual progress bar.
+  CGFloat radius = self.bounds.size.height / 4;
+  NSRect barBounds = NSInsetRect(self.bounds, 0, radius);
+
+  NSBezierPath* path = [NSBezierPath bezierPathWithRoundedRect:barBounds
+                                                       xRadius:radius
+                                                       yRadius:radius];
+
+  // Draw a grayish background first.
+  [[NSColor colorWithDeviceWhite:0 alpha:0.1] setFill];
+  [path fill];
+
+  // Draw a fill in the control accent color for the progress part.
+  NSRect progressFillRect = self.bounds;
+  progressFillRect.size.width *= mFractionValue;
+  [NSGraphicsContext saveGraphicsState];
+  [NSBezierPath clipRect:progressFillRect];
+  [ControlAccentColor() setFill];
+  [path fill];
+  [NSGraphicsContext restoreGraphicsState];
+
+  // Add a shadowy stroke on top.
+  [NSGraphicsContext saveGraphicsState];
+  [path addClip];
+  [[NSColor colorWithDeviceWhite:0 alpha:0.2] setStroke];
+  path.lineWidth = barBounds.size.height / 10;
+  [path stroke];
+  [NSGraphicsContext restoreGraphicsState];
+}
+
+@end
+
+nsMacDockSupport::nsMacDockSupport()
+    : mDockTileWrapperView(nil),
+      mProgressDockOverlayView(nil),
+      mProgressState(STATE_NO_PROGRESS),
+      mProgressFraction(0.0) {}
+
+nsMacDockSupport::~nsMacDockSupport() {
+  if (mDockTileWrapperView) {
+    [mDockTileWrapperView release];
+    mDockTileWrapperView = nil;
+  }
+  if (mProgressDockOverlayView) {
+    [mProgressDockOverlayView release];
+    mProgressDockOverlayView = nil;
+  }
+}
+
+NS_IMETHODIMP
+nsMacDockSupport::GetDockMenu(nsIStandaloneNativeMenu** aDockMenu) {
+  nsCOMPtr<nsIStandaloneNativeMenu> dockMenu(mDockMenu);
+  dockMenu.forget(aDockMenu);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMacDockSupport::SetDockMenu(nsIStandaloneNativeMenu* aDockMenu) {
+  mDockMenu = aDockMenu;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMacDockSupport::ActivateApplication(bool aIgnoreOtherApplications) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  [[NSApplication sharedApplication] activateIgnoringOtherApps:aIgnoreOtherApplications];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsMacDockSupport::SetBadgeText(const nsAString& aBadgeText) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSDockTile* tile = [[NSApplication sharedApplication] dockTile];
+  mBadgeText = aBadgeText;
+  if (aBadgeText.IsEmpty())
+    [tile setBadgeLabel:nil];
+  else
+    [tile setBadgeLabel:[NSString
+                            stringWithCharacters:reinterpret_cast<const unichar*>(mBadgeText.get())
+                                          length:mBadgeText.Length()]];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsMacDockSupport::GetBadgeText(nsAString& aBadgeText) {
+  aBadgeText = mBadgeText;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMacDockSupport::SetProgressState(nsTaskbarProgressState aState, uint64_t aCurrentValue,
+                                   uint64_t aMaxValue) {
+  NS_ENSURE_ARG_RANGE(aState, 0, STATE_PAUSED);
+  if (aState == STATE_NO_PROGRESS || aState == STATE_INDETERMINATE) {
+    NS_ENSURE_TRUE(aCurrentValue == 0, NS_ERROR_INVALID_ARG);
+    NS_ENSURE_TRUE(aMaxValue == 0, NS_ERROR_INVALID_ARG);
+  }
+  if (aCurrentValue > aMaxValue) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  mProgressState = aState;
+  if (aMaxValue == 0) {
+    mProgressFraction = 0;
+  } else {
+    mProgressFraction = (double)aCurrentValue / aMaxValue;
+  }
+
+  return UpdateDockTile();
+}
+
+nsresult nsMacDockSupport::UpdateDockTile() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (mProgressState == STATE_NORMAL || mProgressState == STATE_INDETERMINATE) {
+    if (!mDockTileWrapperView) {
+      // Create the following NSView hierarchy:
+      // * mDockTileWrapperView (NSView)
+      //    * imageView (NSImageView) <- has the application icon
+      //    * mProgressDockOverlayView (MOZProgressDockOverlayView) <- draws the progress bar
+
+      mDockTileWrapperView = [[NSView alloc] initWithFrame:NSMakeRect(0, 0, 32, 32)];
+      mDockTileWrapperView.autoresizingMask = NSViewWidthSizable | NSViewHeightSizable;
+
+      NSImageView* imageView = [[NSImageView alloc] initWithFrame:[mDockTileWrapperView bounds]];
+      imageView.image = [NSImage imageNamed:@"NSApplicationIcon"];
+      imageView.imageScaling = NSImageScaleAxesIndependently;
+      imageView.autoresizingMask = NSViewWidthSizable | NSViewHeightSizable;
+      [mDockTileWrapperView addSubview:imageView];
+
+      mProgressDockOverlayView =
+          [[MOZProgressDockOverlayView alloc] initWithFrame:NSMakeRect(1, 3, 30, 4)];
+      mProgressDockOverlayView.autoresizingMask = NSViewMinXMargin | NSViewWidthSizable |
+                                                  NSViewMaxXMargin | NSViewMinYMargin |
+                                                  NSViewHeightSizable | NSViewMaxYMargin;
+      [mDockTileWrapperView addSubview:mProgressDockOverlayView];
+    }
+    if (NSApp.dockTile.contentView != mDockTileWrapperView) {
+      NSApp.dockTile.contentView = mDockTileWrapperView;
+    }
+
+    if (mProgressState == STATE_NORMAL) {
+      mProgressDockOverlayView.fractionValue = mProgressFraction;
+    } else {
+      // Indeterminate states are rare. Just fill the entire progress bar in
+      // that case.
+      mProgressDockOverlayView.fractionValue = 1.0;
+    }
+    [NSApp.dockTile display];
+  } else if (NSApp.dockTile.contentView) {
+    NSApp.dockTile.contentView = nil;
+    [NSApp.dockTile display];
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+extern "C" {
+// Private CFURL API used by the Dock.
+CFPropertyListRef _CFURLCopyPropertyListRepresentation(CFURLRef url);
+CFURLRef _CFURLCreateFromPropertyListRepresentation(CFAllocatorRef alloc,
+                                                    CFPropertyListRef pListRepresentation);
+}  // extern "C"
+
+namespace {
+
+const NSArray* const browserAppNames =
+    [NSArray arrayWithObjects:@"Firefox.app", @"Firefox Beta.app", @"Firefox Nightly.app",
+                              @"Safari.app", @"WebKit.app", @"Google Chrome.app",
+                              @"Google Chrome Canary.app", @"Chromium.app", @"Opera.app", nil];
+
+constexpr NSString* const kDockDomainName = @"com.apple.dock";
+// See https://developer.apple.com/documentation/devicemanagement/dock
+constexpr NSString* const kDockPersistentAppsKey = @"persistent-apps";
+// See https://developer.apple.com/documentation/devicemanagement/dock/staticitem
+constexpr NSString* const kDockTileDataKey = @"tile-data";
+constexpr NSString* const kDockFileDataKey = @"file-data";
+
+NSArray* GetPersistentAppsFromDockPlist(NSDictionary* aDockPlist) {
+  if (!aDockPlist) {
+    return nil;
+  }
+  NSArray* persistentApps = [aDockPlist objectForKey:kDockPersistentAppsKey];
+  if (![persistentApps isKindOfClass:[NSArray class]]) {
+    return nil;
+  }
+  return persistentApps;
+}
+
+NSString* GetPathForApp(NSDictionary* aPersistantApp) {
+  if (![aPersistantApp isKindOfClass:[NSDictionary class]]) {
+    return nil;
+  }
+  NSDictionary* tileData = aPersistantApp[kDockTileDataKey];
+  if (![tileData isKindOfClass:[NSDictionary class]]) {
+    return nil;
+  }
+  NSDictionary* fileData = tileData[kDockFileDataKey];
+  if (![fileData isKindOfClass:[NSDictionary class]]) {
+    // Some special tiles may not have DockFileData but we can ignore those.
+    return nil;
+  }
+  NSURL* url = CFBridgingRelease(_CFURLCreateFromPropertyListRepresentation(NULL, fileData));
+  if (!url) {
+    return nil;
+  }
+  return [url isFileURL] ? [url path] : nullptr;
+}
+
+// The only reliable way to get our changes to take effect seems to be to use
+// `kill`.
+void RefreshDock(NSDictionary* aDockPlist) {
+  [[NSUserDefaults standardUserDefaults] setPersistentDomain:aDockPlist forName:kDockDomainName];
+  NSRunningApplication* dockApp = [[NSRunningApplication
+      runningApplicationsWithBundleIdentifier:@"com.apple.dock"] firstObject];
+  if (!dockApp) {
+    return;
+  }
+  pid_t pid = [dockApp processIdentifier];
+  if (pid > 0) {
+    kill(pid, SIGTERM);
+  }
+}
+
+}  // namespace
+
+nsresult nsMacDockSupport::GetIsAppInDock(bool* aIsInDock) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  *aIsInDock = false;
+
+  NSDictionary* dockPlist =
+      [[NSUserDefaults standardUserDefaults] persistentDomainForName:kDockDomainName];
+  if (!dockPlist) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSArray* persistentApps = GetPersistentAppsFromDockPlist(dockPlist);
+  if (!persistentApps) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSString* appPath = [[NSBundle mainBundle] bundlePath];
+
+  for (id app in persistentApps) {
+    NSString* persistentAppPath = GetPathForApp(app);
+    if (persistentAppPath && [appPath isEqual:persistentAppPath]) {
+      *aIsInDock = true;
+      break;
+    }
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsMacDockSupport::EnsureAppIsPinnedToDock(const nsAString& aAppPath,
+                                                   const nsAString& aAppToReplacePath,
+                                                   bool* aIsInDock) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_ASSERT(aAppPath != aAppToReplacePath || !aAppPath.IsEmpty());
+
+  *aIsInDock = false;
+
+  NSString* appPath =
+      !aAppPath.IsEmpty() ? nsCocoaUtils::ToNSString(aAppPath) : [[NSBundle mainBundle] bundlePath];
+  NSString* appToReplacePath = nsCocoaUtils::ToNSString(aAppToReplacePath);
+
+  NSMutableDictionary* dockPlist =
+      [NSMutableDictionary dictionaryWithDictionary:[[NSUserDefaults standardUserDefaults]
+                                                        persistentDomainForName:kDockDomainName]];
+  if (!dockPlist) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSMutableArray* persistentApps =
+      [NSMutableArray arrayWithArray:GetPersistentAppsFromDockPlist(dockPlist)];
+  if (!persistentApps) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // See the comment for this method in the .idl file for the strategy that we
+  // use here to determine where to pin the app.
+  NSUInteger preexistingAppIndex = NSNotFound;  // full path matches
+  NSUInteger sameNameAppIndex = NSNotFound;     // app name matches only
+  NSUInteger toReplaceAppIndex = NSNotFound;
+  NSUInteger lastBrowserAppIndex = NSNotFound;
+  for (NSUInteger index = 0; index < [persistentApps count]; ++index) {
+    NSString* persistentAppPath = GetPathForApp([persistentApps objectAtIndex:index]);
+
+    if ([persistentAppPath isEqualToString:appPath]) {
+      preexistingAppIndex = index;
+    } else if (appToReplacePath && [persistentAppPath isEqualToString:appToReplacePath]) {
+      toReplaceAppIndex = index;
+    } else {
+      NSString* appName = [appPath lastPathComponent];
+      NSString* persistentAppName = [persistentAppPath lastPathComponent];
+
+      if ([persistentAppName isEqual:appName]) {
+        if ([appToReplacePath hasPrefix:@"/private/var/folders/"] &&
+            [appToReplacePath containsString:@"/AppTranslocation/"] &&
+            [persistentAppPath hasPrefix:@"/Volumes/"]) {
+          // This is a special case when an app with the same name was
+          // previously dragged and pinned from a quarantined DMG straight to
+          // the Dock and an attempt is now made to pin the same named app to
+          // the Dock. In this case we want to replace the currently pinned app
+          // icon.
+          toReplaceAppIndex = index;
+        } else {
+          sameNameAppIndex = index;
+        }
+      } else {
+        if ([browserAppNames containsObject:persistentAppName]) {
+          lastBrowserAppIndex = index;
+        }
+      }
+    }
+  }
+
+  // Special cases where we're not going to add a new Dock tile:
+  if (preexistingAppIndex != NSNotFound) {
+    if (toReplaceAppIndex != NSNotFound) {
+      [persistentApps removeObjectAtIndex:toReplaceAppIndex];
+      [dockPlist setObject:persistentApps forKey:kDockPersistentAppsKey];
+      RefreshDock(dockPlist);
+    }
+    *aIsInDock = true;
+    return NS_OK;
+  }
+
+  // Create new tile:
+  NSDictionary* newDockTile = nullptr;
+  {
+    NSURL* appUrl = [NSURL fileURLWithPath:appPath isDirectory:YES];
+    NSDictionary* dict =
+        CFBridgingRelease(_CFURLCopyPropertyListRepresentation((__bridge CFURLRef)appUrl));
+    if (!dict) {
+      return NS_ERROR_FAILURE;
+    }
+    NSDictionary* dockTileData = [NSDictionary dictionaryWithObject:dict forKey:kDockFileDataKey];
+    if (dockTileData) {
+      newDockTile = [NSDictionary dictionaryWithObject:dockTileData forKey:kDockTileDataKey];
+    }
+    if (!newDockTile) {
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  // Update the Dock:
+  if (toReplaceAppIndex != NSNotFound) {
+    [persistentApps replaceObjectAtIndex:toReplaceAppIndex withObject:newDockTile];
+  } else {
+    NSUInteger index;
+    if (sameNameAppIndex != NSNotFound) {
+      index = sameNameAppIndex + 1;
+    } else if (lastBrowserAppIndex != NSNotFound) {
+      index = lastBrowserAppIndex + 1;
+    } else {
+      index = [persistentApps count];
+    }
+    [persistentApps insertObject:newDockTile atIndex:index];
+  }
+  [dockPlist setObject:persistentApps forKey:kDockPersistentAppsKey];
+  RefreshDock(dockPlist);
+
+  *aIsInDock = true;
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
diff --git a/widget/cocoa/nsMacFinderProgress.h b/widget/cocoa/nsMacFinderProgress.h
new file mode 100644
index 0000000000..a0e48a0d59
--- /dev/null
+++ b/widget/cocoa/nsMacFinderProgress.h
@@ -0,0 +1,24 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef _MACFINDERPROGRESS_H_
+#define _MACFINDERPROGRESS_H_
+
+#include "nsIMacFinderProgress.h"
+#include "nsCOMPtr.h"
+
+class nsMacFinderProgress : public nsIMacFinderProgress {
+ public:
+  nsMacFinderProgress();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMACFINDERPROGRESS
+
+ protected:
+  virtual ~nsMacFinderProgress();
+
+  NSProgress* mProgress;
+};
+
+#endif
diff --git a/widget/cocoa/nsMacFinderProgress.mm b/widget/cocoa/nsMacFinderProgress.mm
new file mode 100644
index 0000000000..2e518fe012
--- /dev/null
+++ b/widget/cocoa/nsMacFinderProgress.mm
@@ -0,0 +1,87 @@
+/* -*- Mode: Objective-C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsMacFinderProgress.h"
+#include "nsProxyRelease.h"
+#include "nsThreadUtils.h"
+#include "nsString.h"
+#include "nsObjCExceptions.h"
+
+NS_IMPL_ISUPPORTS(nsMacFinderProgress, nsIMacFinderProgress)
+
+nsMacFinderProgress::nsMacFinderProgress() : mProgress(nil) {}
+
+nsMacFinderProgress::~nsMacFinderProgress() {
+  if (mProgress) {
+    [mProgress unpublish];
+    [mProgress release];
+  }
+}
+
+NS_IMETHODIMP
+nsMacFinderProgress::Init(const nsAString& path,
+                          nsIMacFinderProgressCanceledCallback* cancellationCallback) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSURL* pathUrl = [NSURL
+      fileURLWithPath:[NSString
+                          stringWithCharacters:reinterpret_cast<const unichar*>(path.BeginReading())
+                                        length:path.Length()]];
+  NSDictionary* userInfo = @{
+    @"NSProgressFileOperationKindKey" : @"NSProgressFileOperationKindDownloading",
+    @"NSProgressFileURLKey" : pathUrl
+  };
+
+  mProgress = [[NSProgress alloc] initWithParent:nil userInfo:userInfo];
+  mProgress.kind = NSProgressKindFile;
+  mProgress.cancellable = YES;
+
+  nsMainThreadPtrHandle<nsIMacFinderProgressCanceledCallback> cancellationCallbackHandle(
+      new nsMainThreadPtrHolder<nsIMacFinderProgressCanceledCallback>(
+          "MacFinderProgress::CancellationCallback", cancellationCallback));
+
+  mProgress.cancellationHandler = ^{
+    NS_DispatchToMainThread(
+        NS_NewRunnableFunction("MacFinderProgress::Canceled", [cancellationCallbackHandle] {
+          MOZ_ASSERT(NS_IsMainThread());
+          cancellationCallbackHandle->Canceled();
+        }));
+  };
+
+  [mProgress publish];
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsMacFinderProgress::UpdateProgress(uint64_t currentProgress, uint64_t totalProgress) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+  if (mProgress) {
+    mProgress.totalUnitCount = totalProgress;
+    mProgress.completedUnitCount = currentProgress;
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsMacFinderProgress::End() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (mProgress) {
+    [mProgress unpublish];
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
diff --git a/widget/cocoa/nsMacSharingService.h b/widget/cocoa/nsMacSharingService.h
new file mode 100644
index 0000000000..d97ce59380
--- /dev/null
+++ b/widget/cocoa/nsMacSharingService.h
@@ -0,0 +1,22 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMacSharingService_h_
+#define nsMacSharingService_h_
+
+#include "nsIMacSharingService.h"
+
+class nsMacSharingService : public nsIMacSharingService {
+ public:
+  nsMacSharingService() {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMACSHARINGSERVICE
+
+ protected:
+  virtual ~nsMacSharingService() {}
+};
+
+#endif  // nsMacSharingService_h_
diff --git a/widget/cocoa/nsMacSharingService.mm b/widget/cocoa/nsMacSharingService.mm
new file mode 100644
index 0000000000..bc62e5e85e
--- /dev/null
+++ b/widget/cocoa/nsMacSharingService.mm
@@ -0,0 +1,206 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsMacSharingService.h"
+
+#include "jsapi.h"
+#include "js/Array.h"               // JS::NewArrayObject
+#include "js/PropertyAndElement.h"  // JS_SetElement, JS_SetProperty
+#include "nsCocoaUtils.h"
+#include "mozilla/MacStringHelpers.h"
+
+NS_IMPL_ISUPPORTS(nsMacSharingService, nsIMacSharingService)
+
+NSString* const remindersServiceName = @"com.apple.reminders.RemindersShareExtension";
+
+// These are some undocumented constants also used by Safari
+// to let us open the preferences window
+NSString* const extensionPrefPanePath = @"/System/Library/PreferencePanes/Extensions.prefPane";
+const UInt32 openSharingSubpaneDescriptorType = 'ptru';
+NSString* const openSharingSubpaneActionKey = @"action";
+NSString* const openSharingSubpaneActionValue = @"revealExtensionPoint";
+NSString* const openSharingSubpaneProtocolKey = @"protocol";
+NSString* const openSharingSubpaneProtocolValue = @"com.apple.share-services";
+
+// Expose the id so we can pass reference through to JS and back
+@interface NSSharingService (ExposeName)
+- (id)name;
+@end
+
+// Filter providers that we do not want to expose to the user, because they are duplicates or do not
+// work correctly within the context
+static bool ShouldIgnoreProvider(NSString* aProviderName) {
+  return [aProviderName isEqualToString:@"com.apple.share.System.add-to-safari-reading-list"];
+}
+
+// Clean up the activity once the share is complete
+@interface SharingServiceDelegate : NSObject <NSSharingServiceDelegate> {
+  NSUserActivity* mShareActivity;
+}
+
+- (void)cleanup;
+
+@end
+
+@implementation SharingServiceDelegate
+
+- (id)initWithActivity:(NSUserActivity*)activity {
+  self = [super init];
+  mShareActivity = [activity retain];
+  return self;
+}
+
+- (void)cleanup {
+  [mShareActivity resignCurrent];
+  [mShareActivity invalidate];
+  [mShareActivity release];
+  mShareActivity = nil;
+}
+
+- (void)sharingService:(NSSharingService*)sharingService didShareItems:(NSArray*)items {
+  [self cleanup];
+}
+
+- (void)sharingService:(NSSharingService*)service
+    didFailToShareItems:(NSArray*)items
+                  error:(NSError*)error {
+  [self cleanup];
+}
+
+- (void)dealloc {
+  [mShareActivity release];
+  [super dealloc];
+}
+
+@end
+
+static NSString* NSImageToBase64(const NSImage* aImage) {
+  CGImageRef cgRef = [aImage CGImageForProposedRect:nil context:nil hints:nil];
+  NSBitmapImageRep* bitmapRep = [[NSBitmapImageRep alloc] initWithCGImage:cgRef];
+  [bitmapRep setSize:[aImage size]];
+  NSData* imageData = [bitmapRep representationUsingType:NSPNGFileType properties:@{}];
+  NSString* base64Encoded = [imageData base64EncodedStringWithOptions:0];
+  [bitmapRep release];
+  return [NSString stringWithFormat:@"data:image/png;base64,%@", base64Encoded];
+}
+
+static void SetStrAttribute(JSContext* aCx, JS::Rooted<JSObject*>& aObj, const char* aKey,
+                            NSString* aVal) {
+  nsAutoString strVal;
+  mozilla::CopyCocoaStringToXPCOMString(aVal, strVal);
+  JS::Rooted<JSString*> title(aCx, JS_NewUCStringCopyZ(aCx, strVal.get()));
+  JS::Rooted<JS::Value> attVal(aCx, JS::StringValue(title));
+  JS_SetProperty(aCx, aObj, aKey, attVal);
+}
+
+nsresult nsMacSharingService::GetSharingProviders(const nsAString& aPageUrl, JSContext* aCx,
+                                                  JS::MutableHandle<JS::Value> aResult) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSURL* url = nsCocoaUtils::ToNSURL(aPageUrl);
+  if (!url) {
+    // aPageUrl is not a valid URL.
+    return NS_ERROR_FAILURE;
+  }
+
+  NSArray* sharingService = [NSSharingService sharingServicesForItems:@[ url ]];
+  int32_t serviceCount = 0;
+  JS::Rooted<JSObject*> array(aCx, JS::NewArrayObject(aCx, 0));
+
+  for (NSSharingService* currentService in sharingService) {
+    if (ShouldIgnoreProvider([currentService name])) {
+      continue;
+    }
+    JS::Rooted<JSObject*> obj(aCx, JS_NewPlainObject(aCx));
+
+    SetStrAttribute(aCx, obj, "name", [currentService name]);
+    SetStrAttribute(aCx, obj, "menuItemTitle", currentService.menuItemTitle);
+    SetStrAttribute(aCx, obj, "image", NSImageToBase64(currentService.image));
+
+    JS::Rooted<JS::Value> element(aCx, JS::ObjectValue(*obj));
+    JS_SetElement(aCx, array, serviceCount++, element);
+  }
+
+  aResult.setObject(*array);
+
+  return NS_OK;
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsMacSharingService::OpenSharingPreferences() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSURL* prefPaneURL = [NSURL fileURLWithPath:extensionPrefPanePath isDirectory:YES];
+  NSDictionary* args = @{
+    openSharingSubpaneActionKey : openSharingSubpaneActionValue,
+    openSharingSubpaneProtocolKey : openSharingSubpaneProtocolValue
+  };
+  NSData* data = [NSPropertyListSerialization dataWithPropertyList:args
+                                                            format:NSPropertyListXMLFormat_v1_0
+                                                           options:0
+                                                             error:nil];
+  NSAppleEventDescriptor* descriptor =
+      [[NSAppleEventDescriptor alloc] initWithDescriptorType:openSharingSubpaneDescriptorType
+                                                        data:data];
+
+  [[NSWorkspace sharedWorkspace] openURLs:@[ prefPaneURL ]
+                  withAppBundleIdentifier:nil
+                                  options:NSWorkspaceLaunchAsync
+           additionalEventParamDescriptor:descriptor
+                        launchIdentifiers:NULL];
+
+  [descriptor release];
+
+  return NS_OK;
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsMacSharingService::ShareUrl(const nsAString& aServiceName, const nsAString& aPageUrl,
+                              const nsAString& aPageTitle) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSString* serviceName = nsCocoaUtils::ToNSString(aServiceName);
+  NSURL* pageUrl = nsCocoaUtils::ToNSURL(aPageUrl);
+  NSString* pageTitle = nsCocoaUtils::ToNSString(aPageTitle);
+  NSSharingService* service = [NSSharingService sharingServiceNamed:serviceName];
+
+  // Reminders fetch its data from an activity, not the share data
+  if ([[service name] isEqual:remindersServiceName]) {
+    NSUserActivity* shareActivity =
+        [[NSUserActivity alloc] initWithActivityType:NSUserActivityTypeBrowsingWeb];
+
+    if ([pageUrl.scheme hasPrefix:@"http"]) {
+      [shareActivity setWebpageURL:pageUrl];
+    }
+    [shareActivity setEligibleForHandoff:NO];
+    [shareActivity setTitle:pageTitle];
+    [shareActivity becomeCurrent];
+
+    // Pass ownership of shareActivity to shareDelegate, which will release the
+    // activity once sharing has completed.
+    SharingServiceDelegate* shareDelegate =
+        [[SharingServiceDelegate alloc] initWithActivity:shareActivity];
+    [shareActivity release];
+
+    [service setDelegate:shareDelegate];
+    [shareDelegate release];
+  }
+
+  // Twitter likes the the title as an additional share item
+  NSArray* toShare = [[service name] isEqual:NSSharingServiceNamePostOnTwitter]
+                         ? @[ pageUrl, pageTitle ]
+                         : @[ pageUrl ];
+
+  [service setSubject:pageTitle];
+  [service performWithItems:toShare];
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
diff --git a/widget/cocoa/nsMacUserActivityUpdater.h b/widget/cocoa/nsMacUserActivityUpdater.h
new file mode 100644
index 0000000000..6870a66343
--- /dev/null
+++ b/widget/cocoa/nsMacUserActivityUpdater.h
@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMacUserActivityUpdater_h_
+#define nsMacUserActivityUpdater_h_
+
+#include "nsIMacUserActivityUpdater.h"
+#include "nsCocoaWindow.h"
+
+class nsMacUserActivityUpdater : public nsIMacUserActivityUpdater {
+ public:
+  nsMacUserActivityUpdater() {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMACUSERACTIVITYUPDATER
+
+ protected:
+  virtual ~nsMacUserActivityUpdater() {}
+  BaseWindow* GetCocoaWindow(nsIBaseWindow* aWindow);
+};
+
+#endif  // nsMacUserActivityUpdater_h_
diff --git a/widget/cocoa/nsMacUserActivityUpdater.mm b/widget/cocoa/nsMacUserActivityUpdater.mm
new file mode 100644
index 0000000000..cc80e1259b
--- /dev/null
+++ b/widget/cocoa/nsMacUserActivityUpdater.mm
@@ -0,0 +1,64 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsMacUserActivityUpdater.h"
+
+#include "nsCocoaUtils.h"
+#include "nsIBaseWindow.h"
+#include "gfxPlatform.h"
+
+NS_IMPL_ISUPPORTS(nsMacUserActivityUpdater, nsIMacUserActivityUpdater)
+
+NS_IMETHODIMP
+nsMacUserActivityUpdater::UpdateLocation(const nsAString& aPageUrl, const nsAString& aPageTitle,
+                                         nsIBaseWindow* aWindow) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+  if (gfxPlatform::IsHeadless()) {
+    // In headless mode, Handoff will fail since there is no Cocoa window.
+    return NS_OK;
+  }
+
+  BaseWindow* cocoaWin = nsMacUserActivityUpdater::GetCocoaWindow(aWindow);
+  if (!cocoaWin) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSURL* pageUrl = nsCocoaUtils::ToNSURL(aPageUrl);
+  if (!pageUrl ||
+      (![pageUrl.scheme isEqualToString:@"https"] && ![pageUrl.scheme isEqualToString:@"http"])) {
+    [cocoaWin.userActivity invalidate];
+    return NS_OK;
+  }
+
+  NSString* pageTitle = nsCocoaUtils::ToNSString(aPageTitle);
+  if (!pageTitle) {
+    pageTitle = pageUrl.absoluteString;
+  }
+
+  NSUserActivity* userActivity =
+      [[NSUserActivity alloc] initWithActivityType:NSUserActivityTypeBrowsingWeb];
+  userActivity.webpageURL = pageUrl;
+  userActivity.title = pageTitle;
+  cocoaWin.userActivity = userActivity;
+  [userActivity release];
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+BaseWindow* nsMacUserActivityUpdater::GetCocoaWindow(nsIBaseWindow* aWindow) {
+  nsCOMPtr<nsIWidget> widget = nullptr;
+  aWindow->GetMainWidget(getter_AddRefs(widget));
+  if (!widget) {
+    return nil;
+  }
+  BaseWindow* cocoaWin = (BaseWindow*)widget->GetNativeData(NS_NATIVE_WINDOW);
+  if (!cocoaWin) {
+    return nil;
+  }
+  return cocoaWin;
+}
diff --git a/widget/cocoa/nsMacWebAppUtils.h b/widget/cocoa/nsMacWebAppUtils.h
new file mode 100644
index 0000000000..1e79ca92d5
--- /dev/null
+++ b/widget/cocoa/nsMacWebAppUtils.h
@@ -0,0 +1,22 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef _MAC_WEB_APP_UTILS_H_
+#define _MAC_WEB_APP_UTILS_H_
+
+#include "nsIMacWebAppUtils.h"
+
+#define NS_MACWEBAPPUTILS_CONTRACTID "@mozilla.org/widget/mac-web-app-utils;1"
+
+class nsMacWebAppUtils : public nsIMacWebAppUtils {
+ public:
+  nsMacWebAppUtils() {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMACWEBAPPUTILS
+
+ protected:
+  virtual ~nsMacWebAppUtils() {}
+};
+
+#endif  //_MAC_WEB_APP_UTILS_H_
diff --git a/widget/cocoa/nsMacWebAppUtils.mm b/widget/cocoa/nsMacWebAppUtils.mm
new file mode 100644
index 0000000000..9098544724
--- /dev/null
+++ b/widget/cocoa/nsMacWebAppUtils.mm
@@ -0,0 +1,90 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsMacWebAppUtils.h"
+#include "nsCOMPtr.h"
+#include "nsCocoaUtils.h"
+#include "nsString.h"
+
+// This must be included last:
+#include "nsObjCExceptions.h"
+
+// Find the path to the app with the given bundleIdentifier, if any.
+// Note that the OS will return the path to the newest binary, if there is more than one.
+// The determination of 'newest' is complex and beyond the scope of this comment.
+
+NS_IMPL_ISUPPORTS(nsMacWebAppUtils, nsIMacWebAppUtils)
+
+NS_IMETHODIMP nsMacWebAppUtils::PathForAppWithIdentifier(const nsAString& bundleIdentifier,
+                                                         nsAString& outPath) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  outPath.Truncate();
+
+  nsAutoreleasePool localPool;
+
+  // note that the result of this expression might be nil, meaning no matching app was found.
+  NSString* temp = [[NSWorkspace sharedWorkspace]
+      absolutePathForAppBundleWithIdentifier:
+          [NSString stringWithCharacters:reinterpret_cast<const unichar*>(
+                                             ((nsString)bundleIdentifier).get())
+                                  length:((nsString)bundleIdentifier).Length()]];
+
+  if (temp) {
+    // Copy out the resultant absolute path into outPath if non-nil.
+    nsCocoaUtils::GetStringForNSString(temp, outPath);
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP nsMacWebAppUtils::LaunchAppWithIdentifier(const nsAString& bundleIdentifier) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  nsAutoreleasePool localPool;
+
+  // Note this might return false, meaning the app wasnt launched for some reason.
+  BOOL success = [[NSWorkspace sharedWorkspace]
+       launchAppWithBundleIdentifier:[NSString
+                                         stringWithCharacters:reinterpret_cast<const unichar*>(
+                                                                  ((nsString)bundleIdentifier)
+                                                                      .get())
+                                                       length:((nsString)bundleIdentifier).Length()]
+                             options:(NSWorkspaceLaunchOptions)0
+      additionalEventParamDescriptor:nil
+                    launchIdentifier:NULL];
+
+  return success ? NS_OK : NS_ERROR_FAILURE;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP nsMacWebAppUtils::TrashApp(const nsAString& path, nsITrashAppCallback* aCallback) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (NS_WARN_IF(!aCallback)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsCOMPtr<nsITrashAppCallback> callback = aCallback;
+
+  NSString* tempString =
+      [NSString stringWithCharacters:reinterpret_cast<const unichar*>(((nsString)path).get())
+                              length:path.Length()];
+
+  [[NSWorkspace sharedWorkspace]
+            recycleURLs:[NSArray arrayWithObject:[NSURL fileURLWithPath:tempString]]
+      completionHandler:^(NSDictionary* newURLs, NSError* error) {
+        nsresult rv = (error == nil) ? NS_OK : NS_ERROR_FAILURE;
+        callback->TrashAppFinished(rv);
+      }];
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
diff --git a/widget/cocoa/nsMenuBarX.h b/widget/cocoa/nsMenuBarX.h
new file mode 100644
index 0000000000..9990c59bc5
--- /dev/null
+++ b/widget/cocoa/nsMenuBarX.h
@@ -0,0 +1,153 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMenuBarX_h_
+#define nsMenuBarX_h_
+
+#import <Cocoa/Cocoa.h>
+
+#include "mozilla/UniquePtr.h"
+#include "mozilla/WeakPtr.h"
+
+#include "nsISupports.h"
+#include "nsMenuParentX.h"
+#include "nsChangeObserver.h"
+#include "nsTArray.h"
+#include "nsString.h"
+
+class nsMenuBarX;
+class nsMenuGroupOwnerX;
+class nsMenuX;
+class nsIWidget;
+class nsIContent;
+
+namespace mozilla {
+namespace dom {
+class Document;
+class Element;
+}  // namespace dom
+}  // namespace mozilla
+
+// ApplicationMenuDelegate is used to receive Cocoa notifications.
+@interface ApplicationMenuDelegate : NSObject <NSMenuDelegate> {
+  nsMenuBarX* mApplicationMenu;  // weak ref
+}
+- (id)initWithApplicationMenu:(nsMenuBarX*)aApplicationMenu;
+@end
+
+// Objective-C class used to allow us to intervene with keyboard event handling.
+// We allow mouse actions to work normally.
+@interface GeckoNSMenu : NSMenu {
+}
+- (BOOL)performSuperKeyEquivalent:(NSEvent*)aEvent;
+@end
+
+// Objective-C class used as action target for menu items
+@interface NativeMenuItemTarget : NSObject {
+}
+- (IBAction)menuItemHit:(id)aSender;
+@end
+
+// Objective-C class used for menu items on the Services menu to allow Gecko
+// to override their standard behavior in order to stop key equivalents from
+// firing in certain instances.
+@interface GeckoServicesNSMenuItem : NSMenuItem {
+}
+- (id)target;
+- (SEL)action;
+- (void)_doNothing:(id)aSender;
+@end
+
+// Objective-C class used as the Services menu so that Gecko can override the
+// standard behavior of the Services menu in order to stop key equivalents
+// from firing in certain instances.
+@interface GeckoServicesNSMenu : NSMenu {
+}
+- (void)addItem:(NSMenuItem*)aNewItem;
+- (NSMenuItem*)addItemWithTitle:(NSString*)aString
+                         action:(SEL)aSelector
+                  keyEquivalent:(NSString*)aKeyEquiv;
+- (void)insertItem:(NSMenuItem*)aNewItem atIndex:(NSInteger)aIndex;
+- (NSMenuItem*)insertItemWithTitle:(NSString*)aString
+                            action:(SEL)aSelector
+                     keyEquivalent:(NSString*)aKeyEquiv
+                           atIndex:(NSInteger)aIndex;
+- (void)_overrideClassOfMenuItem:(NSMenuItem*)aMenuItem;
+@end
+
+// Once instantiated, this object lives until its DOM node or its parent window is destroyed.
+// Do not hold references to this, they can become invalid any time the DOM node can be destroyed.
+class nsMenuBarX : public nsMenuParentX, public nsChangeObserver, public mozilla::SupportsWeakPtr {
+ public:
+  explicit nsMenuBarX(mozilla::dom::Element* aElement);
+
+  NS_INLINE_DECL_REFCOUNTING(nsMenuBarX)
+
+  static NativeMenuItemTarget* sNativeEventTarget;
+  static nsMenuBarX* sLastGeckoMenuBarPainted;
+
+  // The following content nodes have been removed from the menu system.
+  // We save them here for use in command handling.
+  RefPtr<nsIContent> mAboutItemContent;
+  RefPtr<nsIContent> mPrefItemContent;
+  RefPtr<nsIContent> mAccountItemContent;
+  RefPtr<nsIContent> mQuitItemContent;
+
+  // nsChangeObserver
+  NS_DECL_CHANGEOBSERVER
+
+  // nsMenuParentX
+  nsMenuBarX* AsMenuBar() override { return this; }
+
+  // nsMenuBarX
+  uint32_t GetMenuCount();
+  bool MenuContainsAppMenu();
+  nsMenuX* GetMenuAt(uint32_t aIndex);
+  nsMenuX* GetXULHelpMenu();
+  void SetSystemHelpMenu();
+  nsresult Paint();
+  void ForceUpdateNativeMenuAt(const nsAString& aIndexString);
+  void ForceNativeMenuReload();  // used for testing
+  static void ResetNativeApplicationMenu();
+  void SetNeedsRebuild();
+  void ApplicationMenuOpened();
+  bool PerformKeyEquivalent(NSEvent* aEvent);
+  GeckoNSMenu* NativeNSMenu() { return mNativeMenu; }
+
+  // nsMenuParentX
+  void MenuChildChangedVisibility(const MenuChild& aChild, bool aIsVisible) override;
+
+ protected:
+  virtual ~nsMenuBarX();
+
+  void ConstructNativeMenus();
+  void ConstructFallbackNativeMenus();
+  void InsertMenuAtIndex(RefPtr<nsMenuX>&& aMenu, uint32_t aIndex);
+  void RemoveMenuAtIndex(uint32_t aIndex);
+  RefPtr<mozilla::dom::Element> HideItem(mozilla::dom::Document* aDocument, const nsAString& aID);
+  void AquifyMenuBar();
+  NSMenuItem* CreateNativeAppMenuItem(nsMenuX* aMenu, const nsAString& aNodeID, SEL aAction,
+                                      int aTag, NativeMenuItemTarget* aTarget);
+  void CreateApplicationMenu(nsMenuX* aMenu);
+
+  // Calculates the index at which aChild's NSMenuItem should be inserted into our NSMenu.
+  // The order of NSMenuItems in the NSMenu is the same as the order of nsMenuX objects in
+  // mMenuArray; there are two differences:
+  //  - mMenuArray contains both visible and invisible menus, and the NSMenu only contains visible
+  //    menus.
+  //  - Our NSMenu may also contain an item for the app menu, whereas mMenuArray never does.
+  // So the insertion index is equal to the number of visible previous siblings of aChild in
+  // mMenuArray, plus one if the app menu is present.
+  NSInteger CalculateNativeInsertionPoint(nsMenuX* aChild);
+
+  RefPtr<nsIContent> mContent;
+  RefPtr<nsMenuGroupOwnerX> mMenuGroupOwner;
+  nsTArray<RefPtr<nsMenuX>> mMenuArray;
+  GeckoNSMenu* mNativeMenu;  // root menu, representing entire menu bar
+  bool mNeedsRebuild;
+  ApplicationMenuDelegate* mApplicationMenuDelegate;
+};
+
+#endif  // nsMenuBarX_h_
diff --git a/widget/cocoa/nsMenuBarX.mm b/widget/cocoa/nsMenuBarX.mm
new file mode 100644
index 0000000000..70a17d87f8
--- /dev/null
+++ b/widget/cocoa/nsMenuBarX.mm
@@ -0,0 +1,1072 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <objc/objc-runtime.h>
+
+#include "nsMenuBarX.h"
+#include "nsMenuX.h"
+#include "nsMenuItemX.h"
+#include "nsMenuUtilsX.h"
+#include "nsCocoaUtils.h"
+#include "nsChildView.h"
+
+#include "nsCOMPtr.h"
+#include "nsString.h"
+#include "nsGkAtoms.h"
+#include "nsObjCExceptions.h"
+#include "nsThreadUtils.h"
+#include "nsTouchBarNativeAPIDefines.h"
+
+#include "nsIContent.h"
+#include "nsIWidget.h"
+#include "mozilla/dom/Document.h"
+#include "nsIAppStartup.h"
+#include "nsIStringBundle.h"
+#include "nsToolkitCompsCID.h"
+
+#include "mozilla/Components.h"
+#include "mozilla/dom/Element.h"
+
+using namespace mozilla;
+using mozilla::dom::Element;
+
+NativeMenuItemTarget* nsMenuBarX::sNativeEventTarget = nil;
+nsMenuBarX* nsMenuBarX::sLastGeckoMenuBarPainted = nullptr;
+NSMenu* sApplicationMenu = nil;
+BOOL sApplicationMenuIsFallback = NO;
+BOOL gSomeMenuBarPainted = NO;
+
+// defined in nsCocoaWindow.mm.
+extern BOOL sTouchBarIsInitialized;
+
+// We keep references to the first quit and pref item content nodes we find, which
+// will be from the hidden window. We use these when the document for the current
+// window does not have a quit or pref item. We don't need strong refs here because
+// these items are always strong ref'd by their owning menu bar (instance variable).
+static nsIContent* sAboutItemContent = nullptr;
+static nsIContent* sPrefItemContent = nullptr;
+static nsIContent* sAccountItemContent = nullptr;
+static nsIContent* sQuitItemContent = nullptr;
+
+//
+// ApplicationMenuDelegate Objective-C class
+//
+
+@implementation ApplicationMenuDelegate
+
+- (id)initWithApplicationMenu:(nsMenuBarX*)aApplicationMenu {
+  if ((self = [super init])) {
+    mApplicationMenu = aApplicationMenu;
+  }
+  return self;
+}
+
+- (void)menuWillOpen:(NSMenu*)menu {
+  mApplicationMenu->ApplicationMenuOpened();
+}
+
+- (void)menuDidClose:(NSMenu*)menu {
+}
+
+@end
+
+nsMenuBarX::nsMenuBarX(mozilla::dom::Element* aElement)
+    : mNeedsRebuild(false), mApplicationMenuDelegate(nil) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  mMenuGroupOwner = new nsMenuGroupOwnerX(aElement, this);
+  mMenuGroupOwner->RegisterForLocaleChanges();
+  mNativeMenu = [[GeckoNSMenu alloc] initWithTitle:@"MainMenuBar"];
+
+  mContent = aElement;
+
+  if (mContent) {
+    AquifyMenuBar();
+    mMenuGroupOwner->RegisterForContentChanges(mContent, this);
+    ConstructNativeMenus();
+  } else {
+    ConstructFallbackNativeMenus();
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+nsMenuBarX::~nsMenuBarX() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (nsMenuBarX::sLastGeckoMenuBarPainted == this) {
+    nsMenuBarX::sLastGeckoMenuBarPainted = nullptr;
+  }
+
+  // the quit/pref items of a random window might have been used if there was no
+  // hidden window, thus we need to invalidate the weak references.
+  if (sAboutItemContent == mAboutItemContent) {
+    sAboutItemContent = nullptr;
+  }
+  if (sQuitItemContent == mQuitItemContent) {
+    sQuitItemContent = nullptr;
+  }
+  if (sPrefItemContent == mPrefItemContent) {
+    sPrefItemContent = nullptr;
+  }
+  if (sAccountItemContent == mAccountItemContent) {
+    sAccountItemContent = nullptr;
+  }
+
+  mMenuGroupOwner->UnregisterForLocaleChanges();
+
+  // make sure we unregister ourselves as a content observer
+  if (mContent) {
+    mMenuGroupOwner->UnregisterForContentChanges(mContent);
+  }
+
+  for (nsMenuX* menu : mMenuArray) {
+    menu->DetachFromGroupOwnerRecursive();
+    menu->DetachFromParent();
+  }
+
+  if (mApplicationMenuDelegate) {
+    [mApplicationMenuDelegate release];
+  }
+
+  [mNativeMenu release];
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuBarX::ConstructNativeMenus() {
+  for (nsIContent* menuContent = mContent->GetFirstChild(); menuContent;
+       menuContent = menuContent->GetNextSibling()) {
+    if (menuContent->IsXULElement(nsGkAtoms::menu)) {
+      InsertMenuAtIndex(MakeRefPtr<nsMenuX>(this, mMenuGroupOwner, menuContent->AsElement()),
+                        GetMenuCount());
+    }
+  }
+}
+
+void nsMenuBarX::ConstructFallbackNativeMenus() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (sApplicationMenu) {
+    // Menu has already been built.
+    return;
+  }
+
+  nsCOMPtr<nsIStringBundle> stringBundle;
+
+  nsCOMPtr<nsIStringBundleService> bundleSvc = do_GetService(NS_STRINGBUNDLE_CONTRACTID);
+  bundleSvc->CreateBundle("chrome://global/locale/fallbackMenubar.properties",
+                          getter_AddRefs(stringBundle));
+
+  if (!stringBundle) {
+    return;
+  }
+
+  nsAutoString labelUTF16;
+  nsAutoString keyUTF16;
+
+  const char* labelProp = "quitMenuitem.label";
+  const char* keyProp = "quitMenuitem.key";
+
+  stringBundle->GetStringFromName(labelProp, labelUTF16);
+  stringBundle->GetStringFromName(keyProp, keyUTF16);
+
+  NSString* labelStr = [NSString stringWithUTF8String:NS_ConvertUTF16toUTF8(labelUTF16).get()];
+  NSString* keyStr = [NSString stringWithUTF8String:NS_ConvertUTF16toUTF8(keyUTF16).get()];
+
+  if (!nsMenuBarX::sNativeEventTarget) {
+    nsMenuBarX::sNativeEventTarget = [[NativeMenuItemTarget alloc] init];
+  }
+
+  sApplicationMenu = [[[[NSApp mainMenu] itemAtIndex:0] submenu] retain];
+  if (!mApplicationMenuDelegate) {
+    mApplicationMenuDelegate = [[ApplicationMenuDelegate alloc] initWithApplicationMenu:this];
+  }
+  sApplicationMenu.delegate = mApplicationMenuDelegate;
+  NSMenuItem* quitMenuItem = [[[NSMenuItem alloc] initWithTitle:labelStr
+                                                         action:@selector(menuItemHit:)
+                                                  keyEquivalent:keyStr] autorelease];
+  quitMenuItem.target = nsMenuBarX::sNativeEventTarget;
+  quitMenuItem.tag = eCommand_ID_Quit;
+  [sApplicationMenu addItem:quitMenuItem];
+  sApplicationMenuIsFallback = YES;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+uint32_t nsMenuBarX::GetMenuCount() { return mMenuArray.Length(); }
+
+bool nsMenuBarX::MenuContainsAppMenu() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  return (mNativeMenu.numberOfItems > 0 && [mNativeMenu itemAtIndex:0].submenu == sApplicationMenu);
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuBarX::InsertMenuAtIndex(RefPtr<nsMenuX>&& aMenu, uint32_t aIndex) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // If we've only yet created a fallback global Application menu (using
+  // ContructFallbackNativeMenus()), destroy it before recreating it properly.
+  if (sApplicationMenu && sApplicationMenuIsFallback) {
+    ResetNativeApplicationMenu();
+  }
+  // If we haven't created a global Application menu yet, do it.
+  if (!sApplicationMenu) {
+    CreateApplicationMenu(aMenu.get());
+
+    // Hook the new Application menu up to the menu bar.
+    NSMenu* mainMenu = NSApp.mainMenu;
+    NS_ASSERTION(mainMenu.numberOfItems > 0,
+                 "Main menu does not have any items, something is terribly wrong!");
+    [mainMenu itemAtIndex:0].submenu = sApplicationMenu;
+  }
+
+  // add menu to array that owns our menus
+  mMenuArray.InsertElementAt(aIndex, aMenu);
+
+  // hook up submenus
+  RefPtr<nsIContent> menuContent = aMenu->Content();
+  if (menuContent->GetChildCount() > 0 && !nsMenuUtilsX::NodeIsHiddenOrCollapsed(menuContent)) {
+    MenuChildChangedVisibility(MenuChild(aMenu), true);
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuBarX::RemoveMenuAtIndex(uint32_t aIndex) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (mMenuArray.Length() <= aIndex) {
+    NS_ERROR("Attempting submenu removal with bad index!");
+    return;
+  }
+
+  RefPtr<nsMenuX> menu = mMenuArray[aIndex];
+  mMenuArray.RemoveElementAt(aIndex);
+
+  menu->DetachFromGroupOwnerRecursive();
+  menu->DetachFromParent();
+
+  // Our native menu and our internal menu object array might be out of sync.
+  // This happens, for example, when a submenu is hidden. Because of this we
+  // should not assume that a native submenu is hooked up.
+  NSMenuItem* nativeMenuItem = menu->NativeNSMenuItem();
+  int nativeMenuItemIndex = [mNativeMenu indexOfItem:nativeMenuItem];
+  if (nativeMenuItemIndex != -1) {
+    [mNativeMenu removeItemAtIndex:nativeMenuItemIndex];
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuBarX::ObserveAttributeChanged(mozilla::dom::Document* aDocument, nsIContent* aContent,
+                                         nsAtom* aAttribute) {}
+
+void nsMenuBarX::ObserveContentRemoved(mozilla::dom::Document* aDocument, nsIContent* aContainer,
+                                       nsIContent* aChild, nsIContent* aPreviousSibling) {
+  nsINode* parent = NODE_FROM(aContainer, aDocument);
+  MOZ_ASSERT(parent);
+  const Maybe<uint32_t> index = parent->ComputeIndexOf(aPreviousSibling);
+  MOZ_ASSERT(*index != UINT32_MAX);
+  RemoveMenuAtIndex(index.isSome() ? *index + 1u : 0u);
+}
+
+void nsMenuBarX::ObserveContentInserted(mozilla::dom::Document* aDocument, nsIContent* aContainer,
+                                        nsIContent* aChild) {
+  InsertMenuAtIndex(MakeRefPtr<nsMenuX>(this, mMenuGroupOwner, aChild),
+                    aContainer->ComputeIndexOf(aChild).valueOr(UINT32_MAX));
+}
+
+void nsMenuBarX::ForceUpdateNativeMenuAt(const nsAString& aIndexString) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  NSString* locationString =
+      [NSString stringWithCharacters:reinterpret_cast<const unichar*>(aIndexString.BeginReading())
+                              length:aIndexString.Length()];
+  NSArray* indexes = [locationString componentsSeparatedByString:@"|"];
+  unsigned int indexCount = indexes.count;
+  if (indexCount == 0) {
+    return;
+  }
+
+  RefPtr<nsMenuX> currentMenu = nullptr;
+  int targetIndex = [[indexes objectAtIndex:0] intValue];
+  int visible = 0;
+  uint32_t length = mMenuArray.Length();
+  // first find a menu in the menu bar
+  for (unsigned int i = 0; i < length; i++) {
+    RefPtr<nsMenuX> menu = mMenuArray[i];
+    if (!nsMenuUtilsX::NodeIsHiddenOrCollapsed(menu->Content())) {
+      visible++;
+      if (visible == (targetIndex + 1)) {
+        currentMenu = std::move(menu);
+        break;
+      }
+    }
+  }
+
+  if (!currentMenu) {
+    return;
+  }
+
+  // fake open/close to cause lazy update to happen so submenus populate
+  currentMenu->MenuOpened();
+  currentMenu->MenuClosed();
+
+  // now find the correct submenu
+  for (unsigned int i = 1; currentMenu && i < indexCount; i++) {
+    targetIndex = [[indexes objectAtIndex:i] intValue];
+    visible = 0;
+    length = currentMenu->GetItemCount();
+    for (unsigned int j = 0; j < length; j++) {
+      Maybe<nsMenuX::MenuChild> targetMenu = currentMenu->GetItemAt(j);
+      if (!targetMenu) {
+        return;
+      }
+      RefPtr<nsIContent> content = targetMenu->match(
+          [](const RefPtr<nsMenuX>& aMenu) { return aMenu->Content(); },
+          [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->Content(); });
+      if (!nsMenuUtilsX::NodeIsHiddenOrCollapsed(content)) {
+        visible++;
+        if (targetMenu->is<RefPtr<nsMenuX>>() && visible == (targetIndex + 1)) {
+          currentMenu = targetMenu->as<RefPtr<nsMenuX>>();
+          // fake open/close to cause lazy update to happen
+          currentMenu->MenuOpened();
+          currentMenu->MenuClosed();
+          break;
+        }
+      }
+    }
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+// Calling this forces a full reload of the menu system, reloading all native
+// menus and their items.
+// Without this testing is hard because changes to the DOM affect the native
+// menu system lazily.
+void nsMenuBarX::ForceNativeMenuReload() {
+  // tear down everything
+  while (GetMenuCount() > 0) {
+    RemoveMenuAtIndex(0);
+  }
+
+  // construct everything
+  ConstructNativeMenus();
+}
+
+nsMenuX* nsMenuBarX::GetMenuAt(uint32_t aIndex) {
+  if (mMenuArray.Length() <= aIndex) {
+    NS_ERROR("Requesting menu at invalid index!");
+    return nullptr;
+  }
+  return mMenuArray[aIndex].get();
+}
+
+nsMenuX* nsMenuBarX::GetXULHelpMenu() {
+  // The Help menu is usually (always?) the last one, so we start there and
+  // count back.
+  for (int32_t i = GetMenuCount() - 1; i >= 0; --i) {
+    nsMenuX* aMenu = GetMenuAt(i);
+    if (aMenu && nsMenuX::IsXULHelpMenu(aMenu->Content())) {
+      return aMenu;
+    }
+  }
+  return nil;
+}
+
+// On SnowLeopard and later we must tell the OS which is our Help menu.
+// Otherwise it will only add Spotlight for Help (the Search item) to our
+// Help menu if its label/title is "Help" -- i.e. if the menu is in English.
+// This resolves bugs 489196 and 539317.
+void nsMenuBarX::SetSystemHelpMenu() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  nsMenuX* xulHelpMenu = GetXULHelpMenu();
+  if (xulHelpMenu) {
+    NSMenu* helpMenu = xulHelpMenu->NativeNSMenu();
+    if (helpMenu) {
+      NSApp.helpMenu = helpMenu;
+    }
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+nsresult nsMenuBarX::Paint() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // Don't try to optimize anything in this painting by checking
+  // sLastGeckoMenuBarPainted because the menubar can be manipulated by
+  // native dialogs and sheet code and other things besides this paint method.
+
+  // We have to keep the same menu item for the Application menu so we keep
+  // passing it along.
+  NSMenu* outgoingMenu = NSApp.mainMenu;
+  NS_ASSERTION(outgoingMenu.numberOfItems > 0,
+               "Main menu does not have any items, something is terribly wrong!");
+
+  NSMenuItem* appMenuItem = [[outgoingMenu itemAtIndex:0] retain];
+  [outgoingMenu removeItemAtIndex:0];
+  [mNativeMenu insertItem:appMenuItem atIndex:0];
+  [appMenuItem release];
+
+  // Set menu bar and event target.
+  NSApp.mainMenu = mNativeMenu;
+  SetSystemHelpMenu();
+  nsMenuBarX::sLastGeckoMenuBarPainted = this;
+
+  gSomeMenuBarPainted = YES;
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+/* static */
+void nsMenuBarX::ResetNativeApplicationMenu() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  [sApplicationMenu removeAllItems];
+  [sApplicationMenu release];
+  sApplicationMenu = nil;
+  sApplicationMenuIsFallback = NO;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuBarX::SetNeedsRebuild() { mNeedsRebuild = true; }
+
+void nsMenuBarX::ApplicationMenuOpened() {
+  if (mNeedsRebuild) {
+    if (!mMenuArray.IsEmpty()) {
+      ResetNativeApplicationMenu();
+      CreateApplicationMenu(mMenuArray[0].get());
+    }
+    mNeedsRebuild = false;
+  }
+}
+
+bool nsMenuBarX::PerformKeyEquivalent(NSEvent* aEvent) {
+  return [mNativeMenu performSuperKeyEquivalent:aEvent];
+}
+
+void nsMenuBarX::MenuChildChangedVisibility(const MenuChild& aChild, bool aIsVisible) {
+  MOZ_RELEASE_ASSERT(aChild.is<RefPtr<nsMenuX>>(), "nsMenuBarX only has nsMenuX children");
+  const RefPtr<nsMenuX>& child = aChild.as<RefPtr<nsMenuX>>();
+  NSMenuItem* item = child->NativeNSMenuItem();
+  if (aIsVisible) {
+    NSInteger insertionPoint = CalculateNativeInsertionPoint(child);
+    [mNativeMenu insertItem:child->NativeNSMenuItem() atIndex:insertionPoint];
+  } else if ([mNativeMenu indexOfItem:item] != -1) {
+    [mNativeMenu removeItem:item];
+  }
+}
+
+NSInteger nsMenuBarX::CalculateNativeInsertionPoint(nsMenuX* aChild) {
+  NSInteger insertionPoint = MenuContainsAppMenu() ? 1 : 0;
+  for (auto& currMenu : mMenuArray) {
+    if (currMenu == aChild) {
+      return insertionPoint;
+    }
+    // Only count items that are inside a menu.
+    // XXXmstange Not sure what would cause free-standing items. Maybe for collapsed/hidden menus?
+    // In that case, an nsMenuX::IsVisible() method would be better.
+    if (currMenu->NativeNSMenuItem().menu) {
+      insertionPoint++;
+    }
+  }
+  return insertionPoint;
+}
+
+// Hide the item in the menu by setting the 'hidden' attribute. Returns it so
+// the caller can hang onto it if they so choose.
+RefPtr<Element> nsMenuBarX::HideItem(mozilla::dom::Document* aDocument, const nsAString& aID) {
+  RefPtr<Element> menuElement = aDocument->GetElementById(aID);
+  if (menuElement) {
+    menuElement->SetAttr(kNameSpaceID_None, nsGkAtoms::hidden, u"true"_ns, false);
+  }
+  return menuElement;
+}
+
+// Do what is necessary to conform to the Aqua guidelines for menus.
+void nsMenuBarX::AquifyMenuBar() {
+  RefPtr<mozilla::dom::Document> domDoc = mContent->GetComposedDoc();
+  if (domDoc) {
+    // remove the "About..." item and its separator
+    HideItem(domDoc, u"aboutSeparator"_ns);
+    mAboutItemContent = HideItem(domDoc, u"aboutName"_ns);
+    if (!sAboutItemContent) {
+      sAboutItemContent = mAboutItemContent;
+    }
+
+    // remove quit item and its separator
+    HideItem(domDoc, u"menu_FileQuitSeparator"_ns);
+    mQuitItemContent = HideItem(domDoc, u"menu_FileQuitItem"_ns);
+    if (!sQuitItemContent) {
+      sQuitItemContent = mQuitItemContent;
+    }
+
+    // remove prefs item and its separator, but save off the pref content node
+    // so we can invoke its command later.
+    HideItem(domDoc, u"menu_PrefsSeparator"_ns);
+    mPrefItemContent = HideItem(domDoc, u"menu_preferences"_ns);
+    if (!sPrefItemContent) {
+      sPrefItemContent = mPrefItemContent;
+    }
+
+    // remove Account Settings item.
+    mAccountItemContent = HideItem(domDoc, u"menu_accountmgr"_ns);
+    if (!sAccountItemContent) {
+      sAccountItemContent = mAccountItemContent;
+    }
+
+    // hide items that we use for the Application menu
+    HideItem(domDoc, u"menu_mac_services"_ns);
+    HideItem(domDoc, u"menu_mac_hide_app"_ns);
+    HideItem(domDoc, u"menu_mac_hide_others"_ns);
+    HideItem(domDoc, u"menu_mac_show_all"_ns);
+    HideItem(domDoc, u"menu_mac_touch_bar"_ns);
+  }
+}
+
+// for creating menu items destined for the Application menu
+NSMenuItem* nsMenuBarX::CreateNativeAppMenuItem(nsMenuX* aMenu, const nsAString& aNodeID,
+                                                SEL aAction, int aTag,
+                                                NativeMenuItemTarget* aTarget) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  RefPtr<mozilla::dom::Document> doc = aMenu->Content()->GetUncomposedDoc();
+  if (!doc) {
+    return nil;
+  }
+
+  RefPtr<mozilla::dom::Element> menuItem = doc->GetElementById(aNodeID);
+  if (!menuItem) {
+    return nil;
+  }
+
+  // Check collapsed rather than hidden since the app menu items are always
+  // hidden in AquifyMenuBar.
+  if (menuItem->AttrValueIs(kNameSpaceID_None, nsGkAtoms::collapsed, nsGkAtoms::_true,
+                            eCaseMatters)) {
+    return nil;
+  }
+
+  // Get information from the gecko menu item
+  nsAutoString label;
+  nsAutoString modifiers;
+  nsAutoString key;
+  menuItem->GetAttr(nsGkAtoms::label, label);
+  menuItem->GetAttr(nsGkAtoms::modifiers, modifiers);
+  menuItem->GetAttr(nsGkAtoms::key, key);
+
+  // Get more information about the key equivalent. Start by
+  // finding the key node we need.
+  NSString* keyEquiv = nil;
+  unsigned int macKeyModifiers = 0;
+  if (!key.IsEmpty()) {
+    RefPtr<Element> keyElement = doc->GetElementById(key);
+    if (keyElement) {
+      // first grab the key equivalent character
+      nsAutoString keyChar(u" "_ns);
+      keyElement->GetAttr(kNameSpaceID_None, nsGkAtoms::key, keyChar);
+      if (!keyChar.EqualsLiteral(" ")) {
+        keyEquiv = [[NSString stringWithCharacters:reinterpret_cast<const unichar*>(keyChar.get())
+                                            length:keyChar.Length()] lowercaseString];
+      }
+      // now grab the key equivalent modifiers
+      nsAutoString modifiersStr;
+      keyElement->GetAttr(kNameSpaceID_None, nsGkAtoms::modifiers, modifiersStr);
+      uint8_t geckoModifiers = nsMenuUtilsX::GeckoModifiersForNodeAttribute(modifiersStr);
+      macKeyModifiers = nsMenuUtilsX::MacModifiersForGeckoModifiers(geckoModifiers);
+    }
+  }
+  // get the label into NSString-form
+  NSString* labelString =
+      [NSString stringWithCharacters:reinterpret_cast<const unichar*>(label.get())
+                              length:label.Length()];
+
+  if (!labelString) {
+    labelString = @"";
+  }
+  if (!keyEquiv) {
+    keyEquiv = @"";
+  }
+
+  // put together the actual NSMenuItem
+  NSMenuItem* newMenuItem = [[NSMenuItem alloc] initWithTitle:labelString
+                                                       action:aAction
+                                                keyEquivalent:keyEquiv];
+
+  newMenuItem.tag = aTag;
+  newMenuItem.target = aTarget;
+  newMenuItem.keyEquivalentModifierMask = macKeyModifiers;
+  newMenuItem.representedObject = mMenuGroupOwner->GetRepresentedObject();
+
+  return newMenuItem;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+// build the Application menu shared by all menu bars
+void nsMenuBarX::CreateApplicationMenu(nsMenuX* aMenu) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // At this point, the application menu is the application menu from
+  // the nib in cocoa widgets. We do not have a way to create an application
+  // menu manually, so we grab the one from the nib and use that.
+  sApplicationMenu = [[NSApp.mainMenu itemAtIndex:0].submenu retain];
+
+  /*
+    We support the following menu items here:
+
+    Menu Item                DOM Node ID             Notes
+
+    ========================
+    = About This App       = <- aboutName
+    ========================
+    = Preferences...       = <- menu_preferences
+    = Account Settings     = <- menu_accountmgr      Only on Thunderbird
+    ========================
+    = Services     >       = <- menu_mac_services    <- (do not define key equivalent)
+    ========================
+    = Hide App             = <- menu_mac_hide_app
+    = Hide Others          = <- menu_mac_hide_others
+    = Show All             = <- menu_mac_show_all
+    ========================
+    = Customize Touch Bar… = <- menu_mac_touch_bar
+    ========================
+    = Quit                 = <- menu_FileQuitItem
+    ========================
+
+    If any of them are ommitted from the application's DOM, we just don't add
+    them. We always add a "Quit" item, but if an app developer does not provide a
+    DOM node with the right ID for the Quit item, we add it in English. App
+    developers need only add each node with a label and a key equivalent (if they
+    want one). Other attributes are optional. Like so:
+
+    <menuitem id="menu_preferences"
+           label="&preferencesCmdMac.label;"
+             key="open_prefs_key"/>
+
+    We need to use this system for localization purposes, until we have a better way
+    to define the Application menu to be used on Mac OS X.
+  */
+
+  if (sApplicationMenu) {
+    if (!mApplicationMenuDelegate) {
+      mApplicationMenuDelegate = [[ApplicationMenuDelegate alloc] initWithApplicationMenu:this];
+    }
+    sApplicationMenu.delegate = mApplicationMenuDelegate;
+
+    // This code reads attributes we are going to care about from the DOM elements
+
+    NSMenuItem* itemBeingAdded = nil;
+    BOOL addAboutSeparator = FALSE;
+    BOOL addPrefsSeparator = FALSE;
+
+    // Add the About menu item
+    itemBeingAdded = CreateNativeAppMenuItem(aMenu, u"aboutName"_ns, @selector(menuItemHit:),
+                                             eCommand_ID_About, nsMenuBarX::sNativeEventTarget);
+    if (itemBeingAdded) {
+      [sApplicationMenu addItem:itemBeingAdded];
+      [itemBeingAdded release];
+      itemBeingAdded = nil;
+
+      addAboutSeparator = TRUE;
+    }
+
+    // Add separator if either the About item or software update item exists
+    if (addAboutSeparator) {
+      [sApplicationMenu addItem:[NSMenuItem separatorItem]];
+    }
+
+    // Add the Preferences menu item
+    itemBeingAdded = CreateNativeAppMenuItem(aMenu, u"menu_preferences"_ns, @selector(menuItemHit:),
+                                             eCommand_ID_Prefs, nsMenuBarX::sNativeEventTarget);
+    if (itemBeingAdded) {
+      [sApplicationMenu addItem:itemBeingAdded];
+      [itemBeingAdded release];
+      itemBeingAdded = nil;
+
+      addPrefsSeparator = TRUE;
+    }
+
+    // Add the Account Settings menu item. This is Thunderbird only
+    itemBeingAdded = CreateNativeAppMenuItem(aMenu, u"menu_accountmgr"_ns, @selector(menuItemHit:),
+                                             eCommand_ID_Account, nsMenuBarX::sNativeEventTarget);
+    if (itemBeingAdded) {
+      [sApplicationMenu addItem:itemBeingAdded];
+      [itemBeingAdded release];
+      itemBeingAdded = nil;
+    }
+
+    // Add separator after Preferences menu
+    if (addPrefsSeparator) {
+      [sApplicationMenu addItem:[NSMenuItem separatorItem]];
+    }
+
+    // Add Services menu item
+    itemBeingAdded = CreateNativeAppMenuItem(aMenu, u"menu_mac_services"_ns, nil, 0, nil);
+    if (itemBeingAdded) {
+      [sApplicationMenu addItem:itemBeingAdded];
+
+      // set this menu item up as the Mac OS X Services menu
+      NSMenu* servicesMenu = [[GeckoServicesNSMenu alloc] initWithTitle:@""];
+      itemBeingAdded.submenu = servicesMenu;
+      NSApp.servicesMenu = servicesMenu;
+
+      [itemBeingAdded release];
+      itemBeingAdded = nil;
+
+      // Add separator after Services menu
+      [sApplicationMenu addItem:[NSMenuItem separatorItem]];
+    }
+
+    BOOL addHideShowSeparator = FALSE;
+
+    // Add menu item to hide this application
+    itemBeingAdded =
+        CreateNativeAppMenuItem(aMenu, u"menu_mac_hide_app"_ns, @selector(menuItemHit:),
+                                eCommand_ID_HideApp, nsMenuBarX::sNativeEventTarget);
+    if (itemBeingAdded) {
+      [sApplicationMenu addItem:itemBeingAdded];
+      [itemBeingAdded release];
+      itemBeingAdded = nil;
+
+      addHideShowSeparator = TRUE;
+    }
+
+    // Add menu item to hide other applications
+    itemBeingAdded =
+        CreateNativeAppMenuItem(aMenu, u"menu_mac_hide_others"_ns, @selector(menuItemHit:),
+                                eCommand_ID_HideOthers, nsMenuBarX::sNativeEventTarget);
+    if (itemBeingAdded) {
+      [sApplicationMenu addItem:itemBeingAdded];
+      [itemBeingAdded release];
+      itemBeingAdded = nil;
+
+      addHideShowSeparator = TRUE;
+    }
+
+    // Add menu item to show all applications
+    itemBeingAdded =
+        CreateNativeAppMenuItem(aMenu, u"menu_mac_show_all"_ns, @selector(menuItemHit:),
+                                eCommand_ID_ShowAll, nsMenuBarX::sNativeEventTarget);
+    if (itemBeingAdded) {
+      [sApplicationMenu addItem:itemBeingAdded];
+      [itemBeingAdded release];
+      itemBeingAdded = nil;
+
+      addHideShowSeparator = TRUE;
+    }
+
+    // Add a separator after the hide/show menus if at least one exists
+    if (addHideShowSeparator) {
+      [sApplicationMenu addItem:[NSMenuItem separatorItem]];
+    }
+
+    BOOL addTouchBarSeparator = NO;
+
+    // Add Touch Bar customization menu item.
+    itemBeingAdded =
+        CreateNativeAppMenuItem(aMenu, u"menu_mac_touch_bar"_ns, @selector(menuItemHit:),
+                                eCommand_ID_TouchBar, nsMenuBarX::sNativeEventTarget);
+
+    if (itemBeingAdded) {
+      [sApplicationMenu addItem:itemBeingAdded];
+      // We hide the menu item on Macs that don't have a Touch Bar.
+      if (!sTouchBarIsInitialized) {
+        [itemBeingAdded setHidden:YES];
+      } else {
+        addTouchBarSeparator = YES;
+      }
+      [itemBeingAdded release];
+      itemBeingAdded = nil;
+    }
+
+    // Add a separator after the Touch Bar menu item if it exists
+    if (addTouchBarSeparator) {
+      [sApplicationMenu addItem:[NSMenuItem separatorItem]];
+    }
+
+    // Add quit menu item
+    itemBeingAdded =
+        CreateNativeAppMenuItem(aMenu, u"menu_FileQuitItem"_ns, @selector(menuItemHit:),
+                                eCommand_ID_Quit, nsMenuBarX::sNativeEventTarget);
+    if (itemBeingAdded) {
+      [sApplicationMenu addItem:itemBeingAdded];
+      [itemBeingAdded release];
+      itemBeingAdded = nil;
+    } else {
+      // the current application does not have a DOM node for "Quit". Add one
+      // anyway, in English.
+      NSMenuItem* defaultQuitItem = [[[NSMenuItem alloc] initWithTitle:@"Quit"
+                                                                action:@selector(menuItemHit:)
+                                                         keyEquivalent:@"q"] autorelease];
+      defaultQuitItem.target = nsMenuBarX::sNativeEventTarget;
+      defaultQuitItem.tag = eCommand_ID_Quit;
+      [sApplicationMenu addItem:defaultQuitItem];
+    }
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+//
+// Objective-C class used to allow us to have keyboard commands
+// look like they are doing something but actually do nothing.
+// We allow mouse actions to work normally.
+//
+
+// Controls whether or not native menu items should invoke their commands.
+static BOOL gMenuItemsExecuteCommands = YES;
+
+@implementation GeckoNSMenu
+
+// Keyboard commands should not cause menu items to invoke their
+// commands when there is a key window because we'd rather send
+// the keyboard command to the window. We still have the menus
+// go through the mechanics so they'll give the proper visual
+// feedback.
+- (BOOL)performKeyEquivalent:(NSEvent*)aEvent {
+  // We've noticed that Mac OS X expects this check in subclasses before
+  // calling NSMenu's "performKeyEquivalent:".
+  //
+  // There is no case in which we'd need to do anything or return YES
+  // when we have no items so we can just do this check first.
+  if (self.numberOfItems <= 0) {
+    return NO;
+  }
+
+  NSWindow* keyWindow = NSApp.keyWindow;
+
+  // If there is no key window then just behave normally. This
+  // probably means that this menu is associated with Gecko's
+  // hidden window.
+  if (!keyWindow) {
+    return [super performKeyEquivalent:aEvent];
+  }
+
+  NSResponder* firstResponder = keyWindow.firstResponder;
+
+  gMenuItemsExecuteCommands = NO;
+  [super performKeyEquivalent:aEvent];
+  gMenuItemsExecuteCommands = YES;  // return to default
+
+  // Return YES if we invoked a command and there is now no key window or we changed
+  // the first responder. In this case we do not want to propagate the event because
+  // we don't want it handled again.
+  if (!NSApp.keyWindow || NSApp.keyWindow.firstResponder != firstResponder) {
+    return YES;
+  }
+
+  // Return NO so that we can handle the event via NSView's "keyDown:".
+  return NO;
+}
+
+- (BOOL)performSuperKeyEquivalent:(NSEvent*)aEvent {
+  return [super performKeyEquivalent:aEvent];
+}
+
+@end
+
+//
+// Objective-C class used as action target for menu items
+//
+
+@implementation NativeMenuItemTarget
+
+// called when some menu item in this menu gets hit
+- (IBAction)menuItemHit:(id)aSender {
+  if (!gMenuItemsExecuteCommands) {
+    return;
+  }
+
+  if (![aSender isKindOfClass:[NSMenuItem class]]) {
+    return;
+  }
+
+  NSMenuItem* nativeMenuItem = (NSMenuItem*)aSender;
+  NSInteger tag = nativeMenuItem.tag;
+
+  nsMenuGroupOwnerX* menuGroupOwner = nullptr;
+  nsMenuBarX* menuBar = nullptr;
+  MOZMenuItemRepresentedObject* representedObject = nativeMenuItem.representedObject;
+
+  if (representedObject) {
+    menuGroupOwner = representedObject.menuGroupOwner;
+    if (!menuGroupOwner) {
+      return;
+    }
+    menuBar = menuGroupOwner->GetMenuBar();
+  }
+
+  // Notify containing menu about the fact that a menu item will be activated.
+  NSMenu* menu = nativeMenuItem.menu;
+  if ([menu.delegate isKindOfClass:[MenuDelegate class]]) {
+    [(MenuDelegate*)menu.delegate menu:menu willActivateItem:nativeMenuItem];
+  }
+
+  // Get the modifier flags and button for this menu item activation. The menu system does not pass
+  // an NSEvent to our action selector, but we can query the current NSEvent instead. The current
+  // NSEvent can be a key event or a mouseup event, depending on how the menu item is activated.
+  NSEventModifierFlags modifierFlags = NSApp.currentEvent ? NSApp.currentEvent.modifierFlags : 0;
+  mozilla::MouseButton button = NSApp.currentEvent
+                                    ? nsCocoaUtils::ButtonForEvent(NSApp.currentEvent)
+                                    : mozilla::MouseButton::ePrimary;
+
+  // Do special processing if this is for an app-global command.
+  if (tag == eCommand_ID_About) {
+    nsIContent* mostSpecificContent = sAboutItemContent;
+    if (menuBar && menuBar->mAboutItemContent) {
+      mostSpecificContent = menuBar->mAboutItemContent;
+    }
+    nsMenuUtilsX::DispatchCommandTo(mostSpecificContent, modifierFlags, button);
+    return;
+  }
+  if (tag == eCommand_ID_Prefs) {
+    nsIContent* mostSpecificContent = sPrefItemContent;
+    if (menuBar && menuBar->mPrefItemContent) {
+      mostSpecificContent = menuBar->mPrefItemContent;
+    }
+    nsMenuUtilsX::DispatchCommandTo(mostSpecificContent, modifierFlags, button);
+    return;
+  }
+  if (tag == eCommand_ID_Account) {
+    nsIContent* mostSpecificContent = sAccountItemContent;
+    if (menuBar && menuBar->mAccountItemContent) {
+      mostSpecificContent = menuBar->mAccountItemContent;
+    }
+    nsMenuUtilsX::DispatchCommandTo(mostSpecificContent, modifierFlags, button);
+    return;
+  }
+  if (tag == eCommand_ID_HideApp) {
+    [NSApp hide:aSender];
+    return;
+  }
+  if (tag == eCommand_ID_HideOthers) {
+    [NSApp hideOtherApplications:aSender];
+    return;
+  }
+  if (tag == eCommand_ID_ShowAll) {
+    [NSApp unhideAllApplications:aSender];
+    return;
+  }
+  if (tag == eCommand_ID_TouchBar) {
+    [NSApp toggleTouchBarCustomizationPalette:aSender];
+    return;
+  }
+  if (tag == eCommand_ID_Quit) {
+    nsIContent* mostSpecificContent = sQuitItemContent;
+    if (menuBar && menuBar->mQuitItemContent) {
+      mostSpecificContent = menuBar->mQuitItemContent;
+    }
+    // If we have some content for quit we execute it. Otherwise we send a native app terminate
+    // message. If you want to stop a quit from happening, provide quit content and return
+    // the event as unhandled.
+    if (mostSpecificContent) {
+      nsMenuUtilsX::DispatchCommandTo(mostSpecificContent, modifierFlags, button);
+    } else {
+      nsCOMPtr<nsIAppStartup> appStartup = mozilla::components::AppStartup::Service();
+      if (appStartup) {
+        bool userAllowedQuit = true;
+        appStartup->Quit(nsIAppStartup::eAttemptQuit, 0, &userAllowedQuit);
+      }
+    }
+    return;
+  }
+
+  // given the commandID, look it up in our hashtable and dispatch to
+  // that menu item.
+  if (menuGroupOwner) {
+    if (RefPtr<nsMenuItemX> menuItem =
+            menuGroupOwner->GetMenuItemForCommandID(static_cast<uint32_t>(tag))) {
+      if (nsMenuUtilsX::gIsSynchronouslyActivatingNativeMenuItemDuringTest) {
+        menuItem->DoCommand(modifierFlags, button);
+      } else if (RefPtr<nsMenuX> menu = menuItem->ParentMenu()) {
+        menu->ActivateItemAfterClosing(std::move(menuItem), modifierFlags, button);
+      }
+    }
+  }
+}
+
+@end
+
+// Objective-C class used for menu items on the Services menu to allow Gecko
+// to override their standard behavior in order to stop key equivalents from
+// firing in certain instances. When gMenuItemsExecuteCommands is NO, we return
+// a dummy target and action instead of the actual target and action.
+
+@implementation GeckoServicesNSMenuItem
+
+- (id)target {
+  id realTarget = super.target;
+  if (gMenuItemsExecuteCommands) {
+    return realTarget;
+  }
+  return realTarget ? self : nil;
+}
+
+- (SEL)action {
+  SEL realAction = super.action;
+  if (gMenuItemsExecuteCommands) {
+    return realAction;
+  }
+  return realAction ? @selector(_doNothing:) : nullptr;
+}
+
+- (void)_doNothing:(id)aSender {
+}
+
+@end
+
+// Objective-C class used as the Services menu so that Gecko can override the
+// standard behavior of the Services menu in order to stop key equivalents
+// from firing in certain instances.
+
+@implementation GeckoServicesNSMenu
+
+- (void)addItem:(NSMenuItem*)aNewItem {
+  [self _overrideClassOfMenuItem:aNewItem];
+  [super addItem:aNewItem];
+}
+
+- (NSMenuItem*)addItemWithTitle:(NSString*)aString
+                         action:(SEL)aSelector
+                  keyEquivalent:(NSString*)aKeyEquiv {
+  NSMenuItem* newItem = [super addItemWithTitle:aString action:aSelector keyEquivalent:aKeyEquiv];
+  [self _overrideClassOfMenuItem:newItem];
+  return newItem;
+}
+
+- (void)insertItem:(NSMenuItem*)aNewItem atIndex:(NSInteger)aIndex {
+  [self _overrideClassOfMenuItem:aNewItem];
+  [super insertItem:aNewItem atIndex:aIndex];
+}
+
+- (NSMenuItem*)insertItemWithTitle:(NSString*)aString
+                            action:(SEL)aSelector
+                     keyEquivalent:(NSString*)aKeyEquiv
+                           atIndex:(NSInteger)aIndex {
+  NSMenuItem* newItem = [super insertItemWithTitle:aString
+                                            action:aSelector
+                                     keyEquivalent:aKeyEquiv
+                                           atIndex:aIndex];
+  [self _overrideClassOfMenuItem:newItem];
+  return newItem;
+}
+
+- (void)_overrideClassOfMenuItem:(NSMenuItem*)aMenuItem {
+  if ([aMenuItem class] == [NSMenuItem class]) {
+    object_setClass(aMenuItem, [GeckoServicesNSMenuItem class]);
+  }
+}
+
+@end
diff --git a/widget/cocoa/nsMenuGroupOwnerX.h b/widget/cocoa/nsMenuGroupOwnerX.h
new file mode 100644
index 0000000000..a9060a6029
--- /dev/null
+++ b/widget/cocoa/nsMenuGroupOwnerX.h
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMenuGroupOwnerX_h_
+#define nsMenuGroupOwnerX_h_
+
+#import <Cocoa/Cocoa.h>
+
+#include "mozilla/WeakPtr.h"
+
+#include "nsStubMutationObserver.h"
+#include "nsHashKeys.h"
+#include "nsIObserver.h"
+#include "nsMenuBarX.h"
+#include "nsTHashMap.h"
+#include "nsString.h"
+
+class nsMenuItemX;
+class nsChangeObserver;
+class nsIWidget;
+class nsIContent;
+
+@class MOZMenuItemRepresentedObject;
+
+// Fixed command IDs that work even without a JS listener, for our fallback menu bar.
+// Dynamic command IDs start counting from eCommand_ID_Last.
+enum {
+  eCommand_ID_About = 1,
+  eCommand_ID_Prefs = 2,
+  eCommand_ID_Quit = 3,
+  eCommand_ID_HideApp = 4,
+  eCommand_ID_HideOthers = 5,
+  eCommand_ID_ShowAll = 6,
+  eCommand_ID_Update = 7,
+  eCommand_ID_TouchBar = 8,
+  eCommand_ID_Account = 9,
+  eCommand_ID_Last = 10
+};
+
+// The menu group owner observes DOM mutations, notifies registered nsChangeObservers, and manages
+// command registration.
+// There is one owner per menubar, and one per standalone native menu.
+class nsMenuGroupOwnerX : public nsMultiMutationObserver, public nsIObserver {
+ public:
+  // Both parameters can be null.
+  nsMenuGroupOwnerX(mozilla::dom::Element* aElement, nsMenuBarX* aMenuBarIfMenuBar);
+
+  void RegisterForContentChanges(nsIContent* aContent, nsChangeObserver* aMenuObject);
+  void UnregisterForContentChanges(nsIContent* aContent);
+  uint32_t RegisterForCommand(nsMenuItemX* aMenuItem);
+  void UnregisterCommand(uint32_t aCommandID);
+  nsMenuItemX* GetMenuItemForCommandID(uint32_t aCommandID);
+
+  void RegisterForLocaleChanges();
+  void UnregisterForLocaleChanges();
+
+  // The representedObject that's used for all menu items under this menu group owner.
+  MOZMenuItemRepresentedObject* GetRepresentedObject() { return mRepresentedObject; }
+
+  // If this is the group owner for a menubar, return the menubar, otherwise nullptr.
+  nsMenuBarX* GetMenuBar() { return mMenuBar.get(); }
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+  NS_DECL_NSIMUTATIONOBSERVER
+
+ protected:
+  virtual ~nsMenuGroupOwnerX();
+
+  nsChangeObserver* LookupContentChangeObserver(nsIContent* aContent);
+
+  RefPtr<nsIContent> mContent;
+
+  // Unique command id (per menu-bar) to give to next item that asks.
+  uint32_t mCurrentCommandID = eCommand_ID_Last;
+
+  // stores observers for content change notification
+  nsTHashMap<nsPtrHashKey<nsIContent>, nsChangeObserver*> mContentToObserverTable;
+
+  // stores mapping of command IDs to menu objects
+  nsTHashMap<nsUint32HashKey, nsMenuItemX*> mCommandToMenuObjectTable;
+
+  MOZMenuItemRepresentedObject* mRepresentedObject = nil;  // [strong]
+  mozilla::WeakPtr<nsMenuBarX> mMenuBar;
+};
+
+@interface MOZMenuItemRepresentedObject : NSObject
+- (id)initWithMenuGroupOwner:(nsMenuGroupOwnerX*)aMenuGroupOwner;
+- (void)setMenuGroupOwner:(nsMenuGroupOwnerX*)aMenuGroupOwner;
+- (nsMenuGroupOwnerX*)menuGroupOwner;
+@end
+
+#endif  // nsMenuGroupOwner_h_
diff --git a/widget/cocoa/nsMenuGroupOwnerX.mm b/widget/cocoa/nsMenuGroupOwnerX.mm
new file mode 100644
index 0000000000..e7a0d2cf87
--- /dev/null
+++ b/widget/cocoa/nsMenuGroupOwnerX.mm
@@ -0,0 +1,226 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMenuGroupOwnerX.h"
+#include "nsMenuBarX.h"
+#include "nsMenuX.h"
+#include "nsMenuItemX.h"
+#include "nsMenuUtilsX.h"
+#include "nsCocoaUtils.h"
+#include "nsCocoaWindow.h"
+
+#include "nsCOMPtr.h"
+#include "nsString.h"
+#include "nsObjCExceptions.h"
+#include "nsThreadUtils.h"
+
+#include "mozilla/dom/Element.h"
+#include "nsIWidget.h"
+#include "mozilla/dom/Document.h"
+
+#include "nsINode.h"
+
+using namespace mozilla;
+
+NS_IMPL_ISUPPORTS(nsMenuGroupOwnerX, nsIObserver, nsIMutationObserver)
+
+nsMenuGroupOwnerX::nsMenuGroupOwnerX(mozilla::dom::Element* aElement, nsMenuBarX* aMenuBarIfMenuBar)
+    : mContent(aElement), mMenuBar(aMenuBarIfMenuBar) {
+  mRepresentedObject = [[MOZMenuItemRepresentedObject alloc] initWithMenuGroupOwner:this];
+}
+
+nsMenuGroupOwnerX::~nsMenuGroupOwnerX() {
+  MOZ_ASSERT(mContentToObserverTable.Count() == 0, "have outstanding mutation observers!\n");
+  [mRepresentedObject setMenuGroupOwner:nullptr];
+  [mRepresentedObject release];
+}
+
+//
+// nsIMutationObserver
+//
+
+void nsMenuGroupOwnerX::CharacterDataWillChange(nsIContent* aContent,
+                                                const CharacterDataChangeInfo&) {}
+
+void nsMenuGroupOwnerX::CharacterDataChanged(nsIContent* aContent, const CharacterDataChangeInfo&) {
+}
+
+void nsMenuGroupOwnerX::ContentAppended(nsIContent* aFirstNewContent) {
+  for (nsIContent* cur = aFirstNewContent; cur; cur = cur->GetNextSibling()) {
+    ContentInserted(cur);
+  }
+}
+
+void nsMenuGroupOwnerX::NodeWillBeDestroyed(nsINode* aNode) {}
+
+void nsMenuGroupOwnerX::AttributeWillChange(dom::Element* aElement, int32_t aNameSpaceID,
+                                            nsAtom* aAttribute, int32_t aModType) {}
+
+void nsMenuGroupOwnerX::AttributeChanged(dom::Element* aElement, int32_t aNameSpaceID,
+                                         nsAtom* aAttribute, int32_t aModType,
+                                         const nsAttrValue* aOldValue) {
+  nsCOMPtr<nsIMutationObserver> kungFuDeathGrip(this);
+  nsChangeObserver* obs = LookupContentChangeObserver(aElement);
+  if (obs) {
+    obs->ObserveAttributeChanged(aElement->OwnerDoc(), aElement, aAttribute);
+  }
+}
+
+void nsMenuGroupOwnerX::ContentRemoved(nsIContent* aChild, nsIContent* aPreviousSibling) {
+  nsIContent* container = aChild->GetParent();
+  if (!container) {
+    return;
+  }
+
+  nsCOMPtr<nsIMutationObserver> kungFuDeathGrip(this);
+  nsChangeObserver* obs = LookupContentChangeObserver(container);
+  if (obs) {
+    obs->ObserveContentRemoved(aChild->OwnerDoc(), container, aChild, aPreviousSibling);
+  } else if (container != mContent) {
+    // We do a lookup on the parent container in case things were removed
+    // under a "menupopup" item. That is basically a wrapper for the contents
+    // of a "menu" node.
+    nsCOMPtr<nsIContent> parent = container->GetParent();
+    if (parent) {
+      obs = LookupContentChangeObserver(parent);
+      if (obs) {
+        obs->ObserveContentRemoved(aChild->OwnerDoc(), container, aChild, aPreviousSibling);
+      }
+    }
+  }
+}
+
+void nsMenuGroupOwnerX::ContentInserted(nsIContent* aChild) {
+  nsIContent* container = aChild->GetParent();
+  if (!container) {
+    return;
+  }
+
+  nsCOMPtr<nsIMutationObserver> kungFuDeathGrip(this);
+  nsChangeObserver* obs = LookupContentChangeObserver(container);
+  if (obs) {
+    obs->ObserveContentInserted(aChild->OwnerDoc(), container, aChild);
+  } else if (container != mContent) {
+    // We do a lookup on the parent container in case things were removed
+    // under a "menupopup" item. That is basically a wrapper for the contents
+    // of a "menu" node.
+    nsCOMPtr<nsIContent> parent = container->GetParent();
+    if (parent) {
+      obs = LookupContentChangeObserver(parent);
+      if (obs) {
+        obs->ObserveContentInserted(aChild->OwnerDoc(), container, aChild);
+      }
+    }
+  }
+}
+
+void nsMenuGroupOwnerX::ParentChainChanged(nsIContent* aContent) {}
+
+void nsMenuGroupOwnerX::ARIAAttributeDefaultWillChange(mozilla::dom::Element* aElement,
+                                                       nsAtom* aAttribute, int32_t aModType) {}
+
+void nsMenuGroupOwnerX::ARIAAttributeDefaultChanged(mozilla::dom::Element* aElement,
+                                                    nsAtom* aAttribute, int32_t aModType) {}
+
+// For change management, we don't use a |nsSupportsHashtable| because
+// we know that the lifetime of all these items is bounded by the
+// lifetime of the menubar. No need to add any more strong refs to the
+// picture because the containment hierarchy already uses strong refs.
+void nsMenuGroupOwnerX::RegisterForContentChanges(nsIContent* aContent,
+                                                  nsChangeObserver* aMenuObject) {
+  if (!mContentToObserverTable.Contains(aContent)) {
+    aContent->AddMutationObserver(this);
+  }
+  mContentToObserverTable.InsertOrUpdate(aContent, aMenuObject);
+}
+
+void nsMenuGroupOwnerX::UnregisterForContentChanges(nsIContent* aContent) {
+  if (mContentToObserverTable.Contains(aContent)) {
+    aContent->RemoveMutationObserver(this);
+  }
+  mContentToObserverTable.Remove(aContent);
+}
+
+void nsMenuGroupOwnerX::RegisterForLocaleChanges() {
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (obs) {
+    obs->AddObserver(this, "intl:app-locales-changed", false);
+  }
+}
+
+void nsMenuGroupOwnerX::UnregisterForLocaleChanges() {
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (obs) {
+    obs->RemoveObserver(this, "intl:app-locales-changed");
+  }
+}
+
+NS_IMETHODIMP
+nsMenuGroupOwnerX::Observe(nsISupports* aSubject, const char* aTopic, const char16_t* aData) {
+  if (mMenuBar && !strcmp(aTopic, "intl:app-locales-changed")) {
+    // Rebuild the menu with the new locale strings.
+    mMenuBar->SetNeedsRebuild();
+  }
+  return NS_OK;
+}
+
+nsChangeObserver* nsMenuGroupOwnerX::LookupContentChangeObserver(nsIContent* aContent) {
+  nsChangeObserver* result;
+  if (mContentToObserverTable.Get(aContent, &result)) {
+    return result;
+  }
+  return nullptr;
+}
+
+// Given a menu item, creates a unique 4-character command ID and
+// maps it to the item. Returns the id for use by the client.
+uint32_t nsMenuGroupOwnerX::RegisterForCommand(nsMenuItemX* aMenuItem) {
+  // no real need to check for uniqueness. We always start afresh with each
+  // window at 1. Even if we did get close to the reserved Apple command id's,
+  // those don't start until at least '    ', which is integer 538976288. If
+  // we have that many menu items in one window, I think we have other
+  // problems.
+
+  // make id unique
+  ++mCurrentCommandID;
+
+  mCommandToMenuObjectTable.InsertOrUpdate(mCurrentCommandID, aMenuItem);
+
+  return mCurrentCommandID;
+}
+
+// Removes the mapping between the given 4-character command ID
+// and its associated menu item.
+void nsMenuGroupOwnerX::UnregisterCommand(uint32_t aCommandID) {
+  mCommandToMenuObjectTable.Remove(aCommandID);
+}
+
+nsMenuItemX* nsMenuGroupOwnerX::GetMenuItemForCommandID(uint32_t aCommandID) {
+  nsMenuItemX* result;
+  if (mCommandToMenuObjectTable.Get(aCommandID, &result)) {
+    return result;
+  }
+  return nullptr;
+}
+
+@implementation MOZMenuItemRepresentedObject {
+  nsMenuGroupOwnerX* mMenuGroupOwner;  // weak, cleared by nsMenuGroupOwnerX's destructor
+}
+
+- (id)initWithMenuGroupOwner:(nsMenuGroupOwnerX*)aMenuGroupOwner {
+  self = [super init];
+  mMenuGroupOwner = aMenuGroupOwner;
+  return self;
+}
+
+- (void)setMenuGroupOwner:(nsMenuGroupOwnerX*)aMenuGroupOwner {
+  mMenuGroupOwner = aMenuGroupOwner;
+}
+
+- (nsMenuGroupOwnerX*)menuGroupOwner {
+  return mMenuGroupOwner;
+}
+
+@end
diff --git a/widget/cocoa/nsMenuItemIconX.h b/widget/cocoa/nsMenuItemIconX.h
new file mode 100644
index 0000000000..e60e920f9d
--- /dev/null
+++ b/widget/cocoa/nsMenuItemIconX.h
@@ -0,0 +1,70 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Retrieves and displays icons in native menu items on Mac OS X.
+ */
+
+#ifndef nsMenuItemIconX_h_
+#define nsMenuItemIconX_h_
+
+#import <Cocoa/Cocoa.h>
+
+#include "mozilla/widget/IconLoader.h"
+#include "mozilla/WeakPtr.h"
+
+class nsIconLoaderService;
+class nsIURI;
+class nsIContent;
+class nsIPrincipal;
+class imgRequestProxy;
+class nsMenuParentX;
+class nsPresContext;
+
+namespace mozilla {
+class ComputedStyle;
+}
+
+class nsMenuItemIconX final : public mozilla::widget::IconLoader::Listener {
+ public:
+  class Listener {
+   public:
+    virtual void IconUpdated() = 0;
+  };
+
+  explicit nsMenuItemIconX(Listener* aListener);
+  ~nsMenuItemIconX();
+
+  // SetupIcon starts the icon load. Once the icon has loaded,
+  // nsMenuParentX::IconUpdated will be called. The icon image needs to be
+  // retrieved from GetIconImage(). If aContent is an icon-less menuitem,
+  // GetIconImage() will return nil. If it does have an icon, GetIconImage()
+  // will return a transparent placeholder icon during the load and the actual
+  // icon when the load is completed.
+  void SetupIcon(nsIContent* aContent);
+
+  // Implements this method for mozilla::widget::IconLoader::Listener.
+  // Called once the icon load is complete.
+  nsresult OnComplete(imgIContainer* aImage) override;
+
+  // Returns a weak reference to the icon image that is owned by this class. Can
+  // return nil.
+  NSImage* GetIconImage() const { return mIconImage; }
+
+ protected:
+  // Returns whether there should be an icon.
+  bool StartIconLoad(nsIContent* aContent);
+
+  // GetIconURI returns null if the item should not have any icon.
+  already_AddRefed<nsIURI> GetIconURI(nsIContent* aContent);
+
+  Listener* mListener;  // [weak]
+  RefPtr<const mozilla::ComputedStyle> mComputedStyle;
+  mozilla::WeakPtr<nsPresContext> mPresContext;
+  NSImage* mIconImage = nil;  // [strong]
+  RefPtr<mozilla::widget::IconLoader> mIconLoader;
+};
+
+#endif  // nsMenuItemIconX_h_
diff --git a/widget/cocoa/nsMenuItemIconX.mm b/widget/cocoa/nsMenuItemIconX.mm
new file mode 100644
index 0000000000..db94ec910e
--- /dev/null
+++ b/widget/cocoa/nsMenuItemIconX.mm
@@ -0,0 +1,170 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Retrieves and displays icons in native menu items on Mac OS X.
+ */
+
+/* exception_defines.h defines 'try' to 'if (true)' which breaks objective-c
+   exceptions and produces errors like: error: unexpected '@' in program'.
+   If we define __EXCEPTIONS exception_defines.h will avoid doing this.
+
+   See bug 666609 for more information.
+
+   We use <limits> to get the libstdc++ version. */
+#include <limits>
+#if __GLIBCXX__ <= 20070719
+#  ifndef __EXCEPTIONS
+#    define __EXCEPTIONS
+#  endif
+#endif
+
+#include "MOZIconHelper.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include "nsCocoaUtils.h"
+#include "nsComputedDOMStyle.h"
+#include "nsContentUtils.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+#include "nsIContentPolicy.h"
+#include "nsMenuItemX.h"
+#include "nsMenuItemIconX.h"
+#include "nsNameSpaceManager.h"
+#include "nsObjCExceptions.h"
+
+using namespace mozilla;
+
+using mozilla::dom::Element;
+using mozilla::widget::IconLoader;
+
+static const uint32_t kIconSize = 16;
+
+nsMenuItemIconX::nsMenuItemIconX(Listener* aListener) : mListener(aListener) {
+  MOZ_COUNT_CTOR(nsMenuItemIconX);
+}
+
+nsMenuItemIconX::~nsMenuItemIconX() {
+  if (mIconLoader) {
+    mIconLoader->Destroy();
+  }
+  if (mIconImage) {
+    [mIconImage release];
+    mIconImage = nil;
+  }
+  MOZ_COUNT_DTOR(nsMenuItemIconX);
+}
+
+void nsMenuItemIconX::SetupIcon(nsIContent* aContent) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  bool shouldHaveIcon = StartIconLoad(aContent);
+  if (!shouldHaveIcon) {
+    // There is no icon for this menu item, as an error occurred while loading it.
+    // An icon might have been set earlier or the place holder icon may have
+    // been set.  Clear it.
+    if (mIconImage) {
+      [mIconImage release];
+      mIconImage = nil;
+    }
+    return;
+  }
+
+  if (!mIconImage) {
+    // Set a placeholder icon, so that the menuitem reserves space for the icon during the load and
+    // there is no sudden shift once the icon finishes loading.
+    NSSize iconSize = NSMakeSize(kIconSize, kIconSize);
+    mIconImage = [[MOZIconHelper placeholderIconWithSize:iconSize] retain];
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+bool nsMenuItemIconX::StartIconLoad(nsIContent* aContent) {
+  RefPtr<nsIURI> iconURI = GetIconURI(aContent);
+  if (!iconURI) {
+    return false;
+  }
+
+  if (!mIconLoader) {
+    mIconLoader = new IconLoader(this);
+  }
+
+  nsresult rv = mIconLoader->LoadIcon(iconURI, aContent);
+  return NS_SUCCEEDED(rv);
+}
+
+already_AddRefed<nsIURI> nsMenuItemIconX::GetIconURI(nsIContent* aContent) {
+  // First, look at the content node's "image" attribute.
+  nsAutoString imageURIString;
+  bool hasImageAttr =
+      aContent->IsElement() &&
+      aContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::image, imageURIString);
+
+  if (hasImageAttr) {
+    // Use the URL from the image attribute.
+    // If this menu item shouldn't have an icon, the string will be empty,
+    // and NS_NewURI will fail.
+    RefPtr<nsIURI> iconURI;
+    nsresult rv = NS_NewURI(getter_AddRefs(iconURI), imageURIString);
+    if (NS_FAILED(rv)) {
+      return nullptr;
+    }
+    return iconURI.forget();
+  }
+
+  // If the content node has no "image" attribute, get the
+  // "list-style-image" property from CSS.
+  RefPtr<mozilla::dom::Document> document = aContent->GetComposedDoc();
+  if (!document || !aContent->IsElement()) {
+    return nullptr;
+  }
+
+  RefPtr<const ComputedStyle> sc = nsComputedDOMStyle::GetComputedStyle(aContent->AsElement());
+  if (!sc) {
+    return nullptr;
+  }
+
+  RefPtr<nsIURI> iconURI = sc->StyleList()->GetListStyleImageURI();
+  if (!iconURI) {
+    return nullptr;
+  }
+
+  mComputedStyle = std::move(sc);
+  mPresContext = document->GetPresContext();
+
+  return iconURI.forget();
+}
+
+//
+// mozilla::widget::IconLoader::Listener
+//
+
+nsresult nsMenuItemIconX::OnComplete(imgIContainer* aImage) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (mIconImage) {
+    [mIconImage release];
+    mIconImage = nil;
+  }
+  RefPtr<nsPresContext> pc = mPresContext.get();
+  mIconImage = [[MOZIconHelper iconImageFromImageContainer:aImage
+                                                  withSize:NSMakeSize(kIconSize, kIconSize)
+                                               presContext:pc
+                                             computedStyle:mComputedStyle
+                                               scaleFactor:0.0f] retain];
+  mComputedStyle = nullptr;
+  mPresContext = nullptr;
+
+  if (mListener) {
+    mListener->IconUpdated();
+  }
+
+  mIconLoader->Destroy();
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
diff --git a/widget/cocoa/nsMenuItemX.h b/widget/cocoa/nsMenuItemX.h
new file mode 100644
index 0000000000..980105e123
--- /dev/null
+++ b/widget/cocoa/nsMenuItemX.h
@@ -0,0 +1,105 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMenuItemX_h_
+#define nsMenuItemX_h_
+
+#include "mozilla/RefPtr.h"
+#include "nsISupports.h"
+#include "nsMenuGroupOwnerX.h"
+#include "nsMenuItemIconX.h"
+#include "nsChangeObserver.h"
+#include "nsStringFwd.h"
+
+#import <Cocoa/Cocoa.h>
+
+class nsMenuItemIconX;
+class nsMenuX;
+class nsMenuParentX;
+
+namespace mozilla {
+namespace dom {
+class Element;
+}
+}  // namespace mozilla
+
+enum {
+  knsMenuItemNoModifier = 0,
+  knsMenuItemShiftModifier = (1 << 0),
+  knsMenuItemAltModifier = (1 << 1),
+  knsMenuItemControlModifier = (1 << 2),
+  knsMenuItemCommandModifier = (1 << 3)
+};
+
+enum EMenuItemType {
+  eRegularMenuItemType = 0,
+  eCheckboxMenuItemType,
+  eRadioMenuItemType,
+  eSeparatorMenuItemType
+};
+
+// Once instantiated, this object lives until its DOM node or its parent window
+// is destroyed. Do not hold references to this, they can become invalid any
+// time the DOM node can be destroyed.
+class nsMenuItemX final : public nsChangeObserver,
+                          public nsMenuItemIconX::Listener {
+ public:
+  nsMenuItemX(nsMenuX* aParent, const nsString& aLabel, EMenuItemType aItemType,
+              nsMenuGroupOwnerX* aMenuGroupOwner, nsIContent* aNode);
+
+  bool IsVisible() const { return mIsVisible; }
+
+  // Unregisters nsMenuX from the nsMenuGroupOwner, and nulls out the group
+  // owner pointer. This is needed because nsMenuX is reference-counted and can
+  // outlive its owner, and the menu group owner asserts that everything has
+  // been unregistered when it is destroyed.
+  void DetachFromGroupOwner();
+
+  // Nulls out our reference to the parent.
+  // This is needed because nsMenuX is reference-counted and can outlive its
+  // parent.
+  void DetachFromParent() { mMenuParent = nullptr; }
+
+  NS_INLINE_DECL_REFCOUNTING(nsMenuItemX)
+
+  NS_DECL_CHANGEOBSERVER
+
+  // nsMenuItemIconX::Listener
+  void IconUpdated() override;
+
+  // nsMenuItemX
+  nsresult SetChecked(bool aIsChecked);
+  EMenuItemType GetMenuItemType();
+  void DoCommand(NSEventModifierFlags aModifierFlags, int16_t aButton);
+  nsresult DispatchDOMEvent(const nsString& eventName,
+                            bool* preventDefaultCalled);
+  void SetupIcon();
+  nsMenuX* ParentMenu() { return mMenuParent; }
+  nsIContent* Content() { return mContent; }
+  NSMenuItem* NativeNSMenuItem() { return mNativeMenuItem; }
+
+  void Dump(uint32_t aIndent) const;
+
+ protected:
+  virtual ~nsMenuItemX();
+
+  void UncheckRadioSiblings(nsIContent* aCheckedElement);
+  void SetKeyEquiv();
+
+  nsCOMPtr<nsIContent> mContent;  // XUL <menuitem> or <menuseparator>
+
+  EMenuItemType mType;
+
+  // nsMenuItemX objects should always have a valid native menu item.
+  NSMenuItem* mNativeMenuItem = nil;             // [strong]
+  nsMenuX* mMenuParent = nullptr;                // [weak]
+  nsMenuGroupOwnerX* mMenuGroupOwner = nullptr;  // [weak]
+  RefPtr<mozilla::dom::Element> mCommandElement;
+  mozilla::UniquePtr<nsMenuItemIconX> mIcon;  // always non-null
+  bool mIsChecked = false;
+  bool mIsVisible = false;
+};
+
+#endif  // nsMenuItemX_h_
diff --git a/widget/cocoa/nsMenuItemX.mm b/widget/cocoa/nsMenuItemX.mm
new file mode 100644
index 0000000000..175dad525c
--- /dev/null
+++ b/widget/cocoa/nsMenuItemX.mm
@@ -0,0 +1,401 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMenuItemX.h"
+#include "nsMenuBarX.h"
+#include "nsMenuX.h"
+#include "nsMenuItemIconX.h"
+#include "nsMenuUtilsX.h"
+#include "nsCocoaUtils.h"
+
+#include "nsObjCExceptions.h"
+
+#include "nsCOMPtr.h"
+#include "nsGkAtoms.h"
+
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/ErrorResult.h"
+#include "nsIWidget.h"
+#include "mozilla/dom/Document.h"
+
+using namespace mozilla;
+
+using mozilla::dom::CallerType;
+using mozilla::dom::Event;
+
+nsMenuItemX::nsMenuItemX(nsMenuX* aParent, const nsString& aLabel, EMenuItemType aItemType,
+                         nsMenuGroupOwnerX* aMenuGroupOwner, nsIContent* aNode)
+    : mContent(aNode), mType(aItemType), mMenuParent(aParent), mMenuGroupOwner(aMenuGroupOwner) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  MOZ_COUNT_CTOR(nsMenuItemX);
+
+  MOZ_RELEASE_ASSERT(mContent->IsElement(), "nsMenuItemX should only be created for elements");
+  NS_ASSERTION(mMenuGroupOwner, "No menu owner given, must have one!");
+
+  mMenuGroupOwner->RegisterForContentChanges(mContent, this);
+
+  dom::Document* doc = mContent->GetUncomposedDoc();
+
+  // if we have a command associated with this menu item, register for changes
+  // to the command DOM node
+  if (doc) {
+    nsAutoString ourCommand;
+    mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::command, ourCommand);
+
+    if (!ourCommand.IsEmpty()) {
+      dom::Element* commandElement = doc->GetElementById(ourCommand);
+
+      if (commandElement) {
+        mCommandElement = commandElement;
+        // register to observe the command DOM element
+        mMenuGroupOwner->RegisterForContentChanges(mCommandElement, this);
+      }
+    }
+  }
+
+  // decide enabled state based on command content if it exists, otherwise do it based
+  // on our own content
+  bool isEnabled;
+  if (mCommandElement) {
+    isEnabled = !mCommandElement->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                                              nsGkAtoms::_true, eCaseMatters);
+  } else {
+    isEnabled = !mContent->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                                                    nsGkAtoms::_true, eCaseMatters);
+  }
+
+  // set up the native menu item
+  if (mType == eSeparatorMenuItemType) {
+    mNativeMenuItem = [[NSMenuItem separatorItem] retain];
+  } else {
+    NSString* newCocoaLabelString = nsMenuUtilsX::GetTruncatedCocoaLabel(aLabel);
+    mNativeMenuItem = [[NSMenuItem alloc] initWithTitle:newCocoaLabelString
+                                                 action:nil
+                                          keyEquivalent:@""];
+
+    mIsChecked = mContent->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::checked,
+                                                    nsGkAtoms::_true, eCaseMatters);
+
+    mNativeMenuItem.enabled = isEnabled;
+    mNativeMenuItem.state = mIsChecked ? NSOnState : NSOffState;
+
+    SetKeyEquiv();
+  }
+
+  mIcon = MakeUnique<nsMenuItemIconX>(this);
+
+  mIsVisible = !nsMenuUtilsX::NodeIsHiddenOrCollapsed(mContent);
+
+  // All menu items share the same target and action, and are differentiated
+  // be a unique (representedObject, tag) pair.
+  mNativeMenuItem.target = nsMenuBarX::sNativeEventTarget;
+  mNativeMenuItem.action = @selector(menuItemHit:);
+  mNativeMenuItem.representedObject = mMenuGroupOwner->GetRepresentedObject();
+  mNativeMenuItem.tag = mMenuGroupOwner->RegisterForCommand(this);
+
+  if (mIsVisible) {
+    SetupIcon();
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+nsMenuItemX::~nsMenuItemX() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // autorelease the native menu item so that anything else happening to this
+  // object happens before the native menu item actually dies
+  [mNativeMenuItem autorelease];
+
+  DetachFromGroupOwner();
+
+  MOZ_COUNT_DTOR(nsMenuItemX);
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuItemX::DetachFromGroupOwner() {
+  if (mMenuGroupOwner) {
+    mMenuGroupOwner->UnregisterCommand(mNativeMenuItem.tag);
+
+    if (mContent) {
+      mMenuGroupOwner->UnregisterForContentChanges(mContent);
+    }
+    if (mCommandElement) {
+      mMenuGroupOwner->UnregisterForContentChanges(mCommandElement);
+    }
+  }
+
+  mMenuGroupOwner = nullptr;
+}
+
+nsresult nsMenuItemX::SetChecked(bool aIsChecked) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  mIsChecked = aIsChecked;
+
+  // update the content model. This will also handle unchecking our siblings
+  // if we are a radiomenu
+  if (mIsChecked) {
+    mContent->AsElement()->SetAttr(kNameSpaceID_None, nsGkAtoms::checked, u"true"_ns, true);
+  } else {
+    mContent->AsElement()->UnsetAttr(kNameSpaceID_None, nsGkAtoms::checked, true);
+  }
+
+  // update native menu item
+  mNativeMenuItem.state = mIsChecked ? NSOnState : NSOffState;
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+EMenuItemType nsMenuItemX::GetMenuItemType() { return mType; }
+
+// Executes the "cached" javaScript command.
+// Returns NS_OK if the command was executed properly, otherwise an error code.
+void nsMenuItemX::DoCommand(NSEventModifierFlags aModifierFlags, int16_t aButton) {
+  // flip "checked" state if we're a checkbox menu, or an un-checked radio menu
+  if (mType == eCheckboxMenuItemType || (mType == eRadioMenuItemType && !mIsChecked)) {
+    if (!mContent->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::autocheck,
+                                            nsGkAtoms::_false, eCaseMatters)) {
+      SetChecked(!mIsChecked);
+    }
+    /* the AttributeChanged code will update all the internal state */
+  }
+
+  nsMenuUtilsX::DispatchCommandTo(mContent, aModifierFlags, aButton);
+}
+
+nsresult nsMenuItemX::DispatchDOMEvent(const nsString& eventName, bool* preventDefaultCalled) {
+  if (!mContent) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // get owner document for content
+  nsCOMPtr<dom::Document> parentDoc = mContent->OwnerDoc();
+
+  // create DOM event
+  ErrorResult rv;
+  RefPtr<Event> event = parentDoc->CreateEvent(u"Events"_ns, CallerType::System, rv);
+  if (rv.Failed()) {
+    NS_WARNING("Failed to create Event");
+    return rv.StealNSResult();
+  }
+  event->InitEvent(eventName, true, true);
+
+  // mark DOM event as trusted
+  event->SetTrusted(true);
+
+  // send DOM event
+  *preventDefaultCalled = mContent->DispatchEvent(*event, CallerType::System, rv);
+  if (rv.Failed()) {
+    NS_WARNING("Failed to send DOM event via EventTarget");
+    return rv.StealNSResult();
+  }
+
+  return NS_OK;
+}
+
+// Walk the sibling list looking for nodes with the same name and
+// uncheck them all.
+void nsMenuItemX::UncheckRadioSiblings(nsIContent* aCheckedContent) {
+  nsAutoString myGroupName;
+  aCheckedContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::name, myGroupName);
+  if (!myGroupName.Length()) {  // no groupname, nothing to do
+    return;
+  }
+
+  nsCOMPtr<nsIContent> parent = aCheckedContent->GetParent();
+  if (!parent) {
+    return;
+  }
+
+  // loop over siblings
+  for (nsIContent* sibling = parent->GetFirstChild(); sibling;
+       sibling = sibling->GetNextSibling()) {
+    if (sibling != aCheckedContent && sibling->IsElement()) {  // skip this node
+      // if the current sibling is in the same group, clear it
+      if (sibling->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::name, myGroupName,
+                                            eCaseMatters)) {
+        sibling->AsElement()->SetAttr(kNameSpaceID_None, nsGkAtoms::checked, u"false"_ns, true);
+      }
+    }
+  }
+}
+
+void nsMenuItemX::SetKeyEquiv() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // Set key shortcut and modifiers
+  nsAutoString keyValue;
+  mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::key, keyValue);
+
+  if (!keyValue.IsEmpty() && mContent->GetUncomposedDoc()) {
+    dom::Element* keyContent = mContent->GetUncomposedDoc()->GetElementById(keyValue);
+    if (keyContent) {
+      nsAutoString keyChar;
+      bool hasKey = keyContent->GetAttr(kNameSpaceID_None, nsGkAtoms::key, keyChar);
+
+      if (!hasKey || keyChar.IsEmpty()) {
+        nsAutoString keyCodeName;
+        keyContent->GetAttr(kNameSpaceID_None, nsGkAtoms::keycode, keyCodeName);
+        uint32_t charCode = nsCocoaUtils::ConvertGeckoNameToMacCharCode(keyCodeName);
+        if (charCode) {
+          keyChar.Assign(charCode);
+        } else {
+          keyChar.AssignLiteral(u" ");
+        }
+      }
+
+      nsAutoString modifiersStr;
+      keyContent->GetAttr(kNameSpaceID_None, nsGkAtoms::modifiers, modifiersStr);
+      uint8_t modifiers = nsMenuUtilsX::GeckoModifiersForNodeAttribute(modifiersStr);
+
+      unsigned int macModifiers = nsMenuUtilsX::MacModifiersForGeckoModifiers(modifiers);
+      mNativeMenuItem.keyEquivalentModifierMask = macModifiers;
+
+      NSString* keyEquivalent = [[NSString stringWithCharacters:(unichar*)keyChar.get()
+                                                         length:keyChar.Length()] lowercaseString];
+      if ([keyEquivalent isEqualToString:@" "]) {
+        mNativeMenuItem.keyEquivalent = @"";
+      } else {
+        mNativeMenuItem.keyEquivalent = keyEquivalent;
+      }
+
+      return;
+    }
+  }
+
+  // if the key was removed, clear the key
+  mNativeMenuItem.keyEquivalent = @"";
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuItemX::Dump(uint32_t aIndent) const {
+  printf("%*s - item [%p] %-16s <%s>\n", aIndent * 2, "", this,
+         mType == eSeparatorMenuItemType ? "----" : [mNativeMenuItem.title UTF8String],
+         NS_ConvertUTF16toUTF8(mContent->NodeName()).get());
+}
+
+//
+// nsChangeObserver
+//
+
+void nsMenuItemX::ObserveAttributeChanged(dom::Document* aDocument, nsIContent* aContent,
+                                          nsAtom* aAttribute) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (!aContent) {
+    return;
+  }
+
+  if (aContent == mContent) {  // our own content node changed
+    if (aAttribute == nsGkAtoms::checked) {
+      // if we're a radio menu, uncheck our sibling radio items. No need to
+      // do any of this if we're just a normal check menu.
+      if (mType == eRadioMenuItemType &&
+          mContent->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::checked,
+                                             nsGkAtoms::_true, eCaseMatters)) {
+        UncheckRadioSiblings(mContent);
+      }
+      mMenuParent->SetRebuild(true);
+    } else if (aAttribute == nsGkAtoms::hidden || aAttribute == nsGkAtoms::collapsed) {
+      bool isVisible = !nsMenuUtilsX::NodeIsHiddenOrCollapsed(mContent);
+      if (isVisible != mIsVisible) {
+        mIsVisible = isVisible;
+        RefPtr<nsMenuItemX> self = this;
+        mMenuParent->MenuChildChangedVisibility(nsMenuParentX::MenuChild(self), isVisible);
+        if (mIsVisible) {
+          SetupIcon();
+        }
+      }
+      mMenuParent->SetRebuild(true);
+    } else if (aAttribute == nsGkAtoms::label) {
+      if (mType != eSeparatorMenuItemType) {
+        nsAutoString newLabel;
+        mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::label, newLabel);
+        mNativeMenuItem.title = nsMenuUtilsX::GetTruncatedCocoaLabel(newLabel);
+      }
+    } else if (aAttribute == nsGkAtoms::key) {
+      SetKeyEquiv();
+    } else if (aAttribute == nsGkAtoms::image) {
+      SetupIcon();
+    } else if (aAttribute == nsGkAtoms::disabled) {
+      mNativeMenuItem.enabled = !aContent->AsElement()->AttrValueIs(
+          kNameSpaceID_None, nsGkAtoms::disabled, nsGkAtoms::_true, eCaseMatters);
+    }
+  } else if (aContent == mCommandElement) {
+    // the only thing that really matters when the menu isn't showing is the
+    // enabled state since it enables/disables keyboard commands
+    if (aAttribute == nsGkAtoms::disabled) {
+      // first we sync our menu item DOM node with the command DOM node
+      nsAutoString commandDisabled;
+      nsAutoString menuDisabled;
+      aContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::disabled, commandDisabled);
+      mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::disabled, menuDisabled);
+      if (!commandDisabled.Equals(menuDisabled)) {
+        // The menu's disabled state needs to be updated to match the command.
+        if (commandDisabled.IsEmpty()) {
+          mContent->AsElement()->UnsetAttr(kNameSpaceID_None, nsGkAtoms::disabled, true);
+        } else {
+          mContent->AsElement()->SetAttr(kNameSpaceID_None, nsGkAtoms::disabled, commandDisabled,
+                                         true);
+        }
+      }
+      // now we sync our native menu item with the command DOM node
+      mNativeMenuItem.enabled = !aContent->AsElement()->AttrValueIs(
+          kNameSpaceID_None, nsGkAtoms::disabled, nsGkAtoms::_true, eCaseMatters);
+    }
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+bool IsMenuStructureElement(nsIContent* aContent) {
+  return aContent->IsAnyOfXULElements(nsGkAtoms::menu, nsGkAtoms::menuitem,
+                                      nsGkAtoms::menuseparator);
+}
+
+void nsMenuItemX::ObserveContentRemoved(dom::Document* aDocument, nsIContent* aContainer,
+                                        nsIContent* aChild, nsIContent* aPreviousSibling) {
+  MOZ_RELEASE_ASSERT(mMenuGroupOwner);
+  MOZ_RELEASE_ASSERT(mMenuParent);
+
+  if (aChild == mCommandElement) {
+    mMenuGroupOwner->UnregisterForContentChanges(mCommandElement);
+    mCommandElement = nullptr;
+  }
+  if (IsMenuStructureElement(aChild)) {
+    mMenuParent->SetRebuild(true);
+  }
+}
+
+void nsMenuItemX::ObserveContentInserted(dom::Document* aDocument, nsIContent* aContainer,
+                                         nsIContent* aChild) {
+  MOZ_RELEASE_ASSERT(mMenuParent);
+
+  // The child node could come from the custom element that is for display, so
+  // only rebuild the menu if the child is related to the structure of the
+  // menu.
+  if (IsMenuStructureElement(aChild)) {
+    mMenuParent->SetRebuild(true);
+  }
+}
+
+void nsMenuItemX::SetupIcon() {
+  if (mType != eRegularMenuItemType) {
+    // Don't support icons on checkbox and radio menuitems, for consistency with Windows & Linux.
+    return;
+  }
+
+  mIcon->SetupIcon(mContent);
+  mNativeMenuItem.image = mIcon->GetIconImage();
+}
+
+void nsMenuItemX::IconUpdated() { mNativeMenuItem.image = mIcon->GetIconImage(); }
diff --git a/widget/cocoa/nsMenuParentX.h b/widget/cocoa/nsMenuParentX.h
new file mode 100644
index 0000000000..a1f705631a
--- /dev/null
+++ b/widget/cocoa/nsMenuParentX.h
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMenuParentX_h_
+#define nsMenuParentX_h_
+
+#include "mozilla/RefPtr.h"
+#include "mozilla/Variant.h"
+
+class nsMenuX;
+class nsMenuBarX;
+class nsMenuItemX;
+
+// A base class for objects that can be the parent of an nsMenuX or nsMenuItemX.
+class nsMenuParentX {
+ public:
+  using MenuChild = mozilla::Variant<RefPtr<nsMenuX>, RefPtr<nsMenuItemX>>;
+
+  // XXXmstange double-check that this is still needed
+  virtual nsMenuBarX* AsMenuBar() { return nullptr; }
+
+  // Called when aChild becomes visible or hidden, so that the parent can insert
+  // or remove the child's native menu item from its NSMenu and update its state
+  // of visible items.
+  virtual void MenuChildChangedVisibility(const MenuChild& aChild,
+                                          bool aIsVisible) = 0;
+};
+
+#endif  // nsMenuParentX_h_
diff --git a/widget/cocoa/nsMenuUtilsX.h b/widget/cocoa/nsMenuUtilsX.h
new file mode 100644
index 0000000000..0ec8d8555d
--- /dev/null
+++ b/widget/cocoa/nsMenuUtilsX.h
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMenuUtilsX_h_
+#define nsMenuUtilsX_h_
+
+#include "nscore.h"
+#include "nsStringFwd.h"
+
+#import <Cocoa/Cocoa.h>
+
+class nsIContent;
+class nsMenuBarX;
+class nsMenuX;
+
+// Namespace containing utility functions used in our native menu implementation.
+namespace nsMenuUtilsX {
+void DispatchCommandTo(nsIContent* aTargetContent, NSEventModifierFlags aModifierFlags,
+                       int16_t aButton);
+NSString* GetTruncatedCocoaLabel(const nsString& itemLabel);
+uint8_t GeckoModifiersForNodeAttribute(const nsString& modifiersAttribute);
+unsigned int MacModifiersForGeckoModifiers(uint8_t geckoModifiers);
+nsMenuBarX* GetHiddenWindowMenuBar();   // returned object is not retained
+NSMenuItem* GetStandardEditMenuItem();  // returned object is not retained
+bool NodeIsHiddenOrCollapsed(nsIContent* aContent);
+
+// Find the menu item by following the path aLocationString from aRootMenu.
+// aLocationString is a '|'-separated list of integers, where each integer is
+// the index of the menu item in the menu.
+// aIsMenuBar needs to be true if aRootMenu is the app's mainMenu, so that the
+// app menu can be skipped during the search.
+NSMenuItem* NativeMenuItemWithLocation(NSMenu* aRootMenu, NSString* aLocationString,
+                                       bool aIsMenuBar);
+
+// Traverse the menu tree and check that there are no cycles or NSMenu(Item) objects that are used
+// more than once. If inconsistencies are found, these functions crash the process.
+void CheckNativeMenuConsistency(NSMenu* aMenu);
+void CheckNativeMenuConsistency(NSMenuItem* aMenuItem);
+
+// Print out debugging information about the native menu tree structure.
+void DumpNativeMenu(NSMenu* aMenu);
+void DumpNativeMenuItem(NSMenuItem* aMenuItem);
+
+extern bool gIsSynchronouslyActivatingNativeMenuItemDuringTest;
+
+}  // namespace nsMenuUtilsX
+
+#endif  // nsMenuUtilsX_h_
diff --git a/widget/cocoa/nsMenuUtilsX.mm b/widget/cocoa/nsMenuUtilsX.mm
new file mode 100644
index 0000000000..aca279d64c
--- /dev/null
+++ b/widget/cocoa/nsMenuUtilsX.mm
@@ -0,0 +1,294 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMenuUtilsX.h"
+#include <unordered_set>
+
+#include "mozilla/EventForwards.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/dom/XULCommandEvent.h"
+#include "nsMenuBarX.h"
+#include "nsMenuX.h"
+#include "nsMenuItemX.h"
+#include "NativeMenuMac.h"
+#include "nsObjCExceptions.h"
+#include "nsCocoaUtils.h"
+#include "nsCocoaWindow.h"
+#include "nsGkAtoms.h"
+#include "nsGlobalWindowInner.h"
+#include "nsPIDOMWindow.h"
+#include "nsQueryObject.h"
+
+using namespace mozilla;
+
+bool nsMenuUtilsX::gIsSynchronouslyActivatingNativeMenuItemDuringTest = false;
+
+void nsMenuUtilsX::DispatchCommandTo(nsIContent* aTargetContent,
+                                     NSEventModifierFlags aModifierFlags, int16_t aButton) {
+  MOZ_ASSERT(aTargetContent, "null ptr");
+
+  dom::Document* doc = aTargetContent->OwnerDoc();
+  if (doc) {
+    RefPtr<dom::XULCommandEvent> event =
+        new dom::XULCommandEvent(doc, doc->GetPresContext(), nullptr);
+
+    bool ctrlKey = aModifierFlags & NSEventModifierFlagControl;
+    bool altKey = aModifierFlags & NSEventModifierFlagOption;
+    bool shiftKey = aModifierFlags & NSEventModifierFlagShift;
+    bool cmdKey = aModifierFlags & NSEventModifierFlagCommand;
+
+    IgnoredErrorResult rv;
+    event->InitCommandEvent(u"command"_ns, true, true,
+                            nsGlobalWindowInner::Cast(doc->GetInnerWindow()), 0, ctrlKey, altKey,
+                            shiftKey, cmdKey, aButton, nullptr, 0, rv);
+    if (!rv.Failed()) {
+      event->SetTrusted(true);
+      aTargetContent->DispatchEvent(*event);
+    }
+  }
+}
+
+NSString* nsMenuUtilsX::GetTruncatedCocoaLabel(const nsString& itemLabel) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // We want to truncate long strings to some reasonable pixel length but there is no
+  // good API for doing that which works for all OS versions and architectures. For now
+  // we'll do nothing for consistency and depend on good user interface design to limit
+  // string lengths.
+  return [NSString stringWithCharacters:reinterpret_cast<const unichar*>(itemLabel.get())
+                                 length:itemLabel.Length()];
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+uint8_t nsMenuUtilsX::GeckoModifiersForNodeAttribute(const nsString& modifiersAttribute) {
+  uint8_t modifiers = knsMenuItemNoModifier;
+  char* str = ToNewCString(modifiersAttribute);
+  char* newStr;
+  char* token = strtok_r(str, ", \t", &newStr);
+  while (token != nullptr) {
+    if (strcmp(token, "shift") == 0) {
+      modifiers |= knsMenuItemShiftModifier;
+    } else if (strcmp(token, "alt") == 0) {
+      modifiers |= knsMenuItemAltModifier;
+    } else if (strcmp(token, "control") == 0) {
+      modifiers |= knsMenuItemControlModifier;
+    } else if ((strcmp(token, "accel") == 0) || (strcmp(token, "meta") == 0)) {
+      modifiers |= knsMenuItemCommandModifier;
+    }
+    token = strtok_r(newStr, ", \t", &newStr);
+  }
+  free(str);
+
+  return modifiers;
+}
+
+unsigned int nsMenuUtilsX::MacModifiersForGeckoModifiers(uint8_t geckoModifiers) {
+  unsigned int macModifiers = 0;
+
+  if (geckoModifiers & knsMenuItemShiftModifier) {
+    macModifiers |= NSEventModifierFlagShift;
+  }
+  if (geckoModifiers & knsMenuItemAltModifier) {
+    macModifiers |= NSEventModifierFlagOption;
+  }
+  if (geckoModifiers & knsMenuItemControlModifier) {
+    macModifiers |= NSEventModifierFlagControl;
+  }
+  if (geckoModifiers & knsMenuItemCommandModifier) {
+    macModifiers |= NSEventModifierFlagCommand;
+  }
+
+  return macModifiers;
+}
+
+nsMenuBarX* nsMenuUtilsX::GetHiddenWindowMenuBar() {
+  nsIWidget* hiddenWindowWidgetNoCOMPtr = nsCocoaUtils::GetHiddenWindowWidget();
+  if (hiddenWindowWidgetNoCOMPtr) {
+    return static_cast<nsCocoaWindow*>(hiddenWindowWidgetNoCOMPtr)->GetMenuBar();
+  }
+  return nullptr;
+}
+
+// It would be nice if we could localize these edit menu names.
+NSMenuItem* nsMenuUtilsX::GetStandardEditMenuItem() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // In principle we should be able to allocate this once and then always
+  // return the same object.  But weird interactions happen between native
+  // app-modal dialogs and Gecko-modal dialogs that open above them.  So what
+  // we return here isn't always released before it needs to be added to
+  // another menu.  See bmo bug 468393.
+  NSMenuItem* standardEditMenuItem = [[[NSMenuItem alloc] initWithTitle:@"Edit"
+                                                                 action:nil
+                                                          keyEquivalent:@""] autorelease];
+  NSMenu* standardEditMenu = [[NSMenu alloc] initWithTitle:@"Edit"];
+  standardEditMenuItem.submenu = standardEditMenu;
+  [standardEditMenu release];
+
+  // Add Undo
+  NSMenuItem* undoItem = [[NSMenuItem alloc] initWithTitle:@"Undo"
+                                                    action:@selector(undo:)
+                                             keyEquivalent:@"z"];
+  [standardEditMenu addItem:undoItem];
+  [undoItem release];
+
+  // Add Redo
+  NSMenuItem* redoItem = [[NSMenuItem alloc] initWithTitle:@"Redo"
+                                                    action:@selector(redo:)
+                                             keyEquivalent:@"Z"];
+  [standardEditMenu addItem:redoItem];
+  [redoItem release];
+
+  // Add separator
+  [standardEditMenu addItem:[NSMenuItem separatorItem]];
+
+  // Add Cut
+  NSMenuItem* cutItem = [[NSMenuItem alloc] initWithTitle:@"Cut"
+                                                   action:@selector(cut:)
+                                            keyEquivalent:@"x"];
+  [standardEditMenu addItem:cutItem];
+  [cutItem release];
+
+  // Add Copy
+  NSMenuItem* copyItem = [[NSMenuItem alloc] initWithTitle:@"Copy"
+                                                    action:@selector(copy:)
+                                             keyEquivalent:@"c"];
+  [standardEditMenu addItem:copyItem];
+  [copyItem release];
+
+  // Add Paste
+  NSMenuItem* pasteItem = [[NSMenuItem alloc] initWithTitle:@"Paste"
+                                                     action:@selector(paste:)
+                                              keyEquivalent:@"v"];
+  [standardEditMenu addItem:pasteItem];
+  [pasteItem release];
+
+  // Add Delete
+  NSMenuItem* deleteItem = [[NSMenuItem alloc] initWithTitle:@"Delete"
+                                                      action:@selector(delete:)
+                                               keyEquivalent:@""];
+  [standardEditMenu addItem:deleteItem];
+  [deleteItem release];
+
+  // Add Select All
+  NSMenuItem* selectAllItem = [[NSMenuItem alloc] initWithTitle:@"Select All"
+                                                         action:@selector(selectAll:)
+                                                  keyEquivalent:@"a"];
+  [standardEditMenu addItem:selectAllItem];
+  [selectAllItem release];
+
+  return standardEditMenuItem;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+bool nsMenuUtilsX::NodeIsHiddenOrCollapsed(nsIContent* aContent) {
+  return aContent->IsElement() &&
+         (aContent->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::hidden, nsGkAtoms::_true,
+                                             eCaseMatters) ||
+          aContent->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::collapsed,
+                                             nsGkAtoms::_true, eCaseMatters));
+}
+
+NSMenuItem* nsMenuUtilsX::NativeMenuItemWithLocation(NSMenu* aRootMenu, NSString* aLocationString,
+                                                     bool aIsMenuBar) {
+  NSArray<NSString*>* indexes = [aLocationString componentsSeparatedByString:@"|"];
+  unsigned int pathLength = indexes.count;
+  if (pathLength == 0) {
+    return nil;
+  }
+
+  NSMenu* currentSubmenu = aRootMenu;
+  for (unsigned int depth = 0; depth < pathLength; depth++) {
+    NSInteger targetIndex = [indexes objectAtIndex:depth].integerValue;
+    if (aIsMenuBar && depth == 0) {
+      // We remove the application menu from consideration for the top-level menu.
+      targetIndex++;
+    }
+    int itemCount = currentSubmenu.numberOfItems;
+    if (targetIndex >= itemCount) {
+      return nil;
+    }
+    NSMenuItem* menuItem = [currentSubmenu itemAtIndex:targetIndex];
+    // if this is the last index just return the menu item
+    if (depth == pathLength - 1) {
+      return menuItem;
+    }
+    // if this is not the last index find the submenu and keep going
+    if (menuItem.hasSubmenu) {
+      currentSubmenu = menuItem.submenu;
+    } else {
+      return nil;
+    }
+  }
+
+  return nil;
+}
+
+static void CheckNativeMenuConsistencyImpl(NSMenu* aMenu, std::unordered_set<void*>& aSeenObjects);
+
+static void CheckNativeMenuItemConsistencyImpl(NSMenuItem* aMenuItem,
+                                               std::unordered_set<void*>& aSeenObjects) {
+  bool inserted = aSeenObjects.insert(aMenuItem).second;
+  MOZ_RELEASE_ASSERT(inserted, "Duplicate NSMenuItem object in native menu structure");
+  if (aMenuItem.hasSubmenu) {
+    CheckNativeMenuConsistencyImpl(aMenuItem.submenu, aSeenObjects);
+  }
+}
+
+static void CheckNativeMenuConsistencyImpl(NSMenu* aMenu, std::unordered_set<void*>& aSeenObjects) {
+  bool inserted = aSeenObjects.insert(aMenu).second;
+  MOZ_RELEASE_ASSERT(inserted, "Duplicate NSMenu object in native menu structure");
+  for (NSMenuItem* item in aMenu.itemArray) {
+    CheckNativeMenuItemConsistencyImpl(item, aSeenObjects);
+  }
+}
+
+void nsMenuUtilsX::CheckNativeMenuConsistency(NSMenu* aMenu) {
+  std::unordered_set<void*> seenObjects;
+  CheckNativeMenuConsistencyImpl(aMenu, seenObjects);
+}
+
+void nsMenuUtilsX::CheckNativeMenuConsistency(NSMenuItem* aMenuItem) {
+  std::unordered_set<void*> seenObjects;
+  CheckNativeMenuItemConsistencyImpl(aMenuItem, seenObjects);
+}
+
+static void DumpNativeNSMenuItemImpl(NSMenuItem* aItem, uint32_t aIndent,
+                                     const Maybe<int>& aIndexInParentMenu);
+
+static void DumpNativeNSMenuImpl(NSMenu* aMenu, uint32_t aIndent) {
+  printf("%*sNSMenu [%p] %-16s\n", aIndent * 2, "", aMenu,
+         (aMenu.title.length == 0 ? "(no title)" : aMenu.title.UTF8String));
+  int index = 0;
+  for (NSMenuItem* item in aMenu.itemArray) {
+    DumpNativeNSMenuItemImpl(item, aIndent + 1, Some(index));
+    index++;
+  }
+}
+
+static void DumpNativeNSMenuItemImpl(NSMenuItem* aItem, uint32_t aIndent,
+                                     const Maybe<int>& aIndexInParentMenu) {
+  printf("%*s", aIndent * 2, "");
+  if (aIndexInParentMenu) {
+    printf("[%d] ", *aIndexInParentMenu);
+  }
+  printf("NSMenuItem [%p] %-16s%s\n", aItem,
+         aItem.isSeparatorItem ? "----"
+                               : (aItem.title.length == 0 ? "(no title)" : aItem.title.UTF8String),
+         aItem.hasSubmenu ? " [hasSubmenu]" : "");
+  if (aItem.hasSubmenu) {
+    DumpNativeNSMenuImpl(aItem.submenu, aIndent + 1);
+  }
+}
+
+void nsMenuUtilsX::DumpNativeMenu(NSMenu* aMenu) { DumpNativeNSMenuImpl(aMenu, 0); }
+
+void nsMenuUtilsX::DumpNativeMenuItem(NSMenuItem* aMenuItem) {
+  DumpNativeNSMenuItemImpl(aMenuItem, 0, Nothing());
+}
diff --git a/widget/cocoa/nsMenuX.h b/widget/cocoa/nsMenuX.h
new file mode 100644
index 0000000000..ff78196ea7
--- /dev/null
+++ b/widget/cocoa/nsMenuX.h
@@ -0,0 +1,288 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMenuX_h_
+#define nsMenuX_h_
+
+#import <Cocoa/Cocoa.h>
+
+#include "mozilla/EventForwards.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Variant.h"
+#include "nsISupports.h"
+#include "nsMenuParentX.h"
+#include "nsMenuBarX.h"
+#include "nsMenuGroupOwnerX.h"
+#include "nsMenuItemIconX.h"
+#include "nsCOMPtr.h"
+#include "nsChangeObserver.h"
+#include "nsThreadUtils.h"
+
+class nsMenuX;
+class nsMenuItemX;
+class nsIWidget;
+
+// MenuDelegate is used to receive Cocoa notifications for setting
+// up carbon events. Protocol is defined as of 10.6 SDK.
+@interface MenuDelegate : NSObject <NSMenuDelegate> {
+  nsMenuX* mGeckoMenu;  // weak ref
+  NSMutableArray* mBlocksToRunWhenOpen;
+}
+- (id)initWithGeckoMenu:(nsMenuX*)geckoMenu;
+- (void)runBlockWhenOpen:(void (^)())block;
+- (void)menu:(NSMenu*)menu willActivateItem:(NSMenuItem*)item;
+@property BOOL menuIsInMenubar;
+@end
+
+class nsMenuXObserver {
+ public:
+  // Called when a menu in this menu subtree opens, before popupshowing.
+  // No strong reference is held to the observer during the call.
+  virtual void OnMenuWillOpen(mozilla::dom::Element* aPopupElement) = 0;
+
+  // Called when a menu in this menu subtree opened, after popupshown.
+  // No strong reference is held to the observer during the call.
+  virtual void OnMenuDidOpen(mozilla::dom::Element* aPopupElement) = 0;
+
+  // Called before a menu item is activated.
+  virtual void OnMenuWillActivateItem(mozilla::dom::Element* aPopupElement,
+                                      mozilla::dom::Element* aMenuItemElement) = 0;
+
+  // Called when a menu in this menu subtree closed, after popuphidden.
+  // No strong reference is held to the observer during the call.
+  virtual void OnMenuClosed(mozilla::dom::Element* aPopupElement) = 0;
+};
+
+// Once instantiated, this object lives until its DOM node or its parent window is destroyed.
+// Do not hold references to this, they can become invalid any time the DOM node can be destroyed.
+class nsMenuX final : public nsMenuParentX,
+                      public nsChangeObserver,
+                      public nsMenuItemIconX::Listener,
+                      public nsMenuXObserver {
+ public:
+  using Observer = nsMenuXObserver;
+
+  // aParent is optional.
+  nsMenuX(nsMenuParentX* aParent, nsMenuGroupOwnerX* aMenuGroupOwner, nsIContent* aContent);
+
+  NS_INLINE_DECL_REFCOUNTING(nsMenuX)
+
+  // If > 0, the OS is indexing all the app's menus (triggered by opening
+  // Help menu on Leopard and higher).  There are some things that are
+  // unsafe to do while this is happening.
+  static int32_t sIndexingMenuLevel;
+
+  NS_DECL_CHANGEOBSERVER
+
+  // nsMenuItemIconX::Listener
+  void IconUpdated() override;
+
+  // nsMenuXObserver, to forward notifications from our children to our observer.
+  void OnMenuWillOpen(mozilla::dom::Element* aPopupElement) override;
+  void OnMenuDidOpen(mozilla::dom::Element* aPopupElement) override;
+  void OnMenuWillActivateItem(mozilla::dom::Element* aPopupElement,
+                              mozilla::dom::Element* aMenuItemElement) override;
+  void OnMenuClosed(mozilla::dom::Element* aPopupElement) override;
+
+  bool IsVisible() const { return mVisible; }
+
+  // Unregisters nsMenuX from the nsMenuGroupOwner, and nulls out the group owner pointer, on this
+  // nsMenuX and also all nested nsMenuX and nsMenuItemX objects.
+  // This is needed because nsMenuX is reference-counted and can outlive its owner, and the menu
+  // group owner asserts that everything has been unregistered when it is destroyed.
+  void DetachFromGroupOwnerRecursive();
+
+  // Nulls out our reference to the parent.
+  // This is needed because nsMenuX is reference-counted and can outlive its parent.
+  void DetachFromParent() { mParent = nullptr; }
+
+  mozilla::Maybe<MenuChild> GetItemAt(uint32_t aPos);
+  uint32_t GetItemCount();
+
+  mozilla::Maybe<MenuChild> GetVisibleItemAt(uint32_t aPos);
+  nsresult GetVisibleItemCount(uint32_t& aCount);
+
+  mozilla::Maybe<MenuChild> GetItemForElement(mozilla::dom::Element* aMenuChildElement);
+
+  // Asynchronously runs the command event on aItem, after the root menu has closed.
+  void ActivateItemAfterClosing(RefPtr<nsMenuItemX>&& aItem, NSEventModifierFlags aModifiers,
+                                int16_t aButton);
+
+  bool IsOpenForGecko() const { return mIsOpenForGecko; }
+
+  // Fires the popupshowing event and returns whether the handler allows the popup to open.
+  // When calling this method, the caller must hold a strong reference to this object, because other
+  // references to this object can be dropped during the handling of the DOM event.
+  MOZ_CAN_RUN_SCRIPT bool OnOpen();
+
+  void PopupShowingEventWasSentAndApprovedExternally() { DidFirePopupShowing(); }
+
+  // Called from the menu delegate during menuWillOpen, or to simulate opening.
+  // Ignored if the menu is already considered open.
+  // When calling this method, the caller must hold a strong reference to this object, because other
+  // references to this object can be dropped during the handling of the DOM event.
+  // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY void MenuOpened();
+
+  // Called from the menu delegate during menuDidClose, or to simulate closing.
+  // Ignored if the menu is already considered closed.
+  // When calling this method, the caller must hold a strong reference to this object, because other
+  // references to this object can be dropped during the handling of the DOM event.
+  void MenuClosed();
+
+  // Close the menu if it's open, and flush any pending popuphiding / popuphidden events.
+  bool Close();
+
+  // Called from the menu delegate during menu:willHighlightItem:.
+  // If called with Nothing(), it means that no item is highlighted.
+  // The index only accounts for visible items, i.e. items for which there exists an NSMenuItem* in
+  // mNativeMenu.
+  void OnHighlightedItemChanged(const mozilla::Maybe<uint32_t>& aNewHighlightedIndex);
+
+  // Called from the menu delegate before an item anywhere in this menu is activated.
+  // Called after MenuClosed().
+  void OnWillActivateItem(NSMenuItem* aItem);
+
+  void SetRebuild(bool aMenuEvent);
+  void SetupIcon();
+  nsIContent* Content() { return mContent; }
+  NSMenuItem* NativeNSMenuItem() { return mNativeMenuItem; }
+  GeckoNSMenu* NativeNSMenu() { return mNativeMenu; }
+
+  void SetIconListener(nsMenuItemIconX::Listener* aListener) { mIconListener = aListener; }
+  void ClearIconListener() { mIconListener = nullptr; }
+
+  // nsMenuParentX
+  void MenuChildChangedVisibility(const MenuChild& aChild, bool aIsVisible) override;
+
+  void Dump(uint32_t aIndent) const;
+
+  static bool IsXULHelpMenu(nsIContent* aMenuContent);
+  static bool IsXULWindowMenu(nsIContent* aMenuContent);
+
+  // Set an observer that gets notified of menu opening and closing.
+  // The menu does not keep a strong reference the observer. The observer must
+  // remove itself before it is destroyed.
+  void SetObserver(Observer* aObserver) { mObserver = aObserver; }
+
+  // Stop observing.
+  void ClearObserver() { mObserver = nullptr; }
+
+ protected:
+  virtual ~nsMenuX();
+
+  void RebuildMenu();
+  nsresult RemoveAll();
+  nsresult SetEnabled(bool aIsEnabled);
+  nsresult GetEnabled(bool* aIsEnabled);
+  already_AddRefed<nsIContent> GetMenuPopupContent();
+  void WillInsertChild(const MenuChild& aChild);
+  void WillRemoveChild(const MenuChild& aChild);
+  void AddMenuChild(MenuChild&& aChild);
+  void InsertMenuChild(MenuChild&& aChild);
+  void RemoveMenuChild(const MenuChild& aChild);
+  mozilla::Maybe<MenuChild> CreateMenuChild(nsIContent* aContent);
+  RefPtr<nsMenuItemX> CreateMenuItem(nsIContent* aMenuItemContent);
+  GeckoNSMenu* CreateMenuWithGeckoString(nsString& aMenuTitle);
+  void DidFirePopupShowing();
+
+  // Find the index at which aChild needs to be inserted into mMenuChildren such that mMenuChildren
+  // remains in correct content order, i.e. the order in mMenuChildren is the same as the order of
+  // the DOM children of our <menupopup>.
+  size_t FindInsertionIndex(const MenuChild& aChild);
+
+  // Calculates the index at which aChild's NSMenuItem should be inserted into our NSMenu.
+  // The order of NSMenuItems in the NSMenu is the same as the order of menu children in
+  // mMenuChildren; the only difference is that mMenuChildren contains both visible and invisible
+  // children, and the NSMenu only contains visible items. So the insertion index is equal to the
+  // number of visible previous siblings of aChild in mMenuChildren.
+  NSInteger CalculateNativeInsertionPoint(const MenuChild& aChild);
+
+  // Fires the popupshown event.
+  MOZ_CAN_RUN_SCRIPT void MenuOpenedAsync();
+
+  // Called from mPendingAsyncMenuCloseRunnable asynchronously after MenuClosed(), so that it runs
+  // after any potential menuItemHit calls for clicked menu items.
+  // Fires popuphiding and popuphidden events.
+  // When calling this method, the caller must hold a strong reference to this object, because other
+  // references to this object can be dropped during the handling of the DOM event.
+  MOZ_CAN_RUN_SCRIPT void MenuClosedAsync();
+
+  // If mPendingAsyncMenuOpenRunnable is non-null, call MenuOpenedAsync() to send out the pending
+  // popupshown event.
+  // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY void FlushMenuOpenedRunnable();
+
+  // If mPendingAsyncMenuCloseRunnable is non-null, call MenuClosedAsync() to send out pending
+  // popuphiding/popuphidden events.
+  // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY void FlushMenuClosedRunnable();
+
+  // Make sure the NSMenu contains at least one item, even if mVisibleItemsCount is zero.
+  // Otherwise it won't open.
+  void InsertPlaceholderIfNeeded();
+  // Remove the placeholder before adding an item to mNativeNSMenu.
+  void RemovePlaceholderIfPresent();
+
+  nsCOMPtr<nsIContent> mContent;  // XUL <menu> or <menupopup>
+
+  // Contains nsMenuX and nsMenuItemX objects
+  nsTArray<MenuChild> mMenuChildren;
+
+  nsString mLabel;
+  uint32_t mVisibleItemsCount = 0;                     // cache
+  nsMenuParentX* mParent = nullptr;                    // [weak]
+  nsMenuGroupOwnerX* mMenuGroupOwner = nullptr;        // [weak]
+  nsMenuItemIconX::Listener* mIconListener = nullptr;  // [weak]
+  mozilla::UniquePtr<nsMenuItemIconX> mIcon;
+
+  Observer* mObserver = nullptr;  // non-owning pointer to our observer
+
+  // Non-null between a call to MenuOpened() and MenuOpenedAsync().
+  RefPtr<mozilla::CancelableRunnable> mPendingAsyncMenuOpenRunnable;
+
+  // Non-null between a call to MenuClosed() and MenuClosedAsync().
+  // This is asynchronous so that, if a menu item is clicked, we can fire popuphiding *after* we
+  // execute the menu item command. The macOS menu system calls menuWillClose *before* it calls
+  // menuItemHit.
+  RefPtr<mozilla::CancelableRunnable> mPendingAsyncMenuCloseRunnable;
+
+  struct PendingCommandEvent {
+    RefPtr<nsMenuItemX> mMenuItem;
+    NSEventModifierFlags mModifiers;
+    int16_t mButton;
+  };
+
+  // Any pending command events.
+  // These are queued by ActivateItemAfterClosing and run by MenuClosedAsync.
+  nsTArray<PendingCommandEvent> mPendingCommandEvents;
+
+  GeckoNSMenu* mNativeMenu = nil;     // [strong]
+  MenuDelegate* mMenuDelegate = nil;  // [strong]
+  // nsMenuX objects should always have a valid native menu item.
+  NSMenuItem* mNativeMenuItem = nil;  // [strong]
+
+  // Nothing() if no item is highlighted. The index only accounts for visible items.
+  mozilla::Maybe<uint32_t> mHighlightedItemIndex;
+
+  bool mIsEnabled = true;
+  bool mNeedsRebuild = true;
+
+  // Whether the native NSMenu is considered open.
+  // Also affected by MenuOpened() / MenuClosed() calls for simulated opening / closing.
+  bool mIsOpen = false;
+
+  // Whether the popup is open from Gecko's perspective, based on popupshowing / popuphiding events.
+  bool mIsOpenForGecko = false;
+
+  bool mVisible = true;
+
+  // true between an OnOpen() call that returned true, and the subsequent call
+  // to MenuOpened().
+  bool mDidFirePopupshowingAndIsApprovedToOpen = false;
+};
+
+#endif  // nsMenuX_h_
diff --git a/widget/cocoa/nsMenuX.mm b/widget/cocoa/nsMenuX.mm
new file mode 100644
index 0000000000..a0bd714249
--- /dev/null
+++ b/widget/cocoa/nsMenuX.mm
@@ -0,0 +1,1403 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMenuX.h"
+
+#include <_types/_uint32_t.h>
+#include <dlfcn.h>
+
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/MouseEvents.h"
+
+#include "MOZMenuOpeningCoordinator.h"
+#include "nsMenuItemX.h"
+#include "nsMenuUtilsX.h"
+#include "nsMenuItemIconX.h"
+
+#include "nsObjCExceptions.h"
+
+#include "nsComputedDOMStyle.h"
+#include "nsThreadUtils.h"
+#include "nsToolkit.h"
+#include "nsCocoaUtils.h"
+#include "nsCOMPtr.h"
+#include "prinrval.h"
+#include "nsString.h"
+#include "nsReadableUtils.h"
+#include "nsUnicharUtils.h"
+#include "nsGkAtoms.h"
+#include "nsCRT.h"
+#include "nsBaseWidget.h"
+
+#include "nsIContent.h"
+#include "nsIDocumentObserver.h"
+#include "nsIComponentManager.h"
+#include "nsIRollupListener.h"
+#include "nsIServiceManager.h"
+#include "nsXULPopupManager.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+static bool gConstructingMenu = false;
+static bool gMenuMethodsSwizzled = false;
+
+int32_t nsMenuX::sIndexingMenuLevel = 0;
+
+// TODO: It is unclear whether this is still needed.
+static void SwizzleDynamicIndexingMethods() {
+  if (gMenuMethodsSwizzled) {
+    return;
+  }
+
+  nsToolkit::SwizzleMethods([NSMenu class], @selector(_addItem:toTable:),
+                            @selector(nsMenuX_NSMenu_addItem:toTable:), true);
+  nsToolkit::SwizzleMethods([NSMenu class], @selector(_removeItem:fromTable:),
+                            @selector(nsMenuX_NSMenu_removeItem:fromTable:), true);
+  // On SnowLeopard the Shortcut framework (which contains the
+  // SCTGRLIndex class) is loaded on demand, whenever the user first opens
+  // a menu (which normally hasn't happened yet).  So we need to load it
+  // here explicitly.
+  dlopen("/System/Library/PrivateFrameworks/Shortcut.framework/Shortcut", RTLD_LAZY);
+  Class SCTGRLIndexClass = ::NSClassFromString(@"SCTGRLIndex");
+  nsToolkit::SwizzleMethods(SCTGRLIndexClass, @selector(indexMenuBarDynamically),
+                            @selector(nsMenuX_SCTGRLIndex_indexMenuBarDynamically));
+
+  Class NSServicesMenuUpdaterClass = ::NSClassFromString(@"_NSServicesMenuUpdater");
+  nsToolkit::SwizzleMethods(NSServicesMenuUpdaterClass,
+                            @selector(populateMenu:withServiceEntries:forDisplay:),
+                            @selector(nsMenuX_populateMenu:withServiceEntries:forDisplay:));
+
+  gMenuMethodsSwizzled = true;
+}
+
+//
+// nsMenuX
+//
+
+nsMenuX::nsMenuX(nsMenuParentX* aParent, nsMenuGroupOwnerX* aMenuGroupOwner, nsIContent* aContent)
+    : mContent(aContent), mParent(aParent), mMenuGroupOwner(aMenuGroupOwner) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  MOZ_COUNT_CTOR(nsMenuX);
+
+  SwizzleDynamicIndexingMethods();
+
+  mMenuDelegate = [[MenuDelegate alloc] initWithGeckoMenu:this];
+  mMenuDelegate.menuIsInMenubar = mMenuGroupOwner->GetMenuBar() != nullptr;
+
+  if (!nsMenuBarX::sNativeEventTarget) {
+    nsMenuBarX::sNativeEventTarget = [[NativeMenuItemTarget alloc] init];
+  }
+
+  if (mContent->IsElement()) {
+    mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::label, mLabel);
+  }
+  mNativeMenu = CreateMenuWithGeckoString(mLabel);
+
+  // register this menu to be notified when changes are made to our content object
+  NS_ASSERTION(mMenuGroupOwner, "No menu owner given, must have one");
+  mMenuGroupOwner->RegisterForContentChanges(mContent, this);
+
+  mVisible = !nsMenuUtilsX::NodeIsHiddenOrCollapsed(mContent);
+
+  NSString* newCocoaLabelString = nsMenuUtilsX::GetTruncatedCocoaLabel(mLabel);
+  mNativeMenuItem = [[NSMenuItem alloc] initWithTitle:newCocoaLabelString
+                                               action:nil
+                                        keyEquivalent:@""];
+  mNativeMenuItem.submenu = mNativeMenu;
+
+  SetEnabled(!mContent->IsElement() ||
+             !mContent->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                                                 nsGkAtoms::_true, eCaseMatters));
+
+  // We call RebuildMenu here because keyboard commands are dependent upon
+  // native menu items being created. If we only call RebuildMenu when a menu
+  // is actually selected, then we can't access keyboard commands until the
+  // menu gets selected, which is bad.
+  RebuildMenu();
+
+  if (IsXULWindowMenu(mContent)) {
+    // Let the OS know that this is our Window menu.
+    NSApp.windowsMenu = mNativeMenu;
+  }
+
+  mIcon = MakeUnique<nsMenuItemIconX>(this);
+
+  if (mVisible) {
+    SetupIcon();
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+nsMenuX::~nsMenuX() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // Make sure a pending popupshown event isn't dropped.
+  FlushMenuOpenedRunnable();
+
+  if (mIsOpen) {
+    [mNativeMenu cancelTracking];
+    MOZMenuOpeningCoordinator.needToUnwindForMenuClosing = YES;
+  }
+
+  // Make sure pending popuphiding/popuphidden events aren't dropped.
+  FlushMenuClosedRunnable();
+
+  OnHighlightedItemChanged(Nothing());
+  RemoveAll();
+
+  mNativeMenu.delegate = nil;
+  [mNativeMenu release];
+  [mMenuDelegate release];
+  // autorelease the native menu item so that anything else happening to this
+  // object happens before the native menu item actually dies
+  [mNativeMenuItem autorelease];
+
+  DetachFromGroupOwnerRecursive();
+
+  MOZ_COUNT_DTOR(nsMenuX);
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuX::DetachFromGroupOwnerRecursive() {
+  if (!mMenuGroupOwner) {
+    // Don't recurse if this subtree is already detached.
+    // This avoids repeated recursion during the destruction of nested nsMenuX structures.
+    // Our invariant is: If we are detached, all of our contents are also detached.
+    return;
+  }
+
+  if (mMenuGroupOwner && mContent) {
+    mMenuGroupOwner->UnregisterForContentChanges(mContent);
+  }
+  mMenuGroupOwner = nullptr;
+
+  // Also detach all our children.
+  for (auto& child : mMenuChildren) {
+    child.match([](const RefPtr<nsMenuX>& aMenu) { aMenu->DetachFromGroupOwnerRecursive(); },
+                [](const RefPtr<nsMenuItemX>& aMenuItem) { aMenuItem->DetachFromGroupOwner(); });
+  }
+}
+
+void nsMenuX::OnMenuWillOpen(dom::Element* aPopupElement) {
+  RefPtr<nsMenuX> kungFuDeathGrip(this);
+  if (mObserver) {
+    mObserver->OnMenuWillOpen(aPopupElement);
+  }
+}
+
+void nsMenuX::OnMenuDidOpen(dom::Element* aPopupElement) {
+  RefPtr<nsMenuX> kungFuDeathGrip(this);
+  if (mObserver) {
+    mObserver->OnMenuDidOpen(aPopupElement);
+  }
+}
+
+void nsMenuX::OnMenuWillActivateItem(dom::Element* aPopupElement, dom::Element* aMenuItemElement) {
+  RefPtr<nsMenuX> kungFuDeathGrip(this);
+  if (mObserver) {
+    mObserver->OnMenuWillActivateItem(aPopupElement, aMenuItemElement);
+  }
+}
+
+void nsMenuX::OnMenuClosed(dom::Element* aPopupElement) {
+  RefPtr<nsMenuX> kungFuDeathGrip(this);
+  if (mObserver) {
+    mObserver->OnMenuClosed(aPopupElement);
+  }
+}
+
+void nsMenuX::AddMenuChild(MenuChild&& aChild) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  WillInsertChild(aChild);
+  mMenuChildren.AppendElement(aChild);
+
+  bool isVisible =
+      aChild.match([](const RefPtr<nsMenuX>& aMenu) { return aMenu->IsVisible(); },
+                   [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->IsVisible(); });
+  NSMenuItem* nativeItem = aChild.match(
+      [](const RefPtr<nsMenuX>& aMenu) { return aMenu->NativeNSMenuItem(); },
+      [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->NativeNSMenuItem(); });
+
+  if (isVisible) {
+    RemovePlaceholderIfPresent();
+    [mNativeMenu addItem:nativeItem];
+    ++mVisibleItemsCount;
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuX::InsertMenuChild(MenuChild&& aChild) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  WillInsertChild(aChild);
+  size_t insertionIndex = FindInsertionIndex(aChild);
+  mMenuChildren.InsertElementAt(insertionIndex, aChild);
+
+  bool isVisible =
+      aChild.match([](const RefPtr<nsMenuX>& aMenu) { return aMenu->IsVisible(); },
+                   [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->IsVisible(); });
+  if (isVisible) {
+    MenuChildChangedVisibility(aChild, true);
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuX::RemoveMenuChild(const MenuChild& aChild) {
+  bool isVisible =
+      aChild.match([](const RefPtr<nsMenuX>& aMenu) { return aMenu->IsVisible(); },
+                   [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->IsVisible(); });
+  if (isVisible) {
+    MenuChildChangedVisibility(aChild, false);
+  }
+
+  WillRemoveChild(aChild);
+  mMenuChildren.RemoveElement(aChild);
+}
+
+size_t nsMenuX::FindInsertionIndex(const MenuChild& aChild) {
+  nsCOMPtr<nsIContent> menuPopup = GetMenuPopupContent();
+  MOZ_RELEASE_ASSERT(menuPopup);
+
+  RefPtr<nsIContent> insertedContent =
+      aChild.match([](const RefPtr<nsMenuX>& aMenu) { return aMenu->Content(); },
+                   [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->Content(); });
+
+  MOZ_RELEASE_ASSERT(insertedContent->GetParent() == menuPopup);
+
+  // Iterate over menuPopup's children (insertedContent's siblings) until we encounter
+  // insertedContent. At the same time, keep track of the index in mMenuChildren.
+  size_t index = 0;
+  for (nsIContent* child = menuPopup->GetFirstChild(); child && index < mMenuChildren.Length();
+       child = child->GetNextSibling()) {
+    if (child == insertedContent) {
+      break;
+    }
+
+    RefPtr<nsIContent> contentAtIndex = mMenuChildren[index].match(
+        [](const RefPtr<nsMenuX>& aMenu) { return aMenu->Content(); },
+        [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->Content(); });
+    if (child == contentAtIndex) {
+      index++;
+    }
+  }
+
+  return index;
+}
+
+// Includes all items, including hidden/collapsed ones
+uint32_t nsMenuX::GetItemCount() { return mMenuChildren.Length(); }
+
+// Includes all items, including hidden/collapsed ones
+mozilla::Maybe<nsMenuX::MenuChild> nsMenuX::GetItemAt(uint32_t aPos) {
+  if (aPos >= (uint32_t)mMenuChildren.Length()) {
+    return {};
+  }
+
+  return Some(mMenuChildren[aPos]);
+}
+
+// Only includes visible items
+nsresult nsMenuX::GetVisibleItemCount(uint32_t& aCount) {
+  aCount = mVisibleItemsCount;
+  return NS_OK;
+}
+
+// Only includes visible items. Note that this is provides O(N) access
+// If you need to iterate or search, consider using GetItemAt and doing your own filtering
+Maybe<nsMenuX::MenuChild> nsMenuX::GetVisibleItemAt(uint32_t aPos) {
+  uint32_t count = mMenuChildren.Length();
+  if (aPos >= mVisibleItemsCount || aPos >= count) {
+    return {};
+  }
+
+  // If there are no invisible items, can provide direct access
+  if (mVisibleItemsCount == count) {
+    return GetItemAt(aPos);
+  }
+
+  // Otherwise, traverse the array until we find the the item we're looking for.
+  uint32_t visibleNodeIndex = 0;
+  for (uint32_t i = 0; i < count; i++) {
+    MenuChild item = *GetItemAt(i);
+    RefPtr<nsIContent> content =
+        item.match([](const RefPtr<nsMenuX>& aMenu) { return aMenu->Content(); },
+                   [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->Content(); });
+    if (!nsMenuUtilsX::NodeIsHiddenOrCollapsed(content)) {
+      if (aPos == visibleNodeIndex) {
+        // we found the visible node we're looking for, return it
+        return Some(item);
+      }
+      visibleNodeIndex++;
+    }
+  }
+
+  return {};
+}
+
+Maybe<nsMenuX::MenuChild> nsMenuX::GetItemForElement(Element* aMenuChildElement) {
+  for (auto& child : mMenuChildren) {
+    RefPtr<nsIContent> content =
+        child.match([](const RefPtr<nsMenuX>& aMenu) { return aMenu->Content(); },
+                    [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->Content(); });
+    if (content == aMenuChildElement) {
+      return Some(child);
+    }
+  }
+  return {};
+}
+
+nsresult nsMenuX::RemoveAll() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  [mNativeMenu removeAllItems];
+
+  for (auto& child : mMenuChildren) {
+    WillRemoveChild(child);
+  }
+
+  mMenuChildren.Clear();
+  mVisibleItemsCount = 0;
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuX::WillInsertChild(const MenuChild& aChild) {
+  if (aChild.is<RefPtr<nsMenuX>>()) {
+    aChild.as<RefPtr<nsMenuX>>()->SetObserver(this);
+  }
+}
+
+void nsMenuX::WillRemoveChild(const MenuChild& aChild) {
+  aChild.match(
+      [](const RefPtr<nsMenuX>& aMenu) {
+        aMenu->DetachFromGroupOwnerRecursive();
+        aMenu->DetachFromParent();
+        aMenu->SetObserver(nullptr);
+      },
+      [](const RefPtr<nsMenuItemX>& aMenuItem) {
+        aMenuItem->DetachFromGroupOwner();
+        aMenuItem->DetachFromParent();
+      });
+}
+
+void nsMenuX::MenuOpened() {
+  if (mIsOpen) {
+    return;
+  }
+
+  // Make sure we fire any pending popupshown / popuphiding / popuphidden events first.
+  FlushMenuOpenedRunnable();
+  FlushMenuClosedRunnable();
+
+  if (!mDidFirePopupshowingAndIsApprovedToOpen) {
+    // Fire popupshowing now.
+    bool approvedToOpen = OnOpen();
+    if (!approvedToOpen) {
+      // We can only stop menus from opening which we open ourselves. We cannot stop menubar root
+      // menus or menu submenus from opening.
+      // For context menus, we can call OnOpen() before we ask the system to open the menu.
+      NS_WARNING("The popupshowing event had preventDefault() called on it, but in MenuOpened() it "
+                 "is too late to stop the menu from opening.");
+    }
+  }
+
+  mIsOpen = true;
+
+  // Reset mDidFirePopupshowingAndIsApprovedToOpen for the next menu opening.
+  mDidFirePopupshowingAndIsApprovedToOpen = false;
+
+  if (mNeedsRebuild) {
+    OnHighlightedItemChanged(Nothing());
+    RemoveAll();
+    RebuildMenu();
+  }
+
+  // Fire the popupshown event in MenuOpenedAsync.
+  // MenuOpened() is called during menuWillOpen, and if cancelTracking is called now, menuDidClose
+  // will not be called.
+  // The runnable object must not hold a strong reference to the nsMenuX, so that there is no
+  // reference cycle.
+  class MenuOpenedAsyncRunnable final : public mozilla::CancelableRunnable {
+   public:
+    explicit MenuOpenedAsyncRunnable(nsMenuX* aMenu)
+        : CancelableRunnable("MenuOpenedAsyncRunnable"), mMenu(aMenu) {}
+
+    // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230, bug 1535398)
+    MOZ_CAN_RUN_SCRIPT_BOUNDARY nsresult Run() override {
+      if (RefPtr<nsMenuX> menu = mMenu) {
+        menu->MenuOpenedAsync();
+        mMenu = nullptr;
+      }
+      return NS_OK;
+    }
+    nsresult Cancel() override {
+      mMenu = nullptr;
+      return NS_OK;
+    }
+
+   private:
+    nsMenuX* mMenu;  // weak, cleared by Cancel() and Run()
+  };
+  mPendingAsyncMenuOpenRunnable = new MenuOpenedAsyncRunnable(this);
+  NS_DispatchToCurrentThread(mPendingAsyncMenuOpenRunnable);
+}
+
+void nsMenuX::FlushMenuOpenedRunnable() {
+  if (mPendingAsyncMenuOpenRunnable) {
+    MenuOpenedAsync();
+  }
+}
+
+void nsMenuX::MenuOpenedAsync() {
+  if (mPendingAsyncMenuOpenRunnable) {
+    mPendingAsyncMenuOpenRunnable->Cancel();
+    mPendingAsyncMenuOpenRunnable = nullptr;
+  }
+
+  mIsOpenForGecko = true;
+
+  // Open the node.
+  if (mContent->IsElement()) {
+    mContent->AsElement()->SetAttr(kNameSpaceID_None, nsGkAtoms::open, u"true"_ns, true);
+  }
+
+  RefPtr<nsIContent> popupContent = GetMenuPopupContent();
+
+  // Notify our observer.
+  if (mObserver && popupContent) {
+    mObserver->OnMenuDidOpen(popupContent->AsElement());
+  }
+
+  // Fire popupshown.
+  nsEventStatus status = nsEventStatus_eIgnore;
+  WidgetMouseEvent event(true, eXULPopupShown, nullptr, WidgetMouseEvent::eReal);
+  RefPtr<nsIContent> dispatchTo = popupContent ? popupContent : mContent;
+  EventDispatcher::Dispatch(dispatchTo, nullptr, &event, nullptr, &status);
+}
+
+void nsMenuX::MenuClosed() {
+  if (!mIsOpen) {
+    return;
+  }
+
+  // Make sure we fire any pending popupshown events first.
+  FlushMenuOpenedRunnable();
+
+  // If any of our submenus were opened programmatically, make sure they get closed first.
+  for (auto& child : mMenuChildren) {
+    if (child.is<RefPtr<nsMenuX>>()) {
+      child.as<RefPtr<nsMenuX>>()->MenuClosed();
+    }
+  }
+
+  mIsOpen = false;
+
+  // Do the rest of the MenuClosed work in MenuClosedAsync.
+  // MenuClosed() is called from -[NSMenuDelegate menuDidClose:]. If a menuitem was clicked,
+  // menuDidClose is called *before* menuItemHit for the clicked menu item is called.
+  // This runnable will be canceled if ~nsMenuX runs before the runnable.
+  // The runnable object must not hold a strong reference to the nsMenuX, so that there is no
+  // reference cycle.
+  class MenuClosedAsyncRunnable final : public mozilla::CancelableRunnable {
+   public:
+    explicit MenuClosedAsyncRunnable(nsMenuX* aMenu)
+        : CancelableRunnable("MenuClosedAsyncRunnable"), mMenu(aMenu) {}
+
+    // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230, bug 1535398)
+    MOZ_CAN_RUN_SCRIPT_BOUNDARY nsresult Run() override {
+      if (RefPtr<nsMenuX> menu = mMenu) {
+        menu->MenuClosedAsync();
+        mMenu = nullptr;
+      }
+      return NS_OK;
+    }
+    nsresult Cancel() override {
+      mMenu = nullptr;
+      return NS_OK;
+    }
+
+   private:
+    nsMenuX* mMenu;  // weak, cleared by Cancel() and Run()
+  };
+
+  mPendingAsyncMenuCloseRunnable = new MenuClosedAsyncRunnable(this);
+
+  NS_DispatchToCurrentThread(mPendingAsyncMenuCloseRunnable);
+}
+
+void nsMenuX::FlushMenuClosedRunnable() {
+  // If any of our submenus have a pending menu closed runnable, make sure those run first.
+  for (auto& child : mMenuChildren) {
+    if (child.is<RefPtr<nsMenuX>>()) {
+      child.as<RefPtr<nsMenuX>>()->FlushMenuClosedRunnable();
+    }
+  }
+
+  if (mPendingAsyncMenuCloseRunnable) {
+    MenuClosedAsync();
+  }
+}
+
+void nsMenuX::MenuClosedAsync() {
+  if (mPendingAsyncMenuCloseRunnable) {
+    mPendingAsyncMenuCloseRunnable->Cancel();
+    mPendingAsyncMenuCloseRunnable = nullptr;
+  }
+
+  // If we have pending command events, run those first.
+  nsTArray<PendingCommandEvent> events = std::move(mPendingCommandEvents);
+  for (auto& event : events) {
+    event.mMenuItem->DoCommand(event.mModifiers, event.mButton);
+  }
+
+  // Make sure no item is highlighted.
+  OnHighlightedItemChanged(Nothing());
+
+  nsCOMPtr<nsIContent> popupContent = GetMenuPopupContent();
+  nsCOMPtr<nsIContent> dispatchTo = popupContent ? popupContent : mContent;
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  WidgetMouseEvent popupHiding(true, eXULPopupHiding, nullptr, WidgetMouseEvent::eReal);
+  EventDispatcher::Dispatch(dispatchTo, nullptr, &popupHiding, nullptr, &status);
+
+  mIsOpenForGecko = false;
+
+  if (mContent->IsElement()) {
+    mContent->AsElement()->UnsetAttr(kNameSpaceID_None, nsGkAtoms::open, true);
+  }
+
+  WidgetMouseEvent popupHidden(true, eXULPopupHidden, nullptr, WidgetMouseEvent::eReal);
+  EventDispatcher::Dispatch(dispatchTo, nullptr, &popupHidden, nullptr, &status);
+
+  // Notify our observer.
+  if (mObserver && popupContent) {
+    mObserver->OnMenuClosed(popupContent->AsElement());
+  }
+}
+
+void nsMenuX::ActivateItemAfterClosing(RefPtr<nsMenuItemX>&& aItem, NSEventModifierFlags aModifiers,
+                                       int16_t aButton) {
+  if (mIsOpenForGecko) {
+    // Queue the event into mPendingCommandEvents. We will call aItem->DoCommand in
+    // MenuClosedAsync(). We rely on the assumption that MenuClosedAsync will run soon.
+    mPendingCommandEvents.AppendElement(PendingCommandEvent{std::move(aItem), aModifiers, aButton});
+  } else {
+    // The menu item was activated outside of a regular open / activate / close sequence.
+    // This happens in multiple cases:
+    //  - When a menu item is activated by a keyboard shortcut while all windows are closed
+    //    (otherwise those shortcuts go through Gecko's manual keyboard handling)
+    //  - When a menu item in the Dock menu is clicked
+    //  - During native menu tests
+    //
+    // Run the command synchronously.
+    aItem->DoCommand(aModifiers, aButton);
+  }
+}
+
+bool nsMenuX::Close() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (mDidFirePopupshowingAndIsApprovedToOpen && !mIsOpen) {
+    // Close is being called right after this menu was opened, but before MenuOpened() had a chance
+    // to run. Call it here so that we can go through the entire popupshown -> popuphiding ->
+    // popuphidden sequence. Some callers expect to get a popuphidden event even if they close the
+    // popup before it was fully open.
+    MenuOpened();
+  }
+
+  FlushMenuOpenedRunnable();
+
+  bool wasOpen = mIsOpenForGecko;
+
+  if (mIsOpen) {
+    // Close the menu.
+    // We usually don't get here during normal Firefox usage: If the user closes the menu by
+    // clicking an item, or by clicking outside the menu, or by pressing escape, then the menu gets
+    // closed by macOS, and not by a call to nsMenuX::Close().
+    // If we do get here, it's usually because we're running an automated test. Close the menu
+    // without the fade-out animation so that we don't unnecessarily slow down the automated tests.
+    [mNativeMenu cancelTrackingWithoutAnimation];
+    MOZMenuOpeningCoordinator.needToUnwindForMenuClosing = YES;
+
+    // Handle closing synchronously.
+    MenuClosed();
+  }
+
+  FlushMenuClosedRunnable();
+
+  return wasOpen;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuX::OnHighlightedItemChanged(const Maybe<uint32_t>& aNewHighlightedIndex) {
+  if (mHighlightedItemIndex == aNewHighlightedIndex) {
+    return;
+  }
+
+  if (mHighlightedItemIndex) {
+    Maybe<nsMenuX::MenuChild> target = GetVisibleItemAt(*mHighlightedItemIndex);
+    if (target && target->is<RefPtr<nsMenuItemX>>()) {
+      bool handlerCalledPreventDefault;  // but we don't actually care
+      target->as<RefPtr<nsMenuItemX>>()->DispatchDOMEvent(u"DOMMenuItemInactive"_ns,
+                                                          &handlerCalledPreventDefault);
+    }
+  }
+  if (aNewHighlightedIndex) {
+    Maybe<nsMenuX::MenuChild> target = GetVisibleItemAt(*aNewHighlightedIndex);
+    if (target && target->is<RefPtr<nsMenuItemX>>()) {
+      bool handlerCalledPreventDefault;  // but we don't actually care
+      target->as<RefPtr<nsMenuItemX>>()->DispatchDOMEvent(u"DOMMenuItemActive"_ns,
+                                                          &handlerCalledPreventDefault);
+    }
+  }
+  mHighlightedItemIndex = aNewHighlightedIndex;
+}
+
+void nsMenuX::OnWillActivateItem(NSMenuItem* aItem) {
+  if (!mIsOpenForGecko) {
+    return;
+  }
+
+  if (mMenuGroupOwner && mObserver) {
+    nsMenuItemX* item = mMenuGroupOwner->GetMenuItemForCommandID(uint32_t(aItem.tag));
+    if (item && item->Content()->IsElement()) {
+      RefPtr<dom::Element> itemElement = item->Content()->AsElement();
+      if (nsCOMPtr<nsIContent> popupContent = GetMenuPopupContent()) {
+        mObserver->OnMenuWillActivateItem(popupContent->AsElement(), itemElement);
+      }
+    }
+  }
+}
+
+// Flushes style.
+static NSUserInterfaceLayoutDirection DirectionForElement(dom::Element* aElement) {
+  // Get the direction from the computed style so that inheritance into submenus is respected.
+  // aElement may not have a frame.
+  RefPtr<const ComputedStyle> sc = nsComputedDOMStyle::GetComputedStyle(aElement);
+  if (!sc) {
+    return NSApp.userInterfaceLayoutDirection;
+  }
+
+  switch (sc->StyleVisibility()->mDirection) {
+    case StyleDirection::Ltr:
+      return NSUserInterfaceLayoutDirectionLeftToRight;
+    case StyleDirection::Rtl:
+      return NSUserInterfaceLayoutDirectionRightToLeft;
+  }
+}
+
+void nsMenuX::RebuildMenu() {
+  MOZ_RELEASE_ASSERT(mNeedsRebuild);
+  gConstructingMenu = true;
+
+  // Retrieve our menupopup.
+  nsCOMPtr<nsIContent> menuPopup = GetMenuPopupContent();
+  if (!menuPopup) {
+    gConstructingMenu = false;
+    return;
+  }
+
+  if (menuPopup->IsElement()) {
+    mNativeMenu.userInterfaceLayoutDirection = DirectionForElement(menuPopup->AsElement());
+  }
+
+  // Iterate over the kids
+  for (nsIContent* child = menuPopup->GetFirstChild(); child; child = child->GetNextSibling()) {
+    if (Maybe<MenuChild> menuChild = CreateMenuChild(child)) {
+      AddMenuChild(std::move(*menuChild));
+    }
+  }  // for each menu item
+
+  InsertPlaceholderIfNeeded();
+
+  gConstructingMenu = false;
+  mNeedsRebuild = false;
+}
+
+void nsMenuX::InsertPlaceholderIfNeeded() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if ([mNativeMenu numberOfItems] == 0) {
+    MOZ_RELEASE_ASSERT(mVisibleItemsCount == 0);
+    NSMenuItem* item = [[NSMenuItem alloc] initWithTitle:@"" action:nil keyEquivalent:@""];
+    item.enabled = NO;
+    item.view = [[[NSView alloc] initWithFrame:NSMakeRect(0, 0, 150, 1)] autorelease];
+    [mNativeMenu addItem:item];
+    [item release];
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuX::RemovePlaceholderIfPresent() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (mVisibleItemsCount == 0 && [mNativeMenu numberOfItems] == 1) {
+    // Remove the placeholder.
+    [mNativeMenu removeItemAtIndex:0];
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuX::SetRebuild(bool aNeedsRebuild) {
+  if (!gConstructingMenu) {
+    mNeedsRebuild = aNeedsRebuild;
+    if (mParent && mParent->AsMenuBar()) {
+      mParent->AsMenuBar()->SetNeedsRebuild();
+    }
+  }
+}
+
+nsresult nsMenuX::SetEnabled(bool aIsEnabled) {
+  if (aIsEnabled != mIsEnabled) {
+    // we always want to rebuild when this changes
+    mIsEnabled = aIsEnabled;
+    mNativeMenuItem.enabled = mIsEnabled;
+  }
+  return NS_OK;
+}
+
+nsresult nsMenuX::GetEnabled(bool* aIsEnabled) {
+  NS_ENSURE_ARG_POINTER(aIsEnabled);
+  *aIsEnabled = mIsEnabled;
+  return NS_OK;
+}
+
+GeckoNSMenu* nsMenuX::CreateMenuWithGeckoString(nsString& aMenuTitle) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  NSString* title = [NSString stringWithCharacters:(UniChar*)aMenuTitle.get()
+                                            length:aMenuTitle.Length()];
+  GeckoNSMenu* myMenu = [[GeckoNSMenu alloc] initWithTitle:title];
+  myMenu.delegate = mMenuDelegate;
+
+  // We don't want this menu to auto-enable menu items because then Cocoa
+  // overrides our decisions and things get incorrectly enabled/disabled.
+  myMenu.autoenablesItems = NO;
+
+  // we used to install Carbon event handlers here, but since NSMenu* doesn't
+  // create its underlying MenuRef until just before display, we delay until
+  // that happens. Now we install the event handlers when Cocoa notifies
+  // us that a menu is about to display - see the Cocoa MenuDelegate class.
+
+  return myMenu;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+Maybe<nsMenuX::MenuChild> nsMenuX::CreateMenuChild(nsIContent* aContent) {
+  if (aContent->IsAnyOfXULElements(nsGkAtoms::menuitem, nsGkAtoms::menuseparator)) {
+    return Some(MenuChild(CreateMenuItem(aContent)));
+  }
+  if (aContent->IsXULElement(nsGkAtoms::menu)) {
+    return Some(MenuChild(MakeRefPtr<nsMenuX>(this, mMenuGroupOwner, aContent)));
+  }
+  return {};
+}
+
+RefPtr<nsMenuItemX> nsMenuX::CreateMenuItem(nsIContent* aMenuItemContent) {
+  MOZ_RELEASE_ASSERT(aMenuItemContent);
+
+  nsAutoString menuitemName;
+  if (aMenuItemContent->IsElement()) {
+    aMenuItemContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::label, menuitemName);
+  }
+
+  EMenuItemType itemType = eRegularMenuItemType;
+  if (aMenuItemContent->IsXULElement(nsGkAtoms::menuseparator)) {
+    itemType = eSeparatorMenuItemType;
+  } else if (aMenuItemContent->IsElement()) {
+    static Element::AttrValuesArray strings[] = {nsGkAtoms::checkbox, nsGkAtoms::radio, nullptr};
+    switch (aMenuItemContent->AsElement()->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::type,
+                                                           strings, eCaseMatters)) {
+      case 0:
+        itemType = eCheckboxMenuItemType;
+        break;
+      case 1:
+        itemType = eRadioMenuItemType;
+        break;
+    }
+  }
+
+  return MakeRefPtr<nsMenuItemX>(this, menuitemName, itemType, mMenuGroupOwner, aMenuItemContent);
+}
+
+// This menu is about to open. Returns false if the handler wants to stop the opening of the menu.
+bool nsMenuX::OnOpen() {
+  if (mDidFirePopupshowingAndIsApprovedToOpen) {
+    return true;
+  }
+
+  if (mIsOpen) {
+    NS_WARNING("nsMenuX::OnOpen() called while the menu is already considered to be open. This "
+               "seems odd.");
+  }
+
+  RefPtr<nsIContent> popupContent = GetMenuPopupContent();
+
+  if (mObserver && popupContent) {
+    mObserver->OnMenuWillOpen(popupContent->AsElement());
+  }
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  WidgetMouseEvent event(true, eXULPopupShowing, nullptr, WidgetMouseEvent::eReal);
+
+  nsresult rv = NS_OK;
+  RefPtr<nsIContent> dispatchTo = popupContent ? popupContent : mContent;
+  rv = EventDispatcher::Dispatch(dispatchTo, nullptr, &event, nullptr, &status);
+  if (NS_FAILED(rv) || status == nsEventStatus_eConsumeNoDefault) {
+    return false;
+  }
+
+  DidFirePopupShowing();
+
+  return true;
+}
+
+void nsMenuX::DidFirePopupShowing() {
+  mDidFirePopupshowingAndIsApprovedToOpen = true;
+
+  // If the open is going to succeed we need to walk our menu items, checking to
+  // see if any of them have a command attribute. If so, several attributes
+  // must potentially be updated.
+
+  nsCOMPtr<nsIContent> popupContent = GetMenuPopupContent();
+  if (!popupContent) {
+    return;
+  }
+
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm) {
+    pm->UpdateMenuItems(popupContent->AsElement());
+  }
+}
+
+// Find the |menupopup| child in the |popup| representing this menu. It should be one
+// of a very few children so we won't be iterating over a bazillion menu items to find
+// it (so the strcmp won't kill us).
+already_AddRefed<nsIContent> nsMenuX::GetMenuPopupContent() {
+  // Check to see if we are a "menupopup" node (if we are a native menu).
+  if (mContent->IsXULElement(nsGkAtoms::menupopup)) {
+    return do_AddRef(mContent);
+  }
+
+  // Otherwise check our child nodes.
+
+  for (RefPtr<nsIContent> child = mContent->GetFirstChild(); child;
+       child = child->GetNextSibling()) {
+    if (child->IsXULElement(nsGkAtoms::menupopup)) {
+      return child.forget();
+    }
+  }
+
+  return nullptr;
+}
+
+bool nsMenuX::IsXULHelpMenu(nsIContent* aMenuContent) {
+  bool retval = false;
+  if (aMenuContent && aMenuContent->IsElement()) {
+    nsAutoString id;
+    aMenuContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::id, id);
+    if (id.Equals(u"helpMenu"_ns)) {
+      retval = true;
+    }
+  }
+  return retval;
+}
+
+bool nsMenuX::IsXULWindowMenu(nsIContent* aMenuContent) {
+  bool retval = false;
+  if (aMenuContent && aMenuContent->IsElement()) {
+    nsAutoString id;
+    aMenuContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::id, id);
+    if (id.Equals(u"windowMenu"_ns)) {
+      retval = true;
+    }
+  }
+  return retval;
+}
+
+//
+// nsChangeObserver
+//
+
+void nsMenuX::ObserveAttributeChanged(dom::Document* aDocument, nsIContent* aContent,
+                                      nsAtom* aAttribute) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // ignore the |open| attribute, which is by far the most common
+  if (gConstructingMenu || (aAttribute == nsGkAtoms::open)) {
+    return;
+  }
+
+  if (aAttribute == nsGkAtoms::disabled) {
+    SetEnabled(!mContent->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                                                   nsGkAtoms::_true, eCaseMatters));
+  } else if (aAttribute == nsGkAtoms::label) {
+    mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::label, mLabel);
+    NSString* newCocoaLabelString = nsMenuUtilsX::GetTruncatedCocoaLabel(mLabel);
+    mNativeMenu.title = newCocoaLabelString;
+    mNativeMenuItem.title = newCocoaLabelString;
+  } else if (aAttribute == nsGkAtoms::hidden || aAttribute == nsGkAtoms::collapsed) {
+    SetRebuild(true);
+
+    bool newVisible = !nsMenuUtilsX::NodeIsHiddenOrCollapsed(mContent);
+
+    // don't do anything if the state is correct already
+    if (newVisible == mVisible) {
+      return;
+    }
+
+    mVisible = newVisible;
+    if (mParent) {
+      RefPtr<nsMenuX> self = this;
+      mParent->MenuChildChangedVisibility(MenuChild(self), newVisible);
+    }
+    if (mVisible) {
+      SetupIcon();
+    }
+  } else if (aAttribute == nsGkAtoms::image) {
+    SetupIcon();
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+void nsMenuX::ObserveContentRemoved(dom::Document* aDocument, nsIContent* aContainer,
+                                    nsIContent* aChild, nsIContent* aPreviousSibling) {
+  if (gConstructingMenu) {
+    return;
+  }
+
+  SetRebuild(true);
+  mMenuGroupOwner->UnregisterForContentChanges(aChild);
+
+  if (!mIsOpen) {
+    // We will update the menu contents the next time the menu is opened.
+    return;
+  }
+
+  // The menu is currently open. Remove the child from mMenuChildren and from our NSMenu.
+  nsCOMPtr<nsIContent> popupContent = GetMenuPopupContent();
+  if (popupContent && aContainer == popupContent && aChild->IsElement()) {
+    if (Maybe<MenuChild> child = GetItemForElement(aChild->AsElement())) {
+      RemoveMenuChild(*child);
+    }
+  }
+}
+
+void nsMenuX::ObserveContentInserted(dom::Document* aDocument, nsIContent* aContainer,
+                                     nsIContent* aChild) {
+  if (gConstructingMenu) {
+    return;
+  }
+
+  SetRebuild(true);
+
+  if (!mIsOpen) {
+    // We will update the menu contents the next time the menu is opened.
+    return;
+  }
+
+  // The menu is currently open. Insert the child into mMenuChildren and into our NSMenu.
+  nsCOMPtr<nsIContent> popupContent = GetMenuPopupContent();
+  if (popupContent && aContainer == popupContent) {
+    if (Maybe<MenuChild> child = CreateMenuChild(aChild)) {
+      InsertMenuChild(std::move(*child));
+    }
+  }
+}
+
+void nsMenuX::SetupIcon() {
+  mIcon->SetupIcon(mContent);
+  mNativeMenuItem.image = mIcon->GetIconImage();
+}
+
+void nsMenuX::IconUpdated() {
+  mNativeMenuItem.image = mIcon->GetIconImage();
+  if (mIconListener) {
+    mIconListener->IconUpdated();
+  }
+}
+
+void nsMenuX::MenuChildChangedVisibility(const MenuChild& aChild, bool aIsVisible) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  NSMenuItem* nativeItem = aChild.match(
+      [](const RefPtr<nsMenuX>& aMenu) { return aMenu->NativeNSMenuItem(); },
+      [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->NativeNSMenuItem(); });
+  if (aIsVisible) {
+    MOZ_RELEASE_ASSERT(!nativeItem.menu,
+                       "The native item should not be in a menu while it is hidden");
+    RemovePlaceholderIfPresent();
+    NSInteger insertionPoint = CalculateNativeInsertionPoint(aChild);
+    [mNativeMenu insertItem:nativeItem atIndex:insertionPoint];
+    mVisibleItemsCount++;
+  } else {
+    MOZ_RELEASE_ASSERT([mNativeMenu indexOfItem:nativeItem] != -1,
+                       "The native item should be in this menu while it is visible");
+    [mNativeMenu removeItem:nativeItem];
+    mVisibleItemsCount--;
+    InsertPlaceholderIfNeeded();
+  }
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+NSInteger nsMenuX::CalculateNativeInsertionPoint(const MenuChild& aChild) {
+  NSInteger insertionPoint = 0;
+  for (auto& currItem : mMenuChildren) {
+    // Using GetItemAt instead of GetVisibleItemAt to avoid O(N^2)
+    if (currItem == aChild) {
+      return insertionPoint;
+    }
+    NSMenuItem* nativeItem = currItem.match(
+        [](const RefPtr<nsMenuX>& aMenu) { return aMenu->NativeNSMenuItem(); },
+        [](const RefPtr<nsMenuItemX>& aMenuItem) { return aMenuItem->NativeNSMenuItem(); });
+    // Only count visible items.
+    if (nativeItem.menu) {
+      insertionPoint++;
+    }
+  }
+  return insertionPoint;
+}
+
+void nsMenuX::Dump(uint32_t aIndent) const {
+  printf("%*s - menu [%p] %-16s <%s>", aIndent * 2, "", this,
+         mLabel.IsEmpty() ? "(empty label)" : NS_ConvertUTF16toUTF8(mLabel).get(),
+         NS_ConvertUTF16toUTF8(mContent->NodeName()).get());
+  if (mNeedsRebuild) {
+    printf(" [NeedsRebuild]");
+  }
+  if (mIsOpen) {
+    printf(" [Open]");
+  }
+  if (mVisible) {
+    printf(" [Visible]");
+  }
+  if (mIsEnabled) {
+    printf(" [IsEnabled]");
+  }
+  printf(" (%d visible items)", int(mVisibleItemsCount));
+  printf("\n");
+  for (const auto& subitem : mMenuChildren) {
+    subitem.match([=](const RefPtr<nsMenuX>& aMenu) { aMenu->Dump(aIndent + 1); },
+                  [=](const RefPtr<nsMenuItemX>& aMenuItem) { aMenuItem->Dump(aIndent + 1); });
+  }
+}
+
+//
+// MenuDelegate Objective-C class, used to set up Carbon events
+//
+
+@implementation MenuDelegate
+
+- (id)initWithGeckoMenu:(nsMenuX*)geckoMenu {
+  if ((self = [super init])) {
+    NS_ASSERTION(geckoMenu,
+                 "Cannot initialize native menu delegate with NULL gecko menu! Will crash!");
+    mGeckoMenu = geckoMenu;
+    mBlocksToRunWhenOpen = [[NSMutableArray alloc] init];
+  }
+  return self;
+}
+
+- (void)dealloc {
+  [mBlocksToRunWhenOpen release];
+  [super dealloc];
+}
+
+- (void)runBlockWhenOpen:(void (^)())block {
+  [mBlocksToRunWhenOpen addObject:[[block copy] autorelease]];
+}
+
+- (void)menu:(NSMenu*)aMenu willHighlightItem:(NSMenuItem*)aItem {
+  if (!aMenu || !mGeckoMenu) {
+    return;
+  }
+
+  Maybe<uint32_t> index =
+      aItem ? Some(static_cast<uint32_t>([aMenu indexOfItem:aItem])) : Nothing();
+  mGeckoMenu->OnHighlightedItemChanged(index);
+}
+
+- (void)menuWillOpen:(NSMenu*)menu {
+  for (void (^block)() in mBlocksToRunWhenOpen) {
+    block();
+  }
+  [mBlocksToRunWhenOpen removeAllObjects];
+
+  if (!mGeckoMenu) {
+    return;
+  }
+
+  // Don't do anything while the OS is (re)indexing our menus (on Leopard and
+  // higher).  This stops the Help menu from being able to search in our
+  // menus, but it also resolves many other problems.
+  if (nsMenuX::sIndexingMenuLevel > 0) {
+    return;
+  }
+
+  if (self.menuIsInMenubar) {
+    // If a menu in the menubar is trying open while a non-native menu is open, roll up the
+    // non-native menu and reject the menubar opening attempt, effectively consuming the event.
+    nsIRollupListener* rollupListener = nsBaseWidget::GetActiveRollupListener();
+    if (rollupListener) {
+      nsCOMPtr<nsIWidget> rollupWidget = rollupListener->GetRollupWidget();
+      if (rollupWidget) {
+        rollupListener->Rollup({0, nsIRollupListener::FlushViews::Yes});
+        [menu cancelTracking];
+        return;
+      }
+    }
+  }
+
+  // Hold a strong reference to mGeckoMenu while calling its methods.
+  RefPtr<nsMenuX> geckoMenu = mGeckoMenu;
+  geckoMenu->MenuOpened();
+}
+
+- (void)menuDidClose:(NSMenu*)menu {
+  if (!mGeckoMenu) {
+    return;
+  }
+
+  // Don't do anything while the OS is (re)indexing our menus (on Leopard and
+  // higher).  This stops the Help menu from being able to search in our
+  // menus, but it also resolves many other problems.
+  if (nsMenuX::sIndexingMenuLevel > 0) {
+    return;
+  }
+
+  // Hold a strong reference to mGeckoMenu while calling its methods.
+  RefPtr<nsMenuX> geckoMenu = mGeckoMenu;
+  geckoMenu->MenuClosed();
+}
+
+// This is called after menuDidClose:.
+- (void)menu:(NSMenu*)aMenu willActivateItem:(NSMenuItem*)aItem {
+  if (!mGeckoMenu) {
+    return;
+  }
+
+  // Hold a strong reference to mGeckoMenu while calling its methods.
+  RefPtr<nsMenuX> geckoMenu = mGeckoMenu;
+  geckoMenu->OnWillActivateItem(aItem);
+}
+
+@end
+
+// OS X Leopard (at least as of 10.5.2) has an obscure bug triggered by some
+// behavior that's present in Mozilla.org browsers but not (as best I can
+// tell) in Apple products like Safari.  (It's not yet clear exactly what this
+// behavior is.)
+//
+// The bug is that sometimes you crash on quit in nsMenuX::RemoveAll(), on a
+// call to [NSMenu removeItemAtIndex:].  The crash is caused by trying to
+// access a deleted NSMenuItem object (sometimes (perhaps always?) by trying
+// to send it a _setChangedFlags: message).  Though this object was deleted
+// some time ago, it remains registered as a potential target for a particular
+// key equivalent.  So when [NSMenu removeItemAtIndex:] removes the current
+// target for that same key equivalent, the OS tries to "activate" the
+// previous target.
+//
+// The underlying reason appears to be that NSMenu's _addItem:toTable: and
+// _removeItem:fromTable: methods (which are used to keep a hashtable of
+// registered key equivalents) don't properly "retain" and "release"
+// NSMenuItem objects as they are added to and removed from the hashtable.
+//
+// Our (hackish) workaround is to shadow the OS's hashtable with another
+// hastable of our own (gShadowKeyEquivDB), and use it to "retain" and
+// "release" NSMenuItem objects as needed.  This resolves bmo bugs 422287 and
+// 423669.  When (if) Apple fixes this bug, we can remove this workaround.
+
+static NSMutableDictionary* gShadowKeyEquivDB = nil;
+
+// Class for values in gShadowKeyEquivDB.
+
+@interface KeyEquivDBItem : NSObject {
+  NSMenuItem* mItem;
+  NSMutableSet* mTables;
+}
+
+- (id)initWithItem:(NSMenuItem*)aItem table:(NSMapTable*)aTable;
+- (BOOL)hasTable:(NSMapTable*)aTable;
+- (int)addTable:(NSMapTable*)aTable;
+- (int)removeTable:(NSMapTable*)aTable;
+
+@end
+
+@implementation KeyEquivDBItem
+
+- (id)initWithItem:(NSMenuItem*)aItem table:(NSMapTable*)aTable {
+  if (!gShadowKeyEquivDB) {
+    gShadowKeyEquivDB = [[NSMutableDictionary alloc] init];
+  }
+  self = [super init];
+  if (aItem && aTable) {
+    mTables = [[NSMutableSet alloc] init];
+    mItem = [aItem retain];
+    [mTables addObject:[NSValue valueWithPointer:aTable]];
+  } else {
+    mTables = nil;
+    mItem = nil;
+  }
+  return self;
+}
+
+- (void)dealloc {
+  if (mTables) {
+    [mTables release];
+  }
+  if (mItem) {
+    [mItem release];
+  }
+  [super dealloc];
+}
+
+- (BOOL)hasTable:(NSMapTable*)aTable {
+  return [mTables member:[NSValue valueWithPointer:aTable]] ? YES : NO;
+}
+
+// Does nothing if aTable (its index value) is already present in mTables.
+- (int)addTable:(NSMapTable*)aTable {
+  if (aTable) {
+    [mTables addObject:[NSValue valueWithPointer:aTable]];
+  }
+  return [mTables count];
+}
+
+- (int)removeTable:(NSMapTable*)aTable {
+  if (aTable) {
+    NSValue* objectToRemove = [mTables member:[NSValue valueWithPointer:aTable]];
+    if (objectToRemove) {
+      [mTables removeObject:objectToRemove];
+    }
+  }
+  return [mTables count];
+}
+
+@end
+
+@interface NSMenu (MethodSwizzling)
++ (void)nsMenuX_NSMenu_addItem:(NSMenuItem*)aItem toTable:(NSMapTable*)aTable;
++ (void)nsMenuX_NSMenu_removeItem:(NSMenuItem*)aItem fromTable:(NSMapTable*)aTable;
+@end
+
+@implementation NSMenu (MethodSwizzling)
+
++ (void)nsMenuX_NSMenu_addItem:(NSMenuItem*)aItem toTable:(NSMapTable*)aTable {
+  if (aItem && aTable) {
+    NSValue* key = [NSValue valueWithPointer:aItem];
+    KeyEquivDBItem* shadowItem = [gShadowKeyEquivDB objectForKey:key];
+    if (shadowItem) {
+      [shadowItem addTable:aTable];
+    } else {
+      shadowItem = [[KeyEquivDBItem alloc] initWithItem:aItem table:aTable];
+      [gShadowKeyEquivDB setObject:shadowItem forKey:key];
+      // Release after [NSMutableDictionary setObject:forKey:] retains it (so
+      // that it will get dealloced when removeObjectForKey: is called).
+      [shadowItem release];
+    }
+  }
+
+  [self nsMenuX_NSMenu_addItem:aItem toTable:aTable];
+}
+
++ (void)nsMenuX_NSMenu_removeItem:(NSMenuItem*)aItem fromTable:(NSMapTable*)aTable {
+  [self nsMenuX_NSMenu_removeItem:aItem fromTable:aTable];
+
+  if (aItem && aTable) {
+    NSValue* key = [NSValue valueWithPointer:aItem];
+    KeyEquivDBItem* shadowItem = [gShadowKeyEquivDB objectForKey:key];
+    if (shadowItem && [shadowItem hasTable:aTable]) {
+      if (![shadowItem removeTable:aTable]) {
+        [gShadowKeyEquivDB removeObjectForKey:key];
+      }
+    }
+  }
+}
+
+@end
+
+// This class is needed to keep track of when the OS is (re)indexing all of
+// our menus.  This appears to only happen on Leopard and higher, and can
+// be triggered by opening the Help menu.  Some operations are unsafe while
+// this is happening -- notably the calls to [[NSImage alloc]
+// initWithSize:imageRect.size] and [newImage lockFocus] in nsMenuItemIconX::
+// OnStopFrame().  But we don't yet have a complete list, and Apple doesn't
+// yet have any documentation on this subject.  (Apple also doesn't yet have
+// any documented way to find the information we seek here.)  The "original"
+// of this class (the one whose indexMenuBarDynamically method we hook) is
+// defined in the Shortcut framework in /System/Library/PrivateFrameworks.
+@interface NSObject (SCTGRLIndexMethodSwizzling)
+- (void)nsMenuX_SCTGRLIndex_indexMenuBarDynamically;
+@end
+
+@implementation NSObject (SCTGRLIndexMethodSwizzling)
+
+- (void)nsMenuX_SCTGRLIndex_indexMenuBarDynamically {
+  // This method appears to be called (once) whenever the OS (re)indexes our
+  // menus.  sIndexingMenuLevel is a int32_t just in case it might be
+  // reentered.  As it's running, it spawns calls to two undocumented
+  // HIToolbox methods (_SimulateMenuOpening() and _SimulateMenuClosed()),
+  // which "simulate" the opening and closing of our menus without actually
+  // displaying them.
+  ++nsMenuX::sIndexingMenuLevel;
+  [self nsMenuX_SCTGRLIndex_indexMenuBarDynamically];
+  --nsMenuX::sIndexingMenuLevel;
+}
+
+@end
+
+@interface NSObject (NSServicesMenuUpdaterSwizzling)
+- (void)nsMenuX_populateMenu:(NSMenu*)aMenu
+          withServiceEntries:(NSArray*)aServices
+                  forDisplay:(BOOL)aForDisplay;
+@end
+
+@interface _NSServiceEntry : NSObject
+- (NSString*)bundleIdentifier;
+@end
+
+@implementation NSObject (NSServicesMenuUpdaterSwizzling)
+
+- (void)nsMenuX_populateMenu:(NSMenu*)aMenu
+          withServiceEntries:(NSArray*)aServices
+                  forDisplay:(BOOL)aForDisplay {
+  NSMutableArray* filteredServices = [NSMutableArray array];
+
+  // We need to filter some services, such as "Search with Google", since this
+  // service is duplicating functionality already exposed by our "Search Google
+  // for..." context menu entry and because it opens in Safari, which can cause
+  // confusion for users.
+  for (_NSServiceEntry* service in aServices) {
+    NSString* bundleId = [service bundleIdentifier];
+    NSString* msg = [service valueForKey:@"message"];
+    bool shouldSkip = ([bundleId isEqualToString:@"com.apple.Safari"]) ||
+                      ([bundleId isEqualToString:@"com.apple.systemuiserver"] &&
+                       [msg isEqualToString:@"openURL"]);
+    if (!shouldSkip) {
+      [filteredServices addObject:service];
+    }
+  }
+
+  [self nsMenuX_populateMenu:aMenu withServiceEntries:filteredServices forDisplay:aForDisplay];
+}
+
+@end
diff --git a/widget/cocoa/nsNativeThemeCocoa.h b/widget/cocoa/nsNativeThemeCocoa.h
new file mode 100644
index 0000000000..a6c9812238
--- /dev/null
+++ b/widget/cocoa/nsNativeThemeCocoa.h
@@ -0,0 +1,419 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsNativeThemeCocoa_h_
+#define nsNativeThemeCocoa_h_
+
+#import <Carbon/Carbon.h>
+#import <Cocoa/Cocoa.h>
+
+#include "mozilla/Variant.h"
+
+#include "nsITheme.h"
+#include "ThemeCocoa.h"
+#include "mozilla/dom/RustTypes.h"
+
+@class MOZCellDrawWindow;
+@class MOZCellDrawView;
+@class MOZSearchFieldCell;
+@class NSProgressBarCell;
+class nsDeviceContext;
+struct SegmentedControlRenderSettings;
+
+namespace mozilla {
+namespace gfx {
+class DrawTarget;
+}  // namespace gfx
+}  // namespace mozilla
+
+class nsNativeThemeCocoa : public mozilla::widget::ThemeCocoa {
+  using ThemeCocoa = mozilla::widget::ThemeCocoa;
+
+ public:
+  enum class MenuIcon : uint8_t {
+    eCheckmark,
+    eMenuArrow,
+    eMenuDownScrollArrow,
+    eMenuUpScrollArrow
+  };
+
+  enum class CheckboxOrRadioState : uint8_t { eOff, eOn, eIndeterminate };
+
+  enum class ButtonType : uint8_t {
+    eRegularPushButton,
+    eDefaultPushButton,
+    eSquareBezelPushButton,
+    eArrowButton,
+    eHelpButton,
+    eTreeTwistyPointingRight,
+    eTreeTwistyPointingDown,
+    eDisclosureButtonClosed,
+    eDisclosureButtonOpen
+  };
+
+  enum class SpinButton : uint8_t { eUp, eDown };
+
+  enum class SegmentType : uint8_t { eToolbarButton, eTab };
+
+  enum class OptimumState : uint8_t { eOptimum, eSubOptimum, eSubSubOptimum };
+
+  struct ControlParams {
+    ControlParams()
+        : disabled(false), insideActiveWindow(false), pressed(false), focused(false), rtl(false) {}
+
+    bool disabled : 1;
+    bool insideActiveWindow : 1;
+    bool pressed : 1;
+    bool focused : 1;
+    bool rtl : 1;
+  };
+
+  struct MenuIconParams {
+    MenuIcon icon = MenuIcon::eCheckmark;
+    bool disabled = false;
+    bool insideActiveMenuItem = false;
+    bool centerHorizontally = false;
+    bool rtl = false;
+  };
+
+  struct MenuItemParams {
+    bool checked = false;
+    bool disabled = false;
+    bool selected = false;
+    bool rtl = false;
+  };
+
+  struct CheckboxOrRadioParams {
+    ControlParams controlParams;
+    CheckboxOrRadioState state = CheckboxOrRadioState::eOff;
+    float verticalAlignFactor = 0.5f;
+  };
+
+  struct ButtonParams {
+    ControlParams controlParams;
+    ButtonType button = ButtonType::eRegularPushButton;
+  };
+
+  struct DropdownParams {
+    ControlParams controlParams;
+    bool pullsDown = false;
+    bool editable = false;
+  };
+
+  struct SpinButtonParams {
+    mozilla::Maybe<SpinButton> pressedButton;
+    bool disabled = false;
+    bool insideActiveWindow = false;
+  };
+
+  struct SegmentParams {
+    SegmentType segmentType = SegmentType::eToolbarButton;
+    bool insideActiveWindow = false;
+    bool pressed = false;
+    bool selected = false;
+    bool focused = false;
+    bool atLeftEnd = false;
+    bool atRightEnd = false;
+    bool drawsLeftSeparator = false;
+    bool drawsRightSeparator = false;
+    bool rtl = false;
+  };
+
+  struct TextFieldParams {
+    float verticalAlignFactor = 0.5f;
+    bool insideToolbar = false;
+    bool disabled = false;
+    bool focused = false;
+    bool rtl = false;
+  };
+
+  struct ProgressParams {
+    double value = 0.0;
+    double max = 0.0;
+    float verticalAlignFactor = 0.5f;
+    bool insideActiveWindow = false;
+    bool indeterminate = false;
+    bool horizontal = false;
+    bool rtl = false;
+  };
+
+  struct MeterParams {
+    double value = 0;
+    double min = 0;
+    double max = 0;
+    OptimumState optimumState = OptimumState::eOptimum;
+    float verticalAlignFactor = 0.5f;
+    bool horizontal = true;
+    bool rtl = false;
+  };
+
+  struct TreeHeaderCellParams {
+    ControlParams controlParams;
+    TreeSortDirection sortDirection = eTreeSortDirection_Natural;
+    bool lastTreeHeaderCell = false;
+  };
+
+  struct ScaleParams {
+    int32_t value = 0;
+    int32_t min = 0;
+    int32_t max = 0;
+    bool insideActiveWindow = false;
+    bool disabled = false;
+    bool focused = false;
+    bool horizontal = true;
+    bool reverse = false;
+  };
+
+  enum Widget : uint8_t {
+    eColorFill,       // mozilla::gfx::sRGBColor
+    eMenuIcon,        // MenuIconParams
+    eMenuItem,        // MenuItemParams
+    eMenuSeparator,   // MenuItemParams
+    eCheckbox,        // CheckboxOrRadioParams
+    eRadio,           // CheckboxOrRadioParams
+    eButton,          // ButtonParams
+    eDropdown,        // DropdownParams
+    eSpinButtons,     // SpinButtonParams
+    eSpinButtonUp,    // SpinButtonParams
+    eSpinButtonDown,  // SpinButtonParams
+    eSegment,         // SegmentParams
+    eSeparator,
+    eToolbar,    // bool
+    eStatusBar,  // bool
+    eGroupBox,
+    eTextField,           // TextFieldParams
+    eSearchField,         // TextFieldParams
+    eProgressBar,         // ProgressParams
+    eMeter,               // MeterParams
+    eTreeHeaderCell,      // TreeHeaderCellParams
+    eScale,               // ScaleParams
+    eMultilineTextField,  // bool
+    eListBox,
+    eActiveSourceListSelection,    // bool
+    eInactiveSourceListSelection,  // bool
+    eTabPanel,
+  };
+
+  struct WidgetInfo {
+    static WidgetInfo ColorFill(const mozilla::gfx::sRGBColor& aParams) {
+      return WidgetInfo(Widget::eColorFill, aParams);
+    }
+    static WidgetInfo MenuIcon(const MenuIconParams& aParams) {
+      return WidgetInfo(Widget::eMenuIcon, aParams);
+    }
+    static WidgetInfo MenuItem(const MenuItemParams& aParams) {
+      return WidgetInfo(Widget::eMenuItem, aParams);
+    }
+    static WidgetInfo MenuSeparator(const MenuItemParams& aParams) {
+      return WidgetInfo(Widget::eMenuSeparator, aParams);
+    }
+    static WidgetInfo Checkbox(const CheckboxOrRadioParams& aParams) {
+      return WidgetInfo(Widget::eCheckbox, aParams);
+    }
+    static WidgetInfo Radio(const CheckboxOrRadioParams& aParams) {
+      return WidgetInfo(Widget::eRadio, aParams);
+    }
+    static WidgetInfo Button(const ButtonParams& aParams) {
+      return WidgetInfo(Widget::eButton, aParams);
+    }
+    static WidgetInfo Dropdown(const DropdownParams& aParams) {
+      return WidgetInfo(Widget::eDropdown, aParams);
+    }
+    static WidgetInfo SpinButtons(const SpinButtonParams& aParams) {
+      return WidgetInfo(Widget::eSpinButtons, aParams);
+    }
+    static WidgetInfo SpinButtonUp(const SpinButtonParams& aParams) {
+      return WidgetInfo(Widget::eSpinButtonUp, aParams);
+    }
+    static WidgetInfo SpinButtonDown(const SpinButtonParams& aParams) {
+      return WidgetInfo(Widget::eSpinButtonDown, aParams);
+    }
+    static WidgetInfo Segment(const SegmentParams& aParams) {
+      return WidgetInfo(Widget::eSegment, aParams);
+    }
+    static WidgetInfo Separator() { return WidgetInfo(Widget::eSeparator, false); }
+    static WidgetInfo Toolbar(bool aParams) { return WidgetInfo(Widget::eToolbar, aParams); }
+    static WidgetInfo StatusBar(bool aParams) { return WidgetInfo(Widget::eStatusBar, aParams); }
+    static WidgetInfo GroupBox() { return WidgetInfo(Widget::eGroupBox, false); }
+    static WidgetInfo TextField(const TextFieldParams& aParams) {
+      return WidgetInfo(Widget::eTextField, aParams);
+    }
+    static WidgetInfo SearchField(const TextFieldParams& aParams) {
+      return WidgetInfo(Widget::eSearchField, aParams);
+    }
+    static WidgetInfo ProgressBar(const ProgressParams& aParams) {
+      return WidgetInfo(Widget::eProgressBar, aParams);
+    }
+    static WidgetInfo Meter(const MeterParams& aParams) {
+      return WidgetInfo(Widget::eMeter, aParams);
+    }
+    static WidgetInfo TreeHeaderCell(const TreeHeaderCellParams& aParams) {
+      return WidgetInfo(Widget::eTreeHeaderCell, aParams);
+    }
+    static WidgetInfo Scale(const ScaleParams& aParams) {
+      return WidgetInfo(Widget::eScale, aParams);
+    }
+    static WidgetInfo MultilineTextField(bool aParams) {
+      return WidgetInfo(Widget::eMultilineTextField, aParams);
+    }
+    static WidgetInfo ListBox() { return WidgetInfo(Widget::eListBox, false); }
+    static WidgetInfo ActiveSourceListSelection(bool aParams) {
+      return WidgetInfo(Widget::eActiveSourceListSelection, aParams);
+    }
+    static WidgetInfo InactiveSourceListSelection(bool aParams) {
+      return WidgetInfo(Widget::eInactiveSourceListSelection, aParams);
+    }
+    static WidgetInfo TabPanel(bool aParams) { return WidgetInfo(Widget::eTabPanel, aParams); }
+
+    template <typename T>
+    T Params() const {
+      MOZ_RELEASE_ASSERT(mVariant.is<T>());
+      return mVariant.as<T>();
+    }
+
+    enum Widget Widget() const { return mWidget; }
+
+   private:
+    template <typename T>
+    WidgetInfo(enum Widget aWidget, const T& aParams) : mVariant(aParams), mWidget(aWidget) {}
+
+    mozilla::Variant<mozilla::gfx::sRGBColor, MenuIconParams, MenuItemParams, CheckboxOrRadioParams,
+                     ButtonParams, DropdownParams, SpinButtonParams, SegmentParams, TextFieldParams,
+                     ProgressParams, MeterParams, TreeHeaderCellParams, ScaleParams, bool>
+        mVariant;
+
+    enum Widget mWidget;
+  };
+
+  explicit nsNativeThemeCocoa();
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+  // The nsITheme interface.
+  NS_IMETHOD DrawWidgetBackground(gfxContext* aContext, nsIFrame* aFrame,
+                                  StyleAppearance aAppearance, const nsRect& aRect,
+                                  const nsRect& aDirtyRect, DrawOverflow) override;
+  bool CreateWebRenderCommandsForWidget(mozilla::wr::DisplayListBuilder& aBuilder,
+                                        mozilla::wr::IpcResourceUpdateQueue& aResources,
+                                        const mozilla::layers::StackingContextHelper& aSc,
+                                        mozilla::layers::RenderRootStateManager* aManager,
+                                        nsIFrame* aFrame, StyleAppearance aAppearance,
+                                        const nsRect& aRect) override;
+  [[nodiscard]] LayoutDeviceIntMargin GetWidgetBorder(nsDeviceContext* aContext, nsIFrame* aFrame,
+                                                      StyleAppearance aAppearance) override;
+
+  bool GetWidgetPadding(nsDeviceContext* aContext, nsIFrame* aFrame, StyleAppearance aAppearance,
+                        LayoutDeviceIntMargin* aResult) override;
+
+  virtual bool GetWidgetOverflow(nsDeviceContext* aContext, nsIFrame* aFrame,
+                                 StyleAppearance aAppearance, nsRect* aOverflowRect) override;
+
+  LayoutDeviceIntSize GetMinimumWidgetSize(nsPresContext*, nsIFrame*, StyleAppearance) override;
+  NS_IMETHOD WidgetStateChanged(nsIFrame* aFrame, StyleAppearance aAppearance, nsAtom* aAttribute,
+                                bool* aShouldRepaint, const nsAttrValue* aOldValue) override;
+  NS_IMETHOD ThemeChanged() override;
+  bool ThemeSupportsWidget(nsPresContext* aPresContext, nsIFrame* aFrame,
+                           StyleAppearance aAppearance) override;
+  bool WidgetIsContainer(StyleAppearance aAppearance) override;
+  bool ThemeDrawsFocusForWidget(nsIFrame*, StyleAppearance) override;
+  bool ThemeNeedsComboboxDropmarker() override;
+  virtual bool WidgetAppearanceDependsOnWindowFocus(StyleAppearance aAppearance) override;
+  virtual ThemeGeometryType ThemeGeometryTypeForWidget(nsIFrame* aFrame,
+                                                       StyleAppearance aAppearance) override;
+  virtual Transparency GetWidgetTransparency(nsIFrame* aFrame,
+                                             StyleAppearance aAppearance) override;
+  mozilla::Maybe<WidgetInfo> ComputeWidgetInfo(nsIFrame* aFrame, StyleAppearance aAppearance,
+                                               const nsRect& aRect);
+  void DrawProgress(CGContextRef context, const HIRect& inBoxRect, const ProgressParams& aParams);
+
+ protected:
+  virtual ~nsNativeThemeCocoa();
+
+  LayoutDeviceIntMargin DirectionAwareMargin(const LayoutDeviceIntMargin& aMargin,
+                                             nsIFrame* aFrame);
+  nsIFrame* SeparatorResponsibility(nsIFrame* aBefore, nsIFrame* aAfter);
+  ControlParams ComputeControlParams(nsIFrame* aFrame, mozilla::dom::ElementState aEventState);
+  MenuIconParams ComputeMenuIconParams(nsIFrame* aParams, mozilla::dom::ElementState aEventState,
+                                       MenuIcon aIcon);
+  MenuItemParams ComputeMenuItemParams(nsIFrame* aFrame, mozilla::dom::ElementState aEventState,
+                                       bool aIsChecked);
+  SegmentParams ComputeSegmentParams(nsIFrame* aFrame, mozilla::dom::ElementState aEventState,
+                                     SegmentType aSegmentType);
+  TextFieldParams ComputeTextFieldParams(nsIFrame* aFrame, mozilla::dom::ElementState aEventState);
+  ProgressParams ComputeProgressParams(nsIFrame* aFrame, mozilla::dom::ElementState aEventState,
+                                       bool aIsHorizontal);
+  MeterParams ComputeMeterParams(nsIFrame* aFrame);
+  TreeHeaderCellParams ComputeTreeHeaderCellParams(nsIFrame* aFrame,
+                                                   mozilla::dom::ElementState aEventState);
+  mozilla::Maybe<ScaleParams> ComputeHTMLScaleParams(nsIFrame* aFrame,
+                                                     mozilla::dom::ElementState aEventState);
+
+  // HITheme drawing routines
+  void DrawMeter(CGContextRef context, const HIRect& inBoxRect, const MeterParams& aParams);
+  void DrawSegment(CGContextRef cgContext, const HIRect& inBoxRect, const SegmentParams& aParams);
+  void DrawSegmentBackground(CGContextRef cgContext, const HIRect& inBoxRect,
+                             const SegmentParams& aParams);
+  void DrawTabPanel(CGContextRef context, const HIRect& inBoxRect, bool aIsInsideActiveWindow);
+  void DrawScale(CGContextRef context, const HIRect& inBoxRect, const ScaleParams& aParams);
+  void DrawCheckboxOrRadio(CGContextRef cgContext, bool inCheckbox, const HIRect& inBoxRect,
+                           const CheckboxOrRadioParams& aParams);
+  void DrawSearchField(CGContextRef cgContext, const HIRect& inBoxRect,
+                       const TextFieldParams& aParams);
+  void DrawTextField(CGContextRef cgContext, const HIRect& inBoxRect,
+                     const TextFieldParams& aParams);
+  void DrawPushButton(CGContextRef cgContext, const HIRect& inBoxRect, ButtonType aButtonType,
+                      ControlParams aControlParams);
+  void DrawSquareBezelPushButton(CGContextRef cgContext, const HIRect& inBoxRect,
+                                 ControlParams aControlParams);
+  void DrawHelpButton(CGContextRef cgContext, const HIRect& inBoxRect,
+                      ControlParams aControlParams);
+  void DrawDisclosureButton(CGContextRef cgContext, const HIRect& inBoxRect,
+                            ControlParams aControlParams, NSControlStateValue aState);
+  NSString* GetMenuIconName(const MenuIconParams& aParams);
+  NSSize GetMenuIconSize(MenuIcon aIcon);
+  void DrawMenuIcon(CGContextRef cgContext, const CGRect& aRect, const MenuIconParams& aParams);
+  void DrawMenuItem(CGContextRef cgContext, const CGRect& inBoxRect, const MenuItemParams& aParams);
+  void DrawMenuSeparator(CGContextRef cgContext, const CGRect& inBoxRect,
+                         const MenuItemParams& aParams);
+  void DrawHIThemeButton(CGContextRef cgContext, const HIRect& aRect, ThemeButtonKind aKind,
+                         ThemeButtonValue aValue, ThemeDrawState aState,
+                         ThemeButtonAdornment aAdornment, const ControlParams& aParams);
+  void DrawButton(CGContextRef context, const HIRect& inBoxRect, const ButtonParams& aParams);
+  void DrawTreeHeaderCell(CGContextRef context, const HIRect& inBoxRect,
+                          const TreeHeaderCellParams& aParams);
+  void DrawDropdown(CGContextRef context, const HIRect& inBoxRect, const DropdownParams& aParams);
+  HIThemeButtonDrawInfo SpinButtonDrawInfo(ThemeButtonKind aKind, const SpinButtonParams& aParams);
+  void DrawSpinButtons(CGContextRef context, const HIRect& inBoxRect,
+                       const SpinButtonParams& aParams);
+  void DrawSpinButton(CGContextRef context, const HIRect& inBoxRect, SpinButton aDrawnButton,
+                      const SpinButtonParams& aParams);
+  void DrawToolbar(CGContextRef cgContext, const CGRect& inBoxRect, bool aIsMain);
+  void DrawStatusBar(CGContextRef cgContext, const HIRect& inBoxRect, bool aIsMain);
+  void DrawMultilineTextField(CGContextRef cgContext, const CGRect& inBoxRect, bool aIsFocused);
+  void DrawSourceListSelection(CGContextRef aContext, const CGRect& aRect, bool aWindowIsActive,
+                               bool aSelectionIsActive);
+
+  void RenderWidget(const WidgetInfo& aWidgetInfo, mozilla::ColorScheme,
+                    mozilla::gfx::DrawTarget& aDrawTarget, const mozilla::gfx::Rect& aWidgetRect,
+                    const mozilla::gfx::Rect& aDirtyRect, float aScale);
+
+ private:
+  NSButtonCell* mDisclosureButtonCell;
+  NSButtonCell* mHelpButtonCell;
+  NSButtonCell* mPushButtonCell;
+  NSButtonCell* mRadioButtonCell;
+  NSButtonCell* mCheckboxCell;
+  NSTextFieldCell* mTextFieldCell;
+  MOZSearchFieldCell* mSearchFieldCell;
+  NSPopUpButtonCell* mDropdownCell;
+  NSComboBoxCell* mComboBoxCell;
+  NSProgressBarCell* mProgressBarCell;
+  NSLevelIndicatorCell* mMeterBarCell;
+  NSTableHeaderCell* mTreeHeaderCell;
+  MOZCellDrawWindow* mCellDrawWindow = nil;
+  MOZCellDrawView* mCellDrawView;
+};
+
+#endif  // nsNativeThemeCocoa_h_
diff --git a/widget/cocoa/nsNativeThemeCocoa.mm b/widget/cocoa/nsNativeThemeCocoa.mm
new file mode 100644
index 0000000000..e14f161663
--- /dev/null
+++ b/widget/cocoa/nsNativeThemeCocoa.mm
@@ -0,0 +1,3444 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsNativeThemeCocoa.h"
+#include <objc/NSObjCRuntime.h>
+
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/Helpers.h"
+#include "mozilla/gfx/PathHelpers.h"
+#include "nsChildView.h"
+#include "nsDeviceContext.h"
+#include "nsLayoutUtils.h"
+#include "nsObjCExceptions.h"
+#include "nsNumberControlFrame.h"
+#include "nsRangeFrame.h"
+#include "nsRect.h"
+#include "nsSize.h"
+#include "nsStyleConsts.h"
+#include "nsPresContext.h"
+#include "nsIContent.h"
+#include "mozilla/dom/Document.h"
+#include "nsIFrame.h"
+#include "nsAtom.h"
+#include "nsNameSpaceManager.h"
+#include "nsPresContext.h"
+#include "nsGkAtoms.h"
+#include "nsCocoaFeatures.h"
+#include "nsCocoaWindow.h"
+#include "nsNativeThemeColors.h"
+#include "nsIScrollableFrame.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/Range.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/HTMLMeterElement.h"
+#include "mozilla/layers/StackingContextHelper.h"
+#include "mozilla/StaticPrefs_layout.h"
+#include "mozilla/StaticPrefs_widget.h"
+#include "nsLookAndFeel.h"
+#include "MacThemeGeometryType.h"
+#include "SDKDeclarations.h"
+#include "VibrancyManager.h"
+
+#include "gfxContext.h"
+#include "gfxQuartzSurface.h"
+#include "gfxQuartzNativeDrawing.h"
+#include "gfxUtils.h"  // for ToDeviceColor
+#include <algorithm>
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+using mozilla::dom::HTMLMeterElement;
+
+#define DRAW_IN_FRAME_DEBUG 0
+#define SCROLLBARS_VISUAL_DEBUG 0
+
+// private Quartz routines needed here
+extern "C" {
+CG_EXTERN void CGContextSetCTM(CGContextRef, CGAffineTransform);
+CG_EXTERN void CGContextSetBaseCTM(CGContextRef, CGAffineTransform);
+typedef CFTypeRef CUIRendererRef;
+void CUIDraw(CUIRendererRef r, CGRect rect, CGContextRef ctx, CFDictionaryRef options,
+             CFDictionaryRef* result);
+}
+
+static bool IsDarkAppearance(NSAppearance* appearance) {
+  if (@available(macOS 10.14, *)) {
+    return [appearance.name isEqualToString:NSAppearanceNameDarkAqua];
+  }
+  return false;
+}
+
+// Workaround for NSCell control tint drawing
+// Without this workaround, NSCells are always drawn with the clear control tint
+// as long as they're not attached to an NSControl which is a subview of an active window.
+// XXXmstange Why doesn't Webkit need this?
+@implementation NSCell (ControlTintWorkaround)
+- (int)_realControlTint {
+  return [self controlTint];
+}
+@end
+
+// This is the window for our MOZCellDrawView. When an NSCell is drawn, some NSCell implementations
+// look at the draw view's window to determine whether the cell should draw with the active look.
+@interface MOZCellDrawWindow : NSWindow
+@property BOOL cellsShouldLookActive;
+@end
+
+@implementation MOZCellDrawWindow
+
+// Override three different methods, for good measure. The NSCell implementation could call any one
+// of them.
+- (BOOL)_hasActiveAppearance {
+  return self.cellsShouldLookActive;
+}
+- (BOOL)hasKeyAppearance {
+  return self.cellsShouldLookActive;
+}
+- (BOOL)_hasKeyAppearance {
+  return self.cellsShouldLookActive;
+}
+
+@end
+
+// The purpose of this class is to provide objects that can be used when drawing
+// NSCells using drawWithFrame:inView: without causing any harm. Only a small
+// number of methods are called on the draw view, among those "isFlipped" and
+// "currentEditor": isFlipped needs to return YES in order to avoid drawing bugs
+// on 10.4 (see bug 465069); currentEditor (which isn't even a method of
+// NSView) will be called when drawing search fields, and we only provide it in
+// order to prevent "unrecognized selector" exceptions.
+// There's no need to pass the actual NSView that we're drawing into to
+// drawWithFrame:inView:. What's more, doing so even causes unnecessary
+// invalidations as soon as we draw a focusring!
+// This class needs to be an NSControl so that NSTextFieldCell (and
+// NSSearchFieldCell, which is a subclass of NSTextFieldCell) draws a focus ring.
+@interface MOZCellDrawView : NSControl
+// Called by NSTreeHeaderCell during drawing.
+@property BOOL _drawingEndSeparator;
+@end
+
+@implementation MOZCellDrawView
+
+- (BOOL)isFlipped {
+  return YES;
+}
+
+- (NSText*)currentEditor {
+  return nil;
+}
+
+@end
+
+static void DrawFocusRingForCellIfNeeded(NSCell* aCell, NSRect aWithFrame, NSView* aInView) {
+  if ([aCell showsFirstResponder]) {
+    CGContextRef cgContext = [[NSGraphicsContext currentContext] CGContext];
+    CGContextSaveGState(cgContext);
+
+    // It's important to set the focus ring style before we enter the
+    // transparency layer so that the transparency layer only contains
+    // the normal button mask without the focus ring, and the conversion
+    // to the focus ring shape happens only when the transparency layer is
+    // ended.
+    NSSetFocusRingStyle(NSFocusRingOnly);
+
+    // We need to draw the whole button into a transparency layer because
+    // many button types are composed of multiple parts, and if these parts
+    // were drawn while the focus ring style was active, each individual part
+    // would produce a focus ring for itself. But we only want one focus ring
+    // for the whole button. The transparency layer is a way to merge the
+    // individual button parts together before the focus ring shape is
+    // calculated.
+    CGContextBeginTransparencyLayerWithRect(cgContext, NSRectToCGRect(aWithFrame), 0);
+    [aCell drawFocusRingMaskWithFrame:aWithFrame inView:aInView];
+    CGContextEndTransparencyLayer(cgContext);
+
+    CGContextRestoreGState(cgContext);
+  }
+}
+
+static void DrawCellIncludingFocusRing(NSCell* aCell, NSRect aWithFrame, NSView* aInView) {
+  [aCell drawWithFrame:aWithFrame inView:aInView];
+  DrawFocusRingForCellIfNeeded(aCell, aWithFrame, aInView);
+}
+
+/**
+ * NSProgressBarCell is used to draw progress bars of any size.
+ */
+@interface NSProgressBarCell : NSCell {
+  /*All instance variables are private*/
+  double mValue;
+  double mMax;
+  bool mIsIndeterminate;
+  bool mIsHorizontal;
+}
+
+- (void)setValue:(double)value;
+- (double)value;
+- (void)setMax:(double)max;
+- (double)max;
+- (void)setIndeterminate:(bool)aIndeterminate;
+- (bool)isIndeterminate;
+- (void)setHorizontal:(bool)aIsHorizontal;
+- (bool)isHorizontal;
+- (void)drawWithFrame:(NSRect)cellFrame inView:(NSView*)controlView;
+@end
+
+@implementation NSProgressBarCell
+
+- (void)setMax:(double)aMax {
+  mMax = aMax;
+}
+
+- (double)max {
+  return mMax;
+}
+
+- (void)setValue:(double)aValue {
+  mValue = aValue;
+}
+
+- (double)value {
+  return mValue;
+}
+
+- (void)setIndeterminate:(bool)aIndeterminate {
+  mIsIndeterminate = aIndeterminate;
+}
+
+- (bool)isIndeterminate {
+  return mIsIndeterminate;
+}
+
+- (void)setHorizontal:(bool)aIsHorizontal {
+  mIsHorizontal = aIsHorizontal;
+}
+
+- (bool)isHorizontal {
+  return mIsHorizontal;
+}
+
+- (void)drawWithFrame:(NSRect)cellFrame inView:(NSView*)controlView {
+  CGContext* cgContext = [[NSGraphicsContext currentContext] CGContext];
+
+  HIThemeTrackDrawInfo tdi;
+
+  tdi.version = 0;
+  tdi.min = 0;
+
+  tdi.value = INT32_MAX * (mValue / mMax);
+  tdi.max = INT32_MAX;
+  tdi.bounds = NSRectToCGRect(cellFrame);
+  tdi.attributes = mIsHorizontal ? kThemeTrackHorizontal : 0;
+  tdi.enableState =
+      [self controlTint] == NSClearControlTint ? kThemeTrackInactive : kThemeTrackActive;
+
+  NSControlSize size = [self controlSize];
+  if (size == NSControlSizeRegular) {
+    tdi.kind = mIsIndeterminate ? kThemeLargeIndeterminateBar : kThemeLargeProgressBar;
+  } else {
+    NS_ASSERTION(size == NSControlSizeSmall,
+                 "We shouldn't have another size than small and regular for the moment");
+    tdi.kind = mIsIndeterminate ? kThemeMediumIndeterminateBar : kThemeMediumProgressBar;
+  }
+
+  int32_t stepsPerSecond = mIsIndeterminate ? 60 : 30;
+  int32_t milliSecondsPerStep = 1000 / stepsPerSecond;
+  tdi.trackInfo.progress.phase =
+      uint8_t(PR_IntervalToMilliseconds(PR_IntervalNow()) / milliSecondsPerStep);
+
+  HIThemeDrawTrack(&tdi, NULL, cgContext, kHIThemeOrientationNormal);
+}
+
+@end
+
+@interface MOZSearchFieldCell : NSSearchFieldCell
+@property BOOL shouldUseToolbarStyle;
+@end
+
+@implementation MOZSearchFieldCell
+
+- (instancetype)init {
+  // We would like to render a search field which has the magnifying glass icon at the start of the
+  // search field, and no cancel button.
+  // On 10.12 and 10.13, empty search fields render the magnifying glass icon in the middle of the
+  // field. So in order to get the icon to show at the start of the field, we need to give the field
+  // some content. We achieve this with a single space character.
+  self = [super initTextCell:@" "];
+
+  // However, because the field is now non-empty, by default it shows a cancel button. To hide the
+  // cancel button, override it with a custom NSButtonCell which renders nothing.
+  NSButtonCell* invisibleCell = [[NSButtonCell alloc] initImageCell:nil];
+  invisibleCell.bezeled = NO;
+  invisibleCell.bordered = NO;
+  self.cancelButtonCell = invisibleCell;
+  [invisibleCell release];
+
+  return self;
+}
+
+- (BOOL)_isToolbarMode {
+  return self.shouldUseToolbarStyle;
+}
+
+@end
+
+#define HITHEME_ORIENTATION kHIThemeOrientationNormal
+
+static CGFloat kMaxFocusRingWidth = 0;  // initialized by the nsNativeThemeCocoa constructor
+
+// These enums are for indexing into the margin array.
+enum {
+  leopardOSorlater = 0,  // 10.6 - 10.9
+  yosemiteOSorlater = 1  // 10.10+
+};
+
+enum { miniControlSize, smallControlSize, regularControlSize };
+
+enum { leftMargin, topMargin, rightMargin, bottomMargin };
+
+static size_t EnumSizeForCocoaSize(NSControlSize cocoaControlSize) {
+  if (cocoaControlSize == NSControlSizeMini)
+    return miniControlSize;
+  else if (cocoaControlSize == NSControlSizeSmall)
+    return smallControlSize;
+  else
+    return regularControlSize;
+}
+
+static NSControlSize CocoaSizeForEnum(int32_t enumControlSize) {
+  if (enumControlSize == miniControlSize)
+    return NSControlSizeMini;
+  else if (enumControlSize == smallControlSize)
+    return NSControlSizeSmall;
+  else
+    return NSControlSizeRegular;
+}
+
+static NSString* CUIControlSizeForCocoaSize(NSControlSize aControlSize) {
+  if (aControlSize == NSControlSizeRegular)
+    return @"regular";
+  else if (aControlSize == NSControlSizeSmall)
+    return @"small";
+  else
+    return @"mini";
+}
+
+static void InflateControlRect(NSRect* rect, NSControlSize cocoaControlSize,
+                               const float marginSet[][3][4]) {
+  if (!marginSet) return;
+
+  static int osIndex = yosemiteOSorlater;
+  size_t controlSize = EnumSizeForCocoaSize(cocoaControlSize);
+  const float* buttonMargins = marginSet[osIndex][controlSize];
+  rect->origin.x -= buttonMargins[leftMargin];
+  rect->origin.y -= buttonMargins[bottomMargin];
+  rect->size.width += buttonMargins[leftMargin] + buttonMargins[rightMargin];
+  rect->size.height += buttonMargins[bottomMargin] + buttonMargins[topMargin];
+}
+
+static NSWindow* NativeWindowForFrame(nsIFrame* aFrame, nsIWidget** aTopLevelWidget = NULL) {
+  if (!aFrame) return nil;
+
+  nsIWidget* widget = aFrame->GetNearestWidget();
+  if (!widget) return nil;
+
+  nsIWidget* topLevelWidget = widget->GetTopLevelWidget();
+  if (aTopLevelWidget) *aTopLevelWidget = topLevelWidget;
+
+  return (NSWindow*)topLevelWidget->GetNativeData(NS_NATIVE_WINDOW);
+}
+
+static NSSize WindowButtonsSize(nsIFrame* aFrame) {
+  NSWindow* window = NativeWindowForFrame(aFrame);
+  if (!window) {
+    // Return fallback values.
+    return NSMakeSize(54, 16);
+  }
+
+  NSRect buttonBox = NSZeroRect;
+  NSButton* closeButton = [window standardWindowButton:NSWindowCloseButton];
+  if (closeButton) {
+    buttonBox = NSUnionRect(buttonBox, [closeButton frame]);
+  }
+  NSButton* minimizeButton = [window standardWindowButton:NSWindowMiniaturizeButton];
+  if (minimizeButton) {
+    buttonBox = NSUnionRect(buttonBox, [minimizeButton frame]);
+  }
+  NSButton* zoomButton = [window standardWindowButton:NSWindowZoomButton];
+  if (zoomButton) {
+    buttonBox = NSUnionRect(buttonBox, [zoomButton frame]);
+  }
+  return buttonBox.size;
+}
+
+static BOOL FrameIsInActiveWindow(nsIFrame* aFrame) {
+  nsIWidget* topLevelWidget = NULL;
+  NSWindow* win = NativeWindowForFrame(aFrame, &topLevelWidget);
+  if (!topLevelWidget || !win) return YES;
+
+  // XUL popups, e.g. the toolbar customization popup, can't become key windows,
+  // but controls in these windows should still get the active look.
+  if (topLevelWidget->GetWindowType() == widget::WindowType::Popup) {
+    return YES;
+  }
+  if ([win isSheet]) {
+    return [win isKeyWindow];
+  }
+  return [win isMainWindow] && ![win attachedSheet];
+}
+
+// Toolbar controls and content controls respond to different window
+// activeness states.
+static BOOL IsActive(nsIFrame* aFrame, BOOL aIsToolbarControl) {
+  if (aIsToolbarControl) return [NativeWindowForFrame(aFrame) isMainWindow];
+  return FrameIsInActiveWindow(aFrame);
+}
+
+static bool IsInSourceList(nsIFrame* aFrame) {
+  for (nsIFrame* frame = aFrame->GetParent(); frame;
+       frame = nsLayoutUtils::GetCrossDocParentFrameInProcess(frame)) {
+    if (frame->StyleDisplay()->EffectiveAppearance() == StyleAppearance::MozMacSourceList) {
+      return true;
+    }
+  }
+  return false;
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(nsNativeThemeCocoa, nsNativeTheme, nsITheme)
+
+nsNativeThemeCocoa::nsNativeThemeCocoa() : ThemeCocoa(ScrollbarStyle()) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  kMaxFocusRingWidth = 7;
+
+  // provide a local autorelease pool, as this is called during startup
+  // before the main event-loop pool is in place
+  nsAutoreleasePool pool;
+
+  mDisclosureButtonCell = [[NSButtonCell alloc] initTextCell:@""];
+  [mDisclosureButtonCell setBezelStyle:NSRoundedDisclosureBezelStyle];
+  [mDisclosureButtonCell setButtonType:NSPushOnPushOffButton];
+  [mDisclosureButtonCell setHighlightsBy:NSPushInCellMask];
+
+  mHelpButtonCell = [[NSButtonCell alloc] initTextCell:@""];
+  [mHelpButtonCell setBezelStyle:NSHelpButtonBezelStyle];
+  [mHelpButtonCell setButtonType:NSMomentaryPushInButton];
+  [mHelpButtonCell setHighlightsBy:NSPushInCellMask];
+
+  mPushButtonCell = [[NSButtonCell alloc] initTextCell:@""];
+  [mPushButtonCell setButtonType:NSMomentaryPushInButton];
+  [mPushButtonCell setHighlightsBy:NSPushInCellMask];
+
+  mRadioButtonCell = [[NSButtonCell alloc] initTextCell:@""];
+  [mRadioButtonCell setButtonType:NSRadioButton];
+
+  mCheckboxCell = [[NSButtonCell alloc] initTextCell:@""];
+  [mCheckboxCell setButtonType:NSSwitchButton];
+  [mCheckboxCell setAllowsMixedState:YES];
+
+  mTextFieldCell = [[NSTextFieldCell alloc] initTextCell:@""];
+  [mTextFieldCell setBezeled:YES];
+  [mTextFieldCell setEditable:YES];
+  [mTextFieldCell setFocusRingType:NSFocusRingTypeExterior];
+
+  mSearchFieldCell = [[MOZSearchFieldCell alloc] init];
+  [mSearchFieldCell setBezelStyle:NSTextFieldRoundedBezel];
+  [mSearchFieldCell setBezeled:YES];
+  [mSearchFieldCell setEditable:YES];
+  [mSearchFieldCell setFocusRingType:NSFocusRingTypeExterior];
+
+  mDropdownCell = [[NSPopUpButtonCell alloc] initTextCell:@"" pullsDown:NO];
+
+  mComboBoxCell = [[NSComboBoxCell alloc] initTextCell:@""];
+  [mComboBoxCell setBezeled:YES];
+  [mComboBoxCell setEditable:YES];
+  [mComboBoxCell setFocusRingType:NSFocusRingTypeExterior];
+
+  mProgressBarCell = [[NSProgressBarCell alloc] init];
+
+  mMeterBarCell = [[NSLevelIndicatorCell alloc]
+      initWithLevelIndicatorStyle:NSContinuousCapacityLevelIndicatorStyle];
+
+  mTreeHeaderCell = [[NSTableHeaderCell alloc] init];
+
+  mCellDrawView = [[MOZCellDrawView alloc] init];
+
+  if (XRE_IsParentProcess()) {
+    // Put the cell draw view into a window that is never shown.
+    // This allows us to convince some NSCell implementations (such as NSButtonCell for default
+    // buttons) to draw with the active appearance. Another benefit of putting the draw view in a
+    // window is the fact that it lets NSTextFieldCell (and its subclass NSSearchFieldCell) inherit
+    // the current NSApplication effectiveAppearance automatically, so the field adapts to Dark Mode
+    // correctly.
+    // We don't create this window when the native theme is used in the content process because
+    // NSWindow creation runs into the sandbox and because we never run default buttons in content
+    // processes anyway.
+    mCellDrawWindow = [[MOZCellDrawWindow alloc] initWithContentRect:NSZeroRect
+                                                           styleMask:NSWindowStyleMaskBorderless
+                                                             backing:NSBackingStoreBuffered
+                                                               defer:NO];
+    [mCellDrawWindow.contentView addSubview:mCellDrawView];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsNativeThemeCocoa::~nsNativeThemeCocoa() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mMeterBarCell release];
+  [mProgressBarCell release];
+  [mDisclosureButtonCell release];
+  [mHelpButtonCell release];
+  [mPushButtonCell release];
+  [mRadioButtonCell release];
+  [mCheckboxCell release];
+  [mTextFieldCell release];
+  [mSearchFieldCell release];
+  [mDropdownCell release];
+  [mComboBoxCell release];
+  [mTreeHeaderCell release];
+  [mCellDrawWindow release];
+  [mCellDrawView release];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Limit on the area of the target rect (in pixels^2) in
+// DrawCellWithScaling() and DrawButton() and above which we
+// don't draw the object into a bitmap buffer.  This is to avoid crashes in
+// [NSGraphicsContext graphicsContextWithCGContext:flipped:] and
+// CGContextDrawImage(), and also to avoid very poor drawing performance in
+// CGContextDrawImage() when it scales the bitmap (particularly if xscale or
+// yscale is less than but near 1 -- e.g. 0.9).  This value was determined
+// by trial and error, on OS X 10.4.11 and 10.5.4, and on systems with
+// different amounts of RAM.
+#define BITMAP_MAX_AREA 500000
+
+static int GetBackingScaleFactorForRendering(CGContextRef cgContext) {
+  CGAffineTransform ctm = CGContextGetUserSpaceToDeviceSpaceTransform(cgContext);
+  CGRect transformedUserSpacePixel = CGRectApplyAffineTransform(CGRectMake(0, 0, 1, 1), ctm);
+  float maxScale = std::max(fabs(transformedUserSpacePixel.size.width),
+                            fabs(transformedUserSpacePixel.size.height));
+  return maxScale > 1.0 ? 2 : 1;
+}
+
+/*
+ * Draw the given NSCell into the given cgContext.
+ *
+ * destRect - the size and position of the resulting control rectangle
+ * controlSize - the NSControlSize which will be given to the NSCell before
+ *  asking it to render
+ * naturalSize - The natural dimensions of this control.
+ *  If the control rect size is not equal to either of these, a scale
+ *  will be applied to the context so that rendering the control at the
+ *  natural size will result in it filling the destRect space.
+ *  If a control has no natural dimensions in either/both axes, pass 0.0f.
+ * minimumSize - The minimum dimensions of this control.
+ *  If the control rect size is less than the minimum for a given axis,
+ *  a scale will be applied to the context so that the minimum is used
+ *  for drawing.  If a control has no minimum dimensions in either/both
+ *  axes, pass 0.0f.
+ * marginSet - an array of margins; a multidimensional array of [2][3][4],
+ *  with the first dimension being the OS version (Tiger or Leopard),
+ *  the second being the control size (mini, small, regular), and the third
+ *  being the 4 margin values (left, top, right, bottom).
+ * view - The NSView that we're drawing into. As far as I can tell, it doesn't
+ *  matter if this is really the right view; it just has to return YES when
+ *  asked for isFlipped. Otherwise we'll get drawing bugs on 10.4.
+ * mirrorHorizontal - whether to mirror the cell horizontally
+ */
+static void DrawCellWithScaling(NSCell* cell, CGContextRef cgContext, const HIRect& destRect,
+                                NSControlSize controlSize, NSSize naturalSize, NSSize minimumSize,
+                                const float marginSet[][3][4], NSView* view,
+                                BOOL mirrorHorizontal) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NSRect drawRect =
+      NSMakeRect(destRect.origin.x, destRect.origin.y, destRect.size.width, destRect.size.height);
+
+  if (naturalSize.width != 0.0f) drawRect.size.width = naturalSize.width;
+  if (naturalSize.height != 0.0f) drawRect.size.height = naturalSize.height;
+
+  // Keep aspect ratio when scaling if one dimension is free.
+  if (naturalSize.width == 0.0f && naturalSize.height != 0.0f)
+    drawRect.size.width = destRect.size.width * naturalSize.height / destRect.size.height;
+  if (naturalSize.height == 0.0f && naturalSize.width != 0.0f)
+    drawRect.size.height = destRect.size.height * naturalSize.width / destRect.size.width;
+
+  // Honor minimum sizes.
+  if (drawRect.size.width < minimumSize.width) drawRect.size.width = minimumSize.width;
+  if (drawRect.size.height < minimumSize.height) drawRect.size.height = minimumSize.height;
+
+  [NSGraphicsContext saveGraphicsState];
+
+  // Only skip the buffer if the area of our cell (in pixels^2) is too large.
+  if (drawRect.size.width * drawRect.size.height > BITMAP_MAX_AREA) {
+    // Inflate the rect Gecko gave us by the margin for the control.
+    InflateControlRect(&drawRect, controlSize, marginSet);
+
+    NSGraphicsContext* savedContext = [NSGraphicsContext currentContext];
+    [NSGraphicsContext setCurrentContext:[NSGraphicsContext graphicsContextWithCGContext:cgContext
+                                                                                 flipped:YES]];
+
+    DrawCellIncludingFocusRing(cell, drawRect, view);
+
+    [NSGraphicsContext setCurrentContext:savedContext];
+  } else {
+    float w = ceil(drawRect.size.width);
+    float h = ceil(drawRect.size.height);
+    NSRect tmpRect = NSMakeRect(kMaxFocusRingWidth, kMaxFocusRingWidth, w, h);
+
+    // inflate to figure out the frame we need to tell NSCell to draw in, to get something that's
+    // 0,0,w,h
+    InflateControlRect(&tmpRect, controlSize, marginSet);
+
+    // and then, expand by kMaxFocusRingWidth size to make sure we can capture any focus ring
+    w += kMaxFocusRingWidth * 2.0;
+    h += kMaxFocusRingWidth * 2.0;
+
+    int backingScaleFactor = GetBackingScaleFactorForRendering(cgContext);
+    CGColorSpaceRef rgb = CGColorSpaceCreateDeviceRGB();
+    CGContextRef ctx = CGBitmapContextCreate(
+        NULL, (int)w * backingScaleFactor, (int)h * backingScaleFactor, 8,
+        (int)w * backingScaleFactor * 4, rgb, kCGImageAlphaPremultipliedFirst);
+    CGColorSpaceRelease(rgb);
+
+    // We need to flip the image twice in order to avoid drawing bugs on 10.4, see bug 465069.
+    // This is the first flip transform, applied to cgContext.
+    CGContextScaleCTM(cgContext, 1.0f, -1.0f);
+    CGContextTranslateCTM(cgContext, 0.0f, -(2.0 * destRect.origin.y + destRect.size.height));
+    if (mirrorHorizontal) {
+      CGContextScaleCTM(cgContext, -1.0f, 1.0f);
+      CGContextTranslateCTM(cgContext, -(2.0 * destRect.origin.x + destRect.size.width), 0.0f);
+    }
+
+    NSGraphicsContext* savedContext = [NSGraphicsContext currentContext];
+    [NSGraphicsContext setCurrentContext:[NSGraphicsContext graphicsContextWithCGContext:ctx
+                                                                                 flipped:YES]];
+
+    CGContextScaleCTM(ctx, backingScaleFactor, backingScaleFactor);
+
+    // Set the context's "base transform" to in order to get correctly-sized focus rings.
+    CGContextSetBaseCTM(ctx, CGAffineTransformMakeScale(backingScaleFactor, backingScaleFactor));
+
+    // This is the second flip transform, applied to ctx.
+    CGContextScaleCTM(ctx, 1.0f, -1.0f);
+    CGContextTranslateCTM(ctx, 0.0f, -(2.0 * tmpRect.origin.y + tmpRect.size.height));
+
+    DrawCellIncludingFocusRing(cell, tmpRect, view);
+
+    [NSGraphicsContext setCurrentContext:savedContext];
+
+    CGImageRef img = CGBitmapContextCreateImage(ctx);
+
+    // Drop the image into the original destination rectangle, scaling to fit
+    // Only scale kMaxFocusRingWidth by xscale/yscale when the resulting rect
+    // doesn't extend beyond the overflow rect
+    float xscale = destRect.size.width / drawRect.size.width;
+    float yscale = destRect.size.height / drawRect.size.height;
+    float scaledFocusRingX = xscale < 1.0f ? kMaxFocusRingWidth * xscale : kMaxFocusRingWidth;
+    float scaledFocusRingY = yscale < 1.0f ? kMaxFocusRingWidth * yscale : kMaxFocusRingWidth;
+    CGContextDrawImage(
+        cgContext,
+        CGRectMake(destRect.origin.x - scaledFocusRingX, destRect.origin.y - scaledFocusRingY,
+                   destRect.size.width + scaledFocusRingX * 2,
+                   destRect.size.height + scaledFocusRingY * 2),
+        img);
+
+    CGImageRelease(img);
+    CGContextRelease(ctx);
+  }
+
+  [NSGraphicsContext restoreGraphicsState];
+
+#if DRAW_IN_FRAME_DEBUG
+  CGContextSetRGBFillColor(cgContext, 0.0, 0.0, 0.5, 0.25);
+  CGContextFillRect(cgContext, destRect);
+#endif
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+struct CellRenderSettings {
+  // The natural dimensions of the control.
+  // If a control has no natural dimensions in either/both axes, set to 0.0f.
+  NSSize naturalSizes[3];
+
+  // The minimum dimensions of the control.
+  // If a control has no minimum dimensions in either/both axes, set to 0.0f.
+  NSSize minimumSizes[3];
+
+  // A three-dimensional array,
+  // with the first dimension being the OS version ([0] 10.6-10.9, [1] 10.10 and above),
+  // the second being the control size (mini, small, regular), and the third
+  // being the 4 margin values (left, top, right, bottom).
+  float margins[2][3][4];
+};
+
+/*
+ * This is a helper method that returns the required NSControlSize given a size
+ * and the size of the three controls plus a tolerance.
+ * size - The width or the height of the element to draw.
+ * sizes - An array with the all the width/height of the element for its
+ *         different sizes.
+ * tolerance - The tolerance as passed to DrawCellWithSnapping.
+ * NOTE: returns NSControlSizeRegular if all values in 'sizes' are zero.
+ */
+static NSControlSize FindControlSize(CGFloat size, const CGFloat* sizes, CGFloat tolerance) {
+  for (uint32_t i = miniControlSize; i <= regularControlSize; ++i) {
+    if (sizes[i] == 0) {
+      continue;
+    }
+
+    CGFloat next = 0;
+    // Find next value.
+    for (uint32_t j = i + 1; j <= regularControlSize; ++j) {
+      if (sizes[j] != 0) {
+        next = sizes[j];
+        break;
+      }
+    }
+
+    // If it's the latest value, we pick it.
+    if (next == 0) {
+      return CocoaSizeForEnum(i);
+    }
+
+    if (size <= sizes[i] + tolerance && size < next) {
+      return CocoaSizeForEnum(i);
+    }
+  }
+
+  // If we are here, that means sizes[] was an array with only empty values
+  // or the algorithm above is wrong.
+  // The former can happen but the later would be wrong.
+  NS_ASSERTION(sizes[0] == 0 && sizes[1] == 0 && sizes[2] == 0,
+               "We found no control! We shouldn't be there!");
+  return CocoaSizeForEnum(regularControlSize);
+}
+
+/*
+ * Draw the given NSCell into the given cgContext with a nice control size.
+ *
+ * This function is similar to DrawCellWithScaling, but it decides what
+ * control size to use based on the destRect's size.
+ * Scaling is only applied when the difference between the destRect's size
+ * and the next smaller natural size is greater than snapTolerance. Otherwise
+ * it snaps to the next smaller control size without scaling because unscaled
+ * controls look nicer.
+ */
+static void DrawCellWithSnapping(NSCell* cell, CGContextRef cgContext, const HIRect& destRect,
+                                 const CellRenderSettings settings, float verticalAlignFactor,
+                                 NSView* view, BOOL mirrorHorizontal, float snapTolerance = 2.0f) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  const float rectWidth = destRect.size.width, rectHeight = destRect.size.height;
+  const NSSize* sizes = settings.naturalSizes;
+  const NSSize miniSize = sizes[EnumSizeForCocoaSize(NSControlSizeMini)];
+  const NSSize smallSize = sizes[EnumSizeForCocoaSize(NSControlSizeSmall)];
+  const NSSize regularSize = sizes[EnumSizeForCocoaSize(NSControlSizeRegular)];
+
+  HIRect drawRect = destRect;
+
+  CGFloat controlWidths[3] = {miniSize.width, smallSize.width, regularSize.width};
+  NSControlSize controlSizeX = FindControlSize(rectWidth, controlWidths, snapTolerance);
+  CGFloat controlHeights[3] = {miniSize.height, smallSize.height, regularSize.height};
+  NSControlSize controlSizeY = FindControlSize(rectHeight, controlHeights, snapTolerance);
+
+  NSControlSize controlSize = NSControlSizeRegular;
+  size_t sizeIndex = 0;
+
+  // At some sizes, don't scale but snap.
+  const NSControlSize smallerControlSize =
+      EnumSizeForCocoaSize(controlSizeX) < EnumSizeForCocoaSize(controlSizeY) ? controlSizeX
+                                                                              : controlSizeY;
+  const size_t smallerControlSizeIndex = EnumSizeForCocoaSize(smallerControlSize);
+  const NSSize size = sizes[smallerControlSizeIndex];
+  float diffWidth = size.width ? rectWidth - size.width : 0.0f;
+  float diffHeight = size.height ? rectHeight - size.height : 0.0f;
+  if (diffWidth >= 0.0f && diffHeight >= 0.0f && diffWidth <= snapTolerance &&
+      diffHeight <= snapTolerance) {
+    // Snap to the smaller control size.
+    controlSize = smallerControlSize;
+    sizeIndex = smallerControlSizeIndex;
+    MOZ_ASSERT(sizeIndex < ArrayLength(settings.naturalSizes));
+
+    // Resize and center the drawRect.
+    if (sizes[sizeIndex].width) {
+      drawRect.origin.x += ceil((destRect.size.width - sizes[sizeIndex].width) / 2);
+      drawRect.size.width = sizes[sizeIndex].width;
+    }
+    if (sizes[sizeIndex].height) {
+      drawRect.origin.y +=
+          floor((destRect.size.height - sizes[sizeIndex].height) * verticalAlignFactor);
+      drawRect.size.height = sizes[sizeIndex].height;
+    }
+  } else {
+    // Use the larger control size.
+    controlSize = EnumSizeForCocoaSize(controlSizeX) > EnumSizeForCocoaSize(controlSizeY)
+                      ? controlSizeX
+                      : controlSizeY;
+    sizeIndex = EnumSizeForCocoaSize(controlSize);
+  }
+
+  [cell setControlSize:controlSize];
+
+  MOZ_ASSERT(sizeIndex < ArrayLength(settings.minimumSizes));
+  const NSSize minimumSize = settings.minimumSizes[sizeIndex];
+  DrawCellWithScaling(cell, cgContext, drawRect, controlSize, sizes[sizeIndex], minimumSize,
+                      settings.margins, view, mirrorHorizontal);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+@interface NSWindow (CoreUIRendererPrivate)
++ (CUIRendererRef)coreUIRenderer;
+@end
+
+@interface NSObject (NSAppearanceCoreUIRendering)
+- (void)_drawInRect:(CGRect)rect context:(CGContextRef)cgContext options:(id)options;
+@end
+
+static void RenderWithCoreUI(CGRect aRect, CGContextRef cgContext, NSDictionary* aOptions,
+                             bool aSkipAreaCheck = false) {
+  if (!aSkipAreaCheck && aRect.size.width * aRect.size.height > BITMAP_MAX_AREA) {
+    return;
+  }
+
+  NSAppearance* appearance = NSAppearance.currentAppearance;
+  if (appearance && [appearance respondsToSelector:@selector(_drawInRect:context:options:)]) {
+    // Render through NSAppearance on Mac OS 10.10 and up. This will call
+    // CUIDraw with a CoreUI renderer that will give us the correct 10.10
+    // style. Calling CUIDraw directly with [NSWindow coreUIRenderer] still
+    // renders 10.9-style widgets on 10.10.
+    [appearance _drawInRect:aRect context:cgContext options:aOptions];
+  } else {
+    // 10.9 and below
+    CUIRendererRef renderer =
+        [NSWindow respondsToSelector:@selector(coreUIRenderer)] ? [NSWindow coreUIRenderer] : nil;
+    CUIDraw(renderer, aRect, cgContext, (CFDictionaryRef)aOptions, NULL);
+  }
+}
+
+static float VerticalAlignFactor(nsIFrame* aFrame) {
+  if (!aFrame) return 0.5f;  // default: center
+
+  const auto& va = aFrame->StyleDisplay()->mVerticalAlign;
+  auto kw = va.IsKeyword() ? va.AsKeyword() : StyleVerticalAlignKeyword::Middle;
+  switch (kw) {
+    case StyleVerticalAlignKeyword::Top:
+    case StyleVerticalAlignKeyword::TextTop:
+      return 0.0f;
+
+    case StyleVerticalAlignKeyword::Sub:
+    case StyleVerticalAlignKeyword::Super:
+    case StyleVerticalAlignKeyword::Middle:
+    case StyleVerticalAlignKeyword::MozMiddleWithBaseline:
+      return 0.5f;
+
+    case StyleVerticalAlignKeyword::Baseline:
+    case StyleVerticalAlignKeyword::Bottom:
+    case StyleVerticalAlignKeyword::TextBottom:
+      return 1.0f;
+
+    default:
+      MOZ_ASSERT_UNREACHABLE("invalid vertical-align");
+      return 0.5f;
+  }
+}
+
+static void ApplyControlParamsToNSCell(nsNativeThemeCocoa::ControlParams aControlParams,
+                                       NSCell* aCell) {
+  [aCell setEnabled:!aControlParams.disabled];
+  [aCell setShowsFirstResponder:(aControlParams.focused && !aControlParams.disabled &&
+                                 aControlParams.insideActiveWindow)];
+  [aCell setHighlighted:aControlParams.pressed];
+}
+
+// These are the sizes that Gecko needs to request to draw if it wants
+// to get a standard-sized Aqua radio button drawn. Note that the rects
+// that draw these are actually a little bigger.
+static const CellRenderSettings radioSettings = {{
+                                                     NSMakeSize(11, 11),  // mini
+                                                     NSMakeSize(13, 13),  // small
+                                                     NSMakeSize(16, 16)   // regular
+                                                 },
+                                                 {NSZeroSize, NSZeroSize, NSZeroSize},
+                                                 {{
+                                                      // Leopard
+                                                      {0, 0, 0, 0},  // mini
+                                                      {0, 1, 1, 1},  // small
+                                                      {0, 0, 0, 0}   // regular
+                                                  },
+                                                  {
+                                                      // Yosemite
+                                                      {0, 0, 0, 0},  // mini
+                                                      {1, 1, 1, 2},  // small
+                                                      {0, 0, 0, 0}   // regular
+                                                  }}};
+
+static const CellRenderSettings checkboxSettings = {{
+                                                        NSMakeSize(11, 11),  // mini
+                                                        NSMakeSize(13, 13),  // small
+                                                        NSMakeSize(16, 16)   // regular
+                                                    },
+                                                    {NSZeroSize, NSZeroSize, NSZeroSize},
+                                                    {{
+                                                         // Leopard
+                                                         {0, 1, 0, 0},  // mini
+                                                         {0, 1, 0, 1},  // small
+                                                         {0, 1, 0, 1}   // regular
+                                                     },
+                                                     {
+                                                         // Yosemite
+                                                         {0, 1, 0, 0},  // mini
+                                                         {0, 1, 0, 1},  // small
+                                                         {0, 1, 0, 1}   // regular
+                                                     }}};
+
+static NSControlStateValue CellStateForCheckboxOrRadioState(
+    nsNativeThemeCocoa::CheckboxOrRadioState aState) {
+  switch (aState) {
+    case nsNativeThemeCocoa::CheckboxOrRadioState::eOff:
+      return NSOffState;
+    case nsNativeThemeCocoa::CheckboxOrRadioState::eOn:
+      return NSOnState;
+    case nsNativeThemeCocoa::CheckboxOrRadioState::eIndeterminate:
+      return NSMixedState;
+  }
+}
+
+void nsNativeThemeCocoa::DrawCheckboxOrRadio(CGContextRef cgContext, bool inCheckbox,
+                                             const HIRect& inBoxRect,
+                                             const CheckboxOrRadioParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NSButtonCell* cell = inCheckbox ? mCheckboxCell : mRadioButtonCell;
+  ApplyControlParamsToNSCell(aParams.controlParams, cell);
+
+  [cell setState:CellStateForCheckboxOrRadioState(aParams.state)];
+  [cell setControlTint:(aParams.controlParams.insideActiveWindow ? [NSColor currentControlTint]
+                                                                 : NSClearControlTint)];
+
+  // Ensure that the control is square.
+  float length = std::min(inBoxRect.size.width, inBoxRect.size.height);
+  HIRect drawRect = CGRectMake(inBoxRect.origin.x + (int)((inBoxRect.size.width - length) / 2.0f),
+                               inBoxRect.origin.y + (int)((inBoxRect.size.height - length) / 2.0f),
+                               length, length);
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = aParams.controlParams.insideActiveWindow;
+  }
+  DrawCellWithSnapping(cell, cgContext, drawRect, inCheckbox ? checkboxSettings : radioSettings,
+                       aParams.verticalAlignFactor, mCellDrawView, NO);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static const CellRenderSettings searchFieldSettings = {{
+                                                           NSMakeSize(0, 16),  // mini
+                                                           NSMakeSize(0, 19),  // small
+                                                           NSMakeSize(0, 22)   // regular
+                                                       },
+                                                       {
+                                                           NSMakeSize(32, 0),  // mini
+                                                           NSMakeSize(38, 0),  // small
+                                                           NSMakeSize(44, 0)   // regular
+                                                       },
+                                                       {{
+                                                            // Leopard
+                                                            {0, 0, 0, 0},  // mini
+                                                            {0, 0, 0, 0},  // small
+                                                            {0, 0, 0, 0}   // regular
+                                                        },
+                                                        {
+                                                            // Yosemite
+                                                            {0, 0, 0, 0},  // mini
+                                                            {0, 0, 0, 0},  // small
+                                                            {0, 0, 0, 0}   // regular
+                                                        }}};
+
+static bool IsToolbarStyleContainer(nsIFrame* aFrame) {
+  nsIContent* content = aFrame->GetContent();
+  if (!content) {
+    return false;
+  }
+
+  if (content->IsAnyOfXULElements(nsGkAtoms::toolbar, nsGkAtoms::toolbox, nsGkAtoms::statusbar)) {
+    return true;
+  }
+
+  switch (aFrame->StyleDisplay()->EffectiveAppearance()) {
+    case StyleAppearance::Toolbar:
+    case StyleAppearance::Statusbar:
+      return true;
+    default:
+      return false;
+  }
+}
+
+static bool IsInsideToolbar(nsIFrame* aFrame) {
+  for (nsIFrame* frame = aFrame; frame; frame = frame->GetParent()) {
+    if (IsToolbarStyleContainer(frame)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+nsNativeThemeCocoa::TextFieldParams nsNativeThemeCocoa::ComputeTextFieldParams(
+    nsIFrame* aFrame, ElementState aEventState) {
+  TextFieldParams params;
+  params.insideToolbar = IsInsideToolbar(aFrame);
+  params.disabled = aEventState.HasState(ElementState::DISABLED);
+
+  // See ShouldUnconditionallyDrawFocusRingIfFocused.
+  params.focused = aEventState.HasState(ElementState::FOCUS);
+
+  params.rtl = IsFrameRTL(aFrame);
+  params.verticalAlignFactor = VerticalAlignFactor(aFrame);
+  return params;
+}
+
+void nsNativeThemeCocoa::DrawTextField(CGContextRef cgContext, const HIRect& inBoxRect,
+                                       const TextFieldParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NSTextFieldCell* cell = mTextFieldCell;
+  [cell setEnabled:!aParams.disabled];
+  [cell setShowsFirstResponder:aParams.focused];
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = YES;  // TODO: propagate correct activeness state
+  }
+  DrawCellWithSnapping(cell, cgContext, inBoxRect, searchFieldSettings, aParams.verticalAlignFactor,
+                       mCellDrawView, aParams.rtl);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsNativeThemeCocoa::DrawSearchField(CGContextRef cgContext, const HIRect& inBoxRect,
+                                         const TextFieldParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  mSearchFieldCell.enabled = !aParams.disabled;
+  mSearchFieldCell.showsFirstResponder = aParams.focused;
+  mSearchFieldCell.placeholderString = @"";
+  mSearchFieldCell.shouldUseToolbarStyle = aParams.insideToolbar;
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = YES;  // TODO: propagate correct activeness state
+  }
+  DrawCellWithSnapping(mSearchFieldCell, cgContext, inBoxRect, searchFieldSettings,
+                       aParams.verticalAlignFactor, mCellDrawView, aParams.rtl);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static const NSSize kCheckmarkSize = NSMakeSize(11, 11);
+static const NSSize kMenuarrowSize = NSMakeSize(9, 10);
+static const NSSize kMenuScrollArrowSize = NSMakeSize(10, 8);
+static NSString* kCheckmarkImage = @"MenuOnState";
+static NSString* kMenuarrowRightImage = @"MenuSubmenu";
+static NSString* kMenuarrowLeftImage = @"MenuSubmenuLeft";
+static NSString* kMenuDownScrollArrowImage = @"MenuScrollDown";
+static NSString* kMenuUpScrollArrowImage = @"MenuScrollUp";
+static const CGFloat kMenuIconIndent = 6.0f;
+
+NSString* nsNativeThemeCocoa::GetMenuIconName(const MenuIconParams& aParams) {
+  switch (aParams.icon) {
+    case MenuIcon::eCheckmark:
+      return kCheckmarkImage;
+    case MenuIcon::eMenuArrow:
+      return aParams.rtl ? kMenuarrowLeftImage : kMenuarrowRightImage;
+    case MenuIcon::eMenuDownScrollArrow:
+      return kMenuDownScrollArrowImage;
+    case MenuIcon::eMenuUpScrollArrow:
+      return kMenuUpScrollArrowImage;
+  }
+}
+
+NSSize nsNativeThemeCocoa::GetMenuIconSize(MenuIcon aIcon) {
+  switch (aIcon) {
+    case MenuIcon::eCheckmark:
+      return kCheckmarkSize;
+    case MenuIcon::eMenuArrow:
+      return kMenuarrowSize;
+    case MenuIcon::eMenuDownScrollArrow:
+    case MenuIcon::eMenuUpScrollArrow:
+      return kMenuScrollArrowSize;
+  }
+}
+
+nsNativeThemeCocoa::MenuIconParams nsNativeThemeCocoa::ComputeMenuIconParams(
+    nsIFrame* aFrame, ElementState aEventState, MenuIcon aIcon) {
+  bool isDisabled = aEventState.HasState(ElementState::DISABLED);
+
+  MenuIconParams params;
+  params.icon = aIcon;
+  params.disabled = isDisabled;
+  params.insideActiveMenuItem = !isDisabled && CheckBooleanAttr(aFrame, nsGkAtoms::menuactive);
+  params.centerHorizontally = true;
+  params.rtl = IsFrameRTL(aFrame);
+  return params;
+}
+
+void nsNativeThemeCocoa::DrawMenuIcon(CGContextRef cgContext, const CGRect& aRect,
+                                      const MenuIconParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NSSize size = GetMenuIconSize(aParams.icon);
+
+  // Adjust size and position of our drawRect.
+  CGFloat paddingX = std::max(CGFloat(0.0), aRect.size.width - size.width);
+  CGFloat paddingY = std::max(CGFloat(0.0), aRect.size.height - size.height);
+  CGFloat paddingStartX = std::min(paddingX, kMenuIconIndent);
+  CGFloat paddingEndX = std::max(CGFloat(0.0), paddingX - kMenuIconIndent);
+  CGRect drawRect = CGRectMake(aRect.origin.x + (aParams.centerHorizontally ? ceil(paddingX / 2)
+                                                 : aParams.rtl              ? paddingEndX
+                                                                            : paddingStartX),
+                               aRect.origin.y + ceil(paddingY / 2), size.width, size.height);
+
+  NSString* state;
+  if (aParams.disabled) {
+    state = @"disabled";
+  } else if (aParams.insideActiveMenuItem) {
+    state = @"pressed";
+  } else if (IsDarkAppearance(NSAppearance.currentAppearance)) {
+    // CUIDraw draws the image with a color that's too faint for the dark
+    // appearance. The "pressed" state happens to use white, which looks better
+    // and matches the white text color, so use it instead of "normal".
+    state = @"pressed";
+  } else {
+    state = @"normal";
+  }
+
+  NSString* imageName = GetMenuIconName(aParams);
+
+  RenderWithCoreUI(
+      drawRect, cgContext,
+      [NSDictionary dictionaryWithObjectsAndKeys:@"kCUIBackgroundTypeMenu", @"backgroundTypeKey",
+                                                 imageName, @"imageNameKey", state, @"state",
+                                                 @"image", @"widget", [NSNumber numberWithBool:YES],
+                                                 @"is.flipped", nil]);
+
+#if DRAW_IN_FRAME_DEBUG
+  CGContextSetRGBFillColor(cgContext, 0.0, 0.0, 0.5, 0.25);
+  CGContextFillRect(cgContext, drawRect);
+#endif
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsNativeThemeCocoa::MenuItemParams nsNativeThemeCocoa::ComputeMenuItemParams(
+    nsIFrame* aFrame, ElementState aEventState, bool aIsChecked) {
+  bool isDisabled = aEventState.HasState(ElementState::DISABLED);
+
+  MenuItemParams params;
+  params.checked = aIsChecked;
+  params.disabled = isDisabled;
+  params.selected = !isDisabled && CheckBooleanAttr(aFrame, nsGkAtoms::menuactive);
+  params.rtl = IsFrameRTL(aFrame);
+  return params;
+}
+
+void nsNativeThemeCocoa::DrawMenuItem(CGContextRef cgContext, const CGRect& inBoxRect,
+                                      const MenuItemParams& aParams) {
+  if (aParams.checked) {
+    MenuIconParams params;
+    params.disabled = aParams.disabled;
+    params.insideActiveMenuItem = aParams.selected;
+    params.rtl = aParams.rtl;
+    params.icon = MenuIcon::eCheckmark;
+    DrawMenuIcon(cgContext, inBoxRect, params);
+  }
+}
+
+void nsNativeThemeCocoa::DrawMenuSeparator(CGContextRef cgContext, const CGRect& inBoxRect,
+                                           const MenuItemParams& aParams) {
+  // Workaround for visual artifacts issues with
+  // HIThemeDrawMenuSeparator on macOS Big Sur.
+  if (nsCocoaFeatures::OnBigSurOrLater()) {
+    CGRect separatorRect = inBoxRect;
+    separatorRect.size.height = 1;
+    separatorRect.size.width -= 42;
+    separatorRect.origin.x += 21;
+    if (!IsDarkAppearance(NSAppearance.currentAppearance)) {
+      // Use transparent black with an alpha similar to the native separator.
+      // The values 231 (menu background) and 205 (separator color) have been
+      // sampled from a window screenshot of a native context menu.
+      CGContextSetRGBFillColor(cgContext, 0.0, 0.0, 0.0, (231 - 205) / 231.0);
+    } else {
+      // Similar to above, use white with an alpha. The values 45 (menu
+      // background) and 81 (separator color) were sampled on macOS 12 with the
+      // "Reduce transparency" system setting turned on.
+      CGContextSetRGBFillColor(cgContext, 1.0, 1.0, 1.0, 1.0 + ((45 - 81) / 45.0));
+    }
+    CGContextFillRect(cgContext, separatorRect);
+    return;
+  }
+
+  ThemeMenuState menuState;
+  if (aParams.disabled) {
+    menuState = kThemeMenuDisabled;
+  } else {
+    menuState = aParams.selected ? kThemeMenuSelected : kThemeMenuActive;
+  }
+
+  HIThemeMenuItemDrawInfo midi = {0, kThemeMenuItemPlain, menuState};
+  HIThemeDrawMenuSeparator(&inBoxRect, &inBoxRect, &midi, cgContext, HITHEME_ORIENTATION);
+}
+
+static bool ShouldUnconditionallyDrawFocusRingIfFocused(nsIFrame* aFrame) {
+  // Mac always draws focus rings for textboxes and lists.
+  switch (aFrame->StyleDisplay()->EffectiveAppearance()) {
+    case StyleAppearance::NumberInput:
+    case StyleAppearance::Textfield:
+    case StyleAppearance::Textarea:
+    case StyleAppearance::Searchfield:
+    case StyleAppearance::Listbox:
+      return true;
+    default:
+      return false;
+  }
+}
+
+nsNativeThemeCocoa::ControlParams nsNativeThemeCocoa::ComputeControlParams(
+    nsIFrame* aFrame, ElementState aEventState) {
+  ControlParams params;
+  params.disabled = aEventState.HasState(ElementState::DISABLED);
+  params.insideActiveWindow = FrameIsInActiveWindow(aFrame);
+  params.pressed = aEventState.HasAllStates(ElementState::ACTIVE | ElementState::HOVER);
+  params.focused = aEventState.HasState(ElementState::FOCUS) &&
+                   (aEventState.HasState(ElementState::FOCUSRING) ||
+                    ShouldUnconditionallyDrawFocusRingIfFocused(aFrame));
+  params.rtl = IsFrameRTL(aFrame);
+  return params;
+}
+
+static const NSSize kHelpButtonSize = NSMakeSize(20, 20);
+static const NSSize kDisclosureButtonSize = NSMakeSize(21, 21);
+
+static const CellRenderSettings pushButtonSettings = {{
+                                                          NSMakeSize(0, 16),  // mini
+                                                          NSMakeSize(0, 19),  // small
+                                                          NSMakeSize(0, 22)   // regular
+                                                      },
+                                                      {
+                                                          NSMakeSize(18, 0),  // mini
+                                                          NSMakeSize(26, 0),  // small
+                                                          NSMakeSize(30, 0)   // regular
+                                                      },
+                                                      {{
+                                                           // Leopard
+                                                           {0, 0, 0, 0},  // mini
+                                                           {4, 0, 4, 1},  // small
+                                                           {5, 0, 5, 2}   // regular
+                                                       },
+                                                       {
+                                                           // Yosemite
+                                                           {0, 0, 0, 0},  // mini
+                                                           {4, 0, 4, 1},  // small
+                                                           {5, 0, 5, 2}   // regular
+                                                       }}};
+
+// The height at which we start doing square buttons instead of rounded buttons
+// Rounded buttons look bad if drawn at a height greater than 26, so at that point
+// we switch over to doing square buttons which looks fine at any size.
+#define DO_SQUARE_BUTTON_HEIGHT 26
+
+void nsNativeThemeCocoa::DrawPushButton(CGContextRef cgContext, const HIRect& inBoxRect,
+                                        ButtonType aButtonType, ControlParams aControlParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  ApplyControlParamsToNSCell(aControlParams, mPushButtonCell);
+  [mPushButtonCell setBezelStyle:NSRoundedBezelStyle];
+  mPushButtonCell.keyEquivalent = aButtonType == ButtonType::eDefaultPushButton ? @"\r" : @"";
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = aControlParams.insideActiveWindow;
+  }
+  DrawCellWithSnapping(mPushButtonCell, cgContext, inBoxRect, pushButtonSettings, 0.5f,
+                       mCellDrawView, aControlParams.rtl, 1.0f);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsNativeThemeCocoa::DrawSquareBezelPushButton(CGContextRef cgContext, const HIRect& inBoxRect,
+                                                   ControlParams aControlParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  ApplyControlParamsToNSCell(aControlParams, mPushButtonCell);
+  [mPushButtonCell setBezelStyle:NSShadowlessSquareBezelStyle];
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = aControlParams.insideActiveWindow;
+  }
+  DrawCellWithScaling(mPushButtonCell, cgContext, inBoxRect, NSControlSizeRegular, NSZeroSize,
+                      NSMakeSize(14, 0), NULL, mCellDrawView, aControlParams.rtl);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsNativeThemeCocoa::DrawHelpButton(CGContextRef cgContext, const HIRect& inBoxRect,
+                                        ControlParams aControlParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  ApplyControlParamsToNSCell(aControlParams, mHelpButtonCell);
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = aControlParams.insideActiveWindow;
+  }
+  DrawCellWithScaling(mHelpButtonCell, cgContext, inBoxRect, NSControlSizeRegular, NSZeroSize,
+                      kHelpButtonSize, NULL, mCellDrawView,
+                      false);  // Don't mirror icon in RTL.
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsNativeThemeCocoa::DrawDisclosureButton(CGContextRef cgContext, const HIRect& inBoxRect,
+                                              ControlParams aControlParams,
+                                              NSControlStateValue aCellState) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  ApplyControlParamsToNSCell(aControlParams, mDisclosureButtonCell);
+  [mDisclosureButtonCell setState:aCellState];
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = aControlParams.insideActiveWindow;
+  }
+  DrawCellWithScaling(mDisclosureButtonCell, cgContext, inBoxRect, NSControlSizeRegular, NSZeroSize,
+                      kDisclosureButtonSize, NULL, mCellDrawView,
+                      false);  // Don't mirror icon in RTL.
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+typedef void (*RenderHIThemeControlFunction)(CGContextRef cgContext, const HIRect& aRenderRect,
+                                             void* aData);
+
+static void RenderTransformedHIThemeControl(CGContextRef aCGContext, const HIRect& aRect,
+                                            RenderHIThemeControlFunction aFunc, void* aData,
+                                            BOOL mirrorHorizontally = NO) {
+  CGAffineTransform savedCTM = CGContextGetCTM(aCGContext);
+  CGContextTranslateCTM(aCGContext, aRect.origin.x, aRect.origin.y);
+
+  bool drawDirect;
+  HIRect drawRect = aRect;
+  drawRect.origin = CGPointZero;
+
+  if (!mirrorHorizontally && savedCTM.a == 1.0f && savedCTM.b == 0.0f && savedCTM.c == 0.0f &&
+      (savedCTM.d == 1.0f || savedCTM.d == -1.0f)) {
+    drawDirect = TRUE;
+  } else {
+    drawDirect = FALSE;
+  }
+
+  // Fall back to no bitmap buffer if the area of our control (in pixels^2)
+  // is too large.
+  if (drawDirect || (aRect.size.width * aRect.size.height > BITMAP_MAX_AREA)) {
+    aFunc(aCGContext, drawRect, aData);
+  } else {
+    // Inflate the buffer to capture focus rings.
+    int w = ceil(drawRect.size.width) + 2 * kMaxFocusRingWidth;
+    int h = ceil(drawRect.size.height) + 2 * kMaxFocusRingWidth;
+
+    int backingScaleFactor = GetBackingScaleFactorForRendering(aCGContext);
+    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
+    CGContextRef bitmapctx = CGBitmapContextCreate(
+        NULL, w * backingScaleFactor, h * backingScaleFactor, 8, w * backingScaleFactor * 4,
+        colorSpace, kCGImageAlphaPremultipliedFirst);
+    CGColorSpaceRelease(colorSpace);
+
+    CGContextScaleCTM(bitmapctx, backingScaleFactor, backingScaleFactor);
+    CGContextTranslateCTM(bitmapctx, kMaxFocusRingWidth, kMaxFocusRingWidth);
+
+    // Set the context's "base transform" to in order to get correctly-sized focus rings.
+    CGContextSetBaseCTM(bitmapctx,
+                        CGAffineTransformMakeScale(backingScaleFactor, backingScaleFactor));
+
+    // HITheme always wants to draw into a flipped context, or things
+    // get confused.
+    CGContextTranslateCTM(bitmapctx, 0.0f, aRect.size.height);
+    CGContextScaleCTM(bitmapctx, 1.0f, -1.0f);
+
+    aFunc(bitmapctx, drawRect, aData);
+
+    CGImageRef bitmap = CGBitmapContextCreateImage(bitmapctx);
+
+    CGAffineTransform ctm = CGContextGetCTM(aCGContext);
+
+    // We need to unflip, so that we can do a DrawImage without getting a flipped image.
+    CGContextTranslateCTM(aCGContext, 0.0f, aRect.size.height);
+    CGContextScaleCTM(aCGContext, 1.0f, -1.0f);
+
+    if (mirrorHorizontally) {
+      CGContextTranslateCTM(aCGContext, aRect.size.width, 0);
+      CGContextScaleCTM(aCGContext, -1.0f, 1.0f);
+    }
+
+    HIRect inflatedDrawRect = CGRectMake(-kMaxFocusRingWidth, -kMaxFocusRingWidth, w, h);
+    CGContextDrawImage(aCGContext, inflatedDrawRect, bitmap);
+
+    CGContextSetCTM(aCGContext, ctm);
+
+    CGImageRelease(bitmap);
+    CGContextRelease(bitmapctx);
+  }
+
+  CGContextSetCTM(aCGContext, savedCTM);
+}
+
+static void RenderButton(CGContextRef cgContext, const HIRect& aRenderRect, void* aData) {
+  HIThemeButtonDrawInfo* bdi = (HIThemeButtonDrawInfo*)aData;
+  HIThemeDrawButton(&aRenderRect, bdi, cgContext, kHIThemeOrientationNormal, NULL);
+}
+
+static ThemeDrawState ToThemeDrawState(const nsNativeThemeCocoa::ControlParams& aParams) {
+  if (aParams.disabled) {
+    return kThemeStateUnavailable;
+  }
+  if (aParams.pressed) {
+    return kThemeStatePressed;
+  }
+  return kThemeStateActive;
+}
+
+void nsNativeThemeCocoa::DrawHIThemeButton(CGContextRef cgContext, const HIRect& aRect,
+                                           ThemeButtonKind aKind, ThemeButtonValue aValue,
+                                           ThemeDrawState aState, ThemeButtonAdornment aAdornment,
+                                           const ControlParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  HIThemeButtonDrawInfo bdi;
+  bdi.version = 0;
+  bdi.kind = aKind;
+  bdi.value = aValue;
+  bdi.state = aState;
+  bdi.adornment = aAdornment;
+
+  if (aParams.focused && aParams.insideActiveWindow) {
+    bdi.adornment |= kThemeAdornmentFocus;
+  }
+
+  RenderTransformedHIThemeControl(cgContext, aRect, RenderButton, &bdi, aParams.rtl);
+
+#if DRAW_IN_FRAME_DEBUG
+  CGContextSetRGBFillColor(cgContext, 0.0, 0.0, 0.5, 0.25);
+  CGContextFillRect(cgContext, inBoxRect);
+#endif
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsNativeThemeCocoa::DrawButton(CGContextRef cgContext, const HIRect& inBoxRect,
+                                    const ButtonParams& aParams) {
+  ControlParams controlParams = aParams.controlParams;
+
+  switch (aParams.button) {
+    case ButtonType::eRegularPushButton:
+    case ButtonType::eDefaultPushButton:
+      DrawPushButton(cgContext, inBoxRect, aParams.button, controlParams);
+      return;
+    case ButtonType::eSquareBezelPushButton:
+      DrawSquareBezelPushButton(cgContext, inBoxRect, controlParams);
+      return;
+    case ButtonType::eArrowButton:
+      DrawHIThemeButton(cgContext, inBoxRect, kThemeArrowButton, kThemeButtonOn,
+                        kThemeStateUnavailable, kThemeAdornmentArrowDownArrow, controlParams);
+      return;
+    case ButtonType::eHelpButton:
+      DrawHelpButton(cgContext, inBoxRect, controlParams);
+      return;
+    case ButtonType::eTreeTwistyPointingRight:
+      DrawHIThemeButton(cgContext, inBoxRect, kThemeDisclosureButton, kThemeDisclosureRight,
+                        ToThemeDrawState(controlParams), kThemeAdornmentNone, controlParams);
+      return;
+    case ButtonType::eTreeTwistyPointingDown:
+      DrawHIThemeButton(cgContext, inBoxRect, kThemeDisclosureButton, kThemeDisclosureDown,
+                        ToThemeDrawState(controlParams), kThemeAdornmentNone, controlParams);
+      return;
+    case ButtonType::eDisclosureButtonClosed:
+      DrawDisclosureButton(cgContext, inBoxRect, controlParams, NSOffState);
+      return;
+    case ButtonType::eDisclosureButtonOpen:
+      DrawDisclosureButton(cgContext, inBoxRect, controlParams, NSOnState);
+      return;
+  }
+}
+
+nsNativeThemeCocoa::TreeHeaderCellParams nsNativeThemeCocoa::ComputeTreeHeaderCellParams(
+    nsIFrame* aFrame, ElementState aEventState) {
+  TreeHeaderCellParams params;
+  params.controlParams = ComputeControlParams(aFrame, aEventState);
+  params.sortDirection = GetTreeSortDirection(aFrame);
+  params.lastTreeHeaderCell = IsLastTreeHeaderCell(aFrame);
+  return params;
+}
+
+@interface NSTableHeaderCell (NSTableHeaderCell_setSortable)
+// This method has been present in the same form since at least macOS 10.4.
+- (void)_setSortable:(BOOL)arg1
+    showSortIndicator:(BOOL)arg2
+            ascending:(BOOL)arg3
+             priority:(NSInteger)arg4
+     highlightForSort:(BOOL)arg5;
+@end
+
+void nsNativeThemeCocoa::DrawTreeHeaderCell(CGContextRef cgContext, const HIRect& inBoxRect,
+                                            const TreeHeaderCellParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Without clearing the cell's title, it takes on a default value of "Field",
+  // which is displayed underneath the title set in the front-end.
+  NSCell* cell = (NSCell*)mTreeHeaderCell;
+  cell.title = @"";
+
+  if ([mTreeHeaderCell respondsToSelector:@selector
+                       (_setSortable:showSortIndicator:ascending:priority:highlightForSort:)]) {
+    switch (aParams.sortDirection) {
+      case eTreeSortDirection_Ascending:
+        [mTreeHeaderCell _setSortable:YES
+                    showSortIndicator:YES
+                            ascending:YES
+                             priority:0
+                     highlightForSort:YES];
+        break;
+      case eTreeSortDirection_Descending:
+        [mTreeHeaderCell _setSortable:YES
+                    showSortIndicator:YES
+                            ascending:NO
+                             priority:0
+                     highlightForSort:YES];
+        break;
+      default:
+        // eTreeSortDirection_Natural
+        [mTreeHeaderCell _setSortable:YES
+                    showSortIndicator:NO
+                            ascending:YES
+                             priority:0
+                     highlightForSort:NO];
+        break;
+    }
+  }
+
+  mTreeHeaderCell.enabled = !aParams.controlParams.disabled;
+  mTreeHeaderCell.state =
+      (mTreeHeaderCell.enabled && aParams.controlParams.pressed) ? NSOnState : NSOffState;
+
+  mCellDrawView._drawingEndSeparator = !aParams.lastTreeHeaderCell;
+
+  NSGraphicsContext* savedContext = NSGraphicsContext.currentContext;
+  NSGraphicsContext.currentContext = [NSGraphicsContext graphicsContextWithCGContext:cgContext
+                                                                             flipped:YES];
+  DrawCellIncludingFocusRing(mTreeHeaderCell, inBoxRect, mCellDrawView);
+  NSGraphicsContext.currentContext = savedContext;
+
+#if DRAW_IN_FRAME_DEBUG
+  CGContextSetRGBFillColor(cgContext, 0.0, 0.0, 0.5, 0.25);
+  CGContextFillRect(cgContext, inBoxRect);
+#endif
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static const CellRenderSettings dropdownSettings = {{
+                                                        NSMakeSize(0, 16),  // mini
+                                                        NSMakeSize(0, 19),  // small
+                                                        NSMakeSize(0, 22)   // regular
+                                                    },
+                                                    {
+                                                        NSMakeSize(18, 0),  // mini
+                                                        NSMakeSize(38, 0),  // small
+                                                        NSMakeSize(44, 0)   // regular
+                                                    },
+                                                    {{
+                                                         // Leopard
+                                                         {1, 1, 2, 1},  // mini
+                                                         {3, 0, 3, 1},  // small
+                                                         {3, 0, 3, 0}   // regular
+                                                     },
+                                                     {
+                                                         // Yosemite
+                                                         {1, 1, 2, 1},  // mini
+                                                         {3, 0, 3, 1},  // small
+                                                         {3, 0, 3, 0}   // regular
+                                                     }}};
+
+static const CellRenderSettings editableMenulistSettings = {{
+                                                                NSMakeSize(0, 15),  // mini
+                                                                NSMakeSize(0, 18),  // small
+                                                                NSMakeSize(0, 21)   // regular
+                                                            },
+                                                            {
+                                                                NSMakeSize(18, 0),  // mini
+                                                                NSMakeSize(38, 0),  // small
+                                                                NSMakeSize(44, 0)   // regular
+                                                            },
+                                                            {{
+                                                                 // Leopard
+                                                                 {0, 0, 2, 2},  // mini
+                                                                 {0, 0, 3, 2},  // small
+                                                                 {0, 1, 3, 3}   // regular
+                                                             },
+                                                             {
+                                                                 // Yosemite
+                                                                 {0, 0, 2, 2},  // mini
+                                                                 {0, 0, 3, 2},  // small
+                                                                 {0, 1, 3, 3}   // regular
+                                                             }}};
+
+void nsNativeThemeCocoa::DrawDropdown(CGContextRef cgContext, const HIRect& inBoxRect,
+                                      const DropdownParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mDropdownCell setPullsDown:aParams.pullsDown];
+  NSCell* cell = aParams.editable ? (NSCell*)mComboBoxCell : (NSCell*)mDropdownCell;
+
+  ApplyControlParamsToNSCell(aParams.controlParams, cell);
+
+  if (aParams.controlParams.insideActiveWindow) {
+    [cell setControlTint:[NSColor currentControlTint]];
+  } else {
+    [cell setControlTint:NSClearControlTint];
+  }
+
+  const CellRenderSettings& settings =
+      aParams.editable ? editableMenulistSettings : dropdownSettings;
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = aParams.controlParams.insideActiveWindow;
+  }
+  DrawCellWithSnapping(cell, cgContext, inBoxRect, settings, 0.5f, mCellDrawView,
+                       aParams.controlParams.rtl);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static const CellRenderSettings spinnerSettings = {
+    {
+        NSMakeSize(11, 16),  // mini (width trimmed by 2px to reduce blank border)
+        NSMakeSize(15, 22),  // small
+        NSMakeSize(19, 27)   // regular
+    },
+    {
+        NSMakeSize(11, 16),  // mini (width trimmed by 2px to reduce blank border)
+        NSMakeSize(15, 22),  // small
+        NSMakeSize(19, 27)   // regular
+    },
+    {{
+         // Leopard
+         {0, 0, 0, 0},  // mini
+         {0, 0, 0, 0},  // small
+         {0, 0, 0, 0}   // regular
+     },
+     {
+         // Yosemite
+         {0, 0, 0, 0},  // mini
+         {0, 0, 0, 0},  // small
+         {0, 0, 0, 0}   // regular
+     }}};
+
+HIThemeButtonDrawInfo nsNativeThemeCocoa::SpinButtonDrawInfo(ThemeButtonKind aKind,
+                                                             const SpinButtonParams& aParams) {
+  HIThemeButtonDrawInfo bdi;
+  bdi.version = 0;
+  bdi.kind = aKind;
+  bdi.value = kThemeButtonOff;
+  bdi.adornment = kThemeAdornmentNone;
+
+  if (aParams.disabled) {
+    bdi.state = kThemeStateUnavailable;
+  } else if (aParams.insideActiveWindow && aParams.pressedButton) {
+    if (*aParams.pressedButton == SpinButton::eUp) {
+      bdi.state = kThemeStatePressedUp;
+    } else {
+      bdi.state = kThemeStatePressedDown;
+    }
+  } else {
+    bdi.state = kThemeStateActive;
+  }
+
+  return bdi;
+}
+
+void nsNativeThemeCocoa::DrawSpinButtons(CGContextRef cgContext, const HIRect& inBoxRect,
+                                         const SpinButtonParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  HIThemeButtonDrawInfo bdi = SpinButtonDrawInfo(kThemeIncDecButton, aParams);
+  HIThemeDrawButton(&inBoxRect, &bdi, cgContext, HITHEME_ORIENTATION, NULL);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsNativeThemeCocoa::DrawSpinButton(CGContextRef cgContext, const HIRect& inBoxRect,
+                                        SpinButton aDrawnButton, const SpinButtonParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  HIThemeButtonDrawInfo bdi = SpinButtonDrawInfo(kThemeIncDecButtonMini, aParams);
+
+  // Cocoa only allows kThemeIncDecButton to paint the up and down spin buttons
+  // together as a single unit (presumably because when one button is active,
+  // the appearance of both changes (in different ways)). Here we have to paint
+  // both buttons, using clip to hide the one we don't want to paint.
+  HIRect drawRect = inBoxRect;
+  drawRect.size.height *= 2;
+  if (aDrawnButton == SpinButton::eDown) {
+    drawRect.origin.y -= inBoxRect.size.height;
+  }
+
+  // Shift the drawing a little to the left, since cocoa paints with more
+  // blank space around the visual buttons than we'd like:
+  drawRect.origin.x -= 1;
+
+  CGContextSaveGState(cgContext);
+  CGContextClipToRect(cgContext, inBoxRect);
+
+  HIThemeDrawButton(&drawRect, &bdi, cgContext, HITHEME_ORIENTATION, NULL);
+
+  CGContextRestoreGState(cgContext);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static const CellRenderSettings progressSettings[2][2] = {
+    // Vertical progress bar.
+    {// Determined settings.
+     {{
+          NSZeroSize,         // mini
+          NSMakeSize(10, 0),  // small
+          NSMakeSize(16, 0)   // regular
+      },
+      {NSZeroSize, NSZeroSize, NSZeroSize},
+      {{
+          // Leopard
+          {0, 0, 0, 0},  // mini
+          {1, 1, 1, 1},  // small
+          {1, 1, 1, 1}   // regular
+      }}},
+     // There is no horizontal margin in regular undetermined size.
+     {{
+          NSZeroSize,         // mini
+          NSMakeSize(10, 0),  // small
+          NSMakeSize(16, 0)   // regular
+      },
+      {NSZeroSize, NSZeroSize, NSZeroSize},
+      {{
+           // Leopard
+           {0, 0, 0, 0},  // mini
+           {1, 1, 1, 1},  // small
+           {1, 0, 1, 0}   // regular
+       },
+       {
+           // Yosemite
+           {0, 0, 0, 0},  // mini
+           {1, 1, 1, 1},  // small
+           {1, 0, 1, 0}   // regular
+       }}}},
+    // Horizontal progress bar.
+    {// Determined settings.
+     {{
+          NSZeroSize,         // mini
+          NSMakeSize(0, 10),  // small
+          NSMakeSize(0, 16)   // regular
+      },
+      {NSZeroSize, NSZeroSize, NSZeroSize},
+      {{
+           // Leopard
+           {0, 0, 0, 0},  // mini
+           {1, 1, 1, 1},  // small
+           {1, 1, 1, 1}   // regular
+       },
+       {
+           // Yosemite
+           {0, 0, 0, 0},  // mini
+           {1, 1, 1, 1},  // small
+           {1, 1, 1, 1}   // regular
+       }}},
+     // There is no horizontal margin in regular undetermined size.
+     {{
+          NSZeroSize,         // mini
+          NSMakeSize(0, 10),  // small
+          NSMakeSize(0, 16)   // regular
+      },
+      {NSZeroSize, NSZeroSize, NSZeroSize},
+      {{
+           // Leopard
+           {0, 0, 0, 0},  // mini
+           {1, 1, 1, 1},  // small
+           {0, 1, 0, 1}   // regular
+       },
+       {
+           // Yosemite
+           {0, 0, 0, 0},  // mini
+           {1, 1, 1, 1},  // small
+           {0, 1, 0, 1}   // regular
+       }}}}};
+
+nsNativeThemeCocoa::ProgressParams nsNativeThemeCocoa::ComputeProgressParams(
+    nsIFrame* aFrame, ElementState aEventState, bool aIsHorizontal) {
+  ProgressParams params;
+  params.value = GetProgressValue(aFrame);
+  params.max = GetProgressMaxValue(aFrame);
+  params.verticalAlignFactor = VerticalAlignFactor(aFrame);
+  params.insideActiveWindow = FrameIsInActiveWindow(aFrame);
+  params.indeterminate = aEventState.HasState(ElementState::INDETERMINATE);
+  params.horizontal = aIsHorizontal;
+  params.rtl = IsFrameRTL(aFrame);
+  return params;
+}
+
+void nsNativeThemeCocoa::DrawProgress(CGContextRef cgContext, const HIRect& inBoxRect,
+                                      const ProgressParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NSProgressBarCell* cell = mProgressBarCell;
+
+  [cell setValue:aParams.value];
+  [cell setMax:aParams.max];
+  [cell setIndeterminate:aParams.indeterminate];
+  [cell setHorizontal:aParams.horizontal];
+  [cell setControlTint:(aParams.insideActiveWindow ? [NSColor currentControlTint]
+                                                   : NSClearControlTint)];
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = aParams.insideActiveWindow;
+  }
+  DrawCellWithSnapping(cell, cgContext, inBoxRect,
+                       progressSettings[aParams.horizontal][aParams.indeterminate],
+                       aParams.verticalAlignFactor, mCellDrawView, aParams.rtl);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static const CellRenderSettings meterSetting = {{
+                                                    NSMakeSize(0, 16),  // mini
+                                                    NSMakeSize(0, 16),  // small
+                                                    NSMakeSize(0, 16)   // regular
+                                                },
+                                                {NSZeroSize, NSZeroSize, NSZeroSize},
+                                                {{
+                                                     // Leopard
+                                                     {1, 1, 1, 1},  // mini
+                                                     {1, 1, 1, 1},  // small
+                                                     {1, 1, 1, 1}   // regular
+                                                 },
+                                                 {
+                                                     // Yosemite
+                                                     {1, 1, 1, 1},  // mini
+                                                     {1, 1, 1, 1},  // small
+                                                     {1, 1, 1, 1}   // regular
+                                                 }}};
+
+nsNativeThemeCocoa::MeterParams nsNativeThemeCocoa::ComputeMeterParams(nsIFrame* aFrame) {
+  nsIContent* content = aFrame->GetContent();
+  if (!(content && content->IsHTMLElement(nsGkAtoms::meter))) {
+    return MeterParams();
+  }
+
+  HTMLMeterElement* meterElement = static_cast<HTMLMeterElement*>(content);
+  MeterParams params;
+  params.value = meterElement->Value();
+  params.min = meterElement->Min();
+  params.max = meterElement->Max();
+  ElementState states = meterElement->State();
+  if (states.HasState(ElementState::SUB_OPTIMUM)) {
+    params.optimumState = OptimumState::eSubOptimum;
+  } else if (states.HasState(ElementState::SUB_SUB_OPTIMUM)) {
+    params.optimumState = OptimumState::eSubSubOptimum;
+  }
+  params.horizontal = !IsVerticalMeter(aFrame);
+  params.verticalAlignFactor = VerticalAlignFactor(aFrame);
+  params.rtl = IsFrameRTL(aFrame);
+
+  return params;
+}
+
+void nsNativeThemeCocoa::DrawMeter(CGContextRef cgContext, const HIRect& inBoxRect,
+                                   const MeterParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK
+
+  NSLevelIndicatorCell* cell = mMeterBarCell;
+
+  [cell setMinValue:aParams.min];
+  [cell setMaxValue:aParams.max];
+  [cell setDoubleValue:aParams.value];
+
+  /**
+   * The way HTML and Cocoa defines the meter/indicator widget are different.
+   * So, we are going to use a trick to get the Cocoa widget showing what we
+   * are expecting: we set the warningValue or criticalValue to the current
+   * value when we want to have the widget to be in the warning or critical
+   * state.
+   */
+  switch (aParams.optimumState) {
+    case OptimumState::eOptimum:
+      [cell setWarningValue:aParams.max + 1];
+      [cell setCriticalValue:aParams.max + 1];
+      break;
+    case OptimumState::eSubOptimum:
+      [cell setWarningValue:aParams.value];
+      [cell setCriticalValue:aParams.max + 1];
+      break;
+    case OptimumState::eSubSubOptimum:
+      [cell setWarningValue:aParams.max + 1];
+      [cell setCriticalValue:aParams.value];
+      break;
+  }
+
+  HIRect rect = CGRectStandardize(inBoxRect);
+  BOOL vertical = !aParams.horizontal;
+
+  CGContextSaveGState(cgContext);
+
+  if (vertical) {
+    /**
+     * Cocoa doesn't provide a vertical meter bar so to show one, we have to
+     * show a rotated horizontal meter bar.
+     * Given that we want to show a vertical meter bar, we assume that the rect
+     * has vertical dimensions but we can't correctly draw a meter widget inside
+     * such a rectangle so we need to inverse width and height (and re-position)
+     * to get a rectangle with horizontal dimensions.
+     * Finally, we want to show a vertical meter so we want to rotate the result
+     * so it is vertical. We do that by changing the context.
+     */
+    CGFloat tmp = rect.size.width;
+    rect.size.width = rect.size.height;
+    rect.size.height = tmp;
+    rect.origin.x += rect.size.height / 2.f - rect.size.width / 2.f;
+    rect.origin.y += rect.size.width / 2.f - rect.size.height / 2.f;
+
+    CGContextTranslateCTM(cgContext, CGRectGetMidX(rect), CGRectGetMidY(rect));
+    CGContextRotateCTM(cgContext, -M_PI / 2.f);
+    CGContextTranslateCTM(cgContext, -CGRectGetMidX(rect), -CGRectGetMidY(rect));
+  }
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = YES;  // TODO: propagate correct activeness state
+  }
+  DrawCellWithSnapping(cell, cgContext, rect, meterSetting, aParams.verticalAlignFactor,
+                       mCellDrawView, !vertical && aParams.rtl);
+
+  CGContextRestoreGState(cgContext);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK
+}
+
+void nsNativeThemeCocoa::DrawTabPanel(CGContextRef cgContext, const HIRect& inBoxRect,
+                                      bool aIsInsideActiveWindow) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  HIThemeTabPaneDrawInfo tpdi;
+
+  tpdi.version = 1;
+  tpdi.state = aIsInsideActiveWindow ? kThemeStateActive : kThemeStateInactive;
+  tpdi.direction = kThemeTabNorth;
+  tpdi.size = kHIThemeTabSizeNormal;
+  tpdi.kind = kHIThemeTabKindNormal;
+
+  HIThemeDrawTabPane(&inBoxRect, &tpdi, cgContext, HITHEME_ORIENTATION);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+Maybe<nsNativeThemeCocoa::ScaleParams> nsNativeThemeCocoa::ComputeHTMLScaleParams(
+    nsIFrame* aFrame, ElementState aEventState) {
+  nsRangeFrame* rangeFrame = do_QueryFrame(aFrame);
+  if (!rangeFrame) {
+    return Nothing();
+  }
+
+  bool isHorizontal = IsRangeHorizontal(aFrame);
+
+  // ScaleParams requires integer min, max and value. This is purely for
+  // drawing, so we normalize to a range 0-1000 here.
+  ScaleParams params;
+  params.value = int32_t(rangeFrame->GetValueAsFractionOfRange() * 1000);
+  params.min = 0;
+  params.max = 1000;
+  params.reverse = !isHorizontal || rangeFrame->IsRightToLeft();
+  params.insideActiveWindow = FrameIsInActiveWindow(aFrame);
+  params.focused = aEventState.HasState(ElementState::FOCUSRING);
+  params.disabled = aEventState.HasState(ElementState::DISABLED);
+  params.horizontal = isHorizontal;
+  return Some(params);
+}
+
+void nsNativeThemeCocoa::DrawScale(CGContextRef cgContext, const HIRect& inBoxRect,
+                                   const ScaleParams& aParams) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  HIThemeTrackDrawInfo tdi;
+
+  tdi.version = 0;
+  tdi.kind = kThemeMediumSlider;
+  tdi.bounds = inBoxRect;
+  tdi.min = aParams.min;
+  tdi.max = aParams.max;
+  tdi.value = aParams.value;
+  tdi.attributes = kThemeTrackShowThumb;
+  if (aParams.horizontal) {
+    tdi.attributes |= kThemeTrackHorizontal;
+  }
+  if (aParams.reverse) {
+    tdi.attributes |= kThemeTrackRightToLeft;
+  }
+  if (aParams.focused) {
+    tdi.attributes |= kThemeTrackHasFocus;
+  }
+  if (aParams.disabled) {
+    tdi.enableState = kThemeTrackDisabled;
+  } else {
+    tdi.enableState = aParams.insideActiveWindow ? kThemeTrackActive : kThemeTrackInactive;
+  }
+  tdi.trackInfo.slider.thumbDir = kThemeThumbPlain;
+  tdi.trackInfo.slider.pressState = 0;
+
+  HIThemeDrawTrack(&tdi, NULL, cgContext, HITHEME_ORIENTATION);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsIFrame* nsNativeThemeCocoa::SeparatorResponsibility(nsIFrame* aBefore, nsIFrame* aAfter) {
+  // Usually a separator is drawn by the segment to the right of the
+  // separator, but pressed and selected segments have higher priority.
+  if (!aBefore || !aAfter) return nullptr;
+  if (IsSelectedButton(aAfter)) return aAfter;
+  if (IsSelectedButton(aBefore) || IsPressedButton(aBefore)) return aBefore;
+  return aAfter;
+}
+
+static CGRect SeparatorAdjustedRect(CGRect aRect, nsNativeThemeCocoa::SegmentParams aParams) {
+  // A separator between two segments should always be located in the leftmost
+  // pixel column of the segment to the right of the separator, regardless of
+  // who ends up drawing it.
+  // CoreUI draws the separators inside the drawing rect.
+  if (!aParams.atLeftEnd && !aParams.drawsLeftSeparator) {
+    // The segment to the left of us draws the separator, so we need to make
+    // room for it.
+    aRect.origin.x += 1;
+    aRect.size.width -= 1;
+  }
+  if (aParams.drawsRightSeparator) {
+    // We draw the right separator, so we need to extend the draw rect into the
+    // segment to our right.
+    aRect.size.width += 1;
+  }
+  return aRect;
+}
+
+static NSString* ToolbarButtonPosition(BOOL aIsFirst, BOOL aIsLast) {
+  if (aIsFirst) {
+    if (aIsLast) return @"kCUISegmentPositionOnly";
+    return @"kCUISegmentPositionFirst";
+  }
+  if (aIsLast) return @"kCUISegmentPositionLast";
+  return @"kCUISegmentPositionMiddle";
+}
+
+struct SegmentedControlRenderSettings {
+  const CGFloat* heights;
+  const NSString* widgetName;
+};
+
+static const CGFloat tabHeights[3] = {17, 20, 23};
+
+static const SegmentedControlRenderSettings tabRenderSettings = {tabHeights, @"tab"};
+
+static const CGFloat toolbarButtonHeights[3] = {15, 18, 22};
+
+static const SegmentedControlRenderSettings toolbarButtonRenderSettings = {
+    toolbarButtonHeights, @"kCUIWidgetButtonSegmentedSCurve"};
+
+nsNativeThemeCocoa::SegmentParams nsNativeThemeCocoa::ComputeSegmentParams(
+    nsIFrame* aFrame, ElementState aEventState, SegmentType aSegmentType) {
+  SegmentParams params;
+  params.segmentType = aSegmentType;
+  params.insideActiveWindow = FrameIsInActiveWindow(aFrame);
+  params.pressed = IsPressedButton(aFrame);
+  params.selected = IsSelectedButton(aFrame);
+  params.focused = aEventState.HasState(ElementState::FOCUSRING);
+  bool isRTL = IsFrameRTL(aFrame);
+  nsIFrame* left = GetAdjacentSiblingFrameWithSameAppearance(aFrame, isRTL);
+  nsIFrame* right = GetAdjacentSiblingFrameWithSameAppearance(aFrame, !isRTL);
+  params.atLeftEnd = !left;
+  params.atRightEnd = !right;
+  params.drawsLeftSeparator = SeparatorResponsibility(left, aFrame) == aFrame;
+  params.drawsRightSeparator = SeparatorResponsibility(aFrame, right) == aFrame;
+  params.rtl = isRTL;
+  return params;
+}
+
+static SegmentedControlRenderSettings RenderSettingsForSegmentType(
+    nsNativeThemeCocoa::SegmentType aSegmentType) {
+  switch (aSegmentType) {
+    case nsNativeThemeCocoa::SegmentType::eToolbarButton:
+      return toolbarButtonRenderSettings;
+    case nsNativeThemeCocoa::SegmentType::eTab:
+      return tabRenderSettings;
+  }
+}
+
+void nsNativeThemeCocoa::DrawSegment(CGContextRef cgContext, const HIRect& inBoxRect,
+                                     const SegmentParams& aParams) {
+  SegmentedControlRenderSettings renderSettings = RenderSettingsForSegmentType(aParams.segmentType);
+  NSControlSize controlSize = FindControlSize(inBoxRect.size.height, renderSettings.heights, 4.0f);
+  CGRect drawRect = SeparatorAdjustedRect(inBoxRect, aParams);
+
+  NSDictionary* dict = @{
+    @"widget" : renderSettings.widgetName,
+    @"kCUIPresentationStateKey" : (aParams.insideActiveWindow ? @"kCUIPresentationStateActiveKey"
+                                                              : @"kCUIPresentationStateInactive"),
+    @"kCUIPositionKey" : ToolbarButtonPosition(aParams.atLeftEnd, aParams.atRightEnd),
+    @"kCUISegmentLeadingSeparatorKey" : [NSNumber numberWithBool:aParams.drawsLeftSeparator],
+    @"kCUISegmentTrailingSeparatorKey" : [NSNumber numberWithBool:aParams.drawsRightSeparator],
+    @"value" : [NSNumber numberWithBool:aParams.selected],
+    @"state" :
+        (aParams.pressed ? @"pressed" : (aParams.insideActiveWindow ? @"normal" : @"inactive")),
+    @"focus" : [NSNumber numberWithBool:aParams.focused],
+    @"size" : CUIControlSizeForCocoaSize(controlSize),
+    @"is.flipped" : [NSNumber numberWithBool:YES],
+    @"direction" : @"up"
+  };
+
+  RenderWithCoreUI(drawRect, cgContext, dict);
+}
+
+void nsNativeThemeCocoa::DrawToolbar(CGContextRef cgContext, const CGRect& inBoxRect,
+                                     bool aIsMain) {
+  CGRect drawRect = inBoxRect;
+
+  // top border
+  drawRect.size.height = 1.0f;
+  DrawNativeGreyColorInRect(cgContext, toolbarTopBorderGrey, drawRect, aIsMain);
+
+  // background
+  drawRect.origin.y += drawRect.size.height;
+  drawRect.size.height = inBoxRect.size.height - 2.0f;
+  DrawNativeGreyColorInRect(cgContext, toolbarFillGrey, drawRect, aIsMain);
+
+  // bottom border
+  drawRect.origin.y += drawRect.size.height;
+  drawRect.size.height = 1.0f;
+  DrawNativeGreyColorInRect(cgContext, toolbarBottomBorderGrey, drawRect, aIsMain);
+}
+
+static bool ToolbarCanBeUnified(const gfx::Rect& aRect, NSWindow* aWindow) {
+  if (![aWindow isKindOfClass:[ToolbarWindow class]]) return false;
+
+  ToolbarWindow* win = (ToolbarWindow*)aWindow;
+  float unifiedToolbarHeight = [win unifiedToolbarHeight];
+  return aRect.X() == 0 && aRect.Width() >= [win frame].size.width &&
+         aRect.YMost() <= unifiedToolbarHeight;
+}
+
+void nsNativeThemeCocoa::DrawStatusBar(CGContextRef cgContext, const HIRect& inBoxRect,
+                                       bool aIsMain) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (inBoxRect.size.height < 2.0f) return;
+
+  CGContextSaveGState(cgContext);
+  CGContextClipToRect(cgContext, inBoxRect);
+
+  // kCUIWidgetWindowFrame draws a complete window frame with both title bar
+  // and bottom bar. We only want the bottom bar, so we extend the draw rect
+  // upwards to make space for the title bar, and then we clip it away.
+  CGRect drawRect = inBoxRect;
+  const int extendUpwards = 40;
+  drawRect.origin.y -= extendUpwards;
+  drawRect.size.height += extendUpwards;
+  RenderWithCoreUI(
+      drawRect, cgContext,
+      [NSDictionary
+          dictionaryWithObjectsAndKeys:@"kCUIWidgetWindowFrame", @"widget", @"regularwin",
+                                       @"windowtype", (aIsMain ? @"normal" : @"inactive"), @"state",
+                                       [NSNumber numberWithInt:inBoxRect.size.height],
+                                       @"kCUIWindowFrameBottomBarHeightKey",
+                                       [NSNumber numberWithBool:YES],
+                                       @"kCUIWindowFrameDrawBottomBarSeparatorKey",
+                                       [NSNumber numberWithBool:YES], @"is.flipped", nil]);
+
+  CGContextRestoreGState(cgContext);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsNativeThemeCocoa::DrawMultilineTextField(CGContextRef cgContext, const CGRect& inBoxRect,
+                                                bool aIsFocused) {
+  mTextFieldCell.enabled = YES;
+  mTextFieldCell.showsFirstResponder = aIsFocused;
+
+  if (mCellDrawWindow) {
+    mCellDrawWindow.cellsShouldLookActive = YES;
+  }
+
+  // DrawCellIncludingFocusRing draws into the current NSGraphicsContext, so do the usual
+  // save+restore dance.
+  NSGraphicsContext* savedContext = NSGraphicsContext.currentContext;
+  NSGraphicsContext.currentContext = [NSGraphicsContext graphicsContextWithCGContext:cgContext
+                                                                             flipped:YES];
+  DrawCellIncludingFocusRing(mTextFieldCell, inBoxRect, mCellDrawView);
+  NSGraphicsContext.currentContext = savedContext;
+}
+
+void nsNativeThemeCocoa::DrawSourceListSelection(CGContextRef aContext, const CGRect& aRect,
+                                                 bool aWindowIsActive, bool aSelectionIsActive) {
+  NSColor* fillColor;
+  if (aSelectionIsActive) {
+    // Active selection, blue or graphite.
+    fillColor = ControlAccentColor();
+  } else {
+    // Inactive selection, gray.
+    if (aWindowIsActive) {
+      fillColor = [NSColor colorWithWhite:0.871 alpha:1.0];
+    } else {
+      fillColor = [NSColor colorWithWhite:0.808 alpha:1.0];
+    }
+  }
+  CGContextSetFillColorWithColor(aContext, [fillColor CGColor]);
+  CGContextFillRect(aContext, aRect);
+}
+
+static bool IsHiDPIContext(nsDeviceContext* aContext) {
+  return AppUnitsPerCSSPixel() >= 2 * aContext->AppUnitsPerDevPixelAtUnitFullZoom();
+}
+
+Maybe<nsNativeThemeCocoa::WidgetInfo> nsNativeThemeCocoa::ComputeWidgetInfo(
+    nsIFrame* aFrame, StyleAppearance aAppearance, const nsRect& aRect) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // setup to draw into the correct port
+  int32_t p2a = aFrame->PresContext()->AppUnitsPerDevPixel();
+
+  gfx::Rect nativeWidgetRect(aRect.x, aRect.y, aRect.width, aRect.height);
+  nativeWidgetRect.Scale(1.0 / gfxFloat(p2a));
+  float originalHeight = nativeWidgetRect.Height();
+  nativeWidgetRect.Round();
+  if (nativeWidgetRect.IsEmpty()) {
+    return Nothing();  // Don't attempt to draw invisible widgets.
+  }
+
+  bool hidpi = IsHiDPIContext(aFrame->PresContext()->DeviceContext());
+  if (hidpi) {
+    // Use high-resolution drawing.
+    nativeWidgetRect.Scale(0.5f);
+    originalHeight *= 0.5f;
+  }
+
+  ElementState elementState = GetContentState(aFrame, aAppearance);
+
+  switch (aAppearance) {
+    case StyleAppearance::Menupopup:
+      return Nothing();
+
+    case StyleAppearance::Menuarrow:
+      return Some(
+          WidgetInfo::MenuIcon(ComputeMenuIconParams(aFrame, elementState, MenuIcon::eMenuArrow)));
+
+    case StyleAppearance::Menuitem:
+    case StyleAppearance::Checkmenuitem:
+      return Some(WidgetInfo::MenuItem(ComputeMenuItemParams(
+          aFrame, elementState, aAppearance == StyleAppearance::Checkmenuitem)));
+
+    case StyleAppearance::Menuseparator:
+      return Some(WidgetInfo::MenuSeparator(ComputeMenuItemParams(aFrame, elementState, false)));
+
+    case StyleAppearance::ButtonArrowUp:
+    case StyleAppearance::ButtonArrowDown: {
+      MenuIcon icon = aAppearance == StyleAppearance::ButtonArrowUp
+                          ? MenuIcon::eMenuUpScrollArrow
+                          : MenuIcon::eMenuDownScrollArrow;
+      return Some(WidgetInfo::MenuIcon(ComputeMenuIconParams(aFrame, elementState, icon)));
+    }
+
+    case StyleAppearance::Tooltip:
+      return Nothing();
+
+    case StyleAppearance::Checkbox:
+    case StyleAppearance::Radio: {
+      bool isCheckbox = (aAppearance == StyleAppearance::Checkbox);
+
+      CheckboxOrRadioParams params;
+      params.state = CheckboxOrRadioState::eOff;
+      if (elementState.HasState(ElementState::INDETERMINATE)) {
+        params.state = CheckboxOrRadioState::eIndeterminate;
+      } else if (elementState.HasState(ElementState::CHECKED)) {
+        params.state = CheckboxOrRadioState::eOn;
+      }
+      params.controlParams = ComputeControlParams(aFrame, elementState);
+      params.verticalAlignFactor = VerticalAlignFactor(aFrame);
+      if (isCheckbox) {
+        return Some(WidgetInfo::Checkbox(params));
+      }
+      return Some(WidgetInfo::Radio(params));
+    }
+
+    case StyleAppearance::Button:
+      if (IsDefaultButton(aFrame)) {
+        // Check whether the default button is in a document that does not
+        // match the :-moz-window-inactive pseudoclass. This activeness check
+        // is different from the other "active window" checks in this file
+        // because we absolutely need the button's default button appearance to
+        // be in sync with its text color, and the text color is changed by
+        // such a :-moz-window-inactive rule. (That's because on 10.10 and up,
+        // default buttons in active windows have blue background and white
+        // text, and default buttons in inactive windows have white background
+        // and black text.)
+        DocumentState docState = aFrame->GetContent()->OwnerDoc()->GetDocumentState();
+        ControlParams params = ComputeControlParams(aFrame, elementState);
+        params.insideActiveWindow = !docState.HasState(DocumentState::WINDOW_INACTIVE);
+        return Some(WidgetInfo::Button(ButtonParams{params, ButtonType::eDefaultPushButton}));
+      }
+      if (IsButtonTypeMenu(aFrame)) {
+        ControlParams controlParams = ComputeControlParams(aFrame, elementState);
+        controlParams.pressed = IsOpenButton(aFrame);
+        DropdownParams params;
+        params.controlParams = controlParams;
+        params.pullsDown = true;
+        params.editable = false;
+        return Some(WidgetInfo::Dropdown(params));
+      }
+      if (originalHeight > DO_SQUARE_BUTTON_HEIGHT) {
+        // If the button is tall enough, draw the square button style so that
+        // buttons with non-standard content look good. Otherwise draw normal
+        // rounded aqua buttons.
+        // This comparison is done based on the height that is calculated without
+        // the top, because the snapped height can be affected by the top of the
+        // rect and that may result in different height depending on the top value.
+        return Some(WidgetInfo::Button(ButtonParams{ComputeControlParams(aFrame, elementState),
+                                                    ButtonType::eSquareBezelPushButton}));
+      }
+      return Some(WidgetInfo::Button(ButtonParams{ComputeControlParams(aFrame, elementState),
+                                                  ButtonType::eRegularPushButton}));
+
+    case StyleAppearance::MozMacHelpButton:
+      return Some(WidgetInfo::Button(
+          ButtonParams{ComputeControlParams(aFrame, elementState), ButtonType::eHelpButton}));
+
+    case StyleAppearance::MozMacDisclosureButtonOpen:
+    case StyleAppearance::MozMacDisclosureButtonClosed: {
+      ButtonType buttonType = (aAppearance == StyleAppearance::MozMacDisclosureButtonClosed)
+                                  ? ButtonType::eDisclosureButtonClosed
+                                  : ButtonType::eDisclosureButtonOpen;
+      return Some(
+          WidgetInfo::Button(ButtonParams{ComputeControlParams(aFrame, elementState), buttonType}));
+    }
+
+    case StyleAppearance::Spinner: {
+      bool isSpinner = (aAppearance == StyleAppearance::Spinner);
+      nsIContent* content = aFrame->GetContent();
+      if (isSpinner && content->IsHTMLElement()) {
+        // In HTML the theming for the spin buttons is drawn individually into
+        // their own backgrounds instead of being drawn into the background of
+        // their spinner parent as it is for XUL.
+        break;
+      }
+      SpinButtonParams params;
+      if (content->IsElement()) {
+        if (content->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::state, u"up"_ns,
+                                              eCaseMatters)) {
+          params.pressedButton = Some(SpinButton::eUp);
+        } else if (content->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::state,
+                                                     u"down"_ns, eCaseMatters)) {
+          params.pressedButton = Some(SpinButton::eDown);
+        }
+      }
+      params.disabled = elementState.HasState(ElementState::DISABLED);
+      params.insideActiveWindow = FrameIsInActiveWindow(aFrame);
+
+      return Some(WidgetInfo::SpinButtons(params));
+    }
+
+    case StyleAppearance::SpinnerUpbutton:
+    case StyleAppearance::SpinnerDownbutton: {
+      nsNumberControlFrame* numberControlFrame =
+          nsNumberControlFrame::GetNumberControlFrameForSpinButton(aFrame);
+      if (numberControlFrame) {
+        SpinButtonParams params;
+        if (numberControlFrame->SpinnerUpButtonIsDepressed()) {
+          params.pressedButton = Some(SpinButton::eUp);
+        } else if (numberControlFrame->SpinnerDownButtonIsDepressed()) {
+          params.pressedButton = Some(SpinButton::eDown);
+        }
+        params.disabled = elementState.HasState(ElementState::DISABLED);
+        params.insideActiveWindow = FrameIsInActiveWindow(aFrame);
+        if (aAppearance == StyleAppearance::SpinnerUpbutton) {
+          return Some(WidgetInfo::SpinButtonUp(params));
+        }
+        return Some(WidgetInfo::SpinButtonDown(params));
+      }
+    } break;
+
+    case StyleAppearance::Toolbarbutton: {
+      SegmentParams params =
+          ComputeSegmentParams(aFrame, elementState, SegmentType::eToolbarButton);
+      params.insideActiveWindow = [NativeWindowForFrame(aFrame) isMainWindow];
+      return Some(WidgetInfo::Segment(params));
+    }
+
+    case StyleAppearance::Separator:
+      return Some(WidgetInfo::Separator());
+
+    case StyleAppearance::Toolbar: {
+      NSWindow* win = NativeWindowForFrame(aFrame);
+      bool isMain = [win isMainWindow];
+      if (ToolbarCanBeUnified(nativeWidgetRect, win)) {
+        // Unified toolbars are drawn similar to vibrancy; we communicate their extents via the
+        // theme geometry mechanism and then place native views under Gecko's rendering. So Gecko
+        // just needs to be transparent in the place where the toolbar should be visible.
+        return Nothing();
+      }
+      return Some(WidgetInfo::Toolbar(isMain));
+    }
+
+    case StyleAppearance::MozWindowTitlebar: {
+      return Nothing();
+    }
+
+    case StyleAppearance::Statusbar:
+      return Some(WidgetInfo::StatusBar(IsActive(aFrame, YES)));
+
+    case StyleAppearance::MenulistButton:
+    case StyleAppearance::Menulist: {
+      ControlParams controlParams = ComputeControlParams(aFrame, elementState);
+      controlParams.pressed = IsOpenButton(aFrame);
+      DropdownParams params;
+      params.controlParams = controlParams;
+      params.pullsDown = false;
+      params.editable = false;
+      return Some(WidgetInfo::Dropdown(params));
+    }
+
+    case StyleAppearance::MozMenulistArrowButton:
+      return Some(WidgetInfo::Button(
+          ButtonParams{ComputeControlParams(aFrame, elementState), ButtonType::eArrowButton}));
+
+    case StyleAppearance::Groupbox:
+      return Some(WidgetInfo::GroupBox());
+
+    case StyleAppearance::Textfield:
+    case StyleAppearance::NumberInput:
+      return Some(WidgetInfo::TextField(ComputeTextFieldParams(aFrame, elementState)));
+
+    case StyleAppearance::Searchfield:
+      return Some(WidgetInfo::SearchField(ComputeTextFieldParams(aFrame, elementState)));
+
+    case StyleAppearance::ProgressBar: {
+      if (elementState.HasState(ElementState::INDETERMINATE)) {
+        if (!QueueAnimatedContentForRefresh(aFrame->GetContent(), 30)) {
+          NS_WARNING("Unable to animate progressbar!");
+        }
+      }
+      return Some(WidgetInfo::ProgressBar(
+          ComputeProgressParams(aFrame, elementState, !IsVerticalProgress(aFrame))));
+    }
+
+    case StyleAppearance::Meter:
+      return Some(WidgetInfo::Meter(ComputeMeterParams(aFrame)));
+
+    case StyleAppearance::Progresschunk:
+    case StyleAppearance::Meterchunk:
+      // Do nothing: progress and meter bars cases will draw chunks.
+      break;
+
+    case StyleAppearance::Treetwisty:
+      return Some(WidgetInfo::Button(ButtonParams{ComputeControlParams(aFrame, elementState),
+                                                  ButtonType::eTreeTwistyPointingRight}));
+
+    case StyleAppearance::Treetwistyopen:
+      return Some(WidgetInfo::Button(ButtonParams{ComputeControlParams(aFrame, elementState),
+                                                  ButtonType::eTreeTwistyPointingDown}));
+
+    case StyleAppearance::Treeheadercell:
+      return Some(WidgetInfo::TreeHeaderCell(ComputeTreeHeaderCellParams(aFrame, elementState)));
+
+    case StyleAppearance::Treeitem:
+    case StyleAppearance::Treeview:
+      return Some(WidgetInfo::ColorFill(sRGBColor(1.0, 1.0, 1.0, 1.0)));
+
+    case StyleAppearance::Treeheader:
+      // do nothing, taken care of by individual header cells
+    case StyleAppearance::Treeheadersortarrow:
+      // do nothing, taken care of by treeview header
+    case StyleAppearance::Treeline:
+      // do nothing, these lines don't exist on macos
+      break;
+
+    case StyleAppearance::Range: {
+      Maybe<ScaleParams> params = ComputeHTMLScaleParams(aFrame, elementState);
+      if (params) {
+        return Some(WidgetInfo::Scale(*params));
+      }
+      break;
+    }
+
+    case StyleAppearance::Textarea:
+      return Some(WidgetInfo::MultilineTextField(elementState.HasState(ElementState::FOCUS)));
+
+    case StyleAppearance::Listbox:
+      return Some(WidgetInfo::ListBox());
+
+    case StyleAppearance::MozMacSourceList: {
+      return Nothing();
+    }
+
+    case StyleAppearance::MozMacSourceListSelection:
+    case StyleAppearance::MozMacActiveSourceListSelection: {
+      // We only support vibrancy for source list selections if we're inside
+      // a source list, because we need the background to be transparent.
+      if (IsInSourceList(aFrame)) {
+        return Nothing();
+      }
+      bool isInActiveWindow = FrameIsInActiveWindow(aFrame);
+      if (aAppearance == StyleAppearance::MozMacActiveSourceListSelection) {
+        return Some(WidgetInfo::ActiveSourceListSelection(isInActiveWindow));
+      }
+      return Some(WidgetInfo::InactiveSourceListSelection(isInActiveWindow));
+    }
+
+    case StyleAppearance::Tab: {
+      SegmentParams params = ComputeSegmentParams(aFrame, elementState, SegmentType::eTab);
+      params.pressed = params.pressed && !params.selected;
+      return Some(WidgetInfo::Segment(params));
+    }
+
+    case StyleAppearance::Tabpanels:
+      return Some(WidgetInfo::TabPanel(FrameIsInActiveWindow(aFrame)));
+
+    default:
+      break;
+  }
+
+  return Nothing();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(Nothing());
+}
+
+static bool IsWidgetNonNative(StyleAppearance aAppearance) {
+  return nsNativeTheme::IsWidgetScrollbarPart(aAppearance) ||
+         aAppearance == StyleAppearance::FocusOutline;
+}
+
+NS_IMETHODIMP
+nsNativeThemeCocoa::DrawWidgetBackground(gfxContext* aContext, nsIFrame* aFrame,
+                                         StyleAppearance aAppearance, const nsRect& aRect,
+                                         const nsRect& aDirtyRect, DrawOverflow aDrawOverflow) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (IsWidgetNonNative(aAppearance)) {
+    return ThemeCocoa::DrawWidgetBackground(aContext, aFrame, aAppearance, aRect, aDirtyRect,
+                                            aDrawOverflow);
+  }
+
+  Maybe<WidgetInfo> widgetInfo = ComputeWidgetInfo(aFrame, aAppearance, aRect);
+
+  if (!widgetInfo) {
+    return NS_OK;
+  }
+
+  int32_t p2a = aFrame->PresContext()->AppUnitsPerDevPixel();
+
+  gfx::Rect nativeWidgetRect = NSRectToRect(aRect, p2a);
+  nativeWidgetRect.Round();
+
+  bool hidpi = IsHiDPIContext(aFrame->PresContext()->DeviceContext());
+
+  auto colorScheme = LookAndFeel::ColorSchemeForFrame(aFrame);
+
+  RenderWidget(*widgetInfo, colorScheme, *aContext->GetDrawTarget(), nativeWidgetRect,
+               NSRectToRect(aDirtyRect, p2a), hidpi ? 2.0f : 1.0f);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsNativeThemeCocoa::RenderWidget(const WidgetInfo& aWidgetInfo,
+                                      LookAndFeel::ColorScheme aScheme, DrawTarget& aDrawTarget,
+                                      const gfx::Rect& aWidgetRect, const gfx::Rect& aDirtyRect,
+                                      float aScale) {
+  // Some of the drawing below uses NSAppearance.currentAppearance behind the scenes.
+  // Set it to the appearance we want, the same way as nsLookAndFeel::NativeGetColor.
+  NSAppearance.currentAppearance = NSAppearanceForColorScheme(aScheme);
+
+  // Also set the cell draw window's appearance; this is respected by NSTextFieldCell (and its
+  // subclass NSSearchFieldCell).
+  if (mCellDrawWindow) {
+    mCellDrawWindow.appearance = NSAppearance.currentAppearance;
+  }
+
+  const Widget widget = aWidgetInfo.Widget();
+
+  // Some widgets render using DrawTarget, and some using CGContext.
+  switch (widget) {
+    case Widget::eColorFill: {
+      sRGBColor color = aWidgetInfo.Params<sRGBColor>();
+      aDrawTarget.FillRect(aWidgetRect, ColorPattern(ToDeviceColor(color)));
+      break;
+    }
+    default: {
+      AutoRestoreTransform autoRestoreTransform(&aDrawTarget);
+      gfx::Rect widgetRect = aWidgetRect;
+      gfx::Rect dirtyRect = aDirtyRect;
+
+      dirtyRect.Scale(1.0f / aScale);
+      widgetRect.Scale(1.0f / aScale);
+      aDrawTarget.SetTransform(aDrawTarget.GetTransform().PreScale(aScale, aScale));
+
+      // The remaining widgets require a CGContext.
+      CGRect macRect =
+          CGRectMake(widgetRect.X(), widgetRect.Y(), widgetRect.Width(), widgetRect.Height());
+
+      gfxQuartzNativeDrawing nativeDrawing(aDrawTarget, dirtyRect);
+
+      CGContextRef cgContext = nativeDrawing.BeginNativeDrawing();
+      if (cgContext == nullptr) {
+        // The Quartz surface handles 0x0 surfaces by internally
+        // making all operations no-ops; there's no cgcontext created for them.
+        // Unfortunately, this means that callers that want to render
+        // directly to the CGContext need to be aware of this quirk.
+        return;
+      }
+
+      // Set the context's "base transform" to in order to get correctly-sized focus rings.
+      CGContextSetBaseCTM(cgContext, CGAffineTransformMakeScale(aScale, aScale));
+
+      switch (widget) {
+        case Widget::eColorFill:
+          MOZ_CRASH("already handled in outer switch");
+          break;
+        case Widget::eMenuIcon: {
+          MenuIconParams params = aWidgetInfo.Params<MenuIconParams>();
+          DrawMenuIcon(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eMenuItem: {
+          MenuItemParams params = aWidgetInfo.Params<MenuItemParams>();
+          DrawMenuItem(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eMenuSeparator: {
+          MenuItemParams params = aWidgetInfo.Params<MenuItemParams>();
+          DrawMenuSeparator(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eCheckbox: {
+          CheckboxOrRadioParams params = aWidgetInfo.Params<CheckboxOrRadioParams>();
+          DrawCheckboxOrRadio(cgContext, true, macRect, params);
+          break;
+        }
+        case Widget::eRadio: {
+          CheckboxOrRadioParams params = aWidgetInfo.Params<CheckboxOrRadioParams>();
+          DrawCheckboxOrRadio(cgContext, false, macRect, params);
+          break;
+        }
+        case Widget::eButton: {
+          ButtonParams params = aWidgetInfo.Params<ButtonParams>();
+          DrawButton(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eDropdown: {
+          DropdownParams params = aWidgetInfo.Params<DropdownParams>();
+          DrawDropdown(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eSpinButtons: {
+          SpinButtonParams params = aWidgetInfo.Params<SpinButtonParams>();
+          DrawSpinButtons(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eSpinButtonUp: {
+          SpinButtonParams params = aWidgetInfo.Params<SpinButtonParams>();
+          DrawSpinButton(cgContext, macRect, SpinButton::eUp, params);
+          break;
+        }
+        case Widget::eSpinButtonDown: {
+          SpinButtonParams params = aWidgetInfo.Params<SpinButtonParams>();
+          DrawSpinButton(cgContext, macRect, SpinButton::eDown, params);
+          break;
+        }
+        case Widget::eSegment: {
+          SegmentParams params = aWidgetInfo.Params<SegmentParams>();
+          DrawSegment(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eSeparator: {
+          HIThemeSeparatorDrawInfo sdi = {0, kThemeStateActive};
+          HIThemeDrawSeparator(&macRect, &sdi, cgContext, HITHEME_ORIENTATION);
+          break;
+        }
+        case Widget::eToolbar: {
+          bool isMain = aWidgetInfo.Params<bool>();
+          DrawToolbar(cgContext, macRect, isMain);
+          break;
+        }
+        case Widget::eStatusBar: {
+          bool isMain = aWidgetInfo.Params<bool>();
+          DrawStatusBar(cgContext, macRect, isMain);
+          break;
+        }
+        case Widget::eGroupBox: {
+          HIThemeGroupBoxDrawInfo gdi = {0, kThemeStateActive, kHIThemeGroupBoxKindPrimary};
+          HIThemeDrawGroupBox(&macRect, &gdi, cgContext, HITHEME_ORIENTATION);
+          break;
+        }
+        case Widget::eTextField: {
+          TextFieldParams params = aWidgetInfo.Params<TextFieldParams>();
+          DrawTextField(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eSearchField: {
+          TextFieldParams params = aWidgetInfo.Params<TextFieldParams>();
+          DrawSearchField(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eProgressBar: {
+          ProgressParams params = aWidgetInfo.Params<ProgressParams>();
+          DrawProgress(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eMeter: {
+          MeterParams params = aWidgetInfo.Params<MeterParams>();
+          DrawMeter(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eTreeHeaderCell: {
+          TreeHeaderCellParams params = aWidgetInfo.Params<TreeHeaderCellParams>();
+          DrawTreeHeaderCell(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eScale: {
+          ScaleParams params = aWidgetInfo.Params<ScaleParams>();
+          DrawScale(cgContext, macRect, params);
+          break;
+        }
+        case Widget::eMultilineTextField: {
+          bool isFocused = aWidgetInfo.Params<bool>();
+          DrawMultilineTextField(cgContext, macRect, isFocused);
+          break;
+        }
+        case Widget::eListBox: {
+          // Fill the content with the control background color.
+          CGContextSetFillColorWithColor(cgContext, [NSColor.controlBackgroundColor CGColor]);
+          CGContextFillRect(cgContext, macRect);
+          // Draw the frame using kCUIWidgetScrollViewFrame. This is what NSScrollView uses in
+          // -[NSScrollView drawRect:] if you give it a borderType of NSBezelBorder.
+          RenderWithCoreUI(
+              macRect, cgContext, @{
+                @"widget" : @"kCUIWidgetScrollViewFrame",
+                @"kCUIIsFlippedKey" : @YES,
+                @"kCUIVariantMetal" : @NO,
+              });
+          break;
+        }
+        case Widget::eActiveSourceListSelection:
+        case Widget::eInactiveSourceListSelection: {
+          bool isInActiveWindow = aWidgetInfo.Params<bool>();
+          bool isActiveSelection = aWidgetInfo.Widget() == Widget::eActiveSourceListSelection;
+          DrawSourceListSelection(cgContext, macRect, isInActiveWindow, isActiveSelection);
+          break;
+        }
+        case Widget::eTabPanel: {
+          bool isInsideActiveWindow = aWidgetInfo.Params<bool>();
+          DrawTabPanel(cgContext, macRect, isInsideActiveWindow);
+          break;
+        }
+      }
+
+      // Reset the base CTM.
+      CGContextSetBaseCTM(cgContext, CGAffineTransformIdentity);
+
+      nativeDrawing.EndNativeDrawing();
+    }
+  }
+}
+
+bool nsNativeThemeCocoa::CreateWebRenderCommandsForWidget(
+    mozilla::wr::DisplayListBuilder& aBuilder, mozilla::wr::IpcResourceUpdateQueue& aResources,
+    const mozilla::layers::StackingContextHelper& aSc,
+    mozilla::layers::RenderRootStateManager* aManager, nsIFrame* aFrame,
+    StyleAppearance aAppearance, const nsRect& aRect) {
+  if (IsWidgetNonNative(aAppearance)) {
+    return ThemeCocoa::CreateWebRenderCommandsForWidget(aBuilder, aResources, aSc, aManager, aFrame,
+                                                        aAppearance, aRect);
+  }
+
+  // This list needs to stay consistent with the list in DrawWidgetBackground.
+  // For every switch case in DrawWidgetBackground, there are three choices:
+  //  - If the case in DrawWidgetBackground draws nothing for the given widget
+  //    type, then don't list it here. We will hit the "default: return true;"
+  //    case.
+  //  - If the case in DrawWidgetBackground draws something simple for the given
+  //    widget type, imitate that drawing using WebRender commands.
+  //  - If the case in DrawWidgetBackground draws something complicated for the
+  //    given widget type, return false here.
+  switch (aAppearance) {
+    case StyleAppearance::Menuarrow:
+    case StyleAppearance::Menuitem:
+    case StyleAppearance::Checkmenuitem:
+    case StyleAppearance::Menuseparator:
+    case StyleAppearance::ButtonArrowUp:
+    case StyleAppearance::ButtonArrowDown:
+    case StyleAppearance::Checkbox:
+    case StyleAppearance::Radio:
+    case StyleAppearance::Button:
+    case StyleAppearance::MozMacHelpButton:
+    case StyleAppearance::MozMacDisclosureButtonOpen:
+    case StyleAppearance::MozMacDisclosureButtonClosed:
+    case StyleAppearance::Spinner:
+    case StyleAppearance::SpinnerUpbutton:
+    case StyleAppearance::SpinnerDownbutton:
+    case StyleAppearance::Toolbarbutton:
+    case StyleAppearance::Separator:
+    case StyleAppearance::Toolbar:
+    case StyleAppearance::MozWindowTitlebar:
+    case StyleAppearance::Statusbar:
+    case StyleAppearance::Menulist:
+    case StyleAppearance::MenulistButton:
+    case StyleAppearance::MozMenulistArrowButton:
+    case StyleAppearance::Groupbox:
+    case StyleAppearance::Textfield:
+    case StyleAppearance::NumberInput:
+    case StyleAppearance::Searchfield:
+    case StyleAppearance::ProgressBar:
+    case StyleAppearance::Meter:
+    case StyleAppearance::Treeheadercell:
+    case StyleAppearance::Treetwisty:
+    case StyleAppearance::Treetwistyopen:
+    case StyleAppearance::Treeitem:
+    case StyleAppearance::Treeview:
+    case StyleAppearance::Range:
+      return false;
+
+    case StyleAppearance::Textarea:
+    case StyleAppearance::Listbox:
+    case StyleAppearance::Tab:
+    case StyleAppearance::Tabpanels:
+      return false;
+
+    default:
+      return true;
+  }
+}
+
+LayoutDeviceIntMargin nsNativeThemeCocoa::DirectionAwareMargin(const LayoutDeviceIntMargin& aMargin,
+                                                               nsIFrame* aFrame) {
+  // Assuming aMargin was originally specified for a horizontal LTR context,
+  // reinterpret the values as logical, and then map to physical coords
+  // according to aFrame's actual writing mode.
+  WritingMode wm = aFrame->GetWritingMode();
+  nsMargin m = LogicalMargin(wm, aMargin.top, aMargin.right, aMargin.bottom, aMargin.left)
+                   .GetPhysicalMargin(wm);
+  return LayoutDeviceIntMargin(m.top, m.right, m.bottom, m.left);
+}
+
+static const LayoutDeviceIntMargin kAquaDropdownBorder(1, 22, 2, 5);
+static const LayoutDeviceIntMargin kAquaComboboxBorder(3, 20, 3, 4);
+static const LayoutDeviceIntMargin kAquaSearchfieldBorder(3, 5, 2, 19);
+static const LayoutDeviceIntMargin kAquaSearchfieldBorderBigSur(5, 5, 4, 26);
+
+LayoutDeviceIntMargin nsNativeThemeCocoa::GetWidgetBorder(nsDeviceContext* aContext,
+                                                          nsIFrame* aFrame,
+                                                          StyleAppearance aAppearance) {
+  LayoutDeviceIntMargin result;
+
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+  switch (aAppearance) {
+    case StyleAppearance::Button: {
+      if (IsButtonTypeMenu(aFrame)) {
+        result = DirectionAwareMargin(kAquaDropdownBorder, aFrame);
+      } else {
+        result = DirectionAwareMargin(LayoutDeviceIntMargin(1, 7, 3, 7), aFrame);
+      }
+      break;
+    }
+
+    case StyleAppearance::Toolbarbutton: {
+      result = DirectionAwareMargin(LayoutDeviceIntMargin(1, 4, 1, 4), aFrame);
+      break;
+    }
+
+    case StyleAppearance::Checkbox:
+    case StyleAppearance::Radio: {
+      // nsCheckboxRadioFrame::GetIntrinsicWidth and nsCheckboxRadioFrame::GetIntrinsicHeight
+      // assume a border width of 2px.
+      result.SizeTo(2, 2, 2, 2);
+      break;
+    }
+
+    case StyleAppearance::Menulist:
+    case StyleAppearance::MenulistButton:
+    case StyleAppearance::MozMenulistArrowButton:
+      result = DirectionAwareMargin(kAquaDropdownBorder, aFrame);
+      break;
+
+    case StyleAppearance::Menuarrow:
+      if (nsCocoaFeatures::OnBigSurOrLater()) {
+        result.SizeTo(0, 0, 0, 28);
+      }
+      break;
+
+    case StyleAppearance::NumberInput:
+    case StyleAppearance::Textfield: {
+      SInt32 frameOutset = 0;
+      ::GetThemeMetric(kThemeMetricEditTextFrameOutset, &frameOutset);
+
+      SInt32 textPadding = 0;
+      ::GetThemeMetric(kThemeMetricEditTextWhitespace, &textPadding);
+
+      frameOutset += textPadding;
+
+      result.SizeTo(frameOutset, frameOutset, frameOutset, frameOutset);
+      break;
+    }
+
+    case StyleAppearance::Textarea:
+      result.SizeTo(1, 1, 1, 1);
+      break;
+
+    case StyleAppearance::Searchfield: {
+      auto border = nsCocoaFeatures::OnBigSurOrLater() ? kAquaSearchfieldBorderBigSur
+                                                       : kAquaSearchfieldBorder;
+      result = DirectionAwareMargin(border, aFrame);
+      break;
+    }
+
+    case StyleAppearance::Listbox: {
+      SInt32 frameOutset = 0;
+      ::GetThemeMetric(kThemeMetricListBoxFrameOutset, &frameOutset);
+      result.SizeTo(frameOutset, frameOutset, frameOutset, frameOutset);
+      break;
+    }
+
+    case StyleAppearance::Statusbar:
+      result.SizeTo(1, 0, 0, 0);
+      break;
+
+    default:
+      break;
+  }
+
+  if (IsHiDPIContext(aContext)) {
+    result = result + result;  // doubled
+  }
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(result);
+}
+
+// Return false here to indicate that CSS padding values should be used. There is
+// no reason to make a distinction between padding and border values, just specify
+// whatever values you want in GetWidgetBorder and only use this to return true
+// if you want to override CSS padding values.
+bool nsNativeThemeCocoa::GetWidgetPadding(nsDeviceContext* aContext, nsIFrame* aFrame,
+                                          StyleAppearance aAppearance,
+                                          LayoutDeviceIntMargin* aResult) {
+  // We don't want CSS padding being used for certain widgets.
+  // See bug 381639 for an example of why.
+  switch (aAppearance) {
+    // Radios and checkboxes return a fixed size in GetMinimumWidgetSize
+    // and have a meaningful baseline, so they can't have
+    // author-specified padding.
+    case StyleAppearance::Checkbox:
+    case StyleAppearance::Radio:
+      aResult->SizeTo(0, 0, 0, 0);
+      return true;
+
+    case StyleAppearance::Menuarrow:
+    case StyleAppearance::Searchfield:
+      if (nsCocoaFeatures::OnBigSurOrLater()) {
+        return true;
+      }
+      break;
+
+    default:
+      break;
+  }
+  return false;
+}
+
+bool nsNativeThemeCocoa::GetWidgetOverflow(nsDeviceContext* aContext, nsIFrame* aFrame,
+                                           StyleAppearance aAppearance, nsRect* aOverflowRect) {
+  if (IsWidgetNonNative(aAppearance)) {
+    return ThemeCocoa::GetWidgetOverflow(aContext, aFrame, aAppearance, aOverflowRect);
+  }
+  nsIntMargin overflow;
+  switch (aAppearance) {
+    case StyleAppearance::Button:
+    case StyleAppearance::MozMacDisclosureButtonOpen:
+    case StyleAppearance::MozMacDisclosureButtonClosed:
+    case StyleAppearance::MozMacHelpButton:
+    case StyleAppearance::Toolbarbutton:
+    case StyleAppearance::NumberInput:
+    case StyleAppearance::Textfield:
+    case StyleAppearance::Textarea:
+    case StyleAppearance::Searchfield:
+    case StyleAppearance::Listbox:
+    case StyleAppearance::Menulist:
+    case StyleAppearance::MenulistButton:
+    case StyleAppearance::MozMenulistArrowButton:
+    case StyleAppearance::Checkbox:
+    case StyleAppearance::Radio:
+    case StyleAppearance::Tab: {
+      overflow.SizeTo(kMaxFocusRingWidth, kMaxFocusRingWidth, kMaxFocusRingWidth,
+                      kMaxFocusRingWidth);
+      break;
+    }
+    case StyleAppearance::ProgressBar: {
+      // Progress bars draw a 2 pixel white shadow under their progress indicators.
+      overflow.bottom = 2;
+      break;
+    }
+    case StyleAppearance::Meter: {
+      // Meter bars overflow their boxes by about 2 pixels.
+      overflow.SizeTo(2, 2, 2, 2);
+      break;
+    }
+    default:
+      break;
+  }
+
+  if (IsHiDPIContext(aContext)) {
+    // Double the number of device pixels.
+    overflow += overflow;
+  }
+
+  if (overflow != nsIntMargin()) {
+    int32_t p2a = aFrame->PresContext()->AppUnitsPerDevPixel();
+    aOverflowRect->Inflate(nsMargin(
+        NSIntPixelsToAppUnits(overflow.top, p2a), NSIntPixelsToAppUnits(overflow.right, p2a),
+        NSIntPixelsToAppUnits(overflow.bottom, p2a), NSIntPixelsToAppUnits(overflow.left, p2a)));
+    return true;
+  }
+
+  return false;
+}
+
+LayoutDeviceIntSize nsNativeThemeCocoa::GetMinimumWidgetSize(nsPresContext* aPresContext,
+                                                             nsIFrame* aFrame,
+                                                             StyleAppearance aAppearance) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (IsWidgetNonNative(aAppearance)) {
+    return ThemeCocoa::GetMinimumWidgetSize(aPresContext, aFrame, aAppearance);
+  }
+
+  LayoutDeviceIntSize result;
+  switch (aAppearance) {
+    case StyleAppearance::Button: {
+      result.SizeTo(pushButtonSettings.minimumSizes[miniControlSize].width,
+                    pushButtonSettings.naturalSizes[miniControlSize].height);
+      break;
+    }
+
+    case StyleAppearance::ButtonArrowUp:
+    case StyleAppearance::ButtonArrowDown: {
+      result.SizeTo(kMenuScrollArrowSize.width, kMenuScrollArrowSize.height);
+      break;
+    }
+
+    case StyleAppearance::Menuarrow: {
+      result.SizeTo(kMenuarrowSize.width, kMenuarrowSize.height);
+      break;
+    }
+
+    case StyleAppearance::MozMacDisclosureButtonOpen:
+    case StyleAppearance::MozMacDisclosureButtonClosed: {
+      result.SizeTo(kDisclosureButtonSize.width, kDisclosureButtonSize.height);
+      break;
+    }
+
+    case StyleAppearance::MozMacHelpButton: {
+      result.SizeTo(kHelpButtonSize.width, kHelpButtonSize.height);
+      break;
+    }
+
+    case StyleAppearance::Toolbarbutton: {
+      result.SizeTo(0, toolbarButtonHeights[miniControlSize]);
+      break;
+    }
+
+    case StyleAppearance::Spinner:
+    case StyleAppearance::SpinnerUpbutton:
+    case StyleAppearance::SpinnerDownbutton: {
+      SInt32 buttonHeight = 0, buttonWidth = 0;
+      if (aFrame->GetContent()->IsXULElement()) {
+        ::GetThemeMetric(kThemeMetricLittleArrowsWidth, &buttonWidth);
+        ::GetThemeMetric(kThemeMetricLittleArrowsHeight, &buttonHeight);
+      } else {
+        NSSize size = spinnerSettings.minimumSizes[EnumSizeForCocoaSize(NSControlSizeMini)];
+        buttonWidth = size.width;
+        buttonHeight = size.height;
+        if (aAppearance != StyleAppearance::Spinner) {
+          // the buttons are half the height of the spinner
+          buttonHeight /= 2;
+        }
+      }
+      result.SizeTo(buttonWidth, buttonHeight);
+      break;
+    }
+
+    case StyleAppearance::Menulist:
+    case StyleAppearance::MenulistButton: {
+      SInt32 popupHeight = 0;
+      ::GetThemeMetric(kThemeMetricPopupButtonHeight, &popupHeight);
+      result.SizeTo(0, popupHeight);
+      break;
+    }
+
+    case StyleAppearance::NumberInput:
+    case StyleAppearance::Textfield:
+    case StyleAppearance::Textarea:
+    case StyleAppearance::Searchfield: {
+      // at minimum, we should be tall enough for 9pt text.
+      // I'm using hardcoded values here because the appearance manager
+      // values for the frame size are incorrect.
+      result.SizeTo(0, (2 + 2) /* top */ + 9 + (1 + 1) /* bottom */);
+      break;
+    }
+
+    case StyleAppearance::MozWindowButtonBox: {
+      NSSize size = WindowButtonsSize(aFrame);
+      result.SizeTo(size.width, size.height);
+      break;
+    }
+
+    case StyleAppearance::ProgressBar: {
+      SInt32 barHeight = 0;
+      ::GetThemeMetric(kThemeMetricNormalProgressBarThickness, &barHeight);
+      result.SizeTo(0, barHeight);
+      break;
+    }
+
+    case StyleAppearance::Separator: {
+      result.SizeTo(1, 1);
+      break;
+    }
+
+    case StyleAppearance::Treetwisty:
+    case StyleAppearance::Treetwistyopen: {
+      SInt32 twistyHeight = 0, twistyWidth = 0;
+      ::GetThemeMetric(kThemeMetricDisclosureButtonWidth, &twistyWidth);
+      ::GetThemeMetric(kThemeMetricDisclosureButtonHeight, &twistyHeight);
+      result.SizeTo(twistyWidth, twistyHeight);
+      break;
+    }
+
+    case StyleAppearance::Treeheader:
+    case StyleAppearance::Treeheadercell: {
+      SInt32 headerHeight = 0;
+      ::GetThemeMetric(kThemeMetricListHeaderHeight, &headerHeight);
+      result.SizeTo(0, headerHeight);
+      break;
+    }
+
+    case StyleAppearance::Tab: {
+      result.SizeTo(0, tabHeights[miniControlSize]);
+      break;
+    }
+
+    case StyleAppearance::RangeThumb: {
+      SInt32 width = 0;
+      SInt32 height = 0;
+      ::GetThemeMetric(kThemeMetricSliderMinThumbWidth, &width);
+      ::GetThemeMetric(kThemeMetricSliderMinThumbHeight, &height);
+      result.SizeTo(width, height);
+      break;
+    }
+
+    case StyleAppearance::MozMenulistArrowButton:
+      return ThemeCocoa::GetMinimumWidgetSize(aPresContext, aFrame, aAppearance);
+
+    default:
+      break;
+  }
+
+  if (IsHiDPIContext(aPresContext->DeviceContext())) {
+    result = result * 2;
+  }
+
+  return result;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntSize());
+}
+
+NS_IMETHODIMP
+nsNativeThemeCocoa::WidgetStateChanged(nsIFrame* aFrame, StyleAppearance aAppearance,
+                                       nsAtom* aAttribute, bool* aShouldRepaint,
+                                       const nsAttrValue* aOldValue) {
+  // Some widget types just never change state.
+  switch (aAppearance) {
+    case StyleAppearance::MozWindowTitlebar:
+    case StyleAppearance::Toolbox:
+    case StyleAppearance::Toolbar:
+    case StyleAppearance::Statusbar:
+    case StyleAppearance::Tooltip:
+    case StyleAppearance::Tabpanels:
+    case StyleAppearance::Tabpanel:
+    case StyleAppearance::Dialog:
+    case StyleAppearance::Menupopup:
+    case StyleAppearance::Groupbox:
+    case StyleAppearance::Progresschunk:
+    case StyleAppearance::ProgressBar:
+    case StyleAppearance::Meter:
+    case StyleAppearance::Meterchunk:
+      *aShouldRepaint = false;
+      return NS_OK;
+    default:
+      break;
+  }
+
+  // XXXdwh Not sure what can really be done here.  Can at least guess for
+  // specific widgets that they're highly unlikely to have certain states.
+  // For example, a toolbar doesn't care about any states.
+  if (!aAttribute) {
+    // Hover/focus/active changed.  Always repaint.
+    *aShouldRepaint = true;
+  } else {
+    // Check the attribute to see if it's relevant.
+    // disabled, checked, dlgtype, default, etc.
+    *aShouldRepaint = false;
+    if (aAttribute == nsGkAtoms::disabled || aAttribute == nsGkAtoms::checked ||
+        aAttribute == nsGkAtoms::selected || aAttribute == nsGkAtoms::visuallyselected ||
+        aAttribute == nsGkAtoms::menuactive || aAttribute == nsGkAtoms::sortDirection ||
+        aAttribute == nsGkAtoms::focused || aAttribute == nsGkAtoms::_default ||
+        aAttribute == nsGkAtoms::open || aAttribute == nsGkAtoms::hover)
+      *aShouldRepaint = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsNativeThemeCocoa::ThemeChanged() {
+  // This is unimplemented because we don't care if gecko changes its theme
+  // and macOS system appearance changes are handled by
+  // nsLookAndFeel::SystemWantsDarkTheme.
+  return NS_OK;
+}
+
+bool nsNativeThemeCocoa::ThemeSupportsWidget(nsPresContext* aPresContext, nsIFrame* aFrame,
+                                             StyleAppearance aAppearance) {
+  if (IsWidgetNonNative(aAppearance)) {
+    return ThemeCocoa::ThemeSupportsWidget(aPresContext, aFrame, aAppearance);
+  }
+  // if this is a dropdown button in a combobox the answer is always no
+  if (aAppearance == StyleAppearance::MozMenulistArrowButton) {
+    nsIFrame* parentFrame = aFrame->GetParent();
+    if (parentFrame && parentFrame->IsComboboxControlFrame()) return false;
+  }
+
+  switch (aAppearance) {
+    // Combobox dropdowns don't support native theming in vertical mode.
+    case StyleAppearance::Menulist:
+    case StyleAppearance::MenulistButton:
+    case StyleAppearance::MozMenulistArrowButton:
+    case StyleAppearance::MenulistText:
+      if (aFrame && aFrame->GetWritingMode().IsVertical()) {
+        return false;
+      }
+      [[fallthrough]];
+
+    case StyleAppearance::Listbox:
+    case StyleAppearance::Dialog:
+    case StyleAppearance::Window:
+    case StyleAppearance::MozWindowButtonBox:
+    case StyleAppearance::MozWindowTitlebar:
+    case StyleAppearance::Checkmenuitem:
+    case StyleAppearance::Menupopup:
+    case StyleAppearance::Menuarrow:
+    case StyleAppearance::Menuitem:
+    case StyleAppearance::Menuseparator:
+    case StyleAppearance::Tooltip:
+
+    case StyleAppearance::Checkbox:
+    case StyleAppearance::CheckboxContainer:
+    case StyleAppearance::Radio:
+    case StyleAppearance::RadioContainer:
+    case StyleAppearance::Groupbox:
+    case StyleAppearance::MozMacHelpButton:
+    case StyleAppearance::MozMacDisclosureButtonOpen:
+    case StyleAppearance::MozMacDisclosureButtonClosed:
+    case StyleAppearance::Button:
+    case StyleAppearance::ButtonArrowUp:
+    case StyleAppearance::ButtonArrowDown:
+    case StyleAppearance::Toolbarbutton:
+    case StyleAppearance::Spinner:
+    case StyleAppearance::SpinnerUpbutton:
+    case StyleAppearance::SpinnerDownbutton:
+    case StyleAppearance::Toolbar:
+    case StyleAppearance::Statusbar:
+    case StyleAppearance::NumberInput:
+    case StyleAppearance::Textfield:
+    case StyleAppearance::Textarea:
+    case StyleAppearance::Searchfield:
+    case StyleAppearance::Toolbox:
+    case StyleAppearance::ProgressBar:
+    case StyleAppearance::Progresschunk:
+    case StyleAppearance::Meter:
+    case StyleAppearance::Meterchunk:
+    case StyleAppearance::Separator:
+
+    case StyleAppearance::Tabpanels:
+    case StyleAppearance::Tab:
+
+    case StyleAppearance::Treetwisty:
+    case StyleAppearance::Treetwistyopen:
+    case StyleAppearance::Treeview:
+    case StyleAppearance::Treeheader:
+    case StyleAppearance::Treeheadercell:
+    case StyleAppearance::Treeheadersortarrow:
+    case StyleAppearance::Treeitem:
+    case StyleAppearance::Treeline:
+    case StyleAppearance::MozMacSourceList:
+    case StyleAppearance::MozMacSourceListSelection:
+    case StyleAppearance::MozMacActiveSourceListSelection:
+
+    case StyleAppearance::Range:
+      return !IsWidgetStyled(aPresContext, aFrame, aAppearance);
+
+    default:
+      break;
+  }
+
+  return false;
+}
+
+bool nsNativeThemeCocoa::WidgetIsContainer(StyleAppearance aAppearance) {
+  // flesh this out at some point
+  switch (aAppearance) {
+    case StyleAppearance::MozMenulistArrowButton:
+    case StyleAppearance::Radio:
+    case StyleAppearance::Checkbox:
+    case StyleAppearance::ProgressBar:
+    case StyleAppearance::Meter:
+    case StyleAppearance::Range:
+    case StyleAppearance::MozMacHelpButton:
+    case StyleAppearance::MozMacDisclosureButtonOpen:
+    case StyleAppearance::MozMacDisclosureButtonClosed:
+      return false;
+    default:
+      break;
+  }
+  return true;
+}
+
+bool nsNativeThemeCocoa::ThemeDrawsFocusForWidget(nsIFrame*, StyleAppearance aAppearance) {
+  switch (aAppearance) {
+    case StyleAppearance::Textarea:
+    case StyleAppearance::Textfield:
+    case StyleAppearance::Searchfield:
+    case StyleAppearance::NumberInput:
+    case StyleAppearance::Menulist:
+    case StyleAppearance::MenulistButton:
+    case StyleAppearance::Button:
+    case StyleAppearance::MozMacHelpButton:
+    case StyleAppearance::MozMacDisclosureButtonOpen:
+    case StyleAppearance::MozMacDisclosureButtonClosed:
+    case StyleAppearance::Radio:
+    case StyleAppearance::Range:
+    case StyleAppearance::Checkbox:
+      return true;
+    default:
+      return false;
+  }
+}
+
+bool nsNativeThemeCocoa::ThemeNeedsComboboxDropmarker() { return false; }
+
+bool nsNativeThemeCocoa::WidgetAppearanceDependsOnWindowFocus(StyleAppearance aAppearance) {
+  switch (aAppearance) {
+    case StyleAppearance::Dialog:
+    case StyleAppearance::Groupbox:
+    case StyleAppearance::Tabpanels:
+    case StyleAppearance::ButtonArrowUp:
+    case StyleAppearance::ButtonArrowDown:
+    case StyleAppearance::Checkmenuitem:
+    case StyleAppearance::Menupopup:
+    case StyleAppearance::Menuarrow:
+    case StyleAppearance::Menuitem:
+    case StyleAppearance::Menuseparator:
+    case StyleAppearance::Tooltip:
+    case StyleAppearance::Spinner:
+    case StyleAppearance::SpinnerUpbutton:
+    case StyleAppearance::SpinnerDownbutton:
+    case StyleAppearance::Separator:
+    case StyleAppearance::Toolbox:
+    case StyleAppearance::NumberInput:
+    case StyleAppearance::Textfield:
+    case StyleAppearance::Treeview:
+    case StyleAppearance::Treeline:
+    case StyleAppearance::Textarea:
+    case StyleAppearance::Listbox:
+      return false;
+    default:
+      return true;
+  }
+}
+
+nsITheme::ThemeGeometryType nsNativeThemeCocoa::ThemeGeometryTypeForWidget(
+    nsIFrame* aFrame, StyleAppearance aAppearance) {
+  switch (aAppearance) {
+    case StyleAppearance::MozWindowTitlebar:
+      return eThemeGeometryTypeTitlebar;
+    case StyleAppearance::Toolbar:
+      return eThemeGeometryTypeToolbar;
+    case StyleAppearance::Toolbox:
+      return eThemeGeometryTypeToolbox;
+    case StyleAppearance::MozWindowButtonBox:
+      return eThemeGeometryTypeWindowButtons;
+    case StyleAppearance::Tooltip:
+      return eThemeGeometryTypeTooltip;
+    case StyleAppearance::Menupopup:
+      return eThemeGeometryTypeMenu;
+    case StyleAppearance::Menuitem:
+    case StyleAppearance::Checkmenuitem: {
+      ElementState elementState = GetContentState(aFrame, aAppearance);
+      bool isDisabled = elementState.HasState(ElementState::DISABLED);
+      bool isSelected = !isDisabled && CheckBooleanAttr(aFrame, nsGkAtoms::menuactive);
+      return isSelected ? eThemeGeometryTypeHighlightedMenuItem : eThemeGeometryTypeMenu;
+    }
+    case StyleAppearance::MozMacSourceList:
+      return eThemeGeometryTypeSourceList;
+    case StyleAppearance::MozMacSourceListSelection:
+      return IsInSourceList(aFrame) ? eThemeGeometryTypeSourceListSelection
+                                    : eThemeGeometryTypeUnknown;
+    case StyleAppearance::MozMacActiveSourceListSelection:
+      return IsInSourceList(aFrame) ? eThemeGeometryTypeActiveSourceListSelection
+                                    : eThemeGeometryTypeUnknown;
+    default:
+      return eThemeGeometryTypeUnknown;
+  }
+}
+
+nsITheme::Transparency nsNativeThemeCocoa::GetWidgetTransparency(nsIFrame* aFrame,
+                                                                 StyleAppearance aAppearance) {
+  if (IsWidgetScrollbarPart(aAppearance)) {
+    return ThemeCocoa::GetWidgetTransparency(aFrame, aAppearance);
+  }
+
+  switch (aAppearance) {
+    case StyleAppearance::Menupopup:
+    case StyleAppearance::Tooltip:
+    case StyleAppearance::Dialog:
+    case StyleAppearance::Toolbar:
+      return eTransparent;
+
+    case StyleAppearance::Statusbar:
+      // Knowing that scrollbars and statusbars are opaque improves
+      // performance, because we create layers for them.
+      return eOpaque;
+
+    default:
+      return eUnknownTransparency;
+  }
+}
+
+already_AddRefed<widget::Theme> do_CreateNativeThemeDoNotUseDirectly() {
+  return do_AddRef(new nsNativeThemeCocoa());
+}
diff --git a/widget/cocoa/nsNativeThemeColors.h b/widget/cocoa/nsNativeThemeColors.h
new file mode 100644
index 0000000000..ba51943aef
--- /dev/null
+++ b/widget/cocoa/nsNativeThemeColors.h
@@ -0,0 +1,72 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsNativeThemeColors_h_
+#define nsNativeThemeColors_h_
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsCocoaFeatures.h"
+#include "SDKDeclarations.h"
+#include "mozilla/ColorScheme.h"
+
+enum ColorName {
+  toolbarTopBorderGrey,
+  toolbarFillGrey,
+  toolbarBottomBorderGrey,
+};
+
+static const int sLionThemeColors[][2] = {
+    /* { active window, inactive window } */
+    // toolbar:
+    {0xD0, 0xF0},  // top separator line
+    {0xB2, 0xE1},  // fill color
+    {0x59, 0x87},  // bottom separator line
+};
+
+static const int sYosemiteThemeColors[][2] = {
+    /* { active window, inactive window } */
+    // toolbar:
+    {0xBD, 0xDF},  // top separator line
+    {0xD3, 0xF6},  // fill color
+    {0xB3, 0xD1},  // bottom separator line
+};
+
+inline int NativeGreyColorAsInt(ColorName name, BOOL isMain) {
+  return sYosemiteThemeColors[name][isMain ? 0 : 1];
+}
+
+inline float NativeGreyColorAsFloat(ColorName name, BOOL isMain) {
+  return NativeGreyColorAsInt(name, isMain) / 255.0f;
+}
+
+inline void DrawNativeGreyColorInRect(CGContextRef context, ColorName name, CGRect rect,
+                                      BOOL isMain) {
+  float grey = NativeGreyColorAsFloat(name, isMain);
+  CGContextSetRGBFillColor(context, grey, grey, grey, 1.0f);
+  CGContextFillRect(context, rect);
+}
+
+inline NSColor* ControlAccentColor() {
+  if (@available(macOS 10.14, *)) {
+    return [NSColor controlAccentColor];
+  }
+
+  // Pre-10.14, use hardcoded colors.
+  return [NSColor currentControlTint] == NSGraphiteControlTint
+             ? [NSColor colorWithSRGBRed:0.635 green:0.635 blue:0.655 alpha:1.0]
+             : [NSColor colorWithSRGBRed:0.247 green:0.584 blue:0.965 alpha:1.0];
+}
+
+inline NSAppearance* NSAppearanceForColorScheme(mozilla::ColorScheme aScheme) {
+  if (@available(macOS 10.14, *)) {
+    NSAppearanceName appearanceName =
+        aScheme == mozilla::ColorScheme::Light ? NSAppearanceNameAqua : NSAppearanceNameDarkAqua;
+    return [NSAppearance appearanceNamed:appearanceName];
+  }
+  return [NSAppearance appearanceNamed:NSAppearanceNameAqua];
+}
+
+#endif  // nsNativeThemeColors_h_
diff --git a/widget/cocoa/nsPIWidgetCocoa.idl b/widget/cocoa/nsPIWidgetCocoa.idl
new file mode 100644
index 0000000000..54aa0d5113
--- /dev/null
+++ b/widget/cocoa/nsPIWidgetCocoa.idl
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIWidget;
+
+[ptr] native NSWindowPtr(NSWindow);
+
+//
+// nsPIWidgetCocoa
+//
+// A private interface (unfrozen, private to the widget implementation) that
+// gives us access to some extra features on a widget/window.
+//
+[uuid(f75ff69e-3a51-419e-bd29-042f804bc2ed)]
+interface nsPIWidgetCocoa : nsISupports
+{
+  void SendSetZLevelEvent();
+
+  // Find the displayed child sheet (if aShown) or a child sheet that
+  // wants to be displayed (if !aShown)
+  nsIWidget GetChildSheet(in boolean aShown);
+
+  // Get the parent widget (if any) StandardCreate() was called with.
+  nsIWidget GetRealParent();
+
+  // If the object implementing this interface is a sheet, this will return the
+  // native NSWindow it is attached to
+  readonly attribute NSWindowPtr sheetWindowParent;
+
+  // True if window is a sheet
+  readonly attribute boolean isSheet;
+
+}; // nsPIWidgetCocoa
diff --git a/widget/cocoa/nsPrintDialogX.h b/widget/cocoa/nsPrintDialogX.h
new file mode 100644
index 0000000000..ed8c7dbb05
--- /dev/null
+++ b/widget/cocoa/nsPrintDialogX.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPrintDialog_h_
+#define nsPrintDialog_h_
+
+#include "nsIPrintDialogService.h"
+#include "nsCOMPtr.h"
+#include "nsCocoaUtils.h"
+
+#import <Cocoa/Cocoa.h>
+
+class nsIPrintSettings;
+class nsIStringBundle;
+
+class nsPrintDialogServiceX final : public nsIPrintDialogService {
+  virtual ~nsPrintDialogServiceX();
+
+ public:
+  nsPrintDialogServiceX();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIPRINTDIALOGSERVICE
+};
+
+@interface PrintPanelAccessoryView : NSView {
+  nsIPrintSettings* mSettings;
+  nsIStringBundle* mPrintBundle;
+  NSButton* mPrintSelectionOnlyCheckbox;
+  NSButton* mShrinkToFitCheckbox;
+  NSButton* mPrintBGColorsCheckbox;
+  NSButton* mPrintBGImagesCheckbox;
+  NSPopUpButton* mHeaderLeftList;
+  NSPopUpButton* mHeaderCenterList;
+  NSPopUpButton* mHeaderRightList;
+  NSPopUpButton* mFooterLeftList;
+  NSPopUpButton* mFooterCenterList;
+  NSPopUpButton* mFooterRightList;
+}
+
+- (id)initWithSettings:(nsIPrintSettings*)aSettings haveSelection:(bool)aHaveSelection;
+
+- (void)exportSettings;
+
+@end
+
+@interface PrintPanelAccessoryController : NSViewController <NSPrintPanelAccessorizing>
+
+- (id)initWithSettings:(nsIPrintSettings*)aSettings haveSelection:(bool)aHaveSelection;
+
+- (void)exportSettings;
+
+@end
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsPrintDialogServiceX, NS_IPRINTDIALOGSERVICE_IID)
+
+#endif  // nsPrintDialog_h_
diff --git a/widget/cocoa/nsPrintDialogX.mm b/widget/cocoa/nsPrintDialogX.mm
new file mode 100644
index 0000000000..9a087912a6
--- /dev/null
+++ b/widget/cocoa/nsPrintDialogX.mm
@@ -0,0 +1,590 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/gfx/PrintTargetCG.h"
+#include "mozilla/Preferences.h"
+
+#include "nsPrintDialogX.h"
+#include "nsIPrintSettings.h"
+#include "nsIPrintSettingsService.h"
+#include "nsPrintSettingsX.h"
+#include "nsCOMPtr.h"
+#include "nsQueryObject.h"
+#include "nsServiceManagerUtils.h"
+#include "nsIStringBundle.h"
+#include "nsCRT.h"
+
+#import <Cocoa/Cocoa.h>
+#include "nsObjCExceptions.h"
+
+using namespace mozilla;
+using mozilla::gfx::PrintTarget;
+
+NS_IMPL_ISUPPORTS(nsPrintDialogServiceX, nsIPrintDialogService)
+
+// Splits our single pages-per-sheet count for native NSPrintInfo:
+static void setPagesPerSheet(NSPrintInfo* aPrintInfo, int32_t aPPS) {
+  int32_t across, down;
+  // Assumes portrait - we'll swap if landscape.
+  switch (aPPS) {
+    case 2:
+      across = 1;
+      down = 2;
+      break;
+    case 4:
+      across = 2;
+      down = 2;
+      break;
+    case 6:
+      across = 2;
+      down = 3;
+      break;
+    case 9:
+      across = 3;
+      down = 3;
+      break;
+    case 16:
+      across = 4;
+      down = 4;
+      break;
+    default:
+      across = 1;
+      down = 1;
+      break;
+  }
+  if ([aPrintInfo orientation] == NSPaperOrientationLandscape) {
+    std::swap(across, down);
+  }
+
+  NSMutableDictionary* dict = [aPrintInfo dictionary];
+
+  [dict setObject:[NSNumber numberWithInt:across] forKey:@"NSPagesAcross"];
+  [dict setObject:[NSNumber numberWithInt:down] forKey:@"NSPagesDown"];
+}
+
+nsPrintDialogServiceX::nsPrintDialogServiceX() {}
+
+nsPrintDialogServiceX::~nsPrintDialogServiceX() {}
+
+NS_IMETHODIMP
+nsPrintDialogServiceX::Init() { return NS_OK; }
+
+NS_IMETHODIMP
+nsPrintDialogServiceX::ShowPrintDialog(mozIDOMWindowProxy* aParent, bool aHaveSelection,
+                                       nsIPrintSettings* aSettings) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_ASSERT(aSettings, "aSettings must not be null");
+
+  RefPtr<nsPrintSettingsX> settingsX(do_QueryObject(aSettings));
+  if (!settingsX) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSPrintInfo* printInfo = settingsX->CreateOrCopyPrintInfo(/* aWithScaling = */ true);
+  if (NS_WARN_IF(!printInfo)) {
+    return NS_ERROR_FAILURE;
+  }
+  [printInfo autorelease];
+
+  // Set the print job title
+  nsAutoString docName;
+  nsresult rv = aSettings->GetTitle(docName);
+  if (NS_SUCCEEDED(rv)) {
+    nsAutoString adjustedTitle;
+    PrintTarget::AdjustPrintJobNameForIPP(docName, adjustedTitle);
+    CFStringRef cfTitleString = CFStringCreateWithCharacters(
+        NULL, reinterpret_cast<const UniChar*>(adjustedTitle.BeginReading()),
+        adjustedTitle.Length());
+    if (cfTitleString) {
+      auto pmPrintSettings = static_cast<PMPrintSettings>([printInfo PMPrintSettings]);
+      ::PMPrintSettingsSetJobName(pmPrintSettings, cfTitleString);
+      [printInfo updateFromPMPrintSettings];
+      CFRelease(cfTitleString);
+    }
+  }
+
+  // Temporarily set the pages-per-sheet count set in our print preview to
+  // pre-populate the system dialog with the same value:
+  int32_t pagesPerSheet;
+  aSettings->GetNumPagesPerSheet(&pagesPerSheet);
+  setPagesPerSheet(printInfo, pagesPerSheet);
+
+  // Put the print info into the current print operation, since that's where
+  // [panel runModal] will look for it. We create the view because otherwise
+  // we'll get unrelated warnings printed to the console.
+  NSView* tmpView = [[NSView alloc] init];
+  NSPrintOperation* printOperation = [NSPrintOperation printOperationWithView:tmpView
+                                                                    printInfo:printInfo];
+  [NSPrintOperation setCurrentOperation:printOperation];
+
+  NSPrintPanel* panel = [NSPrintPanel printPanel];
+  [panel setOptions:NSPrintPanelShowsCopies | NSPrintPanelShowsPageRange |
+                    NSPrintPanelShowsPaperSize | NSPrintPanelShowsOrientation |
+                    NSPrintPanelShowsScaling];
+  PrintPanelAccessoryController* viewController =
+      [[PrintPanelAccessoryController alloc] initWithSettings:aSettings
+                                                haveSelection:aHaveSelection];
+  [panel addAccessoryController:viewController];
+  [viewController release];
+
+  // Show the dialog.
+  nsCocoaUtils::PrepareForNativeAppModalDialog();
+  int button = [panel runModal];
+  nsCocoaUtils::CleanUpAfterNativeAppModalDialog();
+
+  // Retrieve a printInfo with the updated settings. (The NSPrintOperation operates on a
+  // copy, so the object we passed in will not have been modified.)
+  NSPrintInfo* result = [[NSPrintOperation currentOperation] printInfo];
+  if (!result) {
+    return NS_ERROR_FAILURE;
+  }
+
+  [NSPrintOperation setCurrentOperation:nil];
+  [tmpView release];
+
+  if (button != NSFileHandlingPanelOKButton) {
+    return NS_ERROR_ABORT;
+  }
+
+  // We handle pages-per-sheet internally and we want to prevent the macOS
+  // printing code from also applying the pages-per-sheet count. So we need
+  // to move the count off the NSPrintInfo and over to the nsIPrintSettings.
+  NSMutableDictionary* dict = [result dictionary];
+  auto pagesAcross = [[dict objectForKey:@"NSPagesAcross"] intValue];
+  auto pagesDown = [[dict objectForKey:@"NSPagesDown"] intValue];
+  [dict setObject:[NSNumber numberWithUnsignedInt:1] forKey:@"NSPagesAcross"];
+  [dict setObject:[NSNumber numberWithUnsignedInt:1] forKey:@"NSPagesDown"];
+  aSettings->SetNumPagesPerSheet(pagesAcross * pagesDown);
+
+  // Export settings.
+  [viewController exportSettings];
+
+  // Update our settings object based on the user's choices in the dialog.
+  // We tell settingsX to adopt this printInfo so that it will be used to run print job,
+  // so that any printer-specific custom settings from print dialog extension panels
+  // will be carried through.
+  settingsX->SetFromPrintInfo(result, /* aAdoptPrintInfo = */ true);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsPrintDialogServiceX::ShowPageSetupDialog(mozIDOMWindowProxy* aParent,
+                                           nsIPrintSettings* aNSSettings) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  MOZ_ASSERT(aParent, "aParent must not be null");
+  MOZ_ASSERT(aNSSettings, "aSettings must not be null");
+  NS_ENSURE_TRUE(aNSSettings, NS_ERROR_FAILURE);
+
+  RefPtr<nsPrintSettingsX> settingsX(do_QueryObject(aNSSettings));
+  if (!settingsX) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSPrintInfo* printInfo = settingsX->CreateOrCopyPrintInfo(/* aWithScaling = */ true);
+  if (NS_WARN_IF(!printInfo)) {
+    return NS_ERROR_FAILURE;
+  }
+  [printInfo autorelease];
+
+  NSPageLayout* pageLayout = [NSPageLayout pageLayout];
+  nsCocoaUtils::PrepareForNativeAppModalDialog();
+  int button = [pageLayout runModalWithPrintInfo:printInfo];
+  nsCocoaUtils::CleanUpAfterNativeAppModalDialog();
+
+  if (button == NSFileHandlingPanelOKButton) {
+    // The Page Setup dialog does not include non-standard settings that need to be preserved,
+    // separate from what the base printSettings object handles, so we do not need it to adopt
+    // the printInfo object here.
+    settingsX->SetFromPrintInfo(printInfo, /* aAdoptPrintInfo = */ false);
+    nsCOMPtr<nsIPrintSettingsService> printSettingsService =
+        do_GetService("@mozilla.org/gfx/printsettings-service;1");
+    if (printSettingsService && Preferences::GetBool("print.save_print_settings", false)) {
+      uint32_t flags = nsIPrintSettings::kInitSavePaperSize |
+                       nsIPrintSettings::kInitSaveOrientation | nsIPrintSettings::kInitSaveScaling;
+      printSettingsService->MaybeSavePrintSettingsToPrefs(aNSSettings, flags);
+    }
+    return NS_OK;
+  }
+  return NS_ERROR_ABORT;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+// Accessory view
+
+@interface PrintPanelAccessoryView (Private)
+
+- (NSString*)localizedString:(const char*)aKey;
+
+- (const char*)headerFooterStringForList:(NSPopUpButton*)aList;
+
+- (void)exportHeaderFooterSettings;
+
+- (void)initBundle;
+
+- (NSTextField*)label:(const char*)aLabel
+            withFrame:(NSRect)aRect
+            alignment:(NSTextAlignment)aAlignment;
+
+- (void)addLabel:(const char*)aLabel withFrame:(NSRect)aRect alignment:(NSTextAlignment)aAlignment;
+
+- (void)addLabel:(const char*)aLabel withFrame:(NSRect)aRect;
+
+- (void)addCenteredLabel:(const char*)aLabel withFrame:(NSRect)aRect;
+
+- (NSButton*)checkboxWithLabel:(const char*)aLabel andFrame:(NSRect)aRect;
+
+- (NSPopUpButton*)headerFooterItemListWithFrame:(NSRect)aRect
+                                   selectedItem:(const nsAString&)aCurrentString;
+
+- (void)addOptionsSection:(bool)aHaveSelection;
+
+- (void)addAppearanceSection;
+
+- (void)addHeaderFooterSection;
+
+- (NSString*)summaryValueForCheckbox:(NSButton*)aCheckbox;
+
+- (NSString*)headerSummaryValue;
+
+- (NSString*)footerSummaryValue;
+
+@end
+
+static const char sHeaderFooterTags[][4] = {"", "&T", "&U", "&D", "&P", "&PT"};
+
+@implementation PrintPanelAccessoryView
+
+// Public methods
+
+- (id)initWithSettings:(nsIPrintSettings*)aSettings haveSelection:(bool)aHaveSelection {
+  [super initWithFrame:NSMakeRect(0, 0, 540, 185)];
+
+  mSettings = aSettings;
+  [self initBundle];
+  [self addOptionsSection:aHaveSelection];
+  [self addAppearanceSection];
+  [self addHeaderFooterSection];
+
+  return self;
+}
+
+- (void)exportSettings {
+  mSettings->SetPrintSelectionOnly([mPrintSelectionOnlyCheckbox state] == NSOnState);
+  mSettings->SetShrinkToFit([mShrinkToFitCheckbox state] == NSOnState);
+  mSettings->SetPrintBGColors([mPrintBGColorsCheckbox state] == NSOnState);
+  mSettings->SetPrintBGImages([mPrintBGImagesCheckbox state] == NSOnState);
+
+  [self exportHeaderFooterSettings];
+}
+
+- (void)dealloc {
+  NS_IF_RELEASE(mPrintBundle);
+  [super dealloc];
+}
+
+// Localization
+
+- (void)initBundle {
+  nsCOMPtr<nsIStringBundleService> bundleSvc = do_GetService(NS_STRINGBUNDLE_CONTRACTID);
+  bundleSvc->CreateBundle("chrome://global/locale/printdialog.properties", &mPrintBundle);
+}
+
+- (NSString*)localizedString:(const char*)aKey {
+  if (!mPrintBundle) return @"";
+
+  nsAutoString intlString;
+  mPrintBundle->GetStringFromName(aKey, intlString);
+  NSMutableString* s =
+      [NSMutableString stringWithUTF8String:NS_ConvertUTF16toUTF8(intlString).get()];
+
+  // Remove all underscores (they're used in the GTK dialog for accesskeys).
+  [s replaceOccurrencesOfString:@"_" withString:@"" options:0 range:NSMakeRange(0, [s length])];
+  return s;
+}
+
+// Widget helpers
+
+- (NSTextField*)label:(const char*)aLabel
+            withFrame:(NSRect)aRect
+            alignment:(NSTextAlignment)aAlignment {
+  NSTextField* label = [[[NSTextField alloc] initWithFrame:aRect] autorelease];
+  [label setStringValue:[self localizedString:aLabel]];
+  [label setEditable:NO];
+  [label setSelectable:NO];
+  [label setBezeled:NO];
+  [label setBordered:NO];
+  [label setDrawsBackground:NO];
+  [label setFont:[NSFont systemFontOfSize:[NSFont systemFontSize]]];
+  [label setAlignment:aAlignment];
+  return label;
+}
+
+- (void)addLabel:(const char*)aLabel withFrame:(NSRect)aRect alignment:(NSTextAlignment)aAlignment {
+  NSTextField* label = [self label:aLabel withFrame:aRect alignment:aAlignment];
+  [self addSubview:label];
+}
+
+- (void)addLabel:(const char*)aLabel withFrame:(NSRect)aRect {
+  [self addLabel:aLabel withFrame:aRect alignment:NSTextAlignmentRight];
+}
+
+- (void)addCenteredLabel:(const char*)aLabel withFrame:(NSRect)aRect {
+  [self addLabel:aLabel withFrame:aRect alignment:NSTextAlignmentCenter];
+}
+
+- (NSButton*)checkboxWithLabel:(const char*)aLabel andFrame:(NSRect)aRect {
+  aRect.origin.y += 4.0f;
+  NSButton* checkbox = [[[NSButton alloc] initWithFrame:aRect] autorelease];
+  [checkbox setButtonType:NSSwitchButton];
+  [checkbox setTitle:[self localizedString:aLabel]];
+  [checkbox setFont:[NSFont systemFontOfSize:[NSFont systemFontSize]]];
+  [checkbox sizeToFit];
+  return checkbox;
+}
+
+- (NSPopUpButton*)headerFooterItemListWithFrame:(NSRect)aRect
+                                   selectedItem:(const nsAString&)aCurrentString {
+  NSPopUpButton* list = [[[NSPopUpButton alloc] initWithFrame:aRect pullsDown:NO] autorelease];
+  [list setFont:[NSFont systemFontOfSize:[NSFont smallSystemFontSize]]];
+  [[list cell] setControlSize:NSControlSizeSmall];
+  NSArray* items = [NSArray arrayWithObjects:[self localizedString:"headerFooterBlank"],
+                                             [self localizedString:"headerFooterTitle"],
+                                             [self localizedString:"headerFooterURL"],
+                                             [self localizedString:"headerFooterDate"],
+                                             [self localizedString:"headerFooterPage"],
+                                             [self localizedString:"headerFooterPageTotal"], nil];
+  [list addItemsWithTitles:items];
+
+  NS_ConvertUTF16toUTF8 currentStringUTF8(aCurrentString);
+  for (unsigned int i = 0; i < ArrayLength(sHeaderFooterTags); i++) {
+    if (!strcmp(currentStringUTF8.get(), sHeaderFooterTags[i])) {
+      [list selectItemAtIndex:i];
+      break;
+    }
+  }
+
+  return list;
+}
+
+// Build sections
+
+- (void)addOptionsSection:(bool)aHaveSelection {
+  // Title
+  [self addLabel:"optionsTitleMac" withFrame:NSMakeRect(0, 155, 151, 22)];
+
+  // "Print Selection Only"
+  mPrintSelectionOnlyCheckbox = [self checkboxWithLabel:"selectionOnly"
+                                               andFrame:NSMakeRect(156, 155, 0, 0)];
+  [mPrintSelectionOnlyCheckbox setEnabled:aHaveSelection];
+
+  if (mSettings->GetPrintSelectionOnly()) {
+    [mPrintSelectionOnlyCheckbox setState:NSOnState];
+  }
+
+  [self addSubview:mPrintSelectionOnlyCheckbox];
+
+  // "Shrink To Fit"
+  mShrinkToFitCheckbox = [self checkboxWithLabel:"shrinkToFit" andFrame:NSMakeRect(156, 133, 0, 0)];
+
+  bool shrinkToFit;
+  mSettings->GetShrinkToFit(&shrinkToFit);
+  [mShrinkToFitCheckbox setState:(shrinkToFit ? NSOnState : NSOffState)];
+
+  [self addSubview:mShrinkToFitCheckbox];
+}
+
+- (void)addAppearanceSection {
+  // Title
+  [self addLabel:"appearanceTitleMac" withFrame:NSMakeRect(0, 103, 151, 22)];
+
+  // "Print Background Colors"
+  mPrintBGColorsCheckbox = [self checkboxWithLabel:"printBGColors"
+                                          andFrame:NSMakeRect(156, 103, 0, 0)];
+
+  bool geckoBool = mSettings->GetPrintBGColors();
+  [mPrintBGColorsCheckbox setState:(geckoBool ? NSOnState : NSOffState)];
+
+  [self addSubview:mPrintBGColorsCheckbox];
+
+  // "Print Background Images"
+  mPrintBGImagesCheckbox = [self checkboxWithLabel:"printBGImages"
+                                          andFrame:NSMakeRect(156, 81, 0, 0)];
+
+  geckoBool = mSettings->GetPrintBGImages();
+  [mPrintBGImagesCheckbox setState:(geckoBool ? NSOnState : NSOffState)];
+
+  [self addSubview:mPrintBGImagesCheckbox];
+}
+
+- (void)addHeaderFooterSection {
+  // Labels
+  [self addLabel:"pageHeadersTitleMac" withFrame:NSMakeRect(0, 44, 151, 22)];
+  [self addLabel:"pageFootersTitleMac" withFrame:NSMakeRect(0, 0, 151, 22)];
+  [self addCenteredLabel:"left" withFrame:NSMakeRect(156, 22, 100, 22)];
+  [self addCenteredLabel:"center" withFrame:NSMakeRect(256, 22, 100, 22)];
+  [self addCenteredLabel:"right" withFrame:NSMakeRect(356, 22, 100, 22)];
+
+  // Lists
+  nsString sel;
+
+  mSettings->GetHeaderStrLeft(sel);
+  mHeaderLeftList = [self headerFooterItemListWithFrame:NSMakeRect(156, 44, 100, 22)
+                                           selectedItem:sel];
+  [self addSubview:mHeaderLeftList];
+
+  mSettings->GetHeaderStrCenter(sel);
+  mHeaderCenterList = [self headerFooterItemListWithFrame:NSMakeRect(256, 44, 100, 22)
+                                             selectedItem:sel];
+  [self addSubview:mHeaderCenterList];
+
+  mSettings->GetHeaderStrRight(sel);
+  mHeaderRightList = [self headerFooterItemListWithFrame:NSMakeRect(356, 44, 100, 22)
+                                            selectedItem:sel];
+  [self addSubview:mHeaderRightList];
+
+  mSettings->GetFooterStrLeft(sel);
+  mFooterLeftList = [self headerFooterItemListWithFrame:NSMakeRect(156, 0, 100, 22)
+                                           selectedItem:sel];
+  [self addSubview:mFooterLeftList];
+
+  mSettings->GetFooterStrCenter(sel);
+  mFooterCenterList = [self headerFooterItemListWithFrame:NSMakeRect(256, 0, 100, 22)
+                                             selectedItem:sel];
+  [self addSubview:mFooterCenterList];
+
+  mSettings->GetFooterStrRight(sel);
+  mFooterRightList = [self headerFooterItemListWithFrame:NSMakeRect(356, 0, 100, 22)
+                                            selectedItem:sel];
+  [self addSubview:mFooterRightList];
+}
+
+// Export settings
+
+- (const char*)headerFooterStringForList:(NSPopUpButton*)aList {
+  NSInteger index = [aList indexOfSelectedItem];
+  NS_ASSERTION(index < NSInteger(ArrayLength(sHeaderFooterTags)),
+               "Index of dropdown is higher than expected!");
+  return sHeaderFooterTags[index];
+}
+
+- (void)exportHeaderFooterSettings {
+  const char* headerFooterStr;
+  headerFooterStr = [self headerFooterStringForList:mHeaderLeftList];
+  mSettings->SetHeaderStrLeft(NS_ConvertUTF8toUTF16(headerFooterStr));
+
+  headerFooterStr = [self headerFooterStringForList:mHeaderCenterList];
+  mSettings->SetHeaderStrCenter(NS_ConvertUTF8toUTF16(headerFooterStr));
+
+  headerFooterStr = [self headerFooterStringForList:mHeaderRightList];
+  mSettings->SetHeaderStrRight(NS_ConvertUTF8toUTF16(headerFooterStr));
+
+  headerFooterStr = [self headerFooterStringForList:mFooterLeftList];
+  mSettings->SetFooterStrLeft(NS_ConvertUTF8toUTF16(headerFooterStr));
+
+  headerFooterStr = [self headerFooterStringForList:mFooterCenterList];
+  mSettings->SetFooterStrCenter(NS_ConvertUTF8toUTF16(headerFooterStr));
+
+  headerFooterStr = [self headerFooterStringForList:mFooterRightList];
+  mSettings->SetFooterStrRight(NS_ConvertUTF8toUTF16(headerFooterStr));
+}
+
+// Summary
+
+- (NSString*)summaryValueForCheckbox:(NSButton*)aCheckbox {
+  if (![aCheckbox isEnabled]) return [self localizedString:"summaryNAValue"];
+
+  return [aCheckbox state] == NSOnState ? [self localizedString:"summaryOnValue"]
+                                        : [self localizedString:"summaryOffValue"];
+}
+
+- (NSString*)headerSummaryValue {
+  return [[mHeaderLeftList titleOfSelectedItem]
+      stringByAppendingString:
+          [@", "
+              stringByAppendingString:
+                  [[mHeaderCenterList titleOfSelectedItem]
+                      stringByAppendingString:
+                          [@", " stringByAppendingString:[mHeaderRightList titleOfSelectedItem]]]]];
+}
+
+- (NSString*)footerSummaryValue {
+  return [[mFooterLeftList titleOfSelectedItem]
+      stringByAppendingString:
+          [@", "
+              stringByAppendingString:
+                  [[mFooterCenterList titleOfSelectedItem]
+                      stringByAppendingString:
+                          [@", " stringByAppendingString:[mFooterRightList titleOfSelectedItem]]]]];
+}
+
+- (NSArray*)localizedSummaryItems {
+  return [NSArray
+      arrayWithObjects:
+          [NSDictionary
+              dictionaryWithObjectsAndKeys:[self localizedString:"summarySelectionOnlyTitle"],
+                                           NSPrintPanelAccessorySummaryItemNameKey,
+                                           [self
+                                               summaryValueForCheckbox:mPrintSelectionOnlyCheckbox],
+                                           NSPrintPanelAccessorySummaryItemDescriptionKey, nil],
+          [NSDictionary
+              dictionaryWithObjectsAndKeys:[self localizedString:"summaryShrinkToFitTitle"],
+                                           NSPrintPanelAccessorySummaryItemNameKey,
+                                           [self summaryValueForCheckbox:mShrinkToFitCheckbox],
+                                           NSPrintPanelAccessorySummaryItemDescriptionKey, nil],
+          [NSDictionary
+              dictionaryWithObjectsAndKeys:[self localizedString:"summaryPrintBGColorsTitle"],
+                                           NSPrintPanelAccessorySummaryItemNameKey,
+                                           [self summaryValueForCheckbox:mPrintBGColorsCheckbox],
+                                           NSPrintPanelAccessorySummaryItemDescriptionKey, nil],
+          [NSDictionary
+              dictionaryWithObjectsAndKeys:[self localizedString:"summaryPrintBGImagesTitle"],
+                                           NSPrintPanelAccessorySummaryItemNameKey,
+                                           [self summaryValueForCheckbox:mPrintBGImagesCheckbox],
+                                           NSPrintPanelAccessorySummaryItemDescriptionKey, nil],
+          [NSDictionary dictionaryWithObjectsAndKeys:[self localizedString:"summaryHeaderTitle"],
+                                                     NSPrintPanelAccessorySummaryItemNameKey,
+                                                     [self headerSummaryValue],
+                                                     NSPrintPanelAccessorySummaryItemDescriptionKey,
+                                                     nil],
+          [NSDictionary dictionaryWithObjectsAndKeys:[self localizedString:"summaryFooterTitle"],
+                                                     NSPrintPanelAccessorySummaryItemNameKey,
+                                                     [self footerSummaryValue],
+                                                     NSPrintPanelAccessorySummaryItemDescriptionKey,
+                                                     nil],
+          nil];
+}
+
+@end
+
+// Accessory controller
+
+@implementation PrintPanelAccessoryController
+
+- (id)initWithSettings:(nsIPrintSettings*)aSettings haveSelection:(bool)aHaveSelection {
+  [super initWithNibName:nil bundle:nil];
+
+  NSView* accView = [[PrintPanelAccessoryView alloc] initWithSettings:aSettings
+                                                        haveSelection:aHaveSelection];
+  [self setView:accView];
+  [accView release];
+  return self;
+}
+
+- (void)exportSettings {
+  return [(PrintPanelAccessoryView*)[self view] exportSettings];
+}
+
+- (NSArray*)localizedSummaryItems {
+  return [(PrintPanelAccessoryView*)[self view] localizedSummaryItems];
+}
+
+@end
diff --git a/widget/cocoa/nsPrintSettingsServiceX.h b/widget/cocoa/nsPrintSettingsServiceX.h
new file mode 100644
index 0000000000..e6e6bff2b9
--- /dev/null
+++ b/widget/cocoa/nsPrintSettingsServiceX.h
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPrintSettingsServiceX_h
+#define nsPrintSettingsServiceX_h
+
+#include "nsPrintSettingsService.h"
+
+namespace mozilla {
+namespace embedding {
+class PrintData;
+}  // namespace embedding
+}  // namespace mozilla
+
+class nsPrintSettingsServiceX final : public nsPrintSettingsService {
+ public:
+  nsPrintSettingsServiceX() {}
+
+  NS_IMETHODIMP SerializeToPrintData(
+      nsIPrintSettings* aSettings,
+      mozilla::embedding::PrintData* data) override;
+
+  NS_IMETHODIMP DeserializeToPrintSettings(
+      const mozilla::embedding::PrintData& data,
+      nsIPrintSettings* settings) override;
+
+ protected:
+  nsresult _CreatePrintSettings(nsIPrintSettings** _retval) override;
+};
+
+#endif  // nsPrintSettingsServiceX_h
diff --git a/widget/cocoa/nsPrintSettingsServiceX.mm b/widget/cocoa/nsPrintSettingsServiceX.mm
new file mode 100644
index 0000000000..7598780086
--- /dev/null
+++ b/widget/cocoa/nsPrintSettingsServiceX.mm
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsPrintSettingsServiceX.h"
+
+#include "mozilla/embedding/PPrintingTypes.h"
+#include "nsCOMPtr.h"
+#include "nsQueryObject.h"
+#include "nsPrintSettingsX.h"
+#include "nsCocoaUtils.h"
+
+using namespace mozilla::embedding;
+
+NS_IMETHODIMP
+nsPrintSettingsServiceX::SerializeToPrintData(nsIPrintSettings* aSettings, PrintData* data) {
+  nsresult rv = nsPrintSettingsService::SerializeToPrintData(aSettings, data);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  RefPtr<nsPrintSettingsX> settingsX(do_QueryObject(aSettings));
+  if (NS_WARN_IF(!settingsX)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  settingsX->GetDisposition(data->disposition());
+  settingsX->GetDestination(&data->destination());
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPrintSettingsServiceX::DeserializeToPrintSettings(const PrintData& data,
+                                                    nsIPrintSettings* settings) {
+  nsresult rv = nsPrintSettingsService::DeserializeToPrintSettings(data, settings);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  RefPtr<nsPrintSettingsX> settingsX(do_QueryObject(settings));
+  if (NS_WARN_IF(!settingsX)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  settingsX->SetDisposition(data.disposition());
+  settingsX->SetDestination(data.destination());
+
+  return NS_OK;
+}
+
+nsresult nsPrintSettingsServiceX::_CreatePrintSettings(nsIPrintSettings** _retval) {
+  nsresult rv;
+  *_retval = nullptr;
+
+  nsPrintSettingsX* printSettings = new nsPrintSettingsX;  // does not initially ref count
+  NS_ENSURE_TRUE(printSettings, NS_ERROR_OUT_OF_MEMORY);
+  NS_ADDREF(*_retval = printSettings);
+
+  rv = printSettings->Init();
+  if (NS_FAILED(rv)) {
+    NS_RELEASE(*_retval);
+    return rv;
+  }
+
+  auto globalPrintSettings = nsIPrintSettings::kGlobalSettings;
+
+  // XXX Why is Mac special? Why are we copying global print settings here?
+  // nsPrintSettingsService::InitPrintSettingsFromPrefs already gets the few
+  // global defaults that we want, doesn't it?
+  InitPrintSettingsFromPrefs(*_retval, false, globalPrintSettings);
+  return rv;
+}
diff --git a/widget/cocoa/nsPrintSettingsX.h b/widget/cocoa/nsPrintSettingsX.h
new file mode 100644
index 0000000000..9f24694bb3
--- /dev/null
+++ b/widget/cocoa/nsPrintSettingsX.h
@@ -0,0 +1,102 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPrintSettingsX_h_
+#define nsPrintSettingsX_h_
+
+#include "nsPrintSettingsImpl.h"
+#import <Cocoa/Cocoa.h>
+
+// clang-format off
+#define NS_PRINTSETTINGSX_IID                        \
+  {                                                  \
+    0x0DF2FDBD, 0x906D, 0x4726, {                    \
+      0x9E, 0x4D, 0xCF, 0xE0, 0x87, 0x8D, 0x70, 0x7C \
+    }                                                \
+  }
+// clang-format on
+
+class nsPrintSettingsX : public nsPrintSettings {
+ public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_PRINTSETTINGSX_IID)
+  NS_DECL_ISUPPORTS_INHERITED
+
+  nsPrintSettingsX();
+  explicit nsPrintSettingsX(const PrintSettingsInitializer& aSettings);
+
+  nsresult Init() { return NS_OK; }
+
+  void SetDestination(uint16_t aDestination) { mDestination = aDestination; }
+  void GetDestination(uint16_t* aDestination) { *aDestination = mDestination; }
+
+  void SetDisposition(const nsString& aDisposition) { mDisposition = aDisposition; }
+  void GetDisposition(nsString& aDisposition) { aDisposition = mDisposition; }
+
+  // Get a Cocoa NSPrintInfo that is configured with our current settings.
+  // This follows Create semantics, so the caller is responsible to release
+  // the returned object when no longer required.
+  //
+  // Pass true for aWithScaling to have the print scaling factor included in
+  // the returned printInfo. Normally we pass false, as scaling is handled
+  // by Gecko and we don't want the Cocoa print system to impose scaling again
+  // on the output, but if we're retrieving the info in order to populate the
+  // system print UI, then we do want to know about it.
+  NSPrintInfo* CreateOrCopyPrintInfo(bool aWithScaling = false);
+
+  // Update our internal settings to reflect the properties of the given
+  // NSPrintInfo.
+  //
+  // If aAdoptPrintInfo is set, the given NSPrintInfo will be retained and
+  // returned by subsequent CreateOrCopyPrintInfo calls, which is required
+  // for custom settings from the OS print dialog to be passed through to
+  // print jobs. However, this means that subsequent changes to print settings
+  // via the generic nsPrintSettings methods will NOT be reflected in the
+  // resulting NSPrintInfo.
+  void SetFromPrintInfo(NSPrintInfo* aPrintInfo, bool aAdoptPrintInfo);
+
+ protected:
+  virtual ~nsPrintSettingsX() {
+    if (mSystemPrintInfo) {
+      [mSystemPrintInfo release];
+    }
+  };
+
+  nsPrintSettingsX& operator=(const nsPrintSettingsX& rhs);
+
+  nsresult _Clone(nsIPrintSettings** _retval) override;
+  nsresult _Assign(nsIPrintSettings* aPS) override;
+
+  int GetCocoaUnit(int16_t aGeckoUnit);
+
+  double PaperSizeFromCocoaPoints(double aPointsValue) {
+    return aPointsValue * (mPaperSizeUnit == kPaperSizeInches ? 1.0 / 72.0 : 25.4 / 72.0);
+  }
+
+  double CocoaPointsFromPaperSize(double aSizeUnitValue) {
+    return aSizeUnitValue * (mPaperSizeUnit == kPaperSizeInches ? 72.0 : 72.0 / 25.4);
+  }
+
+  // Needed to correctly track the various job dispositions (spool, preview,
+  // save to file) that the user can choose via the system print dialog.
+  // Unfortunately it seems to be necessary to set both the Cocoa "job
+  // disposition" and the PrintManager "destination type" in order for all the
+  // various workflows such as "Save to Web Receipts" to work.
+  nsString mDisposition;
+  uint16_t mDestination;
+
+  // If the user has used the system print UI, we retain a reference to its
+  // printInfo because it may contain settings that we don't know how to handle
+  // and that will be lost if we round-trip through nsPrintSettings fields.
+  // We'll use this printInfo if asked to run a print job.
+  //
+  // This "wrapped" printInfo is NOT serialized or copied when printSettings
+  // objects are passed around; it is used only by the settings object to which
+  // it was originally passed.
+  NSPrintInfo* mSystemPrintInfo = nullptr;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsPrintSettingsX, NS_PRINTSETTINGSX_IID)
+
+#endif  // nsPrintSettingsX_h_
diff --git a/widget/cocoa/nsPrintSettingsX.mm b/widget/cocoa/nsPrintSettingsX.mm
new file mode 100644
index 0000000000..f7d6034f95
--- /dev/null
+++ b/widget/cocoa/nsPrintSettingsX.mm
@@ -0,0 +1,362 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsPrintSettingsX.h"
+#include "nsObjCExceptions.h"
+
+#include "plbase64.h"
+
+#include "nsCocoaUtils.h"
+#include "nsXULAppAPI.h"
+
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_print.h"
+#include "nsPrinterCUPS.h"
+
+using namespace mozilla;
+
+NS_IMPL_ISUPPORTS_INHERITED(nsPrintSettingsX, nsPrintSettings, nsPrintSettingsX)
+
+nsPrintSettingsX::nsPrintSettingsX() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  mDestination = kPMDestinationInvalid;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+already_AddRefed<nsIPrintSettings> CreatePlatformPrintSettings(
+    const PrintSettingsInitializer& aSettings) {
+  RefPtr<nsPrintSettings> settings = new nsPrintSettingsX();
+  settings->InitWithInitializer(aSettings);
+  settings->SetDefaultFileName();
+  return settings.forget();
+}
+
+nsPrintSettingsX& nsPrintSettingsX::operator=(const nsPrintSettingsX& rhs) {
+  if (this == &rhs) {
+    return *this;
+  }
+
+  nsPrintSettings::operator=(rhs);
+
+  mDestination = rhs.mDestination;
+  mDisposition = rhs.mDisposition;
+
+  // We don't copy mSystemPrintInfo here, so any copied printSettings will start out
+  // without a wrapped printInfo, just using our internal settings. The system
+  // printInfo is used *only* by the nsPrintSettingsX to which it was originally
+  // passed (when the user ran a system print UI dialog).
+
+  return *this;
+}
+
+nsresult nsPrintSettingsX::_Clone(nsIPrintSettings** _retval) {
+  NS_ENSURE_ARG_POINTER(_retval);
+  auto newSettings = MakeRefPtr<nsPrintSettingsX>();
+  *newSettings = *this;
+  newSettings.forget(_retval);
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsPrintSettingsX::_Assign(nsIPrintSettings* aPS) {
+  nsPrintSettingsX* printSettingsX = static_cast<nsPrintSettingsX*>(aPS);
+  if (!printSettingsX) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  *this = *printSettingsX;
+  return NS_OK;
+}
+
+struct KnownMonochromeSetting {
+  const NSString* mName;
+  const NSString* mValue;
+};
+
+#define DECLARE_KNOWN_MONOCHROME_SETTING(key_, value_) \
+  { @key_, @value_ }                                   \
+  ,
+static const KnownMonochromeSetting kKnownMonochromeSettings[] = {
+    CUPS_EACH_MONOCHROME_PRINTER_SETTING(DECLARE_KNOWN_MONOCHROME_SETTING)};
+#undef DECLARE_KNOWN_MONOCHROME_SETTING
+
+NSPrintInfo* nsPrintSettingsX::CreateOrCopyPrintInfo(bool aWithScaling) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // If we have a printInfo that came from the system print UI, use it so that
+  // any printer-specific settings we don't know about will still be used.
+  if (mSystemPrintInfo) {
+    NSPrintInfo* sysPrintInfo = [mSystemPrintInfo copy];
+    // Any required scaling will be done by Gecko, so we don't want it here.
+    [sysPrintInfo setScalingFactor:1.0f];
+    return sysPrintInfo;
+  }
+
+  // Note that the app shared `sharedPrintInfo` object is special!  The system
+  // print dialog and print settings dialog update it with the values chosen
+  // by the user.  Using that object here to initialize new nsPrintSettingsX
+  // objects could mask bugs in our code where we fail to save and/or restore
+  // print settings ourselves (e.g., bug 1636725).  On other platforms we only
+  // initialize new nsPrintSettings objects from the settings that we save to
+  // prefs.  Perhaps we should stop using sharedPrintInfo here for consistency?
+  NSPrintInfo* printInfo = [[NSPrintInfo sharedPrintInfo] copy];
+
+  NSSize paperSize;
+  if (GetSheetOrientation() == kPortraitOrientation) {
+    paperSize.width = CocoaPointsFromPaperSize(mPaperWidth);
+    paperSize.height = CocoaPointsFromPaperSize(mPaperHeight);
+  } else {
+    paperSize.width = CocoaPointsFromPaperSize(mPaperHeight);
+    paperSize.height = CocoaPointsFromPaperSize(mPaperWidth);
+  }
+  [printInfo setPaperSize:paperSize];
+
+  if (paperSize.width > paperSize.height) {
+    [printInfo setOrientation:NSPaperOrientationLandscape];
+  } else {
+    [printInfo setOrientation:NSPaperOrientationPortrait];
+  }
+
+  [printInfo setTopMargin:mUnwriteableMargin.top];
+  [printInfo setRightMargin:mUnwriteableMargin.right];
+  [printInfo setBottomMargin:mUnwriteableMargin.bottom];
+  [printInfo setLeftMargin:mUnwriteableMargin.left];
+
+  // If the printer name is the name of our pseudo print-to-PDF printer, the
+  // following `setPrinter` call will fail silently, since macOS doesn't know
+  // anything about it. That's OK, because mPrinter is our canonical source of
+  // truth.
+  // Actually, it seems Mac OS X 10.12 (the oldest version of Mac that we
+  // support) hangs if the printer name is not recognized. For now we explicitly
+  // check for our print-to-PDF printer, but that is not ideal since we should
+  // really localize the name of this printer at some point. Once we drop
+  // support for 10.12 we should remove this check.
+  if (!mPrinter.EqualsLiteral("Mozilla Save to PDF")) {
+    [printInfo setPrinter:[NSPrinter printerWithName:nsCocoaUtils::ToNSString(mPrinter)]];
+  }
+
+  // Scaling is handled by gecko, we do NOT want the cocoa printing system to add
+  // a second scaling on top of that. So we only set the true scaling factor here
+  // if the caller explicitly asked for it.
+  [printInfo setScalingFactor:CGFloat(aWithScaling ? mScaling : 1.0f)];
+
+  const bool allPages = mPageRanges.IsEmpty();
+
+  NSMutableDictionary* dict = [printInfo dictionary];
+  [dict setObject:[NSNumber numberWithInt:mNumCopies] forKey:NSPrintCopies];
+  [dict setObject:[NSNumber numberWithBool:allPages] forKey:NSPrintAllPages];
+
+  int32_t start = 1;
+  int32_t end = 1;
+  for (size_t i = 0; i < mPageRanges.Length(); i += 2) {
+    start = std::min(start, mPageRanges[i]);
+    end = std::max(end, mPageRanges[i + 1]);
+  }
+
+  [dict setObject:[NSNumber numberWithInt:start] forKey:NSPrintFirstPage];
+  [dict setObject:[NSNumber numberWithInt:end] forKey:NSPrintLastPage];
+
+  NSURL* jobSavingURL = nullptr;
+  if (!mToFileName.IsEmpty()) {
+    jobSavingURL = [NSURL fileURLWithPath:nsCocoaUtils::ToNSString(mToFileName)];
+    if (jobSavingURL) {
+      // Note: the PMPrintSettingsSetJobName call in nsPrintDialogServiceX::Show
+      // seems to mean that we get a sensible file name pre-populated in the
+      // dialog there, although our mToFileName is expected to be a full path,
+      // and it's less clear where the rest of the path (the directory to save
+      // to) in nsPrintDialogServiceX::Show comes from (perhaps from the use
+      // of `sharedPrintInfo` to initialize new nsPrintSettingsX objects).
+      [dict setObject:jobSavingURL forKey:NSPrintJobSavingURL];
+    }
+  }
+
+  if (mDisposition.IsEmpty()) {
+    // NOTE: It's unclear what to do for kOutputDestinationStream but this is
+    // only for the native print dialog where that can't happen.
+    if (mOutputDestination == kOutputDestinationFile) {
+      [printInfo setJobDisposition:NSPrintSaveJob];
+    } else {
+      [printInfo setJobDisposition:NSPrintSpoolJob];
+    }
+  } else {
+    [printInfo setJobDisposition:nsCocoaUtils::ToNSString(mDisposition)];
+  }
+
+  PMDuplexMode duplexSetting;
+  switch (mDuplex) {
+    default:
+      // This can't happen :) but if it does, we treat it as "none".
+      MOZ_FALLTHROUGH_ASSERT("Unknown duplex value");
+    case kDuplexNone:
+      duplexSetting = kPMDuplexNone;
+      break;
+    case kDuplexFlipOnLongEdge:
+      duplexSetting = kPMDuplexNoTumble;
+      break;
+    case kDuplexFlipOnShortEdge:
+      duplexSetting = kPMDuplexTumble;
+      break;
+  }
+
+  NSMutableDictionary* printSettings = [printInfo printSettings];
+  [printSettings setObject:[NSNumber numberWithUnsignedShort:duplexSetting]
+                    forKey:@"com_apple_print_PrintSettings_PMDuplexing"];
+
+  if (mDestination != kPMDestinationInvalid) {
+    // Required to support PDF-workflow destinations such as Save to Web Receipts.
+    [printSettings setObject:[NSNumber numberWithUnsignedShort:mDestination]
+                      forKey:@"com_apple_print_PrintSettings_PMDestinationType"];
+    if (jobSavingURL) {
+      [printSettings setObject:[jobSavingURL absoluteString]
+                        forKey:@"com_apple_print_PrintSettings_PMOutputFilename"];
+    }
+  }
+
+  if (StaticPrefs::print_cups_monochrome_enabled() && !GetPrintInColor()) {
+    for (const auto& setting : kKnownMonochromeSettings) {
+      [printSettings setObject:setting.mValue forKey:setting.mName];
+    }
+    auto applySetting = [&](const nsACString& aKey, const nsACString& aValue) {
+      [printSettings setObject:nsCocoaUtils::ToNSString(aValue)
+                        forKey:nsCocoaUtils::ToNSString(aKey)];
+    };
+    nsPrinterCUPS::ForEachExtraMonochromeSetting(applySetting);
+  }
+
+  return printInfo;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nullptr);
+}
+
+void nsPrintSettingsX::SetFromPrintInfo(NSPrintInfo* aPrintInfo, bool aAdoptPrintInfo) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Set page-size/margins.
+  NSSize paperSize = [aPrintInfo paperSize];
+  const bool areSheetsOfPaperPortraitMode =
+      ([aPrintInfo orientation] == NSPaperOrientationPortrait);
+
+  // If our MacOS print settings say that we're producing portrait-mode sheets
+  // of paper, then our page format must also be portrait-mode; unless we've
+  // got a pages-per-sheet value with orthogonal pages/sheets, in which case
+  // it's reversed.
+  const bool arePagesPortraitMode = (areSheetsOfPaperPortraitMode != HasOrthogonalSheetsAndPages());
+
+  if (arePagesPortraitMode) {
+    mOrientation = nsIPrintSettings::kPortraitOrientation;
+    SetPaperWidth(PaperSizeFromCocoaPoints(paperSize.width));
+    SetPaperHeight(PaperSizeFromCocoaPoints(paperSize.height));
+  } else {
+    mOrientation = nsIPrintSettings::kLandscapeOrientation;
+    SetPaperWidth(PaperSizeFromCocoaPoints(paperSize.height));
+    SetPaperHeight(PaperSizeFromCocoaPoints(paperSize.width));
+  }
+
+  mUnwriteableMargin.top = [aPrintInfo topMargin];
+  mUnwriteableMargin.right = [aPrintInfo rightMargin];
+  mUnwriteableMargin.bottom = [aPrintInfo bottomMargin];
+  mUnwriteableMargin.left = [aPrintInfo leftMargin];
+
+  if (aAdoptPrintInfo) {
+    // Keep a reference to the printInfo; it may have settings that we don't know how to handle
+    // otherwise.
+    if (mSystemPrintInfo != aPrintInfo) {
+      if (mSystemPrintInfo) {
+        [mSystemPrintInfo release];
+      }
+      mSystemPrintInfo = aPrintInfo;
+      [mSystemPrintInfo retain];
+    }
+  } else {
+    // Clear any stored printInfo.
+    if (mSystemPrintInfo) {
+      [mSystemPrintInfo release];
+      mSystemPrintInfo = nullptr;
+    }
+  }
+
+  nsCocoaUtils::GetStringForNSString([[aPrintInfo printer] name], mPrinter);
+
+  // Only get the scaling value if shrink-to-fit is not selected:
+  bool isShrinkToFitChecked;
+  GetShrinkToFit(&isShrinkToFitChecked);
+  if (!isShrinkToFitChecked) {
+    // Limit scaling precision to whole percentage values.
+    mScaling = round(double([aPrintInfo scalingFactor]) * 100.0) / 100.0;
+  }
+
+  mOutputDestination = [&] {
+    if ([aPrintInfo jobDisposition] == NSPrintSaveJob) {
+      return kOutputDestinationFile;
+    }
+    return kOutputDestinationPrinter;
+  }();
+
+  NSDictionary* dict = [aPrintInfo dictionary];
+  const char* filePath = [[dict objectForKey:NSPrintJobSavingURL] fileSystemRepresentation];
+  if (filePath && *filePath) {
+    CopyUTF8toUTF16(Span(filePath, strlen(filePath)), mToFileName);
+  }
+
+  nsCocoaUtils::GetStringForNSString([aPrintInfo jobDisposition], mDisposition);
+
+  mNumCopies = [[dict objectForKey:NSPrintCopies] intValue];
+  mPageRanges.Clear();
+  if (![[dict objectForKey:NSPrintAllPages] boolValue]) {
+    mPageRanges.AppendElement([[dict objectForKey:NSPrintFirstPage] intValue]);
+    mPageRanges.AppendElement([[dict objectForKey:NSPrintLastPage] intValue]);
+  }
+
+  NSDictionary* printSettings = [aPrintInfo printSettings];
+  NSNumber* value = [printSettings objectForKey:@"com_apple_print_PrintSettings_PMDuplexing"];
+  if (value) {
+    PMDuplexMode duplexSetting = [value unsignedShortValue];
+    switch (duplexSetting) {
+      default:
+        // An unknown value is treated as None.
+        MOZ_FALLTHROUGH_ASSERT("Unknown duplex value");
+      case kPMDuplexNone:
+        mDuplex = kDuplexNone;
+        break;
+      case kPMDuplexNoTumble:
+        mDuplex = kDuplexFlipOnLongEdge;
+        break;
+      case kPMDuplexTumble:
+        mDuplex = kDuplexFlipOnShortEdge;
+        break;
+    }
+  } else {
+    // By default a printSettings dictionary doesn't initially contain the
+    // duplex key at all, so this is not an error; its absence just means no
+    // duplexing has been requested, so we return kDuplexNone.
+    mDuplex = kDuplexNone;
+  }
+
+  value = [printSettings objectForKey:@"com_apple_print_PrintSettings_PMDestinationType"];
+  if (value) {
+    mDestination = [value unsignedShortValue];
+  }
+
+  const bool color = [&] {
+    if (StaticPrefs::print_cups_monochrome_enabled()) {
+      for (const auto& setting : kKnownMonochromeSettings) {
+        NSString* value = [printSettings objectForKey:setting.mName];
+        if (!value) {
+          continue;
+        }
+        if ([setting.mValue isEqualToString:value]) {
+          return false;
+        }
+      }
+    }
+    return true;
+  }();
+
+  SetPrintInColor(color);
+
+  SetIsInitializedFromPrinter(true);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
diff --git a/widget/cocoa/nsSandboxViolationSink.h b/widget/cocoa/nsSandboxViolationSink.h
new file mode 100644
index 0000000000..d4b6e7ce07
--- /dev/null
+++ b/widget/cocoa/nsSandboxViolationSink.h
@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSandboxViolationSink_h_
+#define nsSandboxViolationSink_h_
+
+#include <stdint.h>
+
+// Class for tracking sandbox violations.  Currently it just logs them to
+// stdout and the system console.  In the future it may do more.
+
+// What makes this possible is the fact that Apple' sandboxd calls
+// notify_post("com.apple.sandbox.violation.*") whenever it's notified by the
+// Sandbox kernel extension of a sandbox violation.  We register to receive
+// these notifications.  But the notifications are empty, and are sent for
+// every violation in every process.  So we need to do more to get only "our"
+// violations, and to find out what kind of violation they were.  See the
+// implementation of nsSandboxViolationSink::ViolationHandler().
+
+#define SANDBOX_VIOLATION_QUEUE_NAME "org.mozilla.sandbox.violation.queue"
+#define SANDBOX_VIOLATION_NOTIFICATION_NAME "com.apple.sandbox.violation.*"
+
+class nsSandboxViolationSink {
+ public:
+  static void Start();
+  static void Stop();
+
+ private:
+  static void ViolationHandler();
+  static int mNotifyToken;
+  static uint64_t mLastMsgReceived;
+};
+
+#endif  // nsSandboxViolationSink_h_
diff --git a/widget/cocoa/nsSandboxViolationSink.mm b/widget/cocoa/nsSandboxViolationSink.mm
new file mode 100644
index 0000000000..1399536d6e
--- /dev/null
+++ b/widget/cocoa/nsSandboxViolationSink.mm
@@ -0,0 +1,107 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsSandboxViolationSink.h"
+
+#import <Foundation/NSObjCRuntime.h>
+
+#include <unistd.h>
+#include <time.h>
+#include <asl.h>
+#include <dispatch/dispatch.h>
+#include <notify.h>
+#include "mozilla/Preferences.h"
+#include "mozilla/Sprintf.h"
+
+int nsSandboxViolationSink::mNotifyToken = 0;
+uint64_t nsSandboxViolationSink::mLastMsgReceived = 0;
+
+void nsSandboxViolationSink::Start() {
+  if (mNotifyToken) {
+    return;
+  }
+  notify_register_dispatch(
+      SANDBOX_VIOLATION_NOTIFICATION_NAME, &mNotifyToken,
+      dispatch_queue_create(SANDBOX_VIOLATION_QUEUE_NAME, DISPATCH_QUEUE_SERIAL), ^(int token) {
+        ViolationHandler();
+      });
+}
+
+void nsSandboxViolationSink::Stop() {
+  if (!mNotifyToken) {
+    return;
+  }
+  notify_cancel(mNotifyToken);
+  mNotifyToken = 0;
+}
+
+// We need to query syslogd to find out what violations occurred, and whether
+// they were "ours".  We can use the Apple System Log facility to do this.
+// Besides calling notify_post("com.apple.sandbox.violation.*"), Apple's
+// sandboxd also reports all sandbox violations (sent to it by the Sandbox
+// kernel extension) to syslogd, which stores them and makes them viewable
+// in the system console.  This is the database we query.
+
+// ViolationHandler() is always called on its own secondary thread.  This
+// makes it unlikely it will interfere with other browser activity.
+
+void nsSandboxViolationSink::ViolationHandler() {
+  aslmsg query = asl_new(ASL_TYPE_QUERY);
+
+  asl_set_query(query, ASL_KEY_FACILITY, "com.apple.sandbox", ASL_QUERY_OP_EQUAL);
+
+  // Only get reports that were generated very recently.
+  char query_time[30] = {0};
+  SprintfLiteral(query_time, "%li", time(NULL) - 2);
+  asl_set_query(query, ASL_KEY_TIME, query_time, ASL_QUERY_OP_NUMERIC | ASL_QUERY_OP_GREATER_EQUAL);
+
+  // This code is easier to test if we don't just track "our" violations,
+  // which are (normally) few and far between.  For example (for the time
+  // being at least) four appleeventsd sandbox violations happen every time
+  // we start the browser in e10s mode.  But it makes sense to default to
+  // only tracking "our" violations.
+  if (mozilla::Preferences::GetBool("security.sandbox.mac.track.violations.oursonly", true)) {
+    // This makes each of our processes log its own violations.  It might
+    // be better to make the chrome process log all the other processes'
+    // violations.
+    char query_pid[20] = {0};
+    SprintfLiteral(query_pid, "%u", getpid());
+    asl_set_query(query, ASL_KEY_REF_PID, query_pid, ASL_QUERY_OP_EQUAL);
+  }
+
+  aslresponse response = asl_search(nullptr, query);
+
+  // Each time ViolationHandler() is called we grab as many messages as are
+  // available.  Otherwise we might not get them all.
+  if (response) {
+    while (true) {
+      aslmsg hit = nullptr;
+      aslmsg found = nullptr;
+      const char* id_str;
+
+      while ((hit = aslresponse_next(response))) {
+        // Record the message id to avoid logging the same violation more
+        // than once.
+        id_str = asl_get(hit, ASL_KEY_MSG_ID);
+        uint64_t id_val = atoll(id_str);
+        if (id_val <= mLastMsgReceived) {
+          continue;
+        }
+        mLastMsgReceived = id_val;
+        found = hit;
+        break;
+      }
+      if (!found) {
+        break;
+      }
+
+      const char* pid_str = asl_get(found, ASL_KEY_REF_PID);
+      const char* message_str = asl_get(found, ASL_KEY_MSG);
+      NSLog(@"nsSandboxViolationSink::ViolationHandler(): id %s, pid %s, message %s", id_str,
+            pid_str, message_str);
+    }
+    aslresponse_free(response);
+  }
+}
diff --git a/widget/cocoa/nsSound.h b/widget/cocoa/nsSound.h
new file mode 100644
index 0000000000..cf3b02bd77
--- /dev/null
+++ b/widget/cocoa/nsSound.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSound_h_
+#define nsSound_h_
+
+#include "nsISound.h"
+#include "nsIStreamLoader.h"
+
+class nsSound : public nsISound, public nsIStreamLoaderObserver {
+ public:
+  nsSound();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISOUND
+  NS_DECL_NSISTREAMLOADEROBSERVER
+
+ protected:
+  virtual ~nsSound();
+};
+
+#endif  // nsSound_h_
diff --git a/widget/cocoa/nsSound.mm b/widget/cocoa/nsSound.mm
new file mode 100644
index 0000000000..fb979f6f37
--- /dev/null
+++ b/widget/cocoa/nsSound.mm
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsSound.h"
+#include "nsContentUtils.h"
+#include "nsObjCExceptions.h"
+#include "nsNetUtil.h"
+#include "nsCOMPtr.h"
+#include "nsIURL.h"
+#include "nsString.h"
+
+#import <Cocoa/Cocoa.h>
+
+NS_IMPL_ISUPPORTS(nsSound, nsISound, nsIStreamLoaderObserver)
+
+nsSound::nsSound() {}
+
+nsSound::~nsSound() {}
+
+NS_IMETHODIMP
+nsSound::Beep() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSBeep();
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsSound::OnStreamComplete(nsIStreamLoader* aLoader, nsISupports* context, nsresult aStatus,
+                          uint32_t dataLen, const uint8_t* data) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSData* value = [NSData dataWithBytes:data length:dataLen];
+
+  NSSound* sound = [[NSSound alloc] initWithData:value];
+
+  [sound play];
+
+  [sound autorelease];
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsSound::Play(nsIURL* aURL) {
+  nsCOMPtr<nsIURI> uri(aURL);
+  nsCOMPtr<nsIStreamLoader> loader;
+  return NS_NewStreamLoader(getter_AddRefs(loader), uri,
+                            this,  // aObserver
+                            nsContentUtils::GetSystemPrincipal(),
+                            nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+                            nsIContentPolicy::TYPE_OTHER);
+}
+
+NS_IMETHODIMP
+nsSound::Init() { return NS_OK; }
+
+NS_IMETHODIMP
+nsSound::PlayEventSound(uint32_t aEventId) {
+  // Mac doesn't have system sound settings for each user actions.
+  return NS_OK;
+}
diff --git a/widget/cocoa/nsStandaloneNativeMenu.h b/widget/cocoa/nsStandaloneNativeMenu.h
new file mode 100644
index 0000000000..9d43e5e64d
--- /dev/null
+++ b/widget/cocoa/nsStandaloneNativeMenu.h
@@ -0,0 +1,27 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsStandaloneNativeMenu_h_
+#define nsStandaloneNativeMenu_h_
+
+#include "nsIStandaloneNativeMenu.h"
+#include "NativeMenuMac.h"
+
+class nsStandaloneNativeMenu : public nsIStandaloneNativeMenu {
+ public:
+  nsStandaloneNativeMenu();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISTANDALONENATIVEMENU
+
+  RefPtr<mozilla::widget::NativeMenuMac> GetNativeMenu() { return mMenu; }
+
+ protected:
+  virtual ~nsStandaloneNativeMenu();
+
+  RefPtr<mozilla::widget::NativeMenuMac> mMenu;
+};
+
+#endif
diff --git a/widget/cocoa/nsStandaloneNativeMenu.mm b/widget/cocoa/nsStandaloneNativeMenu.mm
new file mode 100644
index 0000000000..d672f33314
--- /dev/null
+++ b/widget/cocoa/nsStandaloneNativeMenu.mm
@@ -0,0 +1,79 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsStandaloneNativeMenu.h"
+
+#include "mozilla/dom/Element.h"
+#include "NativeMenuMac.h"
+#include "nsISupports.h"
+#include "nsGkAtoms.h"
+
+using namespace mozilla;
+
+using mozilla::dom::Element;
+
+NS_IMPL_ISUPPORTS(nsStandaloneNativeMenu, nsIStandaloneNativeMenu)
+
+nsStandaloneNativeMenu::nsStandaloneNativeMenu() = default;
+
+nsStandaloneNativeMenu::~nsStandaloneNativeMenu() = default;
+
+NS_IMETHODIMP
+nsStandaloneNativeMenu::Init(Element* aElement) {
+  NS_ASSERTION(mMenu == nullptr, "nsNativeMenu::Init - mMenu not null!");
+
+  NS_ENSURE_ARG(aElement);
+
+  if (!aElement->IsAnyOfXULElements(nsGkAtoms::menu, nsGkAtoms::menupopup)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mMenu = new mozilla::widget::NativeMenuMac(aElement);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStandaloneNativeMenu::MenuWillOpen(bool* aResult) {
+  NS_ASSERTION(mMenu != nullptr, "nsStandaloneNativeMenu::OnOpen - mMenu is null!");
+
+  mMenu->MenuWillOpen();
+
+  *aResult = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStandaloneNativeMenu::ActivateNativeMenuItemAt(const nsAString& aIndexString) {
+  if (!mMenu) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  if (mMenu->ActivateNativeMenuItemAt(aIndexString)) {
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsStandaloneNativeMenu::ForceUpdateNativeMenuAt(const nsAString& aIndexString) {
+  if (!mMenu) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  mMenu->ForceUpdateNativeMenuAt(aIndexString);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStandaloneNativeMenu::Dump() {
+  mMenu->Dump();
+
+  return NS_OK;
+}
diff --git a/widget/cocoa/nsSystemStatusBarCocoa.h b/widget/cocoa/nsSystemStatusBarCocoa.h
new file mode 100644
index 0000000000..2af13e2805
--- /dev/null
+++ b/widget/cocoa/nsSystemStatusBarCocoa.h
@@ -0,0 +1,40 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSystemStatusBarCocoa_h_
+#define nsSystemStatusBarCocoa_h_
+
+#include "mozilla/RefPtr.h"
+#include "nsISystemStatusBar.h"
+#include "nsClassHashtable.h"
+
+namespace mozilla::widget {
+class NativeMenuMac;
+}
+@class NSStatusItem;
+
+class nsSystemStatusBarCocoa : public nsISystemStatusBar {
+ public:
+  nsSystemStatusBarCocoa() {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISYSTEMSTATUSBAR
+
+ protected:
+  virtual ~nsSystemStatusBarCocoa() {}
+
+  struct StatusItem {
+    explicit StatusItem(mozilla::widget::NativeMenuMac* aMenu);
+    ~StatusItem();
+
+   private:
+    RefPtr<mozilla::widget::NativeMenuMac> mMenu;
+    NSStatusItem* mStatusItem;
+  };
+
+  nsClassHashtable<nsISupportsHashKey, StatusItem> mItems;
+};
+
+#endif  // nsSystemStatusBarCocoa_h_
diff --git a/widget/cocoa/nsSystemStatusBarCocoa.mm b/widget/cocoa/nsSystemStatusBarCocoa.mm
new file mode 100644
index 0000000000..6261a4b0c4
--- /dev/null
+++ b/widget/cocoa/nsSystemStatusBarCocoa.mm
@@ -0,0 +1,69 @@
+/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsComponentManagerUtils.h"
+#include "nsSystemStatusBarCocoa.h"
+#include "NativeMenuMac.h"
+#include "nsObjCExceptions.h"
+#include "mozilla/dom/Element.h"
+
+using mozilla::dom::Element;
+using mozilla::widget::NativeMenuMac;
+
+NS_IMPL_ISUPPORTS(nsSystemStatusBarCocoa, nsISystemStatusBar)
+
+NS_IMETHODIMP
+nsSystemStatusBarCocoa::AddItem(Element* aElement) {
+  if (!aElement->IsAnyOfXULElements(nsGkAtoms::menu, nsGkAtoms::menupopup)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  RefPtr<NativeMenuMac> menu = new NativeMenuMac(aElement);
+
+  nsCOMPtr<nsISupports> keyPtr = aElement;
+  mItems.InsertOrUpdate(keyPtr, mozilla::MakeUnique<StatusItem>(menu));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSystemStatusBarCocoa::RemoveItem(Element* aElement) {
+  mItems.Remove(aElement);
+  return NS_OK;
+}
+
+nsSystemStatusBarCocoa::StatusItem::StatusItem(NativeMenuMac* aMenu) : mMenu(aMenu) {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  MOZ_COUNT_CTOR(nsSystemStatusBarCocoa::StatusItem);
+
+  mStatusItem =
+      [[NSStatusBar.systemStatusBar statusItemWithLength:NSSquareStatusItemLength] retain];
+  mStatusItem.menu = mMenu->NativeNSMenu();
+  mStatusItem.highlightMode = YES;
+
+  // We want the status item to get its image from menu item that mMenu was
+  // initialized with. Icon loads are asynchronous, so we need to let the menu
+  // know about the item so that it can update its icon as soon as it has
+  // loaded.
+  mMenu->SetContainerStatusBarItem(mStatusItem);
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
+nsSystemStatusBarCocoa::StatusItem::~StatusItem() {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  mMenu->SetContainerStatusBarItem(nil);
+  [NSStatusBar.systemStatusBar removeStatusItem:mStatusItem];
+  [mStatusItem release];
+  mStatusItem = nil;
+
+  MOZ_COUNT_DTOR(nsSystemStatusBarCocoa::StatusItem);
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
diff --git a/widget/cocoa/nsToolkit.h b/widget/cocoa/nsToolkit.h
new file mode 100644
index 0000000000..46b08d0ebe
--- /dev/null
+++ b/widget/cocoa/nsToolkit.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsToolkit_h_
+#define nsToolkit_h_
+
+#include "nscore.h"
+
+#import <Carbon/Carbon.h>
+#import <Cocoa/Cocoa.h>
+#import <objc/Object.h>
+#import <IOKit/IOKitLib.h>
+
+class nsToolkit {
+ public:
+  nsToolkit();
+  virtual ~nsToolkit();
+
+  static nsToolkit* GetToolkit();
+
+  static void Shutdown() {
+    delete gToolkit;
+    gToolkit = nullptr;
+  }
+
+  static void PostSleepWakeNotification(const char* aNotification);
+
+  static nsresult SwizzleMethods(Class aClass, SEL orgMethod, SEL posedMethod,
+                                 bool classMethods = false);
+
+  void MonitorAllProcessMouseEvents();
+  void StopMonitoringAllProcessMouseEvents();
+
+ protected:
+  nsresult RegisterForSleepWakeNotifications();
+  void RemoveSleepWakeNotifications();
+
+ protected:
+  static nsToolkit* gToolkit;
+
+  CFRunLoopSourceRef mSleepWakeNotificationRLS;
+  io_object_t mPowerNotifier;
+
+  id mAllProcessMouseMonitor;
+};
+
+#endif  // nsToolkit_h_
diff --git a/widget/cocoa/nsToolkit.mm b/widget/cocoa/nsToolkit.mm
new file mode 100644
index 0000000000..0180262067
--- /dev/null
+++ b/widget/cocoa/nsToolkit.mm
@@ -0,0 +1,252 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsToolkit.h"
+
+#include <ctype.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <mach/mach_port.h>
+#include <mach/mach_interface.h>
+#include <mach/mach_init.h>
+
+extern "C" {
+#include <mach-o/getsect.h>
+}
+#include <unistd.h>
+#include <dlfcn.h>
+
+#import <Cocoa/Cocoa.h>
+#import <IOKit/pwr_mgt/IOPMLib.h>
+#import <IOKit/IOMessage.h>
+
+#include "nsCocoaUtils.h"
+#include "nsObjCExceptions.h"
+
+#include "nsGkAtoms.h"
+#include "nsIRollupListener.h"
+#include "nsIWidget.h"
+#include "nsBaseWidget.h"
+
+#include "nsIObserverService.h"
+
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+
+#include "NativeMenuSupport.h"
+
+using namespace mozilla;
+
+static io_connect_t gRootPort = MACH_PORT_NULL;
+
+nsToolkit* nsToolkit::gToolkit = nullptr;
+
+nsToolkit::nsToolkit()
+    : mSleepWakeNotificationRLS(nullptr), mPowerNotifier{0}, mAllProcessMouseMonitor(nil) {
+  MOZ_COUNT_CTOR(nsToolkit);
+  RegisterForSleepWakeNotifications();
+}
+
+nsToolkit::~nsToolkit() {
+  MOZ_COUNT_DTOR(nsToolkit);
+  RemoveSleepWakeNotifications();
+  StopMonitoringAllProcessMouseEvents();
+}
+
+void nsToolkit::PostSleepWakeNotification(const char* aNotification) {
+  nsCOMPtr<nsIObserverService> observerService = services::GetObserverService();
+  if (observerService) observerService->NotifyObservers(nullptr, aNotification, nullptr);
+}
+
+// http://developer.apple.com/documentation/DeviceDrivers/Conceptual/IOKitFundamentals/PowerMgmt/chapter_10_section_3.html
+static void ToolkitSleepWakeCallback(void* refCon, io_service_t service, natural_t messageType,
+                                     void* messageArgument) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  switch (messageType) {
+    case kIOMessageSystemWillSleep:
+      // System is going to sleep now.
+      nsToolkit::PostSleepWakeNotification(NS_WIDGET_SLEEP_OBSERVER_TOPIC);
+      ::IOAllowPowerChange(gRootPort, (long)messageArgument);
+      break;
+
+    case kIOMessageCanSystemSleep:
+      // In this case, the computer has been idle for several minutes
+      // and will sleep soon so you must either allow or cancel
+      // this notification. Important: if you don’t respond, there will
+      // be a 30-second timeout before the computer sleeps.
+      // In Mozilla's case, we always allow sleep.
+      ::IOAllowPowerChange(gRootPort, (long)messageArgument);
+      break;
+
+    case kIOMessageSystemHasPoweredOn:
+      // Handle wakeup.
+      nsToolkit::PostSleepWakeNotification(NS_WIDGET_WAKE_OBSERVER_TOPIC);
+      break;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsresult nsToolkit::RegisterForSleepWakeNotifications() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  IONotificationPortRef notifyPortRef;
+
+  NS_ASSERTION(!mSleepWakeNotificationRLS, "Already registered for sleep/wake");
+
+  gRootPort =
+      ::IORegisterForSystemPower(0, &notifyPortRef, ToolkitSleepWakeCallback, &mPowerNotifier);
+  if (gRootPort == MACH_PORT_NULL) {
+    NS_ERROR("IORegisterForSystemPower failed");
+    return NS_ERROR_FAILURE;
+  }
+
+  mSleepWakeNotificationRLS = ::IONotificationPortGetRunLoopSource(notifyPortRef);
+  ::CFRunLoopAddSource(::CFRunLoopGetCurrent(), mSleepWakeNotificationRLS, kCFRunLoopDefaultMode);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsToolkit::RemoveSleepWakeNotifications() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mSleepWakeNotificationRLS) {
+    ::IODeregisterForSystemPower(&mPowerNotifier);
+    ::CFRunLoopRemoveSource(::CFRunLoopGetCurrent(), mSleepWakeNotificationRLS,
+                            kCFRunLoopDefaultMode);
+
+    mSleepWakeNotificationRLS = nullptr;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Cocoa Firefox's use of custom context menus requires that we explicitly
+// handle mouse events from other processes that the OS handles
+// "automatically" for native context menus -- mouseMoved events so that
+// right-click context menus work properly when our browser doesn't have the
+// focus (bmo bug 368077), and mouseDown events so that our browser can
+// dismiss a context menu when a mouseDown happens in another process (bmo
+// bug 339945).
+void nsToolkit::MonitorAllProcessMouseEvents() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mozilla::widget::NativeMenuSupport::ShouldUseNativeContextMenus()) {
+    // Don't do this if we are using native context menus.
+    return;
+  }
+
+  if (getenv("MOZ_NO_GLOBAL_MOUSE_MONITOR")) return;
+
+  if (mAllProcessMouseMonitor == nil) {
+    mAllProcessMouseMonitor = [NSEvent
+        addGlobalMonitorForEventsMatchingMask:NSEventMaskLeftMouseDown | NSEventMaskLeftMouseDown
+                                      handler:^(NSEvent* evt) {
+                                        if ([NSApp isActive]) {
+                                          return;
+                                        }
+
+                                        nsIRollupListener* rollupListener =
+                                            nsBaseWidget::GetActiveRollupListener();
+                                        if (!rollupListener) {
+                                          return;
+                                        }
+
+                                        nsCOMPtr<nsIWidget> rollupWidget =
+                                            rollupListener->GetRollupWidget();
+                                        if (!rollupWidget) {
+                                          return;
+                                        }
+
+                                        NSWindow* ctxMenuWindow =
+                                            (NSWindow*)rollupWidget->GetNativeData(
+                                                NS_NATIVE_WINDOW);
+                                        if (!ctxMenuWindow) {
+                                          return;
+                                        }
+
+                                        // Don't roll up the rollup widget if our mouseDown happens
+                                        // over it (doing so would break the corresponding context
+                                        // menu).
+                                        NSPoint screenLocation = [NSEvent mouseLocation];
+                                        if (NSPointInRect(screenLocation, [ctxMenuWindow frame])) {
+                                          return;
+                                        }
+
+                                        rollupListener->Rollup({});
+                                      }];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsToolkit::StopMonitoringAllProcessMouseEvents() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mAllProcessMouseMonitor != nil) {
+    [NSEvent removeMonitor:mAllProcessMouseMonitor];
+    mAllProcessMouseMonitor = nil;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Return the nsToolkit instance.  If a toolkit does not yet exist, then one
+// will be created.
+// static
+nsToolkit* nsToolkit::GetToolkit() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!gToolkit) {
+    gToolkit = new nsToolkit();
+  }
+
+  return gToolkit;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nullptr);
+}
+
+// An alternative to [NSObject poseAsClass:] that isn't deprecated on OS X
+// Leopard and is available to 64-bit binaries on Leopard and above.  Based on
+// ideas and code from http://www.cocoadev.com/index.pl?MethodSwizzling.
+// Since the Method type becomes an opaque type as of Objective-C 2.0, we'll
+// have to switch to using accessor methods like method_exchangeImplementations()
+// when we build 64-bit binaries that use Objective-C 2.0 (on and for Leopard
+// and above).
+//
+// Be aware that, if aClass doesn't have an orgMethod selector but one of its
+// superclasses does, the method substitution will (in effect) take place in
+// that superclass (rather than in aClass itself).  The substitution has
+// effect on the class where it takes place and all of that class's
+// subclasses.  In order for method swizzling to work properly, posedMethod
+// needs to be unique in the class where the substitution takes place and all
+// of its subclasses.
+nsresult nsToolkit::SwizzleMethods(Class aClass, SEL orgMethod, SEL posedMethod,
+                                   bool classMethods) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  Method original = nil;
+  Method posed = nil;
+
+  if (classMethods) {
+    original = class_getClassMethod(aClass, orgMethod);
+    posed = class_getClassMethod(aClass, posedMethod);
+  } else {
+    original = class_getInstanceMethod(aClass, orgMethod);
+    posed = class_getInstanceMethod(aClass, posedMethod);
+  }
+
+  if (!original || !posed) return NS_ERROR_FAILURE;
+
+  method_exchangeImplementations(original, posed);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
diff --git a/widget/cocoa/nsTouchBar.h b/widget/cocoa/nsTouchBar.h
new file mode 100644
index 0000000000..4432b05c39
--- /dev/null
+++ b/widget/cocoa/nsTouchBar.h
@@ -0,0 +1,136 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTouchBar_h_
+#define nsTouchBar_h_
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsITouchBarHelper.h"
+#include "nsTouchBarInput.h"
+#include "nsTouchBarNativeAPIDefines.h"
+
+const NSTouchBarItemIdentifier kTouchBarBaseIdentifier = @"com.mozilla.firefox.touchbar";
+
+/**
+ * Our TouchBar is its own delegate. This is adequate for our purposes,
+ * since the current implementation only defines Touch Bar buttons for the
+ * main Firefox window. If modals and other windows were to have custom
+ * Touch Bar views, each window would have to be a NSTouchBarDelegate so
+ * they could define their own custom sets of buttons.
+ */
+@interface nsTouchBar : NSTouchBar <NSTouchBarDelegate,
+                                    NSSharingServicePickerTouchBarItemDelegate,
+                                    NSSharingServiceDelegate> {
+  /**
+   * Link to the frontend API that determines which buttons appear
+   * in the Touch Bar
+   */
+  nsCOMPtr<nsITouchBarHelper> mTouchBarHelper;
+}
+
+/**
+ * Contains TouchBarInput representations of the inputs currently in
+ * the Touch Bar. Populated in `init` and updated by nsITouchBarUpdater.
+ */
+@property(strong) NSMutableDictionary<NSTouchBarItemIdentifier, TouchBarInput*>* mappedLayoutItems;
+
+/**
+ * Stores buttons displayed in a NSScrollView. They must be stored separately
+ * because they are untethered from the nsTouchBar. As such, they
+ * cannot be retrieved with [NSTouchBar itemForIdentifier].
+ */
+@property(strong)
+    NSMutableDictionary<NSTouchBarItemIdentifier, NSCustomTouchBarItem*>* scrollViewButtons;
+
+/**
+ * Returns an instance of nsTouchBar based on implementation details
+ * fetched from the frontend through nsTouchBarHelper.
+ */
+- (instancetype)init;
+
+/**
+ * If aInputs is not nil, a nsTouchBar containing the inputs specified is
+ * initialized. Otherwise, a nsTouchBar is initialized containing a default set
+ * of inputs.
+ */
+- (instancetype)initWithInputs:(NSMutableArray<TouchBarInput*>*)aInputs;
+
+- (void)dealloc;
+
+/**
+ * Creates a new NSTouchBarItem and adds it to the Touch Bar.
+ * Reads the passed identifier and creates the
+ * appropriate item type (eg. NSCustomTouchBarItem).
+ * Required as a member of NSTouchBarDelegate.
+ */
+- (NSTouchBarItem*)touchBar:(NSTouchBar*)aTouchBar
+      makeItemForIdentifier:(NSTouchBarItemIdentifier)aIdentifier;
+
+/**
+ * Updates an input on the Touch Bar by redirecting to one of the specific
+ * TouchBarItem types updaters.
+ * Returns true if the input was successfully updated.
+ */
+- (bool)updateItem:(TouchBarInput*)aInput;
+
+/**
+ * Helper function for updateItem. Checks to see if a given input exists within
+ * any of this Touch Bar's popovers and updates it if it exists.
+ */
+- (bool)maybeUpdatePopoverChild:(TouchBarInput*)aInput;
+
+/**
+ * Helper function for updateItem. Checks to see if a given input exists within
+ * any of this Touch Bar's scroll views and updates it if it exists.
+ */
+- (bool)maybeUpdateScrollViewChild:(TouchBarInput*)aInput;
+
+/**
+ * Helper function for updateItem. Replaces an item in the
+ * self.mappedLayoutItems dictionary.
+ */
+- (void)replaceMappedLayoutItem:(TouchBarInput*)aItem;
+
+/**
+ * Update or create various subclasses of TouchBarItem.
+ */
+- (void)updateButton:(NSCustomTouchBarItem*)aButton
+      withIdentifier:(NSTouchBarItemIdentifier)aIdentifier;
+- (void)updateMainButton:(NSCustomTouchBarItem*)aMainButton
+          withIdentifier:(NSTouchBarItemIdentifier)aIdentifier;
+- (void)updatePopover:(NSPopoverTouchBarItem*)aPopoverItem
+       withIdentifier:(NSTouchBarItemIdentifier)aIdentifier;
+- (void)updateScrollView:(NSCustomTouchBarItem*)aScrollViewItem
+          withIdentifier:(NSTouchBarItemIdentifier)aIdentifier;
+- (void)updateLabel:(NSTextField*)aLabel withIdentifier:(NSTouchBarItemIdentifier)aIdentifier;
+- (NSTouchBarItem*)makeShareScrubberForIdentifier:(NSTouchBarItemIdentifier)aIdentifier;
+
+/**
+ * If aShowing is true, aPopover is shown. Otherwise, it is hidden.
+ */
+- (void)showPopover:(TouchBarInput*)aPopover showing:(bool)aShowing;
+
+/**
+ *  Redirects button actions to the appropriate handler.
+ */
+- (void)touchBarAction:(id)aSender;
+
+/**
+ * Helper function to initialize a new nsTouchBarInputIcon and load an icon.
+ */
+- (void)loadIconForInput:(TouchBarInput*)aInput forItem:(NSTouchBarItem*)aItem;
+
+- (NSArray*)itemsForSharingServicePickerTouchBarItem:
+    (NSSharingServicePickerTouchBarItem*)aPickerTouchBarItem;
+
+- (NSArray<NSSharingService*>*)sharingServicePicker:(NSSharingServicePicker*)aSharingServicePicker
+                            sharingServicesForItems:(NSArray*)aItems
+                            proposedSharingServices:(NSArray<NSSharingService*>*)aProposedServices;
+
+- (void)releaseJSObjects;
+
+@end  // nsTouchBar
+
+#endif  // nsTouchBar_h_
diff --git a/widget/cocoa/nsTouchBar.mm b/widget/cocoa/nsTouchBar.mm
new file mode 100644
index 0000000000..f6a7042381
--- /dev/null
+++ b/widget/cocoa/nsTouchBar.mm
@@ -0,0 +1,605 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTouchBar.h"
+
+#include <objc/runtime.h>
+
+#include "mozilla/MacStringHelpers.h"
+#include "mozilla/dom/Document.h"
+#include "nsArrayUtils.h"
+#include "nsCocoaUtils.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsIArray.h"
+#include "nsTouchBarInputIcon.h"
+#include "nsWidgetsCID.h"
+
+@implementation nsTouchBar
+
+// Used to tie action strings to buttons.
+static char sIdentifierAssociationKey;
+
+// The default space between inputs, used where layout is not automatic.
+static const uint32_t kInputSpacing = 8;
+// The width of buttons in Apple's Share ScrollView. We use this in our
+// ScrollViews to give them a native appearance.
+static const uint32_t kScrollViewButtonWidth = 144;
+static const uint32_t kInputIconSize = 16;
+
+// The system default width for Touch Bar inputs is 128px. This is double.
+#define MAIN_BUTTON_WIDTH 256
+
+#pragma mark - NSTouchBarDelegate
+
+- (instancetype)init {
+  return [self initWithInputs:nil];
+}
+
+- (instancetype)initWithInputs:(NSMutableArray<TouchBarInput*>*)aInputs {
+  if ((self = [super init])) {
+    mTouchBarHelper = do_GetService(NS_TOUCHBARHELPER_CID);
+    if (!mTouchBarHelper) {
+      NS_ERROR("Unable to create Touch Bar Helper.");
+      return nil;
+    }
+
+    self.delegate = self;
+    self.mappedLayoutItems = [NSMutableDictionary dictionary];
+    self.customizationAllowedItemIdentifiers = @[];
+
+    if (!aInputs) {
+      // This customization identifier is how users' custom layouts are saved by macOS.
+      // If this changes, all users' layouts would be reset to the default layout.
+      self.customizationIdentifier =
+          [kTouchBarBaseIdentifier stringByAppendingPathExtension:@"defaultbar"];
+      nsCOMPtr<nsIArray> allItems;
+
+      nsresult rv = mTouchBarHelper->GetAllItems(getter_AddRefs(allItems));
+      if (NS_FAILED(rv) || !allItems) {
+        return nil;
+      }
+
+      uint32_t itemCount = 0;
+      allItems->GetLength(&itemCount);
+      // This is copied to self.customizationAllowedItemIdentifiers.
+      // Required since [self.mappedItems allKeys] does not preserve order.
+      // One slot is added for the spacer item.
+      NSMutableArray* orderedIdentifiers = [NSMutableArray arrayWithCapacity:itemCount + 1];
+      for (uint32_t i = 0; i < itemCount; ++i) {
+        nsCOMPtr<nsITouchBarInput> input = do_QueryElementAt(allItems, i);
+        if (!input) {
+          continue;
+        }
+
+        TouchBarInput* convertedInput;
+        NSTouchBarItemIdentifier newInputIdentifier =
+            [TouchBarInput nativeIdentifierWithXPCOM:input];
+        if (!newInputIdentifier) {
+          continue;
+        }
+
+        // If there is already an input in mappedLayoutItems with this identifier,
+        // that means updateItem fired before this initialization. The input
+        // cached by updateItem is more current, so we should use that one.
+        if (self.mappedLayoutItems[newInputIdentifier]) {
+          convertedInput = self.mappedLayoutItems[newInputIdentifier];
+        } else {
+          convertedInput = [[TouchBarInput alloc] initWithXPCOM:input];
+          // Add new input to dictionary for lookup of properties in delegate.
+          self.mappedLayoutItems[[convertedInput nativeIdentifier]] = convertedInput;
+        }
+
+        orderedIdentifiers[i] = [convertedInput nativeIdentifier];
+      }
+      [orderedIdentifiers addObject:@"NSTouchBarItemIdentifierFlexibleSpace"];
+      self.customizationAllowedItemIdentifiers = [orderedIdentifiers copy];
+
+      NSArray* defaultItemIdentifiers = @[
+        [TouchBarInput nativeIdentifierWithType:@"button" withKey:@"back"],
+        [TouchBarInput nativeIdentifierWithType:@"button" withKey:@"forward"],
+        [TouchBarInput nativeIdentifierWithType:@"button" withKey:@"reload"],
+        [TouchBarInput nativeIdentifierWithType:@"mainButton" withKey:@"open-location"],
+        [TouchBarInput nativeIdentifierWithType:@"button" withKey:@"new-tab"],
+        [TouchBarInput shareScrubberIdentifier], [TouchBarInput searchPopoverIdentifier]
+      ];
+      self.defaultItemIdentifiers = [defaultItemIdentifiers copy];
+    } else {
+      NSMutableArray* defaultItemIdentifiers = [NSMutableArray arrayWithCapacity:[aInputs count]];
+      for (TouchBarInput* input in aInputs) {
+        self.mappedLayoutItems[[input nativeIdentifier]] = input;
+        [defaultItemIdentifiers addObject:[input nativeIdentifier]];
+      }
+      self.defaultItemIdentifiers = [defaultItemIdentifiers copy];
+    }
+  }
+
+  return self;
+}
+
+- (void)dealloc {
+  for (NSTouchBarItemIdentifier identifier in self.mappedLayoutItems) {
+    NSTouchBarItem* item = [self itemForIdentifier:identifier];
+    if (!item) {
+      continue;
+    }
+    if ([item isKindOfClass:[NSPopoverTouchBarItem class]]) {
+      [(NSPopoverTouchBarItem*)item setCollapsedRepresentationImage:nil];
+      [(nsTouchBar*)[(NSPopoverTouchBarItem*)item popoverTouchBar] release];
+    } else if ([[item view] isKindOfClass:[NSScrollView class]]) {
+      [[(NSScrollView*)[item view] documentView] release];
+      [(NSScrollView*)[item view] release];
+    }
+
+    [item release];
+  }
+
+  [self.defaultItemIdentifiers release];
+  [self.customizationAllowedItemIdentifiers release];
+  [self.scrollViewButtons removeAllObjects];
+  [self.scrollViewButtons release];
+  [self.mappedLayoutItems removeAllObjects];
+  [self.mappedLayoutItems release];
+  [super dealloc];
+}
+
+- (NSTouchBarItem*)touchBar:(NSTouchBar*)aTouchBar
+      makeItemForIdentifier:(NSTouchBarItemIdentifier)aIdentifier {
+  if (!mTouchBarHelper) {
+    return nil;
+  }
+
+  TouchBarInput* input = self.mappedLayoutItems[aIdentifier];
+  if (!input) {
+    return nil;
+  }
+
+  if ([input baseType] == TouchBarInputBaseType::kScrubber) {
+    // We check the identifier rather than the baseType here as a special case.
+    if (![aIdentifier isEqualToString:[TouchBarInput shareScrubberIdentifier]]) {
+      // We're only supporting the Share scrubber for now.
+      return nil;
+    }
+    return [self makeShareScrubberForIdentifier:aIdentifier];
+  }
+
+  if ([input baseType] == TouchBarInputBaseType::kPopover) {
+    NSPopoverTouchBarItem* newPopoverItem =
+        [[NSPopoverTouchBarItem alloc] initWithIdentifier:aIdentifier];
+    [newPopoverItem setCustomizationLabel:[input title]];
+    // We initialize popoverTouchBar here because we only allow setting this
+    // property on popover creation. Updating popoverTouchBar for every update
+    // of the popover item would be very expensive.
+    newPopoverItem.popoverTouchBar = [[nsTouchBar alloc] initWithInputs:[input children]];
+    [self updatePopover:newPopoverItem withIdentifier:[input nativeIdentifier]];
+    return newPopoverItem;
+  }
+
+  // Our new item, which will be initialized depending on aIdentifier.
+  NSCustomTouchBarItem* newItem = [[NSCustomTouchBarItem alloc] initWithIdentifier:aIdentifier];
+  [newItem setCustomizationLabel:[input title]];
+
+  if ([input baseType] == TouchBarInputBaseType::kScrollView) {
+    [self updateScrollView:newItem withIdentifier:[input nativeIdentifier]];
+    return newItem;
+  } else if ([input baseType] == TouchBarInputBaseType::kLabel) {
+    NSTextField* label = [NSTextField labelWithString:@""];
+    [self updateLabel:label withIdentifier:[input nativeIdentifier]];
+    newItem.view = label;
+    return newItem;
+  }
+
+  // The cases of a button or main button require the same setup.
+  NSButton* button = [NSButton buttonWithTitle:@"" target:self action:@selector(touchBarAction:)];
+  newItem.view = button;
+
+  if ([input baseType] == TouchBarInputBaseType::kButton &&
+      ![[input type] hasPrefix:@"scrollView"]) {
+    [self updateButton:newItem withIdentifier:[input nativeIdentifier]];
+  } else if ([input baseType] == TouchBarInputBaseType::kMainButton) {
+    [self updateMainButton:newItem withIdentifier:[input nativeIdentifier]];
+  }
+  return newItem;
+}
+
+- (bool)updateItem:(TouchBarInput*)aInput {
+  if (!mTouchBarHelper) {
+    return false;
+  }
+
+  NSTouchBarItem* item = [self itemForIdentifier:[aInput nativeIdentifier]];
+
+  // If we can't immediately find item, there are three possibilities:
+  //   * It is a button in a ScrollView, or
+  //   * It is contained within a popover, or
+  //   * It simply does not exist.
+  // We check for each possibility here.
+  if (!self.mappedLayoutItems[[aInput nativeIdentifier]]) {
+    if ([self maybeUpdateScrollViewChild:aInput]) {
+      return true;
+    }
+    if ([self maybeUpdatePopoverChild:aInput]) {
+      return true;
+    }
+    return false;
+  }
+
+  // Update our canonical copy of the input.
+  [self replaceMappedLayoutItem:aInput];
+
+  if ([aInput baseType] == TouchBarInputBaseType::kButton) {
+    [(NSCustomTouchBarItem*)item setCustomizationLabel:[aInput title]];
+    [self updateButton:(NSCustomTouchBarItem*)item withIdentifier:[aInput nativeIdentifier]];
+  } else if ([aInput baseType] == TouchBarInputBaseType::kMainButton) {
+    [(NSCustomTouchBarItem*)item setCustomizationLabel:[aInput title]];
+    [self updateMainButton:(NSCustomTouchBarItem*)item withIdentifier:[aInput nativeIdentifier]];
+  } else if ([aInput baseType] == TouchBarInputBaseType::kScrollView) {
+    [(NSCustomTouchBarItem*)item setCustomizationLabel:[aInput title]];
+    [self updateScrollView:(NSCustomTouchBarItem*)item withIdentifier:[aInput nativeIdentifier]];
+  } else if ([aInput baseType] == TouchBarInputBaseType::kPopover) {
+    [(NSPopoverTouchBarItem*)item setCustomizationLabel:[aInput title]];
+    [self updatePopover:(NSPopoverTouchBarItem*)item withIdentifier:[aInput nativeIdentifier]];
+    for (TouchBarInput* child in [aInput children]) {
+      [(nsTouchBar*)[(NSPopoverTouchBarItem*)item popoverTouchBar] updateItem:child];
+    }
+  } else if ([aInput baseType] == TouchBarInputBaseType::kLabel) {
+    [self updateLabel:(NSTextField*)item.view withIdentifier:[aInput nativeIdentifier]];
+  }
+
+  return true;
+}
+
+- (bool)maybeUpdatePopoverChild:(TouchBarInput*)aInput {
+  for (NSTouchBarItemIdentifier identifier in self.mappedLayoutItems) {
+    TouchBarInput* potentialPopover = self.mappedLayoutItems[identifier];
+    if ([potentialPopover baseType] != TouchBarInputBaseType::kPopover) {
+      continue;
+    }
+    NSTouchBarItem* popover = [self itemForIdentifier:[potentialPopover nativeIdentifier]];
+    if (popover) {
+      if ([(nsTouchBar*)[(NSPopoverTouchBarItem*)popover popoverTouchBar] updateItem:aInput]) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+- (bool)maybeUpdateScrollViewChild:(TouchBarInput*)aInput {
+  NSCustomTouchBarItem* scrollViewButton = self.scrollViewButtons[[aInput nativeIdentifier]];
+  if (scrollViewButton) {
+    // ScrollView buttons are similar to mainButtons except for their width.
+    [self updateMainButton:scrollViewButton withIdentifier:[aInput nativeIdentifier]];
+    NSButton* button = (NSButton*)scrollViewButton.view;
+    uint32_t buttonSize = MAX(button.attributedTitle.size.width + kInputIconSize + kInputSpacing,
+                              kScrollViewButtonWidth);
+    [[button widthAnchor] constraintGreaterThanOrEqualToConstant:buttonSize].active = YES;
+  }
+  // Updating the TouchBarInput* in the ScrollView's mChildren array.
+  for (NSTouchBarItemIdentifier identifier in self.mappedLayoutItems) {
+    TouchBarInput* potentialScrollView = self.mappedLayoutItems[identifier];
+    if ([potentialScrollView baseType] != TouchBarInputBaseType::kScrollView) {
+      continue;
+    }
+    for (uint32_t i = 0; i < [[potentialScrollView children] count]; ++i) {
+      TouchBarInput* child = [potentialScrollView children][i];
+      if (![[child nativeIdentifier] isEqualToString:[aInput nativeIdentifier]]) {
+        continue;
+      }
+      [[potentialScrollView children] replaceObjectAtIndex:i withObject:aInput];
+      [child release];
+      return true;
+    }
+  }
+  return false;
+}
+
+- (void)replaceMappedLayoutItem:(TouchBarInput*)aItem {
+  [self.mappedLayoutItems[[aItem nativeIdentifier]] release];
+  self.mappedLayoutItems[[aItem nativeIdentifier]] = aItem;
+}
+
+- (void)updateButton:(NSCustomTouchBarItem*)aButton
+      withIdentifier:(NSTouchBarItemIdentifier)aIdentifier {
+  if (!aButton || !aIdentifier) {
+    return;
+  }
+
+  TouchBarInput* input = self.mappedLayoutItems[aIdentifier];
+  if (!input) {
+    return;
+  }
+
+  NSButton* button = (NSButton*)[aButton view];
+  button.title = [input title];
+  if ([input imageURI]) {
+    [button setImagePosition:NSImageOnly];
+    [self loadIconForInput:input forItem:aButton];
+    // Because we are hiding the title, NSAccessibility also does not get it.
+    // Therefore, set an accessibility label as alternative text for image-only buttons.
+    [button setAccessibilityLabel:[input title]];
+  }
+
+  [button setEnabled:![input isDisabled]];
+  if ([input color]) {
+    button.bezelColor = [input color];
+  }
+
+  objc_setAssociatedObject(button, &sIdentifierAssociationKey, aIdentifier,
+                           OBJC_ASSOCIATION_RETAIN);
+}
+
+- (void)updateMainButton:(NSCustomTouchBarItem*)aMainButton
+          withIdentifier:(NSTouchBarItemIdentifier)aIdentifier {
+  if (!aMainButton || !aIdentifier) {
+    return;
+  }
+
+  TouchBarInput* input = self.mappedLayoutItems[aIdentifier];
+  if (!input) {
+    return;
+  }
+
+  [self updateButton:aMainButton withIdentifier:aIdentifier];
+  NSButton* button = (NSButton*)[aMainButton view];
+
+  // If empty, string is still being localized. Display a blank input instead.
+  if ([[input title] isEqualToString:@""]) {
+    [button setImagePosition:NSNoImage];
+  } else {
+    [button setImagePosition:NSImageLeft];
+  }
+  button.imageHugsTitle = YES;
+  [button.widthAnchor constraintGreaterThanOrEqualToConstant:MAIN_BUTTON_WIDTH].active = YES;
+  [button setContentHuggingPriority:1.0 forOrientation:NSLayoutConstraintOrientationHorizontal];
+}
+
+- (void)updatePopover:(NSPopoverTouchBarItem*)aPopoverItem
+       withIdentifier:(NSTouchBarItemIdentifier)aIdentifier {
+  if (!aPopoverItem || !aIdentifier) {
+    return;
+  }
+
+  TouchBarInput* input = self.mappedLayoutItems[aIdentifier];
+  if (!input) {
+    return;
+  }
+
+  aPopoverItem.showsCloseButton = YES;
+  if ([input imageURI]) {
+    [self loadIconForInput:input forItem:aPopoverItem];
+  } else if ([input title]) {
+    aPopoverItem.collapsedRepresentationLabel = [input title];
+  }
+
+  // Special handling to show/hide the search popover if the Urlbar is focused.
+  if ([[input nativeIdentifier] isEqualToString:[TouchBarInput searchPopoverIdentifier]]) {
+    // We can reach this code during window shutdown. We only want to toggle
+    // showPopover if we are in a normal running state.
+    if (!mTouchBarHelper) {
+      return;
+    }
+    bool urlbarIsFocused = false;
+    mTouchBarHelper->GetIsUrlbarFocused(&urlbarIsFocused);
+    if (urlbarIsFocused) {
+      [aPopoverItem showPopover:self];
+    }
+  }
+}
+
+- (void)updateScrollView:(NSCustomTouchBarItem*)aScrollViewItem
+          withIdentifier:(NSTouchBarItemIdentifier)aIdentifier {
+  if (!aScrollViewItem || !aIdentifier) {
+    return;
+  }
+
+  TouchBarInput* input = self.mappedLayoutItems[aIdentifier];
+  if (!input || ![input children]) {
+    return;
+  }
+
+  NSMutableDictionary* constraintViews = [NSMutableDictionary dictionary];
+  NSView* documentView = [[NSView alloc] initWithFrame:NSZeroRect];
+  NSString* layoutFormat = @"H:|-8-";
+  NSSize size = NSMakeSize(kInputSpacing, 30);
+  // Layout strings allow only alphanumeric characters. We will use this
+  // NSCharacterSet to strip illegal characters.
+  NSCharacterSet* charactersToRemove = [[NSCharacterSet alphanumericCharacterSet] invertedSet];
+
+  for (TouchBarInput* childInput in [input children]) {
+    if ([childInput baseType] != TouchBarInputBaseType::kButton) {
+      continue;
+    }
+    [self replaceMappedLayoutItem:childInput];
+    NSCustomTouchBarItem* newItem =
+        [[NSCustomTouchBarItem alloc] initWithIdentifier:[childInput nativeIdentifier]];
+    NSButton* button = [NSButton buttonWithTitle:[childInput title]
+                                          target:self
+                                          action:@selector(touchBarAction:)];
+    newItem.view = button;
+    // ScrollView buttons are similar to mainButtons except for their width.
+    [self updateMainButton:newItem withIdentifier:[childInput nativeIdentifier]];
+    uint32_t buttonSize = MAX(button.attributedTitle.size.width + kInputIconSize + kInputSpacing,
+                              kScrollViewButtonWidth);
+    [[button widthAnchor] constraintGreaterThanOrEqualToConstant:buttonSize].active = YES;
+
+    NSCustomTouchBarItem* tempItem = self.scrollViewButtons[[childInput nativeIdentifier]];
+    self.scrollViewButtons[[childInput nativeIdentifier]] = newItem;
+    [tempItem release];
+
+    button.translatesAutoresizingMaskIntoConstraints = NO;
+    [documentView addSubview:button];
+    NSString* layoutKey = [[[childInput nativeIdentifier]
+        componentsSeparatedByCharactersInSet:charactersToRemove] componentsJoinedByString:@""];
+
+    // Iteratively create our layout string.
+    layoutFormat =
+        [layoutFormat stringByAppendingString:[NSString stringWithFormat:@"[%@]-8-", layoutKey]];
+    [constraintViews setObject:button forKey:layoutKey];
+    size.width += kInputSpacing + buttonSize;
+  }
+  layoutFormat = [layoutFormat stringByAppendingString:[NSString stringWithFormat:@"|"]];
+  NSArray* hConstraints =
+      [NSLayoutConstraint constraintsWithVisualFormat:layoutFormat
+                                              options:NSLayoutFormatAlignAllCenterY
+                                              metrics:nil
+                                                views:constraintViews];
+  NSScrollView* scrollView =
+      [[NSScrollView alloc] initWithFrame:CGRectMake(0, 0, size.width, size.height)];
+  [documentView setFrame:NSMakeRect(0, 0, size.width, size.height)];
+  [NSLayoutConstraint activateConstraints:hConstraints];
+  scrollView.documentView = documentView;
+
+  aScrollViewItem.view = scrollView;
+}
+
+- (void)updateLabel:(NSTextField*)aLabel withIdentifier:(NSTouchBarItemIdentifier)aIdentifier {
+  if (!aLabel || !aIdentifier) {
+    return;
+  }
+
+  TouchBarInput* input = self.mappedLayoutItems[aIdentifier];
+  if (!input || ![input title]) {
+    return;
+  }
+  [aLabel setStringValue:[input title]];
+}
+
+- (NSTouchBarItem*)makeShareScrubberForIdentifier:(NSTouchBarItemIdentifier)aIdentifier {
+  TouchBarInput* input = self.mappedLayoutItems[aIdentifier];
+  // System-default share menu
+  NSSharingServicePickerTouchBarItem* servicesItem =
+      [[NSSharingServicePickerTouchBarItem alloc] initWithIdentifier:aIdentifier];
+
+  // buttonImage needs to be set to nil while we wait for our icon to load.
+  // Otherwise, the default Apple share icon is automatically loaded.
+  servicesItem.buttonImage = nil;
+
+  [self loadIconForInput:input forItem:servicesItem];
+
+  servicesItem.delegate = self;
+  return servicesItem;
+}
+
+- (void)showPopover:(TouchBarInput*)aPopover showing:(bool)aShowing {
+  if (!aPopover) {
+    return;
+  }
+  NSPopoverTouchBarItem* popoverItem =
+      (NSPopoverTouchBarItem*)[self itemForIdentifier:[aPopover nativeIdentifier]];
+  if (!popoverItem) {
+    return;
+  }
+  if (aShowing) {
+    [popoverItem showPopover:self];
+  } else {
+    [popoverItem dismissPopover:self];
+  }
+}
+
+- (void)touchBarAction:(id)aSender {
+  NSTouchBarItemIdentifier identifier =
+      objc_getAssociatedObject(aSender, &sIdentifierAssociationKey);
+  if (!identifier || [identifier isEqualToString:@""]) {
+    return;
+  }
+
+  TouchBarInput* input = self.mappedLayoutItems[identifier];
+  if (!input) {
+    return;
+  }
+
+  nsCOMPtr<nsITouchBarInputCallback> callback = [input callback];
+  if (!callback) {
+    NSLog(@"Touch Bar action attempted with no valid callback! Identifier: %@",
+          [input nativeIdentifier]);
+    return;
+  }
+  callback->OnCommand();
+}
+
+- (void)loadIconForInput:(TouchBarInput*)aInput forItem:(NSTouchBarItem*)aItem {
+  if (!aInput || ![aInput imageURI] || !aItem || !mTouchBarHelper) {
+    return;
+  }
+
+  RefPtr<nsTouchBarInputIcon> icon = [aInput icon];
+
+  if (!icon) {
+    RefPtr<Document> document;
+    nsresult rv = mTouchBarHelper->GetDocument(getter_AddRefs(document));
+    if (NS_FAILED(rv) || !document) {
+      return;
+    }
+    icon = new nsTouchBarInputIcon(document, aInput, aItem);
+    [aInput setIcon:icon];
+  }
+  icon->SetupIcon([aInput imageURI]);
+}
+
+- (void)releaseJSObjects {
+  mTouchBarHelper = nil;
+
+  for (NSTouchBarItemIdentifier identifier in self.mappedLayoutItems) {
+    TouchBarInput* input = self.mappedLayoutItems[identifier];
+    if (!input) {
+      continue;
+    }
+
+    // Childless popovers contain the default Touch Bar as its popoverTouchBar.
+    // We check for [input children] since the default Touch Bar contains a
+    // popover (search-popover), so this would infinitely loop if there was no check.
+    if ([input baseType] == TouchBarInputBaseType::kPopover && [input children]) {
+      NSTouchBarItem* item = [self itemForIdentifier:identifier];
+      [(nsTouchBar*)[(NSPopoverTouchBarItem*)item popoverTouchBar] releaseJSObjects];
+    }
+
+    [input releaseJSObjects];
+  }
+}
+
+#pragma mark - NSSharingServicePickerTouchBarItemDelegate
+
+- (NSArray*)itemsForSharingServicePickerTouchBarItem:
+    (NSSharingServicePickerTouchBarItem*)aPickerTouchBarItem {
+  NSURL* urlToShare = nil;
+  NSString* titleToShare = @"";
+  nsAutoString url;
+  nsAutoString title;
+  if (mTouchBarHelper) {
+    nsresult rv = mTouchBarHelper->GetActiveUrl(url);
+    if (!NS_FAILED(rv)) {
+      urlToShare = [NSURL URLWithString:nsCocoaUtils::ToNSString(url)];
+      // NSURL URLWithString returns nil if the URL is invalid. At this point,
+      // it is too late to simply shut down the share menu, so we default to
+      // about:blank if the share button is clicked when the URL is invalid.
+      if (urlToShare == nil) {
+        urlToShare = [NSURL URLWithString:@"about:blank"];
+      }
+    }
+
+    rv = mTouchBarHelper->GetActiveTitle(title);
+    if (!NS_FAILED(rv)) {
+      titleToShare = nsCocoaUtils::ToNSString(title);
+    }
+  }
+
+  return @[ urlToShare, titleToShare ];
+}
+
+- (NSArray<NSSharingService*>*)sharingServicePicker:(NSSharingServicePicker*)aSharingServicePicker
+                            sharingServicesForItems:(NSArray*)aItems
+                            proposedSharingServices:(NSArray<NSSharingService*>*)aProposedServices {
+  // redundant services
+  NSArray* excludedServices = @[
+    @"com.apple.share.System.add-to-safari-reading-list",
+  ];
+
+  NSArray* sharingServices = [aProposedServices
+      filteredArrayUsingPredicate:[NSPredicate
+                                      predicateWithFormat:@"NOT (name IN %@)", excludedServices]];
+
+  return sharingServices;
+}
+
+@end
diff --git a/widget/cocoa/nsTouchBarInput.h b/widget/cocoa/nsTouchBarInput.h
new file mode 100644
index 0000000000..4853660d79
--- /dev/null
+++ b/widget/cocoa/nsTouchBarInput.h
@@ -0,0 +1,90 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTouchBarInput_h_
+#define nsTouchBarInput_h_
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsITouchBarInput.h"
+#include "nsTouchBarNativeAPIDefines.h"
+#include "nsCOMPtr.h"
+
+using namespace mozilla::dom;
+
+enum class TouchBarInputBaseType : uint8_t {
+  kButton,
+  kLabel,
+  kMainButton,
+  kPopover,
+  kScrollView,
+  kScrubber
+};
+
+class nsTouchBarInputIcon;
+
+/**
+ * NSObject representation of nsITouchBarInput.
+ */
+@interface TouchBarInput : NSObject {
+  nsCOMPtr<nsIURI> mImageURI;
+  RefPtr<nsTouchBarInputIcon> mIcon;
+  TouchBarInputBaseType mBaseType;
+  NSString* mType;
+  nsCOMPtr<nsITouchBarInputCallback> mCallback;
+  NSMutableArray<TouchBarInput*>* mChildren;
+}
+
+@property(strong) NSString* key;
+@property(strong) NSString* type;
+@property(strong) NSString* title;
+@property(strong) NSColor* color;
+@property(nonatomic, getter=isDisabled) BOOL disabled;
+
+- (nsCOMPtr<nsIURI>)imageURI;
+- (RefPtr<nsTouchBarInputIcon>)icon;
+- (TouchBarInputBaseType)baseType;
+- (NSTouchBarItemIdentifier)nativeIdentifier;
+- (nsCOMPtr<nsITouchBarInputCallback>)callback;
+- (NSMutableArray<TouchBarInput*>*)children;
+- (void)setImageURI:(nsCOMPtr<nsIURI>)aImageURI;
+- (void)setIcon:(RefPtr<nsTouchBarInputIcon>)aIcon;
+- (void)setCallback:(nsCOMPtr<nsITouchBarInputCallback>)aCallback;
+- (void)setChildren:(NSMutableArray<TouchBarInput*>*)aChildren;
+
+- (id)initWithKey:(NSString*)aKey
+            title:(NSString*)aTitle
+         imageURI:(nsCOMPtr<nsIURI>)aImageURI
+             type:(NSString*)aType
+         callback:(nsCOMPtr<nsITouchBarInputCallback>)aCallback
+            color:(uint32_t)aColor
+         disabled:(BOOL)aDisabled
+         children:(nsCOMPtr<nsIArray>)aChildren;
+
+- (TouchBarInput*)initWithXPCOM:(nsCOMPtr<nsITouchBarInput>)aInput;
+
+- (void)releaseJSObjects;
+
+- (void)dealloc;
+
+/**
+ * We make these helper methods static so that other classes can query a
+ * TouchBarInput's nativeIdentifier (e.g. nsTouchBarUpdater looking up a
+ * popover in mappedLayoutItems).
+ */
++ (NSTouchBarItemIdentifier)nativeIdentifierWithType:(NSString*)aType withKey:(NSString*)aKey;
++ (NSTouchBarItemIdentifier)nativeIdentifierWithXPCOM:(nsCOMPtr<nsITouchBarInput>)aInput;
+
+// Non-JS scrubber implemention for the Share Scrubber,
+// since it is defined by an Apple API.
++ (NSTouchBarItemIdentifier)shareScrubberIdentifier;
+
+// The search popover needs to show/hide depending on if the Urlbar is focused
+// when it is created. We keep track of its identifier to accommodate this
+// special handling.
++ (NSTouchBarItemIdentifier)searchPopoverIdentifier;
+
+@end
+
+#endif  // nsTouchBarInput_h_
diff --git a/widget/cocoa/nsTouchBarInput.mm b/widget/cocoa/nsTouchBarInput.mm
new file mode 100644
index 0000000000..dc50c64e1b
--- /dev/null
+++ b/widget/cocoa/nsTouchBarInput.mm
@@ -0,0 +1,245 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTouchBarInput.h"
+
+#include "mozilla/MacStringHelpers.h"
+#include "nsArrayUtils.h"
+#include "nsCocoaUtils.h"
+#include "nsTouchBar.h"
+#include "nsTouchBarInputIcon.h"
+
+@implementation TouchBarInput
+
+- (nsCOMPtr<nsIURI>)imageURI {
+  return mImageURI;
+}
+
+- (void)setImageURI:(nsCOMPtr<nsIURI>)aImageURI {
+  mImageURI = aImageURI;
+}
+
+- (RefPtr<nsTouchBarInputIcon>)icon {
+  return mIcon;
+}
+
+- (void)setIcon:(RefPtr<nsTouchBarInputIcon>)aIcon {
+  mIcon = aIcon;
+}
+
+- (TouchBarInputBaseType)baseType {
+  return mBaseType;
+}
+
+- (NSString*)type {
+  return mType;
+}
+
+- (void)setType:(NSString*)aType {
+  [aType retain];
+  [mType release];
+  if ([aType hasSuffix:@"button"]) {
+    mBaseType = TouchBarInputBaseType::kButton;
+  } else if ([aType hasSuffix:@"label"]) {
+    mBaseType = TouchBarInputBaseType::kLabel;
+  } else if ([aType hasSuffix:@"mainButton"]) {
+    mBaseType = TouchBarInputBaseType::kMainButton;
+  } else if ([aType hasSuffix:@"popover"]) {
+    mBaseType = TouchBarInputBaseType::kPopover;
+  } else if ([aType hasSuffix:@"scrollView"]) {
+    mBaseType = TouchBarInputBaseType::kScrollView;
+  } else if ([aType hasSuffix:@"scrubber"]) {
+    mBaseType = TouchBarInputBaseType::kScrubber;
+  }
+  mType = aType;
+}
+
+- (NSTouchBarItemIdentifier)nativeIdentifier {
+  return [TouchBarInput nativeIdentifierWithType:mType withKey:self.key];
+}
+
+- (nsCOMPtr<nsITouchBarInputCallback>)callback {
+  return mCallback;
+}
+
+- (void)setCallback:(nsCOMPtr<nsITouchBarInputCallback>)aCallback {
+  mCallback = aCallback;
+}
+
+- (NSMutableArray<TouchBarInput*>*)children {
+  return mChildren;
+}
+
+- (void)setChildren:(NSMutableArray<TouchBarInput*>*)aChildren {
+  [aChildren retain];
+  for (TouchBarInput* child in mChildren) {
+    [child releaseJSObjects];
+  }
+  [mChildren removeAllObjects];
+  [mChildren release];
+  mChildren = aChildren;
+}
+
+- (id)initWithKey:(NSString*)aKey
+            title:(NSString*)aTitle
+         imageURI:(nsCOMPtr<nsIURI>)aImageURI
+             type:(NSString*)aType
+         callback:(nsCOMPtr<nsITouchBarInputCallback>)aCallback
+            color:(uint32_t)aColor
+         disabled:(BOOL)aDisabled
+         children:(nsCOMPtr<nsIArray>)aChildren {
+  if (self = [super init]) {
+    mType = nil;
+
+    self.key = aKey;
+    self.title = aTitle;
+    self.type = aType;
+    self.disabled = aDisabled;
+    [self setImageURI:aImageURI];
+    [self setCallback:aCallback];
+    if (aColor) {
+      [self setColor:[NSColor colorWithDisplayP3Red:((aColor >> 16) & 0xFF) / 255.0
+                                              green:((aColor >> 8) & 0xFF) / 255.0
+                                               blue:((aColor)&0xFF) / 255.0
+                                              alpha:1.0]];
+    }
+    if (aChildren) {
+      uint32_t itemCount = 0;
+      aChildren->GetLength(&itemCount);
+      NSMutableArray* orderedChildren = [NSMutableArray arrayWithCapacity:itemCount];
+      for (uint32_t i = 0; i < itemCount; ++i) {
+        nsCOMPtr<nsITouchBarInput> child = do_QueryElementAt(aChildren, i);
+        if (!child) {
+          continue;
+        }
+        TouchBarInput* convertedChild = [[TouchBarInput alloc] initWithXPCOM:child];
+        if (convertedChild) {
+          orderedChildren[i] = convertedChild;
+        }
+      }
+      [self setChildren:orderedChildren];
+    }
+  }
+
+  return self;
+}
+
+- (TouchBarInput*)initWithXPCOM:(nsCOMPtr<nsITouchBarInput>)aInput {
+  nsAutoString keyStr;
+  nsresult rv = aInput->GetKey(keyStr);
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+
+  nsAutoString titleStr;
+  rv = aInput->GetTitle(titleStr);
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+
+  nsCOMPtr<nsIURI> imageURI;
+  rv = aInput->GetImage(getter_AddRefs(imageURI));
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+
+  nsAutoString typeStr;
+  rv = aInput->GetType(typeStr);
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+
+  nsCOMPtr<nsITouchBarInputCallback> callback;
+  rv = aInput->GetCallback(getter_AddRefs(callback));
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+
+  uint32_t colorInt;
+  rv = aInput->GetColor(&colorInt);
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+
+  bool disabled = false;
+  rv = aInput->GetDisabled(&disabled);
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+
+  nsCOMPtr<nsIArray> children;
+  rv = aInput->GetChildren(getter_AddRefs(children));
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+
+  return [self initWithKey:nsCocoaUtils::ToNSString(keyStr)
+                     title:nsCocoaUtils::ToNSString(titleStr)
+                  imageURI:imageURI
+                      type:nsCocoaUtils::ToNSString(typeStr)
+                  callback:callback
+                     color:colorInt
+                  disabled:(BOOL)disabled
+                  children:children];
+}
+
+- (void)releaseJSObjects {
+  if (mIcon) {
+    mIcon->Destroy();
+    mIcon = nil;
+  }
+  [self setCallback:nil];
+  [self setImageURI:nil];
+  for (TouchBarInput* child in mChildren) {
+    [child releaseJSObjects];
+  }
+}
+
+- (void)dealloc {
+  if (mIcon) {
+    mIcon->Destroy();
+    mIcon = nil;
+  }
+  [mType release];
+  [mChildren removeAllObjects];
+  [mChildren release];
+  [super dealloc];
+}
+
++ (NSTouchBarItemIdentifier)nativeIdentifierWithType:(NSString*)aType withKey:(NSString*)aKey {
+  NSTouchBarItemIdentifier identifier;
+  identifier = [kTouchBarBaseIdentifier stringByAppendingPathExtension:aType];
+  if (aKey) {
+    identifier = [identifier stringByAppendingPathExtension:aKey];
+  }
+  return identifier;
+}
+
++ (NSTouchBarItemIdentifier)nativeIdentifierWithXPCOM:(nsCOMPtr<nsITouchBarInput>)aInput {
+  nsAutoString keyStr;
+  nsresult rv = aInput->GetKey(keyStr);
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+  NSString* key = nsCocoaUtils::ToNSString(keyStr);
+
+  nsAutoString typeStr;
+  rv = aInput->GetType(typeStr);
+  if (NS_FAILED(rv)) {
+    return nil;
+  }
+  NSString* type = nsCocoaUtils::ToNSString(typeStr);
+
+  return [TouchBarInput nativeIdentifierWithType:type withKey:key];
+}
+
++ (NSTouchBarItemIdentifier)shareScrubberIdentifier {
+  return [TouchBarInput nativeIdentifierWithType:@"scrubber" withKey:@"share"];
+}
+
++ (NSTouchBarItemIdentifier)searchPopoverIdentifier {
+  return [TouchBarInput nativeIdentifierWithType:@"popover" withKey:@"search-popover"];
+}
+
+@end
diff --git a/widget/cocoa/nsTouchBarInputIcon.h b/widget/cocoa/nsTouchBarInputIcon.h
new file mode 100644
index 0000000000..115d7a0075
--- /dev/null
+++ b/widget/cocoa/nsTouchBarInputIcon.h
@@ -0,0 +1,71 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Retrieves and displays icons on the macOS Touch Bar.
+ */
+
+#ifndef nsTouchBarInputIcon_h_
+#define nsTouchBarInputIcon_h_
+
+#import <Cocoa/Cocoa.h>
+
+#include "mozilla/widget/IconLoader.h"
+#include "nsTouchBarInput.h"
+#include "nsTouchBarNativeAPIDefines.h"
+
+using namespace mozilla::dom;
+
+class nsIURI;
+class nsIPrincipal;
+class imgRequestProxy;
+
+namespace mozilla::dom {
+class Document;
+}
+
+class nsTouchBarInputIcon : public mozilla::widget::IconLoader::Listener {
+ public:
+  explicit nsTouchBarInputIcon(RefPtr<Document> aDocument,
+                               TouchBarInput* aInput, NSTouchBarItem* aItem);
+
+  NS_INLINE_DECL_REFCOUNTING(nsTouchBarInputIcon)
+
+ private:
+  virtual ~nsTouchBarInputIcon();
+
+ public:
+  // SetupIcon succeeds if it was able to set up the icon, or if there should
+  // be no icon, in which case it clears any existing icon but still succeeds.
+  nsresult SetupIcon(nsCOMPtr<nsIURI> aIconURI);
+
+  // Implements this method for mozilla::widget::IconLoader::Listener.
+  // Called once the icon load is complete.
+  nsresult OnComplete(imgIContainer* aImage) override;
+
+  // Unless we take precautions, we may outlive the object that created us
+  // (mTouchBar, which owns our native menu item (mTouchBarInput)).
+  // Destroy() should be called from mTouchBar's destructor to prevent
+  // this from happening.
+  void Destroy();
+
+  void ReleaseJSObjects();
+
+ protected:
+  RefPtr<Document> mDocument;
+  bool mSetIcon;
+  NSButton* mButton;
+  // We accept a mShareScrubber only as a special case since
+  // NSSharingServicePickerTouchBarItem does not expose an NSButton* on which we
+  // can set the `image` property.
+  NSSharingServicePickerTouchBarItem* mShareScrubber;
+  // We accept a popover only as a special case.
+  NSPopoverTouchBarItem* mPopoverItem;
+  // The icon loader object should never outlive its creating
+  // nsTouchBarInputIcon object.
+  RefPtr<mozilla::widget::IconLoader> mIconLoader;
+};
+
+#endif  // nsTouchBarInputIcon_h_
diff --git a/widget/cocoa/nsTouchBarInputIcon.mm b/widget/cocoa/nsTouchBarInputIcon.mm
new file mode 100644
index 0000000000..ac9e907c8e
--- /dev/null
+++ b/widget/cocoa/nsTouchBarInputIcon.mm
@@ -0,0 +1,133 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Retrieves and displays icons on the macOS Touch Bar.
+ */
+
+#include "nsTouchBarInputIcon.h"
+
+#include "MOZIconHelper.h"
+#include "mozilla/dom/Document.h"
+#include "nsCocoaUtils.h"
+#include "nsComputedDOMStyle.h"
+#include "nsContentUtils.h"
+#include "nsGkAtoms.h"
+#include "nsINode.h"
+#include "nsNameSpaceManager.h"
+#include "nsObjCExceptions.h"
+
+using namespace mozilla;
+using mozilla::widget::IconLoader;
+
+static const uint32_t kIconHeight = 16;
+static const CGFloat kHiDPIScalingFactor = 2.0f;
+
+nsTouchBarInputIcon::nsTouchBarInputIcon(RefPtr<Document> aDocument, TouchBarInput* aInput,
+                                         NSTouchBarItem* aItem)
+    : mDocument(aDocument), mSetIcon(false), mButton(nil), mShareScrubber(nil), mPopoverItem(nil) {
+  if ([[aInput nativeIdentifier] isEqualToString:[TouchBarInput shareScrubberIdentifier]]) {
+    mShareScrubber = (NSSharingServicePickerTouchBarItem*)aItem;
+  } else if ([aInput baseType] == TouchBarInputBaseType::kPopover) {
+    mPopoverItem = (NSPopoverTouchBarItem*)aItem;
+  } else if ([aInput baseType] == TouchBarInputBaseType::kButton ||
+             [aInput baseType] == TouchBarInputBaseType::kMainButton) {
+    mButton = (NSButton*)[aItem view];
+  } else {
+    NS_ERROR("Incompatible Touch Bar input passed to nsTouchBarInputIcon.");
+  }
+  aInput = nil;
+  MOZ_COUNT_CTOR(nsTouchBarInputIcon);
+}
+
+nsTouchBarInputIcon::~nsTouchBarInputIcon() {
+  Destroy();
+  MOZ_COUNT_DTOR(nsTouchBarInputIcon);
+}
+
+// Called from nsTouchBar's destructor, to prevent us from outliving it
+// (as might otherwise happen if calls to our imgINotificationObserver methods
+// are still outstanding).  nsTouchBar owns our mTouchBarInput.
+void nsTouchBarInputIcon::Destroy() {
+  ReleaseJSObjects();
+  if (mIconLoader) {
+    mIconLoader->Destroy();
+    mIconLoader = nullptr;
+  }
+
+  mButton = nil;
+  mShareScrubber = nil;
+  mPopoverItem = nil;
+}
+
+nsresult nsTouchBarInputIcon::SetupIcon(nsCOMPtr<nsIURI> aIconURI) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // We might not have a document if the Touch Bar tries to update when the main
+  // window is closed.
+  if (!mDocument) {
+    return NS_OK;
+  }
+
+  if (!(mButton || mShareScrubber || mPopoverItem)) {
+    NS_ERROR("No Touch Bar input provided.");
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!mIconLoader) {
+    mIconLoader = new IconLoader(this);
+  }
+
+  if (!mSetIcon) {
+    // Load placeholder icon.
+    NSSize iconSize = NSMakeSize(kIconHeight, kIconHeight);
+    NSImage* placeholder = [MOZIconHelper placeholderIconWithSize:iconSize];
+    [mButton setImage:placeholder];
+    [mShareScrubber setButtonImage:placeholder];
+    [mPopoverItem setCollapsedRepresentationImage:placeholder];
+  }
+
+  nsresult rv = mIconLoader->LoadIcon(aIconURI, mDocument, true /* aIsInternalIcon */);
+  if (NS_FAILED(rv)) {
+    // There is no icon for this menu item, as an error occurred while loading it.
+    // An icon might have been set earlier or the place holder icon may have
+    // been set.  Clear it.
+    [mButton setImage:nil];
+    [mShareScrubber setButtonImage:nil];
+    [mPopoverItem setCollapsedRepresentationImage:nil];
+  }
+
+  mSetIcon = true;
+
+  return rv;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsTouchBarInputIcon::ReleaseJSObjects() { mDocument = nil; }
+
+//
+// mozilla::widget::IconLoader::Listener
+//
+
+nsresult nsTouchBarInputIcon::OnComplete(imgIContainer* aImage) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN
+
+  // We ask only for the HiDPI images since all Touch Bars are Retina
+  // displays and we have no need for icons @1x.
+  NSImage* image = [MOZIconHelper iconImageFromImageContainer:aImage
+                                                     withSize:NSMakeSize(kIconHeight, kIconHeight)
+                                                  presContext:nullptr
+                                                computedStyle:nullptr
+                                                  scaleFactor:kHiDPIScalingFactor];
+  [mButton setImage:image];
+  [mShareScrubber setButtonImage:image];
+  [mPopoverItem setCollapsedRepresentationImage:image];
+
+  mIconLoader->Destroy();
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE)
+}
diff --git a/widget/cocoa/nsTouchBarNativeAPIDefines.h b/widget/cocoa/nsTouchBarNativeAPIDefines.h
new file mode 100644
index 0000000000..1317a1bc79
--- /dev/null
+++ b/widget/cocoa/nsTouchBarNativeAPIDefines.h
@@ -0,0 +1,67 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTouchBarNativeAPIDefines_h
+#define nsTouchBarNativeAPIDefines_h
+
+#import <Cocoa/Cocoa.h>
+
+#if !defined(MAC_OS_X_VERSION_10_12_2) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_12_2
+@interface NSApplication (TouchBarMenu)
+- (IBAction)toggleTouchBarCustomizationPalette:(id)sender;
+@end
+
+typedef NSString* NSTouchBarItemIdentifier;
+__attribute__((weak_import))
+@interface NSTouchBarItem : NSObject
+@property(readonly) NSView* view;
+@property(readonly) NSString* customizationLabel;
+- (instancetype)initWithIdentifier:(NSTouchBarItemIdentifier)aIdentifier;
+@end
+
+@protocol NSSharingServicePickerTouchBarItemDelegate
+@end
+
+__attribute__((weak_import))
+@interface NSSharingServicePickerTouchBarItem : NSTouchBarItem
+@property(strong) id<NSSharingServicePickerTouchBarItemDelegate> delegate;
+@property(strong) NSImage* buttonImage;
+@end
+
+__attribute__((weak_import))
+@interface NSCustomTouchBarItem : NSTouchBarItem
+@property(strong) NSView* view;
+@property(strong) NSString* customizationLabel;
+@end
+
+@protocol NSTouchBarDelegate
+@end
+
+typedef NSString* NSTouchBarCustomizationIdentifier;
+__attribute__((weak_import))
+@interface NSTouchBar : NSObject
+@property(strong) NSArray<NSTouchBarItemIdentifier>* defaultItemIdentifiers;
+@property(strong) id<NSTouchBarDelegate> delegate;
+@property(strong) NSTouchBarCustomizationIdentifier customizationIdentifier;
+@property(strong) NSArray<NSTouchBarItemIdentifier>* customizationAllowedItemIdentifiers;
+- (NSTouchBarItem*)itemForIdentifier:(NSTouchBarItemIdentifier)aIdentifier;
+@end
+
+__attribute__((weak_import))
+@interface NSPopoverTouchBarItem : NSTouchBarItem
+@property(strong) NSString* customizationLabel;
+@property(strong) NSView* collapsedRepresentation;
+@property(strong) NSImage* collapsedRepresentationImage;
+@property(strong) NSString* collapsedRepresentationLabel;
+@property(strong) NSTouchBar* popoverTouchBar;
+@property BOOL showsCloseButton;
+- (void)showPopover:(id)sender;
+- (void)dismissPopover:(id)sender;
+@end
+
+@interface NSButton (TouchBarButton)
+@property(strong) NSColor* bezelColor;
+@end
+#endif  // !defined(MAC_OS_X_VERSION_10_12_2)
+#endif  // nsTouchBarNativeAPIDefines_h
diff --git a/widget/cocoa/nsTouchBarUpdater.h b/widget/cocoa/nsTouchBarUpdater.h
new file mode 100644
index 0000000000..38039f69a0
--- /dev/null
+++ b/widget/cocoa/nsTouchBarUpdater.h
@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTouchBarUpdater_h_
+#define nsTouchBarUpdater_h_
+
+#include "nsITouchBarUpdater.h"
+#include "nsCocoaWindow.h"
+
+class nsTouchBarUpdater : public nsITouchBarUpdater {
+ public:
+  nsTouchBarUpdater() {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSITOUCHBARUPDATER
+
+ protected:
+  virtual ~nsTouchBarUpdater() {}
+  BaseWindow* GetCocoaWindow(nsIBaseWindow* aWindow);
+};
+
+#endif  // nsTouchBarUpdater_h_
diff --git a/widget/cocoa/nsTouchBarUpdater.mm b/widget/cocoa/nsTouchBarUpdater.mm
new file mode 100644
index 0000000000..6b4b25f992
--- /dev/null
+++ b/widget/cocoa/nsTouchBarUpdater.mm
@@ -0,0 +1,116 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsTouchBar.h"
+#include "nsTouchBarInput.h"
+#include "nsTouchBarUpdater.h"
+#include "nsTouchBarNativeAPIDefines.h"
+
+#include "nsIBaseWindow.h"
+#include "nsIWidget.h"
+
+// defined in nsCocoaWindow.mm.
+extern BOOL sTouchBarIsInitialized;
+
+#if !defined(MAC_OS_X_VERSION_10_12_2) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_12_2
+@interface BaseWindow (NSTouchBarProvider)
+@property(strong) NSTouchBar* touchBar;
+@end
+#endif
+
+NS_IMPL_ISUPPORTS(nsTouchBarUpdater, nsITouchBarUpdater);
+
+NS_IMETHODIMP
+nsTouchBarUpdater::UpdateTouchBarInputs(nsIBaseWindow* aWindow,
+                                        const nsTArray<RefPtr<nsITouchBarInput>>& aInputs) {
+  if (!sTouchBarIsInitialized || !aWindow) {
+    return NS_OK;
+  }
+
+  BaseWindow* cocoaWin = nsTouchBarUpdater::GetCocoaWindow(aWindow);
+  if (!cocoaWin) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if ([cocoaWin respondsToSelector:@selector(touchBar)]) {
+    size_t itemCount = aInputs.Length();
+    for (size_t i = 0; i < itemCount; ++i) {
+      nsCOMPtr<nsITouchBarInput> input(aInputs.ElementAt(i));
+      if (!input) {
+        continue;
+      }
+
+      NSTouchBarItemIdentifier newIdentifier = [TouchBarInput nativeIdentifierWithXPCOM:input];
+      // We don't support updating the Share scrubber since it's a special
+      // Apple-made component that behaves differently from the other inputs.
+      if ([newIdentifier isEqualToString:[TouchBarInput nativeIdentifierWithType:@"scrubber"
+                                                                         withKey:@"share"]]) {
+        continue;
+      }
+
+      TouchBarInput* convertedInput = [[TouchBarInput alloc] initWithXPCOM:input];
+      [(nsTouchBar*)cocoaWin.touchBar updateItem:convertedInput];
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTouchBarUpdater::ShowPopover(nsIBaseWindow* aWindow, nsITouchBarInput* aPopover, bool aShowing) {
+  if (!sTouchBarIsInitialized || !aPopover || !aWindow) {
+    return NS_OK;
+  }
+
+  BaseWindow* cocoaWin = nsTouchBarUpdater::GetCocoaWindow(aWindow);
+  if (!cocoaWin) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if ([cocoaWin respondsToSelector:@selector(touchBar)]) {
+    // We don't need to completely reinitialize the popover. We only need its
+    // identifier to look it up in [nsTouchBar mappedLayoutItems].
+    NSTouchBarItemIdentifier popoverIdentifier = [TouchBarInput nativeIdentifierWithXPCOM:aPopover];
+
+    TouchBarInput* popoverItem =
+        [[(nsTouchBar*)cocoaWin.touchBar mappedLayoutItems] objectForKey:popoverIdentifier];
+
+    [(nsTouchBar*)cocoaWin.touchBar showPopover:popoverItem showing:aShowing];
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTouchBarUpdater::EnterCustomizeMode() {
+  [NSApp toggleTouchBarCustomizationPalette:(id)this];
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTouchBarUpdater::IsTouchBarInitialized(bool* aResult) {
+  *aResult = sTouchBarIsInitialized;
+  return NS_OK;
+}
+
+BaseWindow* nsTouchBarUpdater::GetCocoaWindow(nsIBaseWindow* aWindow) {
+  nsCOMPtr<nsIWidget> widget = nullptr;
+  aWindow->GetMainWidget(getter_AddRefs(widget));
+  if (!widget) {
+    return nil;
+  }
+  BaseWindow* cocoaWin = (BaseWindow*)widget->GetNativeData(NS_NATIVE_WINDOW);
+  if (!cocoaWin) {
+    return nil;
+  }
+  return cocoaWin;
+}
+
+// NOTE: This method is for internal unit tests only.
+NS_IMETHODIMP
+nsTouchBarUpdater::SetTouchBarInitialized(bool aIsInitialized) {
+  sTouchBarIsInitialized = aIsInitialized;
+  return NS_OK;
+}
diff --git a/widget/cocoa/nsUserIdleServiceX.h b/widget/cocoa/nsUserIdleServiceX.h
new file mode 100644
index 0000000000..cdd5130a33
--- /dev/null
+++ b/widget/cocoa/nsUserIdleServiceX.h
@@ -0,0 +1,30 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsUserIdleServiceX_h_
+#define nsUserIdleServiceX_h_
+
+#include "nsUserIdleService.h"
+
+class nsUserIdleServiceX : public nsUserIdleService {
+ public:
+  NS_INLINE_DECL_REFCOUNTING_INHERITED(nsUserIdleServiceX, nsUserIdleService)
+
+  bool PollIdleTime(uint32_t* aIdleTime) override;
+
+  static already_AddRefed<nsUserIdleServiceX> GetInstance() {
+    RefPtr<nsUserIdleService> idleService = nsUserIdleService::GetInstance();
+    if (!idleService) {
+      idleService = new nsUserIdleServiceX();
+    }
+
+    return idleService.forget().downcast<nsUserIdleServiceX>();
+  }
+
+ protected:
+  nsUserIdleServiceX() {}
+  virtual ~nsUserIdleServiceX() {}
+};
+
+#endif  // nsUserIdleServiceX_h_
diff --git a/widget/cocoa/nsUserIdleServiceX.mm b/widget/cocoa/nsUserIdleServiceX.mm
new file mode 100644
index 0000000000..bedaf0773b
--- /dev/null
+++ b/widget/cocoa/nsUserIdleServiceX.mm
@@ -0,0 +1,58 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsUserIdleServiceX.h"
+#include "nsObjCExceptions.h"
+#import <Foundation/Foundation.h>
+
+bool nsUserIdleServiceX::PollIdleTime(uint32_t* aIdleTime) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  kern_return_t rval;
+  mach_port_t masterPort;
+
+  rval = IOMasterPort(kIOMasterPortDefault, &masterPort);
+  if (rval != KERN_SUCCESS) return false;
+
+  io_iterator_t hidItr;
+  rval = IOServiceGetMatchingServices(masterPort, IOServiceMatching("IOHIDSystem"), &hidItr);
+
+  if (rval != KERN_SUCCESS) return false;
+  NS_ASSERTION(hidItr, "Our iterator is null, but it ought not to be!");
+
+  io_registry_entry_t entry = IOIteratorNext(hidItr);
+  NS_ASSERTION(entry, "Our IO Registry Entry is null, but it shouldn't be!");
+
+  IOObjectRelease(hidItr);
+
+  NSMutableDictionary* hidProps;
+  rval = IORegistryEntryCreateCFProperties(entry, (CFMutableDictionaryRef*)&hidProps,
+                                           kCFAllocatorDefault, 0);
+  if (rval != KERN_SUCCESS) return false;
+  NS_ASSERTION(hidProps, "HIDProperties is null, but no error was returned.");
+  [hidProps autorelease];
+
+  id idleObj = [hidProps objectForKey:@"HIDIdleTime"];
+  NS_ASSERTION([idleObj isKindOfClass:[NSData class]] || [idleObj isKindOfClass:[NSNumber class]],
+               "What we got for the idle object is not what we expect!");
+
+  uint64_t time;
+  if ([idleObj isKindOfClass:[NSData class]])
+    [idleObj getBytes:&time length:sizeof(time)];
+  else
+    time = [idleObj unsignedLongLongValue];
+
+  IOObjectRelease(entry);
+
+  // convert to ms from ns
+  time /= 1000000;
+  if (time > UINT32_MAX)  // Overflow will occur
+    return false;
+
+  *aIdleTime = static_cast<uint32_t>(time);
+
+  return true;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
diff --git a/widget/cocoa/nsWidgetFactory.h b/widget/cocoa/nsWidgetFactory.h
new file mode 100644
index 0000000000..ce3ca756db
--- /dev/null
+++ b/widget/cocoa/nsWidgetFactory.h
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This file contains forward declarations for classes defined in static
+// components. The appropriate headers for those types cannot be included in
+// the generated static component code directly.
+
+#include "nsID.h"
+
+namespace mozilla {
+class OSXNotificationCenter;
+}  // namespace mozilla
+
+namespace mozilla::widget {
+class ScreenManager;
+}
+
+class nsClipboardHelper;
+class nsColorPicker;
+class nsDeviceContextSpecX;
+class nsDragService;
+class nsFilePicker;
+class nsHTMLFormatConverter;
+class nsMacDockSupport;
+class nsMacFinderProgress;
+class nsMacSharingService;
+class nsMacUserActivityUpdater;
+class nsMacWebAppUtils;
+class nsPrintDialogServiceX;
+class nsPrintSettingsServiceX;
+class nsPrinterListCUPS;
+class nsSound;
+class nsStandaloneNativeMenu;
+class nsSystemStatusBarCocoa;
+class nsTouchBarUpdater;
+class nsTransferable;
+class nsUserIdleServiceX;
+
+nsresult nsAppShellConstructor(const nsIID&, void**);
+
+void nsWidgetCocoaModuleCtor();
+void nsWidgetCocoaModuleDtor();
diff --git a/widget/cocoa/nsWidgetFactory.mm b/widget/cocoa/nsWidgetFactory.mm
new file mode 100644
index 0000000000..3126b8c225
--- /dev/null
+++ b/widget/cocoa/nsWidgetFactory.mm
@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.h"
+#include "mozilla/Components.h"
+#include "mozilla/ModuleUtils.h"
+#include "mozilla/WidgetUtils.h"
+
+#include "nsWidgetsCID.h"
+
+#include "nsChildView.h"
+#include "nsAppShell.h"
+#include "nsAppShellSingleton.h"
+#include "nsFilePicker.h"
+#include "nsColorPicker.h"
+
+#include "nsClipboard.h"
+#include "nsClipboardHelper.h"
+#include "HeadlessClipboard.h"
+#include "gfxPlatform.h"
+#include "nsTransferable.h"
+#include "nsHTMLFormatConverter.h"
+#include "nsDragService.h"
+#include "nsToolkit.h"
+
+#include "nsLookAndFeel.h"
+
+#include "nsSound.h"
+#include "nsUserIdleServiceX.h"
+#include "NativeKeyBindings.h"
+#include "OSXNotificationCenter.h"
+
+#include "nsDeviceContextSpecX.h"
+#include "nsPrinterListCUPS.h"
+#include "nsPrintSettingsServiceX.h"
+#include "nsPrintDialogX.h"
+#include "nsToolkitCompsCID.h"
+
+#include "mozilla/widget/ScreenManager.h"
+
+using namespace mozilla;
+using namespace mozilla::widget;
+
+NS_IMPL_COMPONENT_FACTORY(nsIClipboard) {
+  nsCOMPtr<nsIClipboard> inst;
+  if (gfxPlatform::IsHeadless()) {
+    inst = new HeadlessClipboard();
+  } else {
+    inst = new nsClipboard();
+  }
+
+  return inst.forget();
+}
+
+#define MAKE_GENERIC_CTOR(class_, iface_)    \
+  NS_IMPL_COMPONENT_FACTORY(class_) {        \
+    RefPtr inst = new class_();              \
+    return inst.forget().downcast<iface_>(); \
+  }
+
+#define MAKE_GENERIC_CTOR_INIT(class_, iface_, init_) \
+  NS_IMPL_COMPONENT_FACTORY(class_) {                 \
+    RefPtr inst = new class_();                       \
+    if (NS_SUCCEEDED(inst->init_())) {                \
+      return inst.forget().downcast<iface_>();        \
+    }                                                 \
+    return nullptr;                                   \
+  }
+
+#define MAKE_GENERIC_SINGLETON_CTOR(iface_, func_) \
+  NS_IMPL_COMPONENT_FACTORY(iface_) { return func_(); }
+
+MAKE_GENERIC_CTOR(nsFilePicker, nsIFilePicker)
+MAKE_GENERIC_CTOR(nsColorPicker, nsIColorPicker)
+MAKE_GENERIC_CTOR(nsSound, nsISound)
+MAKE_GENERIC_CTOR(nsTransferable, nsITransferable)
+MAKE_GENERIC_CTOR(nsHTMLFormatConverter, nsIFormatConverter)
+MAKE_GENERIC_CTOR(nsClipboardHelper, nsIClipboardHelper)
+MAKE_GENERIC_CTOR(nsDragService, nsIDragService)
+MAKE_GENERIC_CTOR(nsDeviceContextSpecX, nsIDeviceContextSpec)
+MAKE_GENERIC_CTOR(nsPrinterListCUPS, nsIPrinterList)
+MAKE_GENERIC_CTOR_INIT(nsPrintSettingsServiceX, nsIPrintSettingsService, Init)
+MAKE_GENERIC_CTOR_INIT(nsPrintDialogServiceX, nsIPrintDialogService, Init)
+MAKE_GENERIC_SINGLETON_CTOR(nsUserIdleServiceX, nsUserIdleServiceX::GetInstance)
+MAKE_GENERIC_SINGLETON_CTOR(ScreenManager, ScreenManager::GetAddRefedSingleton)
+MAKE_GENERIC_CTOR_INIT(OSXNotificationCenter, nsIAlertsService, Init)
+
+#include "nsMacDockSupport.h"
+MAKE_GENERIC_CTOR(nsMacDockSupport, nsIMacDockSupport)
+
+#include "nsMacFinderProgress.h"
+MAKE_GENERIC_CTOR(nsMacFinderProgress, nsIMacFinderProgress)
+
+#include "nsMacSharingService.h"
+MAKE_GENERIC_CTOR(nsMacSharingService, nsIMacSharingService)
+
+#include "nsMacUserActivityUpdater.h"
+MAKE_GENERIC_CTOR(nsMacUserActivityUpdater, nsIMacUserActivityUpdater)
+
+#include "nsMacWebAppUtils.h"
+MAKE_GENERIC_CTOR(nsMacWebAppUtils, nsIMacWebAppUtils)
+
+#include "nsStandaloneNativeMenu.h"
+MAKE_GENERIC_CTOR(nsStandaloneNativeMenu, nsIStandaloneNativeMenu)
+
+#include "nsSystemStatusBarCocoa.h"
+MAKE_GENERIC_CTOR(nsSystemStatusBarCocoa, nsISystemStatusBar)
+
+#include "nsTouchBarUpdater.h"
+MAKE_GENERIC_CTOR(nsTouchBarUpdater, nsITouchBarUpdater)
+
+void nsWidgetCocoaModuleCtor() { nsAppShellInit(); }
+
+void nsWidgetCocoaModuleDtor() {
+  // Shutdown all XP level widget classes.
+  WidgetUtils::Shutdown();
+
+  NativeKeyBindings::Shutdown();
+  nsLookAndFeel::Shutdown();
+  nsToolkit::Shutdown();
+  nsAppShellShutdown();
+}
diff --git a/widget/cocoa/nsWindowMap.h b/widget/cocoa/nsWindowMap.h
new file mode 100644
index 0000000000..9326415df7
--- /dev/null
+++ b/widget/cocoa/nsWindowMap.h
@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsWindowMap_h_
+#define nsWindowMap_h_
+
+#import <Cocoa/Cocoa.h>
+
+//  WindowDataMap
+//
+//  In both mozilla and embedding apps, we need to have a place to put
+//  per-top-level-window logic and data, to handle such things as IME
+//  commit when the window gains/loses focus. We can't use a window
+//  delegate, because an embeddor probably already has one. Nor can we
+//  subclass NSWindow, again because we can't impose that burden on the
+//  embeddor.
+//
+//  So we have a global map of NSWindow -> TopLevelWindowData, and set
+//  up TopLevelWindowData as a notification observer etc.
+
+@interface WindowDataMap : NSObject {
+ @private
+  NSMutableDictionary* mWindowMap;  // dict of TopLevelWindowData keyed by address of NSWindow
+}
+
++ (WindowDataMap*)sharedWindowDataMap;
+
+- (void)ensureDataForWindow:(NSWindow*)inWindow;
+- (id)dataForWindow:(NSWindow*)inWindow;
+
+// set data for a given window. inData is retained (and any previously set data
+// is released).
+- (void)setData:(id)inData forWindow:(NSWindow*)inWindow;
+
+// remove the data for the given window. the data is released.
+- (void)removeDataForWindow:(NSWindow*)inWindow;
+
+@end
+
+@class ChildView;
+
+//  TopLevelWindowData
+//
+//  Class to hold per-window data, and handle window state changes.
+
+@interface TopLevelWindowData : NSObject {
+ @private
+}
+
+  - (id)initWithWindow:(NSWindow*)inWindow;
+  + (void)activateInWindow:(NSWindow*)aWindow;
+  + (void)deactivateInWindow:(NSWindow*)aWindow;
+  + (void)activateInWindowViews:(NSWindow*)aWindow;
+  + (void)deactivateInWindowViews:(NSWindow*)aWindow;
+
+  @end
+
+#endif  // nsWindowMap_h_
diff --git a/widget/cocoa/nsWindowMap.mm b/widget/cocoa/nsWindowMap.mm
new file mode 100644
index 0000000000..010ed76cd7
--- /dev/null
+++ b/widget/cocoa/nsWindowMap.mm
@@ -0,0 +1,281 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsWindowMap.h"
+#include "nsObjCExceptions.h"
+#include "nsChildView.h"
+#include "nsCocoaWindow.h"
+
+@interface WindowDataMap (Private)
+
+- (NSString*)keyForWindow:(NSWindow*)inWindow;
+
+@end
+
+@interface TopLevelWindowData (Private)
+
+- (void)windowResignedKey:(NSNotification*)inNotification;
+- (void)windowBecameKey:(NSNotification*)inNotification;
+- (void)windowWillClose:(NSNotification*)inNotification;
+
+@end
+
+#pragma mark -
+
+@implementation WindowDataMap
+
++ (WindowDataMap*)sharedWindowDataMap {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  static WindowDataMap* sWindowMap = nil;
+  if (!sWindowMap) sWindowMap = [[WindowDataMap alloc] init];
+
+  return sWindowMap;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (id)init {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if ((self = [super init])) {
+    mWindowMap = [[NSMutableDictionary alloc] initWithCapacity:10];
+  }
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)dealloc {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mWindowMap release];
+  [super dealloc];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)ensureDataForWindow:(NSWindow*)inWindow {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!inWindow || [self dataForWindow:inWindow]) return;
+
+  TopLevelWindowData* windowData = [[TopLevelWindowData alloc] initWithWindow:inWindow];
+  [self setData:windowData forWindow:inWindow];  // takes ownership
+  [windowData release];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (id)dataForWindow:(NSWindow*)inWindow {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [mWindowMap objectForKey:[self keyForWindow:inWindow]];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)setData:(id)inData forWindow:(NSWindow*)inWindow {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mWindowMap setObject:inData forKey:[self keyForWindow:inWindow]];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)removeDataForWindow:(NSWindow*)inWindow {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [mWindowMap removeObjectForKey:[self keyForWindow:inWindow]];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (NSString*)keyForWindow:(NSWindow*)inWindow {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return [NSString stringWithFormat:@"%p", inWindow];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+@end
+
+//  TopLevelWindowData
+//
+//  This class holds data about top-level windows. We can't use a window
+//  delegate, because an embedder may already have one.
+
+@implementation TopLevelWindowData
+
+- (id)initWithWindow:(NSWindow*)inWindow {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if ((self = [super init])) {
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(windowBecameKey:)
+                                                 name:NSWindowDidBecomeKeyNotification
+                                               object:inWindow];
+
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(windowResignedKey:)
+                                                 name:NSWindowDidResignKeyNotification
+                                               object:inWindow];
+
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(windowBecameMain:)
+                                                 name:NSWindowDidBecomeMainNotification
+                                               object:inWindow];
+
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(windowResignedMain:)
+                                                 name:NSWindowDidResignMainNotification
+                                               object:inWindow];
+
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(windowWillClose:)
+                                                 name:NSWindowWillCloseNotification
+                                               object:inWindow];
+  }
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)dealloc {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+  [super dealloc];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// As best I can tell, if the notification's object has a corresponding
+// top-level widget (an nsCocoaWindow object), it has a delegate (set in
+// nsCocoaWindow::StandardCreate()) of class WindowDelegate, and otherwise
+// not (Camino didn't use top-level widgets (nsCocoaWindow objects) --
+// only child widgets (nsChildView objects)).  (The notification is sent
+// to windowBecameKey: or windowBecameMain: below.)
+//
+// For use with clients that (like Firefox) do use top-level widgets (and
+// have NSWindow delegates of class WindowDelegate).
++ (void)activateInWindow:(NSWindow*)aWindow {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  WindowDelegate* delegate = (WindowDelegate*)[aWindow delegate];
+  if (!delegate || ![delegate isKindOfClass:[WindowDelegate class]]) return;
+
+  if ([delegate toplevelActiveState]) return;
+  [delegate sendToplevelActivateEvents];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// See comments above activateInWindow:
+//
+// If we're using top-level widgets (nsCocoaWindow objects), we send them
+// NS_DEACTIVATE events (which propagate to child widgets (nsChildView
+// objects) via nsWebShellWindow::HandleEvent()).
+//
+// For use with clients that (like Firefox) do use top-level widgets (and
+// have NSWindow delegates of class WindowDelegate).
++ (void)deactivateInWindow:(NSWindow*)aWindow {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  WindowDelegate* delegate = (WindowDelegate*)[aWindow delegate];
+  if (!delegate || ![delegate isKindOfClass:[WindowDelegate class]]) return;
+
+  if (![delegate toplevelActiveState]) return;
+  [delegate sendToplevelDeactivateEvents];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// For use with clients that (like Camino) don't use top-level widgets (and
+// don't have NSWindow delegates of class WindowDelegate).
++ (void)activateInWindowViews:(NSWindow*)aWindow {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  id firstResponder = [aWindow firstResponder];
+  if ([firstResponder isKindOfClass:[ChildView class]]) [firstResponder viewsWindowDidBecomeKey];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// For use with clients that (like Camino) don't use top-level widgets (and
+// don't have NSWindow delegates of class WindowDelegate).
++ (void)deactivateInWindowViews:(NSWindow*)aWindow {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  id firstResponder = [aWindow firstResponder];
+  if ([firstResponder isKindOfClass:[ChildView class]]) [firstResponder viewsWindowDidResignKey];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// We make certain exceptions for top-level windows in non-embedders (see
+// comment above windowBecameMain below).  And we need (elsewhere) to guard
+// against sending duplicate events.  But in general the NS_ACTIVATE event
+// should be sent when a native window becomes key, and the NS_DEACTIVATE
+// event should be sent when it resignes key.
+- (void)windowBecameKey:(NSNotification*)inNotification {
+  NSWindow* window = (NSWindow*)[inNotification object];
+
+  id delegate = [window delegate];
+  if (!delegate || ![delegate isKindOfClass:[WindowDelegate class]]) {
+    [TopLevelWindowData activateInWindowViews:window];
+  } else if ([window isSheet] || [NSApp modalWindow]) {
+    [TopLevelWindowData activateInWindow:window];
+  }
+}
+
+- (void)windowResignedKey:(NSNotification*)inNotification {
+  NSWindow* window = (NSWindow*)[inNotification object];
+
+  id delegate = [window delegate];
+  if (!delegate || ![delegate isKindOfClass:[WindowDelegate class]]) {
+    [TopLevelWindowData deactivateInWindowViews:window];
+  } else if ([window isSheet] || [NSApp modalWindow]) {
+    [TopLevelWindowData deactivateInWindow:window];
+  }
+}
+
+// The appearance of a top-level window depends on its main state (not its key
+// state).  So (for non-embedders) we need to ensure that a top-level window
+// is main when an NS_ACTIVATE event is sent to Gecko for it.
+- (void)windowBecameMain:(NSNotification*)inNotification {
+  NSWindow* window = (NSWindow*)[inNotification object];
+
+  id delegate = [window delegate];
+  // Don't send events to a top-level window that has a sheet/modal-window open
+  // above it -- as far as Gecko is concerned, it's inactive, and stays so until
+  // the sheet/modal-window closes.
+  if (delegate && [delegate isKindOfClass:[WindowDelegate class]] &&
+      ![window attachedSheet] && ![NSApp modalWindow])
+    [TopLevelWindowData activateInWindow:window];
+}
+
+- (void)windowResignedMain:(NSNotification*)inNotification {
+  NSWindow* window = (NSWindow*)[inNotification object];
+
+  id delegate = [window delegate];
+  if (delegate && [delegate isKindOfClass:[WindowDelegate class]] && ![window attachedSheet])
+    [TopLevelWindowData deactivateInWindow:window];
+}
+
+- (void)windowWillClose:(NSNotification*)inNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // postpone our destruction
+  [[self retain] autorelease];
+
+  // remove ourselves from the window map (which owns us)
+  [[WindowDataMap sharedWindowDataMap] removeDataForWindow:[inNotification object]];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+@end
diff --git a/widget/cocoa/resources/MainMenu.nib/classes.nib b/widget/cocoa/resources/MainMenu.nib/classes.nib
new file mode 100644
index 0000000000..b9b4b09f6b
--- /dev/null
+++ b/widget/cocoa/resources/MainMenu.nib/classes.nib
@@ -0,0 +1,4 @@
+{
+    IBClasses = ({CLASS = FirstResponder; LANGUAGE = ObjC; SUPERCLASS = NSObject; }); 
+    IBVersion = 1; 
+}
\ No newline at end of file
diff --git a/widget/cocoa/resources/MainMenu.nib/info.nib b/widget/cocoa/resources/MainMenu.nib/info.nib
new file mode 100644
index 0000000000..bcf3ace841
--- /dev/null
+++ b/widget/cocoa/resources/MainMenu.nib/info.nib
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IBDocumentLocation</key>
+	<string>159 127 356 240 0 0 1920 1178 </string>
+	<key>IBEditorPositions</key>
+	<dict>
+		<key>29</key>
+		<string>413 971 130 44 0 0 1920 1178 </string>
+	</dict>
+	<key>IBFramework Version</key>
+	<string>443.0</string>
+	<key>IBOpenObjects</key>
+	<array>
+		<integer>29</integer>
+	</array>
+	<key>IBSystem Version</key>
+	<string>8F46</string>
+</dict>
+</plist>
diff --git a/widget/cocoa/resources/MainMenu.nib/keyedobjects.nib b/widget/cocoa/resources/MainMenu.nib/keyedobjects.nib
new file mode 100644
index 0000000000..16b3f7e523
--- /dev/null
+++ b/widget/cocoa/resources/MainMenu.nib/keyedobjects.nib