Adding upstream version 115.7.0esr.upstream/115.7.0esr

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

94 files changed, 17872 insertions, 0 deletions

diff --git a/widget/android/AndroidAlerts.cpp b/widget/android/AndroidAlerts.cpp
new file mode 100644
index 0000000000..456dc08290
--- /dev/null
+++ b/widget/android/AndroidAlerts.cpp
@@ -0,0 +1,159 @@
+/* -*- 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 "AndroidAlerts.h"
+#include "mozilla/java/GeckoRuntimeWrappers.h"
+#include "mozilla/java/WebNotificationWrappers.h"
+#include "nsIPrincipal.h"
+#include "nsIURI.h"
+
+namespace mozilla {
+namespace widget {
+
+NS_IMPL_ISUPPORTS(AndroidAlerts, nsIAlertsService)
+
+StaticAutoPtr<AndroidAlerts::ListenerMap> AndroidAlerts::sListenerMap;
+nsTHashMap<nsStringHashKey, java::WebNotification::GlobalRef>
+    AndroidAlerts::mNotificationsMap;
+
+NS_IMETHODIMP
+AndroidAlerts::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) {
+  MOZ_ASSERT_UNREACHABLE("Should be implemented by nsAlertsService.");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+AndroidAlerts::ShowAlert(nsIAlertNotification* aAlert,
+                         nsIObserver* aAlertListener) {
+  return ShowPersistentNotification(u""_ns, aAlert, aAlertListener);
+}
+
+NS_IMETHODIMP
+AndroidAlerts::ShowPersistentNotification(const nsAString& aPersistentData,
+                                          nsIAlertNotification* aAlert,
+                                          nsIObserver* aAlertListener) {
+  // nsAlertsService disables our alerts backend if we ever return failure
+  // here. To keep the backend enabled, we always return NS_OK even if we
+  // encounter an error here.
+  nsresult rv;
+
+  nsAutoString imageUrl;
+  rv = aAlert->GetImageURL(imageUrl);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  nsAutoString title;
+  rv = aAlert->GetTitle(title);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  nsAutoString text;
+  rv = aAlert->GetText(text);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  nsAutoString cookie;
+  rv = aAlert->GetCookie(cookie);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  nsAutoString name;
+  rv = aAlert->GetName(name);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  nsAutoString lang;
+  rv = aAlert->GetLang(lang);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  nsAutoString dir;
+  rv = aAlert->GetDir(dir);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  bool requireInteraction;
+  rv = aAlert->GetRequireInteraction(&requireInteraction);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  nsCOMPtr<nsIURI> uri;
+  rv = aAlert->GetURI(getter_AddRefs(uri));
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  nsCString spec;
+  if (uri) {
+    rv = uri->GetDisplaySpec(spec);
+    NS_ENSURE_SUCCESS(rv, NS_OK);
+  }
+
+  bool silent;
+  rv = aAlert->GetSilent(&silent);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  bool privateBrowsing;
+  rv = aAlert->GetInPrivateBrowsing(&privateBrowsing);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  nsTArray<uint32_t> vibrate;
+  rv = aAlert->GetVibrate(vibrate);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  if (aPersistentData.IsEmpty() && aAlertListener) {
+    if (!sListenerMap) {
+      sListenerMap = new ListenerMap();
+    }
+    // This will remove any observers already registered for this name.
+    sListenerMap->InsertOrUpdate(name, aAlertListener);
+  }
+
+  java::WebNotification::LocalRef notification = notification->New(
+      title, name, cookie, text, imageUrl, dir, lang, requireInteraction, spec,
+      silent, privateBrowsing, jni::IntArray::From(vibrate));
+  java::GeckoRuntime::LocalRef runtime = java::GeckoRuntime::GetInstance();
+  if (runtime != NULL) {
+    runtime->NotifyOnShow(notification);
+  }
+  mNotificationsMap.InsertOrUpdate(name, notification);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AndroidAlerts::CloseAlert(const nsAString& aAlertName, bool aContextClosed) {
+  java::WebNotification::LocalRef notification =
+      mNotificationsMap.Get(aAlertName);
+  if (!notification) {
+    return NS_OK;
+  }
+
+  java::GeckoRuntime::LocalRef runtime = java::GeckoRuntime::GetInstance();
+  if (runtime != NULL) {
+    runtime->NotifyOnClose(notification);
+  }
+  mNotificationsMap.Remove(aAlertName);
+
+  return NS_OK;
+}
+
+void AndroidAlerts::NotifyListener(const nsAString& aName, const char* aTopic,
+                                   const char16_t* aCookie) {
+  if (!sListenerMap) {
+    return;
+  }
+
+  nsCOMPtr<nsIObserver> listener = sListenerMap->Get(aName);
+  if (!listener) {
+    return;
+  }
+
+  listener->Observe(nullptr, aTopic, aCookie);
+
+  if ("alertfinished"_ns.Equals(aTopic)) {
+    sListenerMap->Remove(aName);
+    mNotificationsMap.Remove(aName);
+  }
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/AndroidAlerts.h b/widget/android/AndroidAlerts.h
new file mode 100644
index 0000000000..f4a9822dc1
--- /dev/null
+++ b/widget/android/AndroidAlerts.h
@@ -0,0 +1,46 @@
+/* -*- 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_AndroidAlerts_h__
+#define mozilla_widget_AndroidAlerts_h__
+
+#include "nsTHashMap.h"
+#include "nsInterfaceHashtable.h"
+#include "nsCOMPtr.h"
+#include "nsHashKeys.h"
+#include "nsIAlertsService.h"
+#include "nsIObserver.h"
+
+#include "mozilla/java/WebNotificationWrappers.h"
+
+#include "mozilla/StaticPtr.h"
+
+namespace mozilla {
+namespace widget {
+
+class AndroidAlerts : public nsIAlertsService {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIALERTSSERVICE
+
+  AndroidAlerts() {}
+
+  static void NotifyListener(const nsAString& aName, const char* aTopic,
+                             const char16_t* aCookie);
+
+  static nsTHashMap<nsStringHashKey, mozilla::java::WebNotification::GlobalRef>
+      mNotificationsMap;
+
+ protected:
+  virtual ~AndroidAlerts() { sListenerMap = nullptr; }
+
+  using ListenerMap = nsInterfaceHashtable<nsStringHashKey, nsIObserver>;
+  static StaticAutoPtr<ListenerMap> sListenerMap;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // nsAndroidAlerts_h__
diff --git a/widget/android/AndroidBridge.cpp b/widget/android/AndroidBridge.cpp
new file mode 100644
index 0000000000..024b64036d
--- /dev/null
+++ b/widget/android/AndroidBridge.cpp
@@ -0,0 +1,431 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 <android/log.h>
+#include <dlfcn.h>
+#include <math.h>
+#include <GLES2/gl2.h>
+
+#include "mozilla/layers/CompositorBridgeChild.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+
+#include "mozilla/Hal.h"
+#include "nsXULAppAPI.h"
+#include <prthread.h>
+#include "AndroidBridge.h"
+#include "AndroidBridgeUtilities.h"
+#include "nsAlertsUtils.h"
+#include "nsAppShell.h"
+#include "nsOSHelperAppService.h"
+#include "nsWindow.h"
+#include "mozilla/Preferences.h"
+#include "nsThreadUtils.h"
+#include "nsPresContext.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/Mutex.h"
+#include "nsPrintfCString.h"
+#include "nsContentUtils.h"
+
+#include "EventDispatcher.h"
+
+#include "mozilla/TimeStamp.h"
+#include "mozilla/UniquePtr.h"
+#include "WidgetUtils.h"
+
+#include "mozilla/java/EventDispatcherWrappers.h"
+#include "mozilla/java/GeckoAppShellWrappers.h"
+#include "mozilla/java/GeckoThreadWrappers.h"
+
+using namespace mozilla;
+
+AndroidBridge* AndroidBridge::sBridge = nullptr;
+static jobject sGlobalContext = nullptr;
+nsTHashMap<nsStringHashKey, nsString> AndroidBridge::sStoragePaths;
+
+jmethodID AndroidBridge::GetMethodID(JNIEnv* env, jclass jClass,
+                                     const char* methodName,
+                                     const char* methodType) {
+  jmethodID methodID = env->GetMethodID(jClass, methodName, methodType);
+  if (!methodID) {
+    ALOG(
+        ">>> FATAL JNI ERROR! GetMethodID(methodName=\"%s\", "
+        "methodType=\"%s\") failed. Did ProGuard optimize away something it "
+        "shouldn't have?",
+        methodName, methodType);
+    env->ExceptionDescribe();
+    MOZ_CRASH();
+  }
+  return methodID;
+}
+
+jmethodID AndroidBridge::GetStaticMethodID(JNIEnv* env, jclass jClass,
+                                           const char* methodName,
+                                           const char* methodType) {
+  jmethodID methodID = env->GetStaticMethodID(jClass, methodName, methodType);
+  if (!methodID) {
+    ALOG(
+        ">>> FATAL JNI ERROR! GetStaticMethodID(methodName=\"%s\", "
+        "methodType=\"%s\") failed. Did ProGuard optimize away something it "
+        "shouldn't have?",
+        methodName, methodType);
+    env->ExceptionDescribe();
+    MOZ_CRASH();
+  }
+  return methodID;
+}
+
+jfieldID AndroidBridge::GetFieldID(JNIEnv* env, jclass jClass,
+                                   const char* fieldName,
+                                   const char* fieldType) {
+  jfieldID fieldID = env->GetFieldID(jClass, fieldName, fieldType);
+  if (!fieldID) {
+    ALOG(
+        ">>> FATAL JNI ERROR! GetFieldID(fieldName=\"%s\", "
+        "fieldType=\"%s\") failed. Did ProGuard optimize away something it "
+        "shouldn't have?",
+        fieldName, fieldType);
+    env->ExceptionDescribe();
+    MOZ_CRASH();
+  }
+  return fieldID;
+}
+
+jfieldID AndroidBridge::GetStaticFieldID(JNIEnv* env, jclass jClass,
+                                         const char* fieldName,
+                                         const char* fieldType) {
+  jfieldID fieldID = env->GetStaticFieldID(jClass, fieldName, fieldType);
+  if (!fieldID) {
+    ALOG(
+        ">>> FATAL JNI ERROR! GetStaticFieldID(fieldName=\"%s\", "
+        "fieldType=\"%s\") failed. Did ProGuard optimize away something it "
+        "shouldn't have?",
+        fieldName, fieldType);
+    env->ExceptionDescribe();
+    MOZ_CRASH();
+  }
+  return fieldID;
+}
+
+void AndroidBridge::ConstructBridge() {
+  /* NSS hack -- bionic doesn't handle recursive unloads correctly,
+   * because library finalizer functions are called with the dynamic
+   * linker lock still held.  This results in a deadlock when trying
+   * to call dlclose() while we're already inside dlclose().
+   * Conveniently, NSS has an env var that can prevent it from unloading.
+   */
+  putenv(const_cast<char*>("NSS_DISABLE_UNLOAD=1"));
+
+  MOZ_ASSERT(!sBridge);
+  sBridge = new AndroidBridge();
+}
+
+void AndroidBridge::DeconstructBridge() {
+  if (sBridge) {
+    delete sBridge;
+    // AndroidBridge destruction requires sBridge to still be valid,
+    // so we set sBridge to nullptr after deleting it.
+    sBridge = nullptr;
+  }
+}
+
+AndroidBridge::~AndroidBridge() {}
+
+AndroidBridge::AndroidBridge() {
+  ALOG_BRIDGE("AndroidBridge::Init");
+
+  JNIEnv* const jEnv = jni::GetGeckoThreadEnv();
+  AutoLocalJNIFrame jniFrame(jEnv);
+
+  mMessageQueue = java::GeckoThread::MsgQueue();
+  auto msgQueueClass = jni::Class::LocalRef::Adopt(
+      jEnv, jEnv->GetObjectClass(mMessageQueue.Get()));
+  // mMessageQueueNext must not be null
+  mMessageQueueNext =
+      GetMethodID(jEnv, msgQueueClass.Get(), "next", "()Landroid/os/Message;");
+  // mMessageQueueMessages may be null (e.g. due to proguard optimization)
+  mMessageQueueMessages = jEnv->GetFieldID(msgQueueClass.Get(), "mMessages",
+                                           "Landroid/os/Message;");
+}
+
+void AndroidBridge::Vibrate(const nsTArray<uint32_t>& aPattern) {
+  ALOG_BRIDGE("%s", __PRETTY_FUNCTION__);
+
+  uint32_t len = aPattern.Length();
+  if (!len) {
+    ALOG_BRIDGE("  invalid 0-length array");
+    return;
+  }
+
+  // It's clear if this worth special-casing, but it creates less
+  // java junk, so dodges the GC.
+  if (len == 1) {
+    jlong d = aPattern[0];
+    if (d < 0) {
+      ALOG_BRIDGE("  invalid vibration duration < 0");
+      return;
+    }
+    java::GeckoAppShell::Vibrate(d);
+    return;
+  }
+
+  // First element of the array vibrate() expects is how long to wait
+  // *before* vibrating.  For us, this is always 0.
+
+  JNIEnv* const env = jni::GetGeckoThreadEnv();
+  AutoLocalJNIFrame jniFrame(env, 1);
+
+  jlongArray array = env->NewLongArray(len + 1);
+  if (!array) {
+    ALOG_BRIDGE("  failed to allocate array");
+    return;
+  }
+
+  jlong* elts = env->GetLongArrayElements(array, nullptr);
+  elts[0] = 0;
+  for (uint32_t i = 0; i < aPattern.Length(); ++i) {
+    jlong d = aPattern[i];
+    if (d < 0) {
+      ALOG_BRIDGE("  invalid vibration duration < 0");
+      env->ReleaseLongArrayElements(array, elts, JNI_ABORT);
+      return;
+    }
+    elts[i + 1] = d;
+  }
+  env->ReleaseLongArrayElements(array, elts, 0);
+
+  java::GeckoAppShell::Vibrate(jni::LongArray::Ref::From(array),
+                               -1 /* don't repeat */);
+}
+
+void AndroidBridge::GetIconForExtension(const nsACString& aFileExt,
+                                        uint32_t aIconSize,
+                                        uint8_t* const aBuf) {
+  ALOG_BRIDGE("AndroidBridge::GetIconForExtension");
+  NS_ASSERTION(aBuf != nullptr,
+               "AndroidBridge::GetIconForExtension: aBuf is null!");
+  if (!aBuf) return;
+
+  auto arr = java::GeckoAppShell::GetIconForExtension(
+      NS_ConvertUTF8toUTF16(aFileExt), aIconSize);
+
+  NS_ASSERTION(
+      arr != nullptr,
+      "AndroidBridge::GetIconForExtension: Returned pixels array is null!");
+  if (!arr) return;
+
+  JNIEnv* const env = arr.Env();
+  uint32_t len = static_cast<uint32_t>(env->GetArrayLength(arr.Get()));
+  jbyte* elements = env->GetByteArrayElements(arr.Get(), 0);
+
+  uint32_t bufSize = aIconSize * aIconSize * 4;
+  NS_ASSERTION(
+      len == bufSize,
+      "AndroidBridge::GetIconForExtension: Pixels array is incomplete!");
+  if (len == bufSize) memcpy(aBuf, elements, bufSize);
+
+  env->ReleaseByteArrayElements(arr.Get(), elements, 0);
+}
+
+namespace mozilla {
+class TracerRunnable : public Runnable {
+ public:
+  TracerRunnable() : Runnable("TracerRunnable") {
+    mTracerLock = new Mutex("TracerRunnable");
+    mTracerCondVar = new CondVar(*mTracerLock, "TracerRunnable");
+    mMainThread = do_GetMainThread();
+  }
+  ~TracerRunnable() {
+    delete mTracerCondVar;
+    delete mTracerLock;
+    mTracerLock = nullptr;
+    mTracerCondVar = nullptr;
+  }
+
+  virtual nsresult Run() {
+    MutexAutoLock lock(*mTracerLock);
+    if (!AndroidBridge::Bridge()) return NS_OK;
+
+    mHasRun = true;
+    mTracerCondVar->Notify();
+    return NS_OK;
+  }
+
+  bool Fire() {
+    if (!mTracerLock || !mTracerCondVar) return false;
+    MutexAutoLock lock(*mTracerLock);
+    mHasRun = false;
+    mMainThread->Dispatch(this, NS_DISPATCH_NORMAL);
+    while (!mHasRun) mTracerCondVar->Wait();
+    return true;
+  }
+
+  void Signal() {
+    MutexAutoLock lock(*mTracerLock);
+    mHasRun = true;
+    mTracerCondVar->Notify();
+  }
+
+ private:
+  Mutex* mTracerLock;
+  CondVar* mTracerCondVar;
+  bool mHasRun;
+  nsCOMPtr<nsIThread> mMainThread;
+};
+StaticRefPtr<TracerRunnable> sTracerRunnable;
+
+bool InitWidgetTracing() {
+  if (!sTracerRunnable) sTracerRunnable = new TracerRunnable();
+  return true;
+}
+
+void CleanUpWidgetTracing() { sTracerRunnable = nullptr; }
+
+bool FireAndWaitForTracerEvent() {
+  if (sTracerRunnable) return sTracerRunnable->Fire();
+  return false;
+}
+
+void SignalTracerThread() {
+  if (sTracerRunnable) return sTracerRunnable->Signal();
+}
+
+}  // namespace mozilla
+
+void AndroidBridge::GetCurrentBatteryInformation(
+    hal::BatteryInformation* aBatteryInfo) {
+  ALOG_BRIDGE("AndroidBridge::GetCurrentBatteryInformation");
+
+  // To prevent calling too many methods through JNI, the Java method returns
+  // an array of double even if we actually want a double and a boolean.
+  auto arr = java::GeckoAppShell::GetCurrentBatteryInformation();
+
+  JNIEnv* const env = arr.Env();
+  if (!arr || env->GetArrayLength(arr.Get()) != 3) {
+    return;
+  }
+
+  jdouble* info = env->GetDoubleArrayElements(arr.Get(), 0);
+
+  aBatteryInfo->level() = info[0];
+  aBatteryInfo->charging() = info[1] == 1.0f;
+  aBatteryInfo->remainingTime() = info[2];
+
+  env->ReleaseDoubleArrayElements(arr.Get(), info, 0);
+}
+
+void AndroidBridge::GetCurrentNetworkInformation(
+    hal::NetworkInformation* aNetworkInfo) {
+  ALOG_BRIDGE("AndroidBridge::GetCurrentNetworkInformation");
+
+  // To prevent calling too many methods through JNI, the Java method returns
+  // an array of double even if we actually want an integer, a boolean, and an
+  // integer.
+
+  auto arr = java::GeckoAppShell::GetCurrentNetworkInformation();
+
+  JNIEnv* const env = arr.Env();
+  if (!arr || env->GetArrayLength(arr.Get()) != 3) {
+    return;
+  }
+
+  jdouble* info = env->GetDoubleArrayElements(arr.Get(), 0);
+
+  aNetworkInfo->type() = info[0];
+  aNetworkInfo->isWifi() = info[1] == 1.0f;
+  aNetworkInfo->dhcpGateway() = info[2];
+
+  env->ReleaseDoubleArrayElements(arr.Get(), info, 0);
+}
+
+jobject AndroidBridge::GetGlobalContextRef() {
+  // The context object can change, so get a fresh copy every time.
+  auto context = java::GeckoAppShell::GetApplicationContext();
+  sGlobalContext = jni::Object::GlobalRef(context).Forget();
+  MOZ_ASSERT(sGlobalContext);
+  return sGlobalContext;
+}
+
+/* Implementation file */
+NS_IMPL_ISUPPORTS(nsAndroidBridge, nsIAndroidEventDispatcher, nsIAndroidBridge)
+
+nsAndroidBridge::nsAndroidBridge() {
+  if (jni::IsAvailable()) {
+    RefPtr<widget::EventDispatcher> dispatcher = new widget::EventDispatcher();
+    dispatcher->Attach(java::EventDispatcher::GetInstance(),
+                       /* window */ nullptr);
+    mEventDispatcher = dispatcher;
+  }
+}
+
+NS_IMETHODIMP
+nsAndroidBridge::GetDispatcherByName(const char* aName,
+                                     nsIAndroidEventDispatcher** aResult) {
+  if (!jni::IsAvailable()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  RefPtr<widget::EventDispatcher> dispatcher = new widget::EventDispatcher();
+  dispatcher->Attach(java::EventDispatcher::ByName(aName),
+                     /* window */ nullptr);
+  dispatcher.forget(aResult);
+  return NS_OK;
+}
+
+nsAndroidBridge::~nsAndroidBridge() {}
+
+hal::ScreenOrientation AndroidBridge::GetScreenOrientation() {
+  ALOG_BRIDGE("AndroidBridge::GetScreenOrientation");
+
+  int16_t orientation = java::GeckoAppShell::GetScreenOrientation();
+
+  return hal::ScreenOrientation(orientation);
+}
+
+uint16_t AndroidBridge::GetScreenAngle() {
+  return java::GeckoAppShell::GetScreenAngle();
+}
+
+nsresult AndroidBridge::GetProxyForURI(const nsACString& aSpec,
+                                       const nsACString& aScheme,
+                                       const nsACString& aHost,
+                                       const int32_t aPort,
+                                       nsACString& aResult) {
+  if (!jni::IsAvailable()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  auto jstrRet =
+      java::GeckoAppShell::GetProxyForURI(aSpec, aScheme, aHost, aPort);
+
+  if (!jstrRet) return NS_ERROR_FAILURE;
+
+  aResult = jstrRet->ToCString();
+  return NS_OK;
+}
+
+bool AndroidBridge::PumpMessageLoop() {
+  JNIEnv* const env = jni::GetGeckoThreadEnv();
+
+  if (mMessageQueueMessages) {
+    auto msg = jni::Object::LocalRef::Adopt(
+        env, env->GetObjectField(mMessageQueue.Get(), mMessageQueueMessages));
+    // if queue.mMessages is null, queue.next() will block, which we don't
+    // want. It turns out to be an order of magnitude more performant to do
+    // this extra check here and block less vs. one fewer checks here and
+    // more blocking.
+    if (!msg) {
+      return false;
+    }
+  }
+
+  auto msg = jni::Object::LocalRef::Adopt(
+      env, env->CallObjectMethod(mMessageQueue.Get(), mMessageQueueNext));
+  if (!msg) {
+    return false;
+  }
+
+  return java::GeckoThread::PumpMessageLoop(msg);
+}
diff --git a/widget/android/AndroidBridge.h b/widget/android/AndroidBridge.h
new file mode 100644
index 0000000000..f2070ef31a
--- /dev/null
+++ b/widget/android/AndroidBridge.h
@@ -0,0 +1,275 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 AndroidBridge_h__
+#define AndroidBridge_h__
+
+#include <unistd.h>  // for gettid
+
+#include "nsCOMPtr.h"
+
+#include "mozilla/jni/Refs.h"
+
+#include "nsIMutableArray.h"
+#include "nsIMIMEInfo.h"
+
+#include "nsIAndroidBridge.h"
+
+#include "mozilla/jni/Utils.h"
+#include "nsTHashMap.h"
+
+// Some debug #defines
+// #define DEBUG_ANDROID_EVENTS
+// #define DEBUG_ANDROID_WIDGET
+
+namespace mozilla {
+
+class AutoLocalJNIFrame;
+
+namespace hal {
+class BatteryInformation;
+class NetworkInformation;
+enum class ScreenOrientation : uint32_t;
+}  // namespace hal
+
+class AndroidBridge final {
+ public:
+  static bool IsJavaUiThread() {
+    return mozilla::jni::GetUIThreadId() == gettid();
+  }
+
+  static void ConstructBridge();
+  static void DeconstructBridge();
+
+  static AndroidBridge* Bridge() { return sBridge; }
+
+  bool GetHandlersForURL(const nsAString& aURL,
+                         nsIMutableArray* handlersArray = nullptr,
+                         nsIHandlerApp** aDefaultApp = nullptr,
+                         const nsAString& aAction = u""_ns);
+
+  bool GetHandlersForMimeType(const nsAString& aMimeType,
+                              nsIMutableArray* handlersArray = nullptr,
+                              nsIHandlerApp** aDefaultApp = nullptr,
+                              const nsAString& aAction = u""_ns);
+
+  void GetMimeTypeFromExtensions(const nsACString& aFileExt,
+                                 nsCString& aMimeType);
+  void GetExtensionFromMimeType(const nsACString& aMimeType,
+                                nsACString& aFileExt);
+
+  void Vibrate(const nsTArray<uint32_t>& aPattern);
+
+  void GetIconForExtension(const nsACString& aFileExt, uint32_t aIconSize,
+                           uint8_t* const aBuf);
+
+  // Returns a global reference to the Context for Fennec's Activity. The
+  // caller is responsible for ensuring this doesn't leak by calling
+  // DeleteGlobalRef() when the context is no longer needed.
+  jobject GetGlobalContextRef(void);
+
+  void GetCurrentBatteryInformation(hal::BatteryInformation* aBatteryInfo);
+
+  void GetCurrentNetworkInformation(hal::NetworkInformation* aNetworkInfo);
+
+  hal::ScreenOrientation GetScreenOrientation();
+  uint16_t GetScreenAngle();
+
+  nsresult GetProxyForURI(const nsACString& aSpec, const nsACString& aScheme,
+                          const nsACString& aHost, const int32_t aPort,
+                          nsACString& aResult);
+
+  bool PumpMessageLoop();
+
+  // Utility methods.
+  static jfieldID GetFieldID(JNIEnv* env, jclass jClass, const char* fieldName,
+                             const char* fieldType);
+  static jfieldID GetStaticFieldID(JNIEnv* env, jclass jClass,
+                                   const char* fieldName,
+                                   const char* fieldType);
+  static jmethodID GetMethodID(JNIEnv* env, jclass jClass,
+                               const char* methodName, const char* methodType);
+  static jmethodID GetStaticMethodID(JNIEnv* env, jclass jClass,
+                                     const char* methodName,
+                                     const char* methodType);
+
+  static jni::Object::LocalRef ChannelCreate(jni::Object::Param);
+
+  static void InputStreamClose(jni::Object::Param obj);
+  static uint32_t InputStreamAvailable(jni::Object::Param obj);
+  static nsresult InputStreamRead(jni::Object::Param obj, char* aBuf,
+                                  uint32_t aCount, uint32_t* aRead);
+
+ protected:
+  static nsTHashMap<nsStringHashKey, nsString> sStoragePaths;
+
+  static AndroidBridge* sBridge;
+
+  AndroidBridge();
+  ~AndroidBridge();
+
+  jni::Object::GlobalRef mMessageQueue;
+  jfieldID mMessageQueueMessages;
+  jmethodID mMessageQueueNext;
+};
+
+class AutoJNIClass {
+ private:
+  JNIEnv* const mEnv;
+  const jclass mClass;
+
+ public:
+  AutoJNIClass(JNIEnv* jEnv, const char* name)
+      : mEnv(jEnv), mClass(jni::GetClassRef(jEnv, name)) {}
+
+  ~AutoJNIClass() { mEnv->DeleteLocalRef(mClass); }
+
+  jclass getRawRef() const { return mClass; }
+
+  jclass getGlobalRef() const {
+    return static_cast<jclass>(mEnv->NewGlobalRef(mClass));
+  }
+
+  jfieldID getField(const char* name, const char* type) const {
+    return AndroidBridge::GetFieldID(mEnv, mClass, name, type);
+  }
+
+  jfieldID getStaticField(const char* name, const char* type) const {
+    return AndroidBridge::GetStaticFieldID(mEnv, mClass, name, type);
+  }
+
+  jmethodID getMethod(const char* name, const char* type) const {
+    return AndroidBridge::GetMethodID(mEnv, mClass, name, type);
+  }
+
+  jmethodID getStaticMethod(const char* name, const char* type) const {
+    return AndroidBridge::GetStaticMethodID(mEnv, mClass, name, type);
+  }
+};
+
+class AutoJObject {
+ public:
+  explicit AutoJObject(JNIEnv* aJNIEnv = nullptr) : mObject(nullptr) {
+    mJNIEnv = aJNIEnv ? aJNIEnv : jni::GetGeckoThreadEnv();
+  }
+
+  AutoJObject(JNIEnv* aJNIEnv, jobject aObject) {
+    mJNIEnv = aJNIEnv ? aJNIEnv : jni::GetGeckoThreadEnv();
+    mObject = aObject;
+  }
+
+  ~AutoJObject() {
+    if (mObject) mJNIEnv->DeleteLocalRef(mObject);
+  }
+
+  jobject operator=(jobject aObject) {
+    if (mObject) {
+      mJNIEnv->DeleteLocalRef(mObject);
+    }
+    return mObject = aObject;
+  }
+
+  operator jobject() { return mObject; }
+
+ private:
+  JNIEnv* mJNIEnv;
+  jobject mObject;
+};
+
+class AutoLocalJNIFrame {
+ public:
+  explicit AutoLocalJNIFrame(int nEntries = 15)
+      : mEntries(nEntries),
+        mJNIEnv(jni::GetGeckoThreadEnv()),
+        mHasFrameBeenPushed(false) {
+    MOZ_ASSERT(mJNIEnv);
+    Push();
+  }
+
+  explicit AutoLocalJNIFrame(JNIEnv* aJNIEnv, int nEntries = 15)
+      : mEntries(nEntries),
+        mJNIEnv(aJNIEnv ? aJNIEnv : jni::GetGeckoThreadEnv()),
+        mHasFrameBeenPushed(false) {
+    MOZ_ASSERT(mJNIEnv);
+    Push();
+  }
+
+  ~AutoLocalJNIFrame() {
+    if (mHasFrameBeenPushed) {
+      Pop();
+    }
+  }
+
+  JNIEnv* GetEnv() { return mJNIEnv; }
+
+  bool CheckForException() {
+    if (mJNIEnv->ExceptionCheck()) {
+      MOZ_CATCH_JNI_EXCEPTION(mJNIEnv);
+      return true;
+    }
+    return false;
+  }
+
+  // Note! Calling Purge makes all previous local refs created in
+  // the AutoLocalJNIFrame's scope INVALID; be sure that you locked down
+  // any local refs that you need to keep around in global refs!
+  void Purge() {
+    Pop();
+    Push();
+  }
+
+  template <typename ReturnType = jobject>
+  ReturnType Pop(ReturnType aResult = nullptr) {
+    MOZ_ASSERT(mHasFrameBeenPushed);
+    mHasFrameBeenPushed = false;
+    return static_cast<ReturnType>(
+        mJNIEnv->PopLocalFrame(static_cast<jobject>(aResult)));
+  }
+
+ private:
+  void Push() {
+    MOZ_ASSERT(!mHasFrameBeenPushed);
+    // Make sure there is enough space to store a local ref to the
+    // exception.  I am not completely sure this is needed, but does
+    // not hurt.
+    if (mJNIEnv->PushLocalFrame(mEntries + 1) != 0) {
+      CheckForException();
+      return;
+    }
+    mHasFrameBeenPushed = true;
+  }
+
+  const int mEntries;
+  JNIEnv* const mJNIEnv;
+  bool mHasFrameBeenPushed;
+};
+
+}  // namespace mozilla
+
+#define NS_ANDROIDBRIDGE_CID                         \
+  {                                                  \
+    0x0FE2321D, 0xEBD9, 0x467D, {                    \
+      0xA7, 0x43, 0x03, 0xA6, 0x8D, 0x40, 0x59, 0x9E \
+    }                                                \
+  }
+
+class nsAndroidBridge final : public nsIAndroidBridge {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIANDROIDBRIDGE
+
+  NS_FORWARD_SAFE_NSIANDROIDEVENTDISPATCHER(mEventDispatcher)
+
+  nsAndroidBridge();
+
+ private:
+  ~nsAndroidBridge();
+
+  nsCOMPtr<nsIAndroidEventDispatcher> mEventDispatcher;
+
+ protected:
+};
+
+#endif /* AndroidBridge_h__ */
diff --git a/widget/android/AndroidBridgeUtilities.h b/widget/android/AndroidBridgeUtilities.h
new file mode 100644
index 0000000000..2d67c7ff46
--- /dev/null
+++ b/widget/android/AndroidBridgeUtilities.h
@@ -0,0 +1,19 @@
+/* -*- 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 ALOG
+#  if defined(DEBUG) || defined(FORCE_ALOG)
+#    define ALOG(args...) __android_log_print(ANDROID_LOG_INFO, "Gecko", ##args)
+#  else
+#    define ALOG(args...) ((void)0)
+#  endif
+#endif
+
+#ifdef DEBUG
+#  define ALOG_BRIDGE(args...) ALOG(args)
+#else
+#  define ALOG_BRIDGE(args...) ((void)0)
+#endif
diff --git a/widget/android/AndroidCompositorWidget.cpp b/widget/android/AndroidCompositorWidget.cpp
new file mode 100644
index 0000000000..a7eeb665e1
--- /dev/null
+++ b/widget/android/AndroidCompositorWidget.cpp
@@ -0,0 +1,105 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=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 "AndroidCompositorWidget.h"
+
+#include "mozilla/gfx/Logging.h"
+#include "mozilla/widget/PlatformWidgetTypes.h"
+#include "nsWindow.h"
+
+namespace mozilla {
+namespace widget {
+
+AndroidCompositorWidget::AndroidCompositorWidget(
+    const AndroidCompositorWidgetInitData& aInitData,
+    const layers::CompositorOptions& aOptions)
+    : CompositorWidget(aOptions),
+      mWidgetId(aInitData.widgetId()),
+      mNativeWindow(nullptr),
+      mFormat(WINDOW_FORMAT_RGBA_8888),
+      mClientSize(aInitData.clientSize()) {}
+
+AndroidCompositorWidget::~AndroidCompositorWidget() {
+  if (mNativeWindow) {
+    ANativeWindow_release(mNativeWindow);
+  }
+}
+
+already_AddRefed<gfx::DrawTarget>
+AndroidCompositorWidget::StartRemoteDrawingInRegion(
+    const LayoutDeviceIntRegion& aInvalidRegion,
+    layers::BufferMode* aBufferMode) {
+  if (!mNativeWindow) {
+    EGLNativeWindowType window = GetEGLNativeWindow();
+    JNIEnv* const env = jni::GetEnvForThread();
+    mNativeWindow =
+        ANativeWindow_fromSurface(env, reinterpret_cast<jobject>(window));
+    if (mNativeWindow) {
+      mFormat = ANativeWindow_getFormat(mNativeWindow);
+      ANativeWindow_acquire(mNativeWindow);
+    } else {
+      return nullptr;
+    }
+  }
+
+  if (mFormat != WINDOW_FORMAT_RGBA_8888 &&
+      mFormat != WINDOW_FORMAT_RGBX_8888) {
+    gfxCriticalNoteOnce << "Non supported format: " << mFormat;
+    return nullptr;
+  }
+
+  // XXX Handle inOutDirtyBounds
+  if (ANativeWindow_lock(mNativeWindow, &mBuffer, nullptr) != 0) {
+    return nullptr;
+  }
+
+  const int bpp = 4;
+  gfx::SurfaceFormat format = gfx::SurfaceFormat::R8G8B8A8;
+  if (mFormat == WINDOW_FORMAT_RGBX_8888) {
+    format = gfx::SurfaceFormat::R8G8B8X8;
+  }
+
+  RefPtr<gfx::DrawTarget> dt = gfx::Factory::CreateDrawTargetForData(
+      gfx::BackendType::SKIA, static_cast<unsigned char*>(mBuffer.bits),
+      gfx::IntSize(mBuffer.width, mBuffer.height), mBuffer.stride * bpp, format,
+      true);
+
+  return dt.forget();
+}
+
+void AndroidCompositorWidget::EndRemoteDrawingInRegion(
+    gfx::DrawTarget* aDrawTarget, const LayoutDeviceIntRegion& aInvalidRegion) {
+  ANativeWindow_unlockAndPost(mNativeWindow);
+}
+
+bool AndroidCompositorWidget::OnResumeComposition() {
+  OnCompositorSurfaceChanged();
+
+  if (!mSurface) {
+    gfxCriticalError() << "OnResumeComposition called with null Surface";
+    return false;
+  }
+
+  return true;
+}
+
+EGLNativeWindowType AndroidCompositorWidget::GetEGLNativeWindow() {
+  return (EGLNativeWindowType)mSurface.Get();
+}
+
+LayoutDeviceIntSize AndroidCompositorWidget::GetClientSize() {
+  return mClientSize;
+}
+
+void AndroidCompositorWidget::NotifyClientSizeChanged(
+    const LayoutDeviceIntSize& aClientSize) {
+  mClientSize =
+      LayoutDeviceIntSize(std::min(aClientSize.width, MOZ_WIDGET_MAX_SIZE),
+                          std::min(aClientSize.height, MOZ_WIDGET_MAX_SIZE));
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/AndroidCompositorWidget.h b/widget/android/AndroidCompositorWidget.h
new file mode 100644
index 0000000000..c478477b5f
--- /dev/null
+++ b/widget/android/AndroidCompositorWidget.h
@@ -0,0 +1,70 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 mozilla_widget_AndroidCompositorWidget_h
+#define mozilla_widget_AndroidCompositorWidget_h
+
+#include "CompositorWidget.h"
+#include "AndroidNativeWindow.h"
+#include "GLDefs.h"
+
+namespace mozilla {
+namespace widget {
+
+class PlatformCompositorWidgetDelegate : public CompositorWidgetDelegate {
+ public:
+  virtual void NotifyClientSizeChanged(
+      const LayoutDeviceIntSize& aClientSize) = 0;
+
+  // CompositorWidgetDelegate Overrides
+  PlatformCompositorWidgetDelegate* AsPlatformSpecificDelegate() override {
+    return this;
+  }
+};
+
+class AndroidCompositorWidgetInitData;
+
+class AndroidCompositorWidget : public CompositorWidget {
+ public:
+  AndroidCompositorWidget(const AndroidCompositorWidgetInitData& aInitData,
+                          const layers::CompositorOptions& aOptions);
+  ~AndroidCompositorWidget() override;
+
+  EGLNativeWindowType GetEGLNativeWindow();
+
+  // CompositorWidget overrides
+
+  already_AddRefed<gfx::DrawTarget> StartRemoteDrawingInRegion(
+      const LayoutDeviceIntRegion& aInvalidRegion,
+      layers::BufferMode* aBufferMode) override;
+  void EndRemoteDrawingInRegion(
+      gfx::DrawTarget* aDrawTarget,
+      const LayoutDeviceIntRegion& aInvalidRegion) override;
+
+  bool OnResumeComposition() override;
+
+  AndroidCompositorWidget* AsAndroid() override { return this; }
+
+  LayoutDeviceIntSize GetClientSize() override;
+  void NotifyClientSizeChanged(const LayoutDeviceIntSize& aClientSize);
+
+ protected:
+  int32_t mWidgetId;
+  java::sdk::Surface::GlobalRef mSurface;
+  ANativeWindow* mNativeWindow;
+  ANativeWindow_Buffer mBuffer;
+  int32_t mFormat;
+  LayoutDeviceIntSize mClientSize;
+
+ private:
+  // Called whenever the compositor surface may have changed. The derived class
+  // should update mSurface to the new compositor surface.
+  virtual void OnCompositorSurfaceChanged() = 0;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_AndroidCompositorWidget_h
diff --git a/widget/android/AndroidContentController.cpp b/widget/android/AndroidContentController.cpp
new file mode 100644
index 0000000000..c1029fd4a2
--- /dev/null
+++ b/widget/android/AndroidContentController.cpp
@@ -0,0 +1,70 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 "AndroidContentController.h"
+
+#include "AndroidBridge.h"
+#include "base/message_loop.h"
+#include "mozilla/layers/APZCCallbackHelper.h"
+#include "mozilla/layers/IAPZCTreeManager.h"
+#include "nsIObserverService.h"
+#include "nsLayoutUtils.h"
+#include "nsWindow.h"
+
+using mozilla::layers::IAPZCTreeManager;
+
+namespace mozilla {
+namespace widget {
+
+void AndroidContentController::Destroy() {
+  mAndroidWindow = nullptr;
+  ChromeProcessController::Destroy();
+}
+
+void AndroidContentController::UpdateOverscrollVelocity(
+    const ScrollableLayerGuid& aGuid, const float aX, const float aY,
+    const bool aIsRootContent) {
+  if (aIsRootContent && mAndroidWindow) {
+    mAndroidWindow->UpdateOverscrollVelocity(aX, aY);
+  }
+}
+
+void AndroidContentController::UpdateOverscrollOffset(
+    const ScrollableLayerGuid& aGuid, const float aX, const float aY,
+    const bool aIsRootContent) {
+  if (aIsRootContent && mAndroidWindow) {
+    mAndroidWindow->UpdateOverscrollOffset(aX, aY);
+  }
+}
+
+void AndroidContentController::NotifyAPZStateChange(
+    const ScrollableLayerGuid& aGuid, APZStateChange aChange, int aArg,
+    Maybe<uint64_t> aInputBlockId) {
+  // This function may get invoked twice, if the first invocation is not on
+  // the main thread then the ChromeProcessController version of this function
+  // will redispatch to the main thread. We want to make sure that our handling
+  // only happens on the main thread.
+  ChromeProcessController::NotifyAPZStateChange(aGuid, aChange, aArg,
+                                                aInputBlockId);
+  if (NS_IsMainThread()) {
+    nsCOMPtr<nsIObserverService> observerService =
+        mozilla::services::GetObserverService();
+    if (aChange ==
+        layers::GeckoContentController::APZStateChange::eTransformEnd) {
+      // This is used by tests to determine when the APZ is done doing whatever
+      // it's doing. XXX generify this as needed when writing additional tests.
+      observerService->NotifyObservers(nullptr, "APZ:TransformEnd", nullptr);
+      observerService->NotifyObservers(nullptr, "PanZoom:StateChange",
+                                       u"NOTHING");
+    } else if (aChange == layers::GeckoContentController::APZStateChange::
+                              eTransformBegin) {
+      observerService->NotifyObservers(nullptr, "PanZoom:StateChange",
+                                       u"PANNING");
+    }
+  }
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/AndroidContentController.h b/widget/android/AndroidContentController.h
new file mode 100644
index 0000000000..04640deb4e
--- /dev/null
+++ b/widget/android/AndroidContentController.h
@@ -0,0 +1,52 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 AndroidContentController_h__
+#define AndroidContentController_h__
+
+#include "mozilla/layers/ChromeProcessController.h"
+#include "mozilla/EventForwards.h"  // for Modifiers
+#include "mozilla/StaticPtr.h"
+#include "mozilla/TimeStamp.h"
+#include "nsTArray.h"
+#include "nsWindow.h"
+
+namespace mozilla {
+namespace layers {
+class APZEventState;
+class IAPZCTreeManager;
+}  // namespace layers
+namespace widget {
+
+class AndroidContentController final
+    : public mozilla::layers::ChromeProcessController {
+ public:
+  AndroidContentController(nsWindow* aWindow,
+                           mozilla::layers::APZEventState* aAPZEventState,
+                           mozilla::layers::IAPZCTreeManager* aAPZCTreeManager)
+      : mozilla::layers::ChromeProcessController(aWindow, aAPZEventState,
+                                                 aAPZCTreeManager),
+        mAndroidWindow(aWindow) {}
+
+  // ChromeProcessController methods
+  virtual void Destroy() override;
+  void UpdateOverscrollVelocity(const ScrollableLayerGuid& aGuid,
+                                const float aX, const float aY,
+                                const bool aIsRootContent) override;
+  void UpdateOverscrollOffset(const ScrollableLayerGuid& aGuid, const float aX,
+                              const float aY,
+                              const bool aIsRootContent) override;
+  void NotifyAPZStateChange(const ScrollableLayerGuid& aGuid,
+                            APZStateChange aChange, int aArg,
+                            Maybe<uint64_t> aInputBlockId) override;
+
+ private:
+  nsWindow* mAndroidWindow;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif
diff --git a/widget/android/AndroidUiThread.cpp b/widget/android/AndroidUiThread.cpp
new file mode 100644
index 0000000000..dc8d56b163
--- /dev/null
+++ b/widget/android/AndroidUiThread.cpp
@@ -0,0 +1,377 @@
+/* -*- Mode: C++; tab-width: 8; 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 "base/message_loop.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/EventQueue.h"
+#include "mozilla/java/GeckoThreadWrappers.h"
+#include "mozilla/LinkedList.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/ThreadEventQueue.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/UniquePtr.h"
+#include "GeckoProfiler.h"
+#include "nsThread.h"
+#include "nsThreadManager.h"
+#include "nsThreadUtils.h"
+
+#include <android/api-level.h>
+#include <pthread.h>
+
+using namespace mozilla;
+
+namespace {
+
+class AndroidUiThread;
+class AndroidUiTask;
+
+StaticAutoPtr<LinkedList<AndroidUiTask> > sTaskQueue;
+StaticAutoPtr<mozilla::Mutex> sTaskQueueLock;
+StaticRefPtr<AndroidUiThread> sThread;
+static bool sThreadDestroyed;
+static MessageLoop* sMessageLoop;
+static Atomic<Monitor*> sMessageLoopAccessMonitor;
+
+void EnqueueTask(already_AddRefed<nsIRunnable> aTask, int aDelayMs);
+
+/*
+ * The AndroidUiThread is derived from nsThread so that nsIRunnable objects that
+ * get dispatched may be intercepted. Only nsIRunnable objects that need to be
+ * synchronously executed are passed into the nsThread to be queued. All other
+ * nsIRunnable object are immediately dispatched to the Android UI thread.
+ * AndroidUiThread is derived from nsThread instead of being an nsIEventTarget
+ * wrapper that contains an nsThread object because if nsIRunnable objects with
+ * a delay were dispatch directly to an nsThread object, such as obtained from
+ * nsThreadManager::GetCurrentThread(), the nsIRunnable could get stuck in the
+ * nsThread nsIRunnable queue. This is due to the fact that Android controls the
+ * event loop in the Android UI thread and has no knowledge of when the nsThread
+ * needs to be drained.
+ */
+
+class AndroidUiThread : public nsThread {
+ public:
+  NS_INLINE_DECL_REFCOUNTING_INHERITED(AndroidUiThread, nsThread)
+  AndroidUiThread()
+      : nsThread(
+            MakeNotNull<ThreadEventQueue*>(MakeUnique<mozilla::EventQueue>()),
+            nsThread::NOT_MAIN_THREAD, {.stackSize = 0}) {}
+
+  nsresult Dispatch(already_AddRefed<nsIRunnable> aEvent,
+                    uint32_t aFlags) override;
+  nsresult DelayedDispatch(already_AddRefed<nsIRunnable> aEvent,
+                           uint32_t aDelayMs) override;
+
+ private:
+  ~AndroidUiThread() {}
+};
+
+NS_IMETHODIMP
+AndroidUiThread::Dispatch(already_AddRefed<nsIRunnable> aEvent,
+                          uint32_t aFlags) {
+  EnqueueTask(std::move(aEvent), 0);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AndroidUiThread::DelayedDispatch(already_AddRefed<nsIRunnable> aEvent,
+                                 uint32_t aDelayMs) {
+  EnqueueTask(std::move(aEvent), aDelayMs);
+  return NS_OK;
+}
+
+static void PumpEvents() { NS_ProcessPendingEvents(sThread.get()); }
+
+class ThreadObserver : public nsIThreadObserver {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSITHREADOBSERVER
+
+  ThreadObserver() {}
+
+ private:
+  virtual ~ThreadObserver() {}
+};
+
+NS_IMPL_ISUPPORTS(ThreadObserver, nsIThreadObserver)
+
+NS_IMETHODIMP
+ThreadObserver::OnDispatchedEvent() {
+  EnqueueTask(NS_NewRunnableFunction("PumpEvents", &PumpEvents), 0);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ThreadObserver::OnProcessNextEvent(nsIThreadInternal* thread, bool mayWait) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ThreadObserver::AfterProcessNextEvent(nsIThreadInternal* thread,
+                                      bool eventWasProcessed) {
+  return NS_OK;
+}
+
+class AndroidUiTask : public LinkedListElement<AndroidUiTask> {
+  using TimeStamp = mozilla::TimeStamp;
+  using TimeDuration = mozilla::TimeDuration;
+
+ public:
+  explicit AndroidUiTask(already_AddRefed<nsIRunnable> aTask)
+      : mTask(aTask),
+        mRunTime()  // Null timestamp representing no delay.
+  {}
+
+  AndroidUiTask(already_AddRefed<nsIRunnable> aTask, int aDelayMs)
+      : mTask(aTask),
+        mRunTime(TimeStamp::Now() + TimeDuration::FromMilliseconds(aDelayMs)) {}
+
+  bool IsEarlierThan(const AndroidUiTask& aOther) const {
+    if (mRunTime) {
+      return aOther.mRunTime ? mRunTime < aOther.mRunTime : false;
+    }
+    // In the case of no delay, we're earlier if aOther has a delay.
+    // Otherwise, we're not earlier, to maintain task order.
+    return !!aOther.mRunTime;
+  }
+
+  int64_t MillisecondsToRunTime() const {
+    if (mRunTime) {
+      return int64_t((mRunTime - TimeStamp::Now()).ToMilliseconds());
+    }
+    return 0;
+  }
+
+  already_AddRefed<nsIRunnable> TakeTask() { return mTask.forget(); }
+
+ private:
+  nsCOMPtr<nsIRunnable> mTask;
+  const TimeStamp mRunTime;
+};
+
+class CreateOnUiThread : public Runnable {
+ public:
+  CreateOnUiThread() : Runnable("CreateOnUiThread") {}
+
+  NS_IMETHOD Run() override {
+    MOZ_ASSERT(!sThreadDestroyed);
+    MOZ_ASSERT(sMessageLoopAccessMonitor);
+    MonitorAutoLock lock(*sMessageLoopAccessMonitor);
+    sThread = new AndroidUiThread();
+    sThread->InitCurrentThread();
+    sThread->SetObserver(new ThreadObserver());
+    RegisterThreadWithProfiler();
+    sMessageLoop =
+        new MessageLoop(MessageLoop::TYPE_MOZILLA_ANDROID_UI, sThread.get());
+    lock.NotifyAll();
+    return NS_OK;
+  }
+
+ private:
+  static void RegisterThreadWithProfiler() {
+#if defined(MOZ_GECKO_PROFILER)
+    // We don't use the PROFILER_REGISTER_THREAD macro here because by this
+    // point the Android UI thread is already quite a ways into its stack;
+    // the profiler's sampler thread will ignore a lot of frames if we do not
+    // provide a better value for the stack top. We'll manually obtain that
+    // info via pthreads.
+
+    // Fallback address if any pthread calls fail
+    char fallback;
+    char* stackTop = &fallback;
+
+    auto regOnExit = MakeScopeExit(
+        [&stackTop]() { profiler_register_thread("AndroidUI", stackTop); });
+
+    // Bionic does not properly support pthread_attr_getstack for the UI thread
+    // until Lollipop (API 21).
+#  if __ANDROID_API__ >= __ANDROID_API_L__
+    pthread_attr_t attrs;
+    if (pthread_getattr_np(pthread_self(), &attrs)) {
+      return;
+    }
+
+    void* stackBase;
+    size_t stackSize;
+    if (pthread_attr_getstack(&attrs, &stackBase, &stackSize)) {
+      return;
+    }
+
+    stackTop = static_cast<char*>(stackBase) + stackSize - 1;
+#  endif  // __ANDROID_API__ >= __ANDROID_API_L__
+#endif    // defined(MOZ_GECKO_PROFILER)
+  }
+};
+
+class DestroyOnUiThread : public Runnable {
+ public:
+  DestroyOnUiThread() : Runnable("DestroyOnUiThread"), mDestroyed(false) {}
+
+  NS_IMETHOD Run() override {
+    MOZ_ASSERT(!sThreadDestroyed);
+    MOZ_ASSERT(sMessageLoopAccessMonitor);
+    MOZ_ASSERT(sTaskQueue);
+    MonitorAutoLock lock(*sMessageLoopAccessMonitor);
+    sThreadDestroyed = true;
+
+    {
+      // Flush the queue
+      MutexAutoLock lock(*sTaskQueueLock);
+      while (AndroidUiTask* task = sTaskQueue->getFirst()) {
+        delete task;
+      }
+    }
+
+    delete sMessageLoop;
+    sMessageLoop = nullptr;
+    MOZ_ASSERT(sThread);
+    PROFILER_UNREGISTER_THREAD();
+    nsThreadManager::get().UnregisterCurrentThread(*sThread);
+    sThread = nullptr;
+    mDestroyed = true;
+    lock.NotifyAll();
+    return NS_OK;
+  }
+
+  void WaitForDestruction() {
+    MOZ_ASSERT(sMessageLoopAccessMonitor);
+    MonitorAutoLock lock(*sMessageLoopAccessMonitor);
+    while (!mDestroyed) {
+      lock.Wait();
+    }
+  }
+
+ private:
+  bool mDestroyed;
+};
+
+void EnqueueTask(already_AddRefed<nsIRunnable> aTask, int aDelayMs) {
+  if (sThreadDestroyed) {
+    return;
+  }
+
+  // add the new task into the sTaskQueue, sorted with
+  // the earliest task first in the queue
+  AndroidUiTask* newTask =
+      (aDelayMs ? new AndroidUiTask(std::move(aTask), aDelayMs)
+                : new AndroidUiTask(std::move(aTask)));
+
+  bool headOfList = false;
+  {
+    MOZ_ASSERT(sTaskQueue);
+    MOZ_ASSERT(sTaskQueueLock);
+    MutexAutoLock lock(*sTaskQueueLock);
+
+    AndroidUiTask* task = sTaskQueue->getFirst();
+
+    while (task) {
+      if (newTask->IsEarlierThan(*task)) {
+        task->setPrevious(newTask);
+        break;
+      }
+      task = task->getNext();
+    }
+
+    if (!newTask->isInList()) {
+      sTaskQueue->insertBack(newTask);
+    }
+    headOfList = !newTask->getPrevious();
+  }
+
+  if (headOfList) {
+    // if we're inserting it at the head of the queue, notify Java because
+    // we need to get a callback at an earlier time than the last scheduled
+    // callback
+    java::GeckoThread::RequestUiThreadCallback(int64_t(aDelayMs));
+  }
+}
+
+}  // namespace
+
+namespace mozilla {
+
+void CreateAndroidUiThread() {
+  MOZ_ASSERT(!sThread);
+  MOZ_ASSERT(!sMessageLoopAccessMonitor);
+  sTaskQueue = new LinkedList<AndroidUiTask>();
+  sTaskQueueLock = new Mutex("AndroidUiThreadTaskQueueLock");
+  sMessageLoopAccessMonitor =
+      new Monitor("AndroidUiThreadMessageLoopAccessMonitor");
+  sThreadDestroyed = false;
+  RefPtr<CreateOnUiThread> runnable = new CreateOnUiThread;
+  EnqueueTask(do_AddRef(runnable), 0);
+}
+
+void DestroyAndroidUiThread() {
+  MOZ_ASSERT(sThread);
+  RefPtr<DestroyOnUiThread> runnable = new DestroyOnUiThread;
+  EnqueueTask(do_AddRef(runnable), 0);
+  runnable->WaitForDestruction();
+  delete sMessageLoopAccessMonitor;
+  sMessageLoopAccessMonitor = nullptr;
+}
+
+MessageLoop* GetAndroidUiThreadMessageLoop() {
+  if (!sMessageLoopAccessMonitor) {
+    return nullptr;
+  }
+
+  MonitorAutoLock lock(*sMessageLoopAccessMonitor);
+  while (!sMessageLoop) {
+    lock.Wait();
+  }
+
+  return sMessageLoop;
+}
+
+RefPtr<nsThread> GetAndroidUiThread() {
+  if (!sMessageLoopAccessMonitor) {
+    return nullptr;
+  }
+
+  MonitorAutoLock lock(*sMessageLoopAccessMonitor);
+  while (!sThread) {
+    lock.Wait();
+  }
+
+  return sThread;
+}
+
+int64_t RunAndroidUiTasks() {
+  MutexAutoLock lock(*sTaskQueueLock);
+
+  if (sThreadDestroyed) {
+    return -1;
+  }
+
+  while (!sTaskQueue->isEmpty()) {
+    AndroidUiTask* task = sTaskQueue->getFirst();
+    const int64_t timeLeft = task->MillisecondsToRunTime();
+    if (timeLeft > 0) {
+      // this task (and therefore all remaining tasks)
+      // have not yet reached their runtime. return the
+      // time left until we should be called again
+      return timeLeft;
+    }
+
+    // Retrieve task before unlocking/running.
+    nsCOMPtr<nsIRunnable> runnable(task->TakeTask());
+    // LinkedListElements auto remove from list upon destruction
+    delete task;
+
+    // Unlock to allow posting new tasks reentrantly.
+    MutexAutoUnlock unlock(*sTaskQueueLock);
+    runnable->Run();
+    if (sThreadDestroyed) {
+      return -1;
+    }
+  }
+  return -1;
+}
+
+}  // namespace mozilla
diff --git a/widget/android/AndroidUiThread.h b/widget/android/AndroidUiThread.h
new file mode 100644
index 0000000000..af722fb048
--- /dev/null
+++ b/widget/android/AndroidUiThread.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; 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 AndroidUiThread_h__
+#define AndroidUiThread_h__
+
+#include <mozilla/RefPtr.h>
+#include <nsThread.h>
+
+class MessageLoop;
+
+namespace mozilla {
+
+void CreateAndroidUiThread();
+void DestroyAndroidUiThread();
+int64_t RunAndroidUiTasks();
+
+MessageLoop* GetAndroidUiThreadMessageLoop();
+RefPtr<nsThread> GetAndroidUiThread();
+
+}  // namespace mozilla
+
+#endif  // AndroidUiThread_h__
diff --git a/widget/android/AndroidView.h b/widget/android/AndroidView.h
new file mode 100644
index 0000000000..173db8b5c1
--- /dev/null
+++ b/widget/android/AndroidView.h
@@ -0,0 +1,35 @@
+/* -*- 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_AndroidView_h
+#define mozilla_widget_AndroidView_h
+
+#include "mozilla/widget/EventDispatcher.h"
+
+namespace mozilla {
+namespace widget {
+
+class AndroidView final : public nsIAndroidView {
+  virtual ~AndroidView() {}
+
+ public:
+  const RefPtr<mozilla::widget::EventDispatcher> mEventDispatcher{
+      new mozilla::widget::EventDispatcher()};
+
+  AndroidView() {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIANDROIDVIEW
+
+  NS_FORWARD_NSIANDROIDEVENTDISPATCHER(mEventDispatcher->)
+
+  mozilla::java::GeckoBundle::GlobalRef mInitData;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_AndroidView_h
diff --git a/widget/android/AndroidVsync.cpp b/widget/android/AndroidVsync.cpp
new file mode 100644
index 0000000000..6aed5f1e53
--- /dev/null
+++ b/widget/android/AndroidVsync.cpp
@@ -0,0 +1,150 @@
+/* -*- 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 "AndroidVsync.h"
+
+#include "AndroidBridge.h"
+#include "nsTArray.h"
+
+/**
+ * Implementation for the AndroidVsync class.
+ */
+
+namespace mozilla {
+namespace widget {
+
+StaticDataMutex<ThreadSafeWeakPtr<AndroidVsync>> AndroidVsync::sInstance(
+    "AndroidVsync::sInstance");
+
+/* static */ RefPtr<AndroidVsync> AndroidVsync::GetInstance() {
+  auto weakInstance = sInstance.Lock();
+  RefPtr<AndroidVsync> instance(*weakInstance);
+  if (!instance) {
+    instance = new AndroidVsync();
+    *weakInstance = instance;
+  }
+  return instance;
+}
+
+/**
+ * Owned by the Java AndroidVsync instance.
+ */
+class AndroidVsyncSupport final
+    : public java::AndroidVsync::Natives<AndroidVsyncSupport> {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AndroidVsyncSupport)
+
+  using Base = java::AndroidVsync::Natives<AndroidVsyncSupport>;
+  using Base::AttachNative;
+  using Base::DisposeNative;
+
+  explicit AndroidVsyncSupport(AndroidVsync* aAndroidVsync)
+      : mAndroidVsync(std::move(aAndroidVsync),
+                      "AndroidVsyncSupport::mAndroidVsync") {}
+
+  // Called by Java
+  void NotifyVsync(const java::AndroidVsync::LocalRef& aInstance,
+                   int64_t aFrameTimeNanos) {
+    auto androidVsync = mAndroidVsync.Lock();
+    if (*androidVsync) {
+      (*androidVsync)->NotifyVsync(aFrameTimeNanos);
+    }
+  }
+
+  // Called by the AndroidVsync destructor
+  void Unlink() {
+    auto androidVsync = mAndroidVsync.Lock();
+    *androidVsync = nullptr;
+  }
+
+ protected:
+  ~AndroidVsyncSupport() = default;
+
+  DataMutex<AndroidVsync*> mAndroidVsync;
+};
+
+AndroidVsync::AndroidVsync() : mImpl("AndroidVsync.mImpl") {
+  AndroidVsyncSupport::Init();
+
+  auto impl = mImpl.Lock();
+  impl->mSupport = new AndroidVsyncSupport(this);
+  impl->mSupportJava = java::AndroidVsync::New();
+  AndroidVsyncSupport::AttachNative(impl->mSupportJava, impl->mSupport);
+}
+
+AndroidVsync::~AndroidVsync() {
+  auto impl = mImpl.Lock();
+  impl->mInputObservers.Clear();
+  impl->mRenderObservers.Clear();
+  impl->UpdateObservingVsync();
+  impl->mSupport->Unlink();
+}
+
+void AndroidVsync::RegisterObserver(Observer* aObserver, ObserverType aType) {
+  auto impl = mImpl.Lock();
+  if (aType == AndroidVsync::INPUT) {
+    impl->mInputObservers.AppendElement(aObserver);
+  } else {
+    impl->mRenderObservers.AppendElement(aObserver);
+  }
+  impl->UpdateObservingVsync();
+}
+
+void AndroidVsync::UnregisterObserver(Observer* aObserver, ObserverType aType) {
+  auto impl = mImpl.Lock();
+  if (aType == AndroidVsync::INPUT) {
+    impl->mInputObservers.RemoveElement(aObserver);
+  } else {
+    impl->mRenderObservers.RemoveElement(aObserver);
+  }
+  aObserver->Dispose();
+  impl->UpdateObservingVsync();
+}
+
+void AndroidVsync::Impl::UpdateObservingVsync() {
+  bool shouldObserve =
+      !mInputObservers.IsEmpty() || !mRenderObservers.IsEmpty();
+  if (shouldObserve != mObservingVsync) {
+    mObservingVsync = mSupportJava->ObserveVsync(shouldObserve);
+  }
+}
+
+// Always called on the Java UI thread.
+void AndroidVsync::NotifyVsync(int64_t aFrameTimeNanos) {
+  MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+
+  // Convert aFrameTimeNanos to a TimeStamp. The value converts trivially to
+  // the internal ticks representation of TimeStamp_posix; both use the
+  // monotonic clock and are in nanoseconds.
+  TimeStamp timeStamp = TimeStamp::FromSystemTime(aFrameTimeNanos);
+
+  // Do not keep the lock held while calling OnVsync.
+  nsTArray<Observer*> observers;
+  {
+    auto impl = mImpl.Lock();
+    observers.AppendElements(impl->mInputObservers);
+    observers.AppendElements(impl->mRenderObservers);
+  }
+  for (Observer* observer : observers) {
+    observer->OnVsync(timeStamp);
+  }
+}
+
+void AndroidVsync::OnMaybeUpdateRefreshRate() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  auto impl = mImpl.Lock();
+
+  nsTArray<Observer*> observers;
+  observers.AppendElements(impl->mRenderObservers);
+
+  for (Observer* observer : observers) {
+    observer->OnMaybeUpdateRefreshRate();
+  }
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/AndroidVsync.h b/widget/android/AndroidVsync.h
new file mode 100644
index 0000000000..d50e1ec71f
--- /dev/null
+++ b/widget/android/AndroidVsync.h
@@ -0,0 +1,79 @@
+/* -*- 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_AndroidVsync_h
+#define mozilla_widget_AndroidVsync_h
+
+#include "mozilla/DataMutex.h"
+#include "mozilla/java/AndroidVsyncNatives.h"
+#include "mozilla/ThreadSafeWeakPtr.h"
+#include "mozilla/TimeStamp.h"
+
+namespace mozilla {
+namespace widget {
+
+class AndroidVsyncSupport;
+
+/**
+ * A thread-safe way to listen to vsync notifications on Android. All methods
+ * can be called on any thread.
+ * Observers must keep a strong reference to the AndroidVsync instance until
+ * they unregister themselves.
+ */
+class AndroidVsync final : public SupportsThreadSafeWeakPtr<AndroidVsync> {
+ public:
+  MOZ_DECLARE_REFCOUNTED_TYPENAME(AndroidVsync)
+
+  static RefPtr<AndroidVsync> GetInstance();
+
+  ~AndroidVsync();
+
+  class Observer {
+   public:
+    // Will be called on the Java UI thread.
+    virtual void OnVsync(const TimeStamp& aTimeStamp) = 0;
+    // Will be called on the Java UI thread.
+    virtual void OnMaybeUpdateRefreshRate() {}
+    // Called when the observer is unregistered, in case it wants to
+    // manage its own lifetime.
+    virtual void Dispose() {}
+    virtual ~Observer() = default;
+  };
+
+  // INPUT observers are called before RENDER observers.
+  enum ObserverType { INPUT, RENDER };
+  void RegisterObserver(Observer* aObserver, ObserverType aType);
+  void UnregisterObserver(Observer* aObserver, ObserverType aType);
+
+  void OnMaybeUpdateRefreshRate();
+
+ private:
+  friend class AndroidVsyncSupport;
+
+  AndroidVsync();
+
+  // Called by Java, via AndroidVsyncSupport
+  void NotifyVsync(int64_t aFrameTimeNanos);
+
+  struct Impl {
+    void UpdateObservingVsync();
+
+    nsTArray<Observer*> mInputObservers;
+    nsTArray<Observer*> mRenderObservers;
+    RefPtr<AndroidVsyncSupport> mSupport;
+    java::AndroidVsync::GlobalRef mSupportJava;
+    bool mObservingVsync = false;
+  };
+
+  DataMutex<Impl> mImpl;
+
+  static StaticDataMutex<ThreadSafeWeakPtr<AndroidVsync>> sInstance;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_AndroidVsync_h
diff --git a/widget/android/Base64UtilsSupport.h b/widget/android/Base64UtilsSupport.h
new file mode 100644
index 0000000000..8ac4347aaa
--- /dev/null
+++ b/widget/android/Base64UtilsSupport.h
@@ -0,0 +1,52 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 Base64UtilsSupport_h__
+#define Base64UtilsSupport_h__
+
+#include "mozilla/Base64.h"
+#include "mozilla/java/Base64UtilsNatives.h"
+
+namespace mozilla {
+namespace widget {
+
+class Base64UtilsSupport final
+    : public java::Base64Utils::Natives<Base64UtilsSupport> {
+ public:
+  static jni::ByteArray::LocalRef Decode(jni::String::Param data) {
+    if (!data) {
+      return nullptr;
+    }
+
+    FallibleTArray<uint8_t> bytes;
+    if (NS_FAILED(Base64URLDecode(
+            data->ToCString(), Base64URLDecodePaddingPolicy::Ignore, bytes))) {
+      return nullptr;
+    }
+
+    return jni::ByteArray::New((const signed char*)bytes.Elements(),
+                               bytes.Length());
+  }
+
+  static jni::String::LocalRef Encode(jni::ByteArray::Param data) {
+    if (!data) {
+      return nullptr;
+    }
+
+    nsTArray<int8_t> bytes = data->GetElements();
+    nsCString result;
+    if (NS_FAILED(
+            Base64URLEncode(data->Length(), (const uint8_t*)bytes.Elements(),
+                            Base64URLEncodePaddingPolicy::Omit, result))) {
+      return nullptr;
+    }
+    return jni::StringParam(result);
+  }
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // Base64UtilsSupport_h__
diff --git a/widget/android/CompositorWidgetChild.cpp b/widget/android/CompositorWidgetChild.cpp
new file mode 100644
index 0000000000..ba51dda7a5
--- /dev/null
+++ b/widget/android/CompositorWidgetChild.cpp
@@ -0,0 +1,42 @@
+/* -*- 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 "CompositorWidgetChild.h"
+#include "mozilla/Unused.h"
+#include "gfxPlatform.h"
+
+namespace mozilla {
+namespace widget {
+
+CompositorWidgetChild::CompositorWidgetChild(
+    RefPtr<CompositorVsyncDispatcher> aVsyncDispatcher,
+    RefPtr<CompositorWidgetVsyncObserver> aVsyncObserver,
+    const CompositorWidgetInitData&)
+    : mVsyncDispatcher(aVsyncDispatcher), mVsyncObserver(aVsyncObserver) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(!gfxPlatform::IsHeadless());
+}
+
+CompositorWidgetChild::~CompositorWidgetChild() = default;
+
+bool CompositorWidgetChild::Initialize() { return true; }
+
+mozilla::ipc::IPCResult CompositorWidgetChild::RecvObserveVsync() {
+  mVsyncDispatcher->SetCompositorVsyncObserver(mVsyncObserver);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorWidgetChild::RecvUnobserveVsync() {
+  mVsyncDispatcher->SetCompositorVsyncObserver(nullptr);
+  return IPC_OK();
+}
+
+void CompositorWidgetChild::NotifyClientSizeChanged(
+    const LayoutDeviceIntSize& aClientSize) {
+  Unused << SendNotifyClientSizeChanged(aClientSize);
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/CompositorWidgetChild.h b/widget/android/CompositorWidgetChild.h
new file mode 100644
index 0000000000..88cb2913e9
--- /dev/null
+++ b/widget/android/CompositorWidgetChild.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 widget_android_CompositorWidgetChild_h
+#define widget_android_CompositorWidgetChild_h
+
+#include "AndroidCompositorWidget.h"
+#include "mozilla/widget/PCompositorWidgetChild.h"
+#include "mozilla/widget/CompositorWidgetVsyncObserver.h"
+
+namespace mozilla {
+namespace widget {
+
+class CompositorWidgetChild final : public PCompositorWidgetChild,
+                                    public PlatformCompositorWidgetDelegate {
+ public:
+  CompositorWidgetChild(RefPtr<CompositorVsyncDispatcher> aVsyncDispatcher,
+                        RefPtr<CompositorWidgetVsyncObserver> aVsyncObserver,
+                        const CompositorWidgetInitData&);
+  ~CompositorWidgetChild() override;
+
+  bool Initialize();
+
+  mozilla::ipc::IPCResult RecvObserveVsync() override;
+  mozilla::ipc::IPCResult RecvUnobserveVsync() override;
+
+  // PlatformCompositorWidgetDelegate overrides
+
+  void NotifyClientSizeChanged(const LayoutDeviceIntSize& aClientSize) override;
+
+ private:
+  RefPtr<CompositorVsyncDispatcher> mVsyncDispatcher;
+  RefPtr<CompositorWidgetVsyncObserver> mVsyncObserver;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // widget_android_CompositorWidgetChild_h
diff --git a/widget/android/CompositorWidgetParent.cpp b/widget/android/CompositorWidgetParent.cpp
new file mode 100644
index 0000000000..93b87f3cd3
--- /dev/null
+++ b/widget/android/CompositorWidgetParent.cpp
@@ -0,0 +1,54 @@
+/* -*- 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 "CompositorWidgetParent.h"
+#include "mozilla/Unused.h"
+#include "mozilla/java/GeckoServiceGpuProcessWrappers.h"
+#include "mozilla/widget/PlatformWidgetTypes.h"
+
+namespace mozilla {
+namespace widget {
+
+CompositorWidgetParent::CompositorWidgetParent(
+    const CompositorWidgetInitData& aInitData,
+    const layers::CompositorOptions& aOptions)
+    : AndroidCompositorWidget(aInitData.get_AndroidCompositorWidgetInitData(),
+                              aOptions) {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_GPU);
+}
+
+CompositorWidgetParent::~CompositorWidgetParent() = default;
+
+nsIWidget* CompositorWidgetParent::RealWidget() { return nullptr; }
+
+void CompositorWidgetParent::ObserveVsync(VsyncObserver* aObserver) {
+  if (aObserver) {
+    Unused << SendObserveVsync();
+  } else {
+    Unused << SendUnobserveVsync();
+  }
+  mVsyncObserver = aObserver;
+}
+
+RefPtr<VsyncObserver> CompositorWidgetParent::GetVsyncObserver() const {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_GPU);
+  return mVsyncObserver;
+}
+
+mozilla::ipc::IPCResult CompositorWidgetParent::RecvNotifyClientSizeChanged(
+    const LayoutDeviceIntSize& aClientSize) {
+  NotifyClientSizeChanged(aClientSize);
+  return IPC_OK();
+}
+
+void CompositorWidgetParent::OnCompositorSurfaceChanged() {
+  java::GeckoServiceGpuProcess::RemoteCompositorSurfaceManager::LocalRef
+      manager = java::GeckoServiceGpuProcess::RemoteCompositorSurfaceManager::
+          GetInstance();
+  mSurface = manager->GetCompositorSurface(mWidgetId);
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/CompositorWidgetParent.h b/widget/android/CompositorWidgetParent.h
new file mode 100644
index 0000000000..cd6e4241ca
--- /dev/null
+++ b/widget/android/CompositorWidgetParent.h
@@ -0,0 +1,42 @@
+/* -*- 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_android_CompositorWidgetParent_h
+#define widget_android_CompositorWidgetParent_h
+
+#include "AndroidCompositorWidget.h"
+#include "mozilla/VsyncDispatcher.h"
+#include "mozilla/widget/PCompositorWidgetParent.h"
+
+namespace mozilla {
+namespace widget {
+
+class CompositorWidgetParent final : public PCompositorWidgetParent,
+                                     public AndroidCompositorWidget {
+ public:
+  explicit CompositorWidgetParent(const CompositorWidgetInitData& aInitData,
+                                  const layers::CompositorOptions& aOptions);
+  ~CompositorWidgetParent() override;
+
+  // CompositorWidget overrides
+
+  nsIWidget* RealWidget() override;
+  void ObserveVsync(VsyncObserver* aObserver) override;
+  RefPtr<VsyncObserver> GetVsyncObserver() const override;
+
+  mozilla::ipc::IPCResult RecvNotifyClientSizeChanged(
+      const LayoutDeviceIntSize& aClientSize) override;
+
+ private:
+  // AndroidCompositorWidget overrides
+  void OnCompositorSurfaceChanged() override;
+
+  RefPtr<VsyncObserver> mVsyncObserver;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // widget_android_CompositorWidgetParent_h
diff --git a/widget/android/EventDispatcher.cpp b/widget/android/EventDispatcher.cpp
new file mode 100644
index 0000000000..ab876de136
--- /dev/null
+++ b/widget/android/EventDispatcher.cpp
@@ -0,0 +1,776 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; indent-tabs-mode: nil; -*-
+ * vim: set sw=2 ts=4 expandtab:
+ * 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 "EventDispatcher.h"
+
+#include "JavaBuiltins.h"
+#include "nsAppShell.h"
+#include "nsJSUtils.h"
+#include "js/Array.h"  // JS::GetArrayLength, JS::IsArrayObject, JS::NewArrayObject
+#include "js/PropertyAndElement.h"  // JS_Enumerate, JS_GetElement, JS_GetProperty, JS_GetPropertyById, JS_SetElement, JS_SetUCProperty
+#include "js/String.h"              // JS::StringHasLatin1Chars
+#include "js/Warnings.h"            // JS::WarnUTF8
+#include "xpcpublic.h"
+
+#include "mozilla/fallible.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/java/EventCallbackWrappers.h"
+#include "mozilla/jni/GeckoBundleUtils.h"
+
+// Disable the C++ 2a warning. See bug #1509926
+#if defined(__clang__)
+#  pragma clang diagnostic push
+#  pragma clang diagnostic ignored "-Wc++2a-compat"
+#endif
+
+namespace mozilla {
+namespace widget {
+
+namespace detail {
+
+bool CheckJS(JSContext* aCx, bool aResult) {
+  if (!aResult) {
+    JS_ClearPendingException(aCx);
+  }
+  return aResult;
+}
+
+nsresult BoxData(const nsAString& aEvent, JSContext* aCx,
+                 JS::Handle<JS::Value> aData, jni::Object::LocalRef& aOut,
+                 bool aObjectOnly) {
+  nsresult rv = jni::BoxData(aCx, aData, aOut, aObjectOnly);
+  if (rv != NS_ERROR_INVALID_ARG) {
+    return rv;
+  }
+
+  NS_ConvertUTF16toUTF8 event(aEvent);
+  if (JS_IsExceptionPending(aCx)) {
+    JS::WarnUTF8(aCx, "Error dispatching %s", event.get());
+  } else {
+    JS_ReportErrorUTF8(aCx, "Invalid event data for %s", event.get());
+  }
+  return NS_ERROR_INVALID_ARG;
+}
+
+nsresult UnboxString(JSContext* aCx, const jni::Object::LocalRef& aData,
+                     JS::MutableHandle<JS::Value> aOut) {
+  if (!aData) {
+    aOut.setNull();
+    return NS_OK;
+  }
+
+  MOZ_ASSERT(aData.IsInstanceOf<jni::String>());
+
+  JNIEnv* const env = aData.Env();
+  const jstring jstr = jstring(aData.Get());
+  const size_t len = env->GetStringLength(jstr);
+  const jchar* const jchars = env->GetStringChars(jstr, nullptr);
+
+  if (NS_WARN_IF(!jchars)) {
+    env->ExceptionClear();
+    return NS_ERROR_FAILURE;
+  }
+
+  auto releaseStr = MakeScopeExit([env, jstr, jchars] {
+    env->ReleaseStringChars(jstr, jchars);
+    env->ExceptionClear();
+  });
+
+  JS::Rooted<JSString*> str(
+      aCx,
+      JS_NewUCStringCopyN(aCx, reinterpret_cast<const char16_t*>(jchars), len));
+  NS_ENSURE_TRUE(CheckJS(aCx, !!str), NS_ERROR_FAILURE);
+
+  aOut.setString(str);
+  return NS_OK;
+}
+
+nsresult UnboxValue(JSContext* aCx, const jni::Object::LocalRef& aData,
+                    JS::MutableHandle<JS::Value> aOut);
+
+nsresult UnboxBundle(JSContext* aCx, const jni::Object::LocalRef& aData,
+                     JS::MutableHandle<JS::Value> aOut) {
+  if (!aData) {
+    aOut.setNull();
+    return NS_OK;
+  }
+
+  MOZ_ASSERT(aData.IsInstanceOf<java::GeckoBundle>());
+
+  JNIEnv* const env = aData.Env();
+  const auto& bundle = java::GeckoBundle::Ref::From(aData);
+  jni::ObjectArray::LocalRef keys = bundle->Keys();
+  jni::ObjectArray::LocalRef values = bundle->Values();
+  const size_t len = keys->Length();
+  JS::Rooted<JSObject*> obj(aCx, JS_NewPlainObject(aCx));
+
+  NS_ENSURE_TRUE(CheckJS(aCx, !!obj), NS_ERROR_FAILURE);
+  NS_ENSURE_TRUE(values->Length() == len, NS_ERROR_FAILURE);
+
+  for (size_t i = 0; i < len; i++) {
+    jni::String::LocalRef key = keys->GetElement(i);
+    const size_t keyLen = env->GetStringLength(key.Get());
+    const jchar* const keyChars = env->GetStringChars(key.Get(), nullptr);
+    if (NS_WARN_IF(!keyChars)) {
+      env->ExceptionClear();
+      return NS_ERROR_FAILURE;
+    }
+
+    auto releaseKeyChars = MakeScopeExit([env, &key, keyChars] {
+      env->ReleaseStringChars(key.Get(), keyChars);
+      env->ExceptionClear();
+    });
+
+    JS::Rooted<JS::Value> value(aCx);
+    nsresult rv = UnboxValue(aCx, values->GetElement(i), &value);
+    if (rv == NS_ERROR_INVALID_ARG && !JS_IsExceptionPending(aCx)) {
+      JS_ReportErrorUTF8(
+          aCx, u8"Invalid event data property %s",
+          NS_ConvertUTF16toUTF8(
+              nsString(reinterpret_cast<const char16_t*>(keyChars), keyLen))
+              .get());
+    }
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    NS_ENSURE_TRUE(
+        CheckJS(aCx, JS_SetUCProperty(
+                         aCx, obj, reinterpret_cast<const char16_t*>(keyChars),
+                         keyLen, value)),
+        NS_ERROR_FAILURE);
+  }
+
+  aOut.setObject(*obj);
+  return NS_OK;
+}
+
+template <typename Type, typename JNIType, typename ArrayType,
+          JNIType* (JNIEnv::*GetElements)(ArrayType, jboolean*),
+          void (JNIEnv::*ReleaseElements)(ArrayType, JNIType*, jint),
+          JS::Value (*ToValue)(Type)>
+nsresult UnboxArrayPrimitive(JSContext* aCx, const jni::Object::LocalRef& aData,
+                             JS::MutableHandle<JS::Value> aOut) {
+  JNIEnv* const env = aData.Env();
+  const ArrayType jarray = ArrayType(aData.Get());
+  JNIType* const array = (env->*GetElements)(jarray, nullptr);
+  JS::RootedVector<JS::Value> elements(aCx);
+
+  if (NS_WARN_IF(!array)) {
+    env->ExceptionClear();
+    return NS_ERROR_FAILURE;
+  }
+
+  auto releaseArray = MakeScopeExit([env, jarray, array] {
+    (env->*ReleaseElements)(jarray, array, JNI_ABORT);
+    env->ExceptionClear();
+  });
+
+  const size_t len = env->GetArrayLength(jarray);
+  NS_ENSURE_TRUE(elements.initCapacity(len), NS_ERROR_FAILURE);
+
+  for (size_t i = 0; i < len; i++) {
+    NS_ENSURE_TRUE(elements.append((*ToValue)(Type(array[i]))),
+                   NS_ERROR_FAILURE);
+  }
+
+  JS::Rooted<JSObject*> obj(
+      aCx, JS::NewArrayObject(aCx, JS::HandleValueArray(elements)));
+  NS_ENSURE_TRUE(CheckJS(aCx, !!obj), NS_ERROR_FAILURE);
+
+  aOut.setObject(*obj);
+  return NS_OK;
+}
+
+struct StringArray : jni::ObjectBase<StringArray> {
+  static const char name[];
+};
+
+struct GeckoBundleArray : jni::ObjectBase<GeckoBundleArray> {
+  static const char name[];
+};
+
+const char StringArray::name[] = "[Ljava/lang/String;";
+const char GeckoBundleArray::name[] = "[Lorg/mozilla/gecko/util/GeckoBundle;";
+
+template <nsresult (*Unbox)(JSContext*, const jni::Object::LocalRef&,
+                            JS::MutableHandle<JS::Value>)>
+nsresult UnboxArrayObject(JSContext* aCx, const jni::Object::LocalRef& aData,
+                          JS::MutableHandle<JS::Value> aOut) {
+  jni::ObjectArray::LocalRef array(aData.Env(),
+                                   jni::ObjectArray::Ref::From(aData));
+  const size_t len = array->Length();
+  JS::Rooted<JSObject*> obj(aCx, JS::NewArrayObject(aCx, len));
+  NS_ENSURE_TRUE(CheckJS(aCx, !!obj), NS_ERROR_FAILURE);
+
+  for (size_t i = 0; i < len; i++) {
+    jni::Object::LocalRef element = array->GetElement(i);
+    JS::Rooted<JS::Value> value(aCx);
+    nsresult rv = (*Unbox)(aCx, element, &value);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    NS_ENSURE_TRUE(CheckJS(aCx, JS_SetElement(aCx, obj, i, value)),
+                   NS_ERROR_FAILURE);
+  }
+
+  aOut.setObject(*obj);
+  return NS_OK;
+}
+
+nsresult UnboxValue(JSContext* aCx, const jni::Object::LocalRef& aData,
+                    JS::MutableHandle<JS::Value> aOut) {
+  using jni::Java2Native;
+
+  if (!aData) {
+    aOut.setNull();
+  } else if (aData.IsInstanceOf<jni::Boolean>()) {
+    aOut.setBoolean(Java2Native<bool>(aData, aData.Env()));
+  } else if (aData.IsInstanceOf<jni::Integer>()) {
+    aOut.setInt32(Java2Native<int>(aData, aData.Env()));
+  } else if (aData.IsInstanceOf<jni::Byte>() ||
+             aData.IsInstanceOf<jni::Short>()) {
+    aOut.setInt32(java::sdk::Number::Ref::From(aData)->IntValue());
+  } else if (aData.IsInstanceOf<jni::Double>()) {
+    aOut.setNumber(Java2Native<double>(aData, aData.Env()));
+  } else if (aData.IsInstanceOf<jni::Float>() ||
+             aData.IsInstanceOf<jni::Long>()) {
+    aOut.setNumber(java::sdk::Number::Ref::From(aData)->DoubleValue());
+  } else if (aData.IsInstanceOf<jni::String>()) {
+    return UnboxString(aCx, aData, aOut);
+  } else if (aData.IsInstanceOf<jni::Character>()) {
+    return UnboxString(aCx, java::sdk::String::ValueOf(aData), aOut);
+  } else if (aData.IsInstanceOf<java::GeckoBundle>()) {
+    return UnboxBundle(aCx, aData, aOut);
+
+  } else if (aData.IsInstanceOf<jni::BooleanArray>()) {
+    return UnboxArrayPrimitive<
+        bool, jboolean, jbooleanArray, &JNIEnv::GetBooleanArrayElements,
+        &JNIEnv::ReleaseBooleanArrayElements, &JS::BooleanValue>(aCx, aData,
+                                                                 aOut);
+
+  } else if (aData.IsInstanceOf<jni::IntArray>()) {
+    return UnboxArrayPrimitive<
+        int32_t, jint, jintArray, &JNIEnv::GetIntArrayElements,
+        &JNIEnv::ReleaseIntArrayElements, &JS::Int32Value>(aCx, aData, aOut);
+
+  } else if (aData.IsInstanceOf<jni::DoubleArray>()) {
+    return UnboxArrayPrimitive<
+        double, jdouble, jdoubleArray, &JNIEnv::GetDoubleArrayElements,
+        &JNIEnv::ReleaseDoubleArrayElements, &JS::DoubleValue>(aCx, aData,
+                                                               aOut);
+
+  } else if (aData.IsInstanceOf<StringArray>()) {
+    return UnboxArrayObject<&UnboxString>(aCx, aData, aOut);
+  } else if (aData.IsInstanceOf<GeckoBundleArray>()) {
+    return UnboxArrayObject<&UnboxBundle>(aCx, aData, aOut);
+  } else {
+    NS_WARNING("Invalid type");
+    return NS_ERROR_INVALID_ARG;
+  }
+  return NS_OK;
+}
+
+nsresult UnboxData(jni::String::Param aEvent, JSContext* aCx,
+                   jni::Object::Param aData, JS::MutableHandle<JS::Value> aOut,
+                   bool aBundleOnly) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  jni::Object::LocalRef jniData(jni::GetGeckoThreadEnv(), aData);
+  nsresult rv = NS_ERROR_INVALID_ARG;
+
+  if (!aBundleOnly) {
+    rv = UnboxValue(aCx, jniData, aOut);
+  } else if (!jniData || jniData.IsInstanceOf<java::GeckoBundle>()) {
+    rv = UnboxBundle(aCx, jniData, aOut);
+  }
+  if (rv != NS_ERROR_INVALID_ARG || !aEvent) {
+    return rv;
+  }
+
+  nsCString event = aEvent->ToCString();
+  if (JS_IsExceptionPending(aCx)) {
+    JS::WarnUTF8(aCx, "Error dispatching %s", event.get());
+  } else {
+    JS_ReportErrorUTF8(aCx, "Invalid event data for %s", event.get());
+  }
+  return NS_ERROR_INVALID_ARG;
+}
+
+class JavaCallbackDelegate final : public nsIAndroidEventCallback {
+  const java::EventCallback::GlobalRef mCallback;
+
+  virtual ~JavaCallbackDelegate() {}
+
+  NS_IMETHOD Call(JSContext* aCx, JS::Handle<JS::Value> aData,
+                  void (java::EventCallback::*aCall)(jni::Object::Param)
+                      const) {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    jni::Object::LocalRef data(jni::GetGeckoThreadEnv());
+    nsresult rv = BoxData(u"callback"_ns, aCx, aData, data,
+                          /* ObjectOnly */ false);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    dom::AutoNoJSAPI nojsapi;
+
+    (java::EventCallback(*mCallback).*aCall)(data);
+    return NS_OK;
+  }
+
+ public:
+  explicit JavaCallbackDelegate(java::EventCallback::Param aCallback)
+      : mCallback(jni::GetGeckoThreadEnv(), aCallback) {}
+
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD OnSuccess(JS::Handle<JS::Value> aData, JSContext* aCx) override {
+    return Call(aCx, aData, &java::EventCallback::SendSuccess);
+  }
+
+  NS_IMETHOD OnError(JS::Handle<JS::Value> aData, JSContext* aCx) override {
+    return Call(aCx, aData, &java::EventCallback::SendError);
+  }
+};
+
+NS_IMPL_ISUPPORTS(JavaCallbackDelegate, nsIAndroidEventCallback)
+
+class NativeCallbackDelegateSupport final
+    : public java::EventDispatcher::NativeCallbackDelegate ::Natives<
+          NativeCallbackDelegateSupport> {
+  using CallbackDelegate = java::EventDispatcher::NativeCallbackDelegate;
+  using Base = CallbackDelegate::Natives<NativeCallbackDelegateSupport>;
+
+  const nsCOMPtr<nsIAndroidEventCallback> mCallback;
+  const nsCOMPtr<nsIAndroidEventFinalizer> mFinalizer;
+  const nsCOMPtr<nsIGlobalObject> mGlobalObject;
+
+  void Call(jni::Object::Param aData,
+            nsresult (nsIAndroidEventCallback::*aCall)(JS::Handle<JS::Value>,
+                                                       JSContext*)) {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    // Use either the attached window's realm or a default realm.
+
+    dom::AutoJSAPI jsapi;
+    NS_ENSURE_TRUE_VOID(jsapi.Init(mGlobalObject));
+
+    JS::Rooted<JS::Value> data(jsapi.cx());
+    nsresult rv = UnboxData(u"callback"_ns, jsapi.cx(), aData, &data,
+                            /* BundleOnly */ false);
+    NS_ENSURE_SUCCESS_VOID(rv);
+
+    rv = (mCallback->*aCall)(data, jsapi.cx());
+    NS_ENSURE_SUCCESS_VOID(rv);
+  }
+
+ public:
+  using Base::AttachNative;
+
+  template <typename Functor>
+  static void OnNativeCall(Functor&& aCall) {
+    if (NS_IsMainThread()) {
+      // Invoke callbacks synchronously if we're already on Gecko thread.
+      return aCall();
+    }
+    NS_DispatchToMainThread(
+        NS_NewRunnableFunction("OnNativeCall", std::move(aCall)));
+  }
+
+  static void Finalize(const CallbackDelegate::LocalRef& aInstance) {
+    DisposeNative(aInstance);
+  }
+
+  NativeCallbackDelegateSupport(nsIAndroidEventCallback* callback,
+                                nsIAndroidEventFinalizer* finalizer,
+                                nsIGlobalObject* globalObject)
+      : mCallback(callback),
+        mFinalizer(finalizer),
+        mGlobalObject(globalObject) {}
+
+  ~NativeCallbackDelegateSupport() {
+    if (mFinalizer) {
+      mFinalizer->OnFinalize();
+    }
+  }
+
+  void SendSuccess(jni::Object::Param aData) {
+    Call(aData, &nsIAndroidEventCallback::OnSuccess);
+  }
+
+  void SendError(jni::Object::Param aData) {
+    Call(aData, &nsIAndroidEventCallback::OnError);
+  }
+};
+
+class FinalizingCallbackDelegate final : public nsIAndroidEventCallback {
+  const nsCOMPtr<nsIAndroidEventCallback> mCallback;
+  const nsCOMPtr<nsIAndroidEventFinalizer> mFinalizer;
+
+  virtual ~FinalizingCallbackDelegate() {
+    if (mFinalizer) {
+      mFinalizer->OnFinalize();
+    }
+  }
+
+ public:
+  FinalizingCallbackDelegate(nsIAndroidEventCallback* aCallback,
+                             nsIAndroidEventFinalizer* aFinalizer)
+      : mCallback(aCallback), mFinalizer(aFinalizer) {}
+
+  NS_DECL_ISUPPORTS
+  NS_FORWARD_NSIANDROIDEVENTCALLBACK(mCallback->);
+};
+
+NS_IMPL_ISUPPORTS(FinalizingCallbackDelegate, nsIAndroidEventCallback)
+
+}  // namespace detail
+
+using namespace detail;
+
+NS_IMPL_ISUPPORTS(EventDispatcher, nsIAndroidEventDispatcher)
+
+nsIGlobalObject* EventDispatcher::GetGlobalObject() {
+  if (mDOMWindow) {
+    return nsGlobalWindowInner::Cast(mDOMWindow->GetCurrentInnerWindow());
+  }
+  return xpc::NativeGlobal(xpc::PrivilegedJunkScope());
+}
+
+nsresult EventDispatcher::DispatchOnGecko(ListenersList* list,
+                                          const nsAString& aEvent,
+                                          JS::Handle<JS::Value> aData,
+                                          nsIAndroidEventCallback* aCallback) {
+  MOZ_ASSERT(NS_IsMainThread());
+  dom::AutoNoJSAPI nojsapi;
+
+  list->lockCount++;
+
+  auto iteratingScope = MakeScopeExit([list] {
+    list->lockCount--;
+    if (list->lockCount || !list->unregistering) {
+      return;
+    }
+
+    list->unregistering = false;
+    for (ssize_t i = list->listeners.Count() - 1; i >= 0; i--) {
+      if (list->listeners[i]) {
+        continue;
+      }
+      list->listeners.RemoveObjectAt(i);
+    }
+  });
+
+  const size_t count = list->listeners.Count();
+  for (size_t i = 0; i < count; i++) {
+    if (!list->listeners[i]) {
+      // Unregistered.
+      continue;
+    }
+    const nsresult rv = list->listeners[i]->OnEvent(aEvent, aData, aCallback);
+    Unused << NS_WARN_IF(NS_FAILED(rv));
+  }
+  return NS_OK;
+}
+
+java::EventDispatcher::NativeCallbackDelegate::LocalRef
+EventDispatcher::WrapCallback(nsIAndroidEventCallback* aCallback,
+                              nsIAndroidEventFinalizer* aFinalizer) {
+  if (!aCallback) {
+    return java::EventDispatcher::NativeCallbackDelegate::LocalRef(
+        jni::GetGeckoThreadEnv());
+  }
+
+  java::EventDispatcher::NativeCallbackDelegate::LocalRef callback =
+      java::EventDispatcher::NativeCallbackDelegate::New();
+  NativeCallbackDelegateSupport::AttachNative(
+      callback, MakeUnique<NativeCallbackDelegateSupport>(aCallback, aFinalizer,
+                                                          GetGlobalObject()));
+  return callback;
+}
+
+bool EventDispatcher::HasListener(const char16_t* aEvent) {
+  java::EventDispatcher::LocalRef dispatcher(mDispatcher);
+  if (!dispatcher) {
+    return false;
+  }
+
+  nsDependentString event(aEvent);
+  return dispatcher->HasListener(event);
+}
+
+NS_IMETHODIMP
+EventDispatcher::Dispatch(JS::Handle<JS::Value> aEvent,
+                          JS::Handle<JS::Value> aData,
+                          nsIAndroidEventCallback* aCallback,
+                          nsIAndroidEventFinalizer* aFinalizer,
+                          JSContext* aCx) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!aEvent.isString()) {
+    NS_WARNING("Invalid event name");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsAutoJSString event;
+  NS_ENSURE_TRUE(CheckJS(aCx, event.init(aCx, aEvent.toString())),
+                 NS_ERROR_OUT_OF_MEMORY);
+
+  // Don't need to lock here because we're on the main thread, and we can't
+  // race against Register/UnregisterListener.
+
+  ListenersList* list = mListenersMap.Get(event);
+  if (list) {
+    if (!aCallback || !aFinalizer) {
+      return DispatchOnGecko(list, event, aData, aCallback);
+    }
+    nsCOMPtr<nsIAndroidEventCallback> callback(
+        new FinalizingCallbackDelegate(aCallback, aFinalizer));
+    return DispatchOnGecko(list, event, aData, callback);
+  }
+
+  java::EventDispatcher::LocalRef dispatcher(mDispatcher);
+  if (!dispatcher) {
+    return NS_OK;
+  }
+
+  jni::Object::LocalRef data(jni::GetGeckoThreadEnv());
+  nsresult rv = BoxData(event, aCx, aData, data, /* ObjectOnly */ true);
+  // Keep XPConnect from overriding the JSContext exception with one
+  // based on the nsresult.
+  //
+  // XXXbz Does xpconnect still do that?  Needs to be checked/tested.
+  NS_ENSURE_SUCCESS(rv, JS_IsExceptionPending(aCx) ? NS_OK : rv);
+
+  dom::AutoNoJSAPI nojsapi;
+  dispatcher->DispatchToThreads(event, data,
+                                WrapCallback(aCallback, aFinalizer));
+  return NS_OK;
+}
+
+nsresult EventDispatcher::Dispatch(const char16_t* aEvent,
+                                   java::GeckoBundle::Param aData,
+                                   nsIAndroidEventCallback* aCallback) {
+  nsDependentString event(aEvent);
+
+  ListenersList* list = mListenersMap.Get(event);
+  if (list) {
+    dom::AutoJSAPI jsapi;
+    NS_ENSURE_TRUE(jsapi.Init(GetGlobalObject()), NS_ERROR_FAILURE);
+    JS::Rooted<JS::Value> data(jsapi.cx());
+    nsresult rv = UnboxData(/* Event */ nullptr, jsapi.cx(), aData, &data,
+                            /* BundleOnly */ true);
+    NS_ENSURE_SUCCESS(rv, rv);
+    return DispatchOnGecko(list, event, data, aCallback);
+  }
+
+  java::EventDispatcher::LocalRef dispatcher(mDispatcher);
+  if (!dispatcher) {
+    return NS_OK;
+  }
+
+  dispatcher->DispatchToThreads(event, aData, WrapCallback(aCallback));
+  return NS_OK;
+}
+
+nsresult EventDispatcher::IterateEvents(JSContext* aCx,
+                                        JS::Handle<JS::Value> aEvents,
+                                        IterateEventsCallback aCallback,
+                                        nsIAndroidEventListener* aListener) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  MutexAutoLock lock(mLock);
+
+  auto processEvent = [this, aCx, aCallback,
+                       aListener](JS::Handle<JS::Value> event) -> nsresult {
+    nsAutoJSString str;
+    NS_ENSURE_TRUE(CheckJS(aCx, str.init(aCx, event.toString())),
+                   NS_ERROR_OUT_OF_MEMORY);
+    return (this->*aCallback)(str, aListener);
+  };
+
+  if (aEvents.isString()) {
+    return processEvent(aEvents);
+  }
+
+  bool isArray = false;
+  NS_ENSURE_TRUE(aEvents.isObject(), NS_ERROR_INVALID_ARG);
+  NS_ENSURE_TRUE(CheckJS(aCx, JS::IsArrayObject(aCx, aEvents, &isArray)),
+                 NS_ERROR_INVALID_ARG);
+  NS_ENSURE_TRUE(isArray, NS_ERROR_INVALID_ARG);
+
+  JS::Rooted<JSObject*> events(aCx, &aEvents.toObject());
+  uint32_t length = 0;
+  NS_ENSURE_TRUE(CheckJS(aCx, JS::GetArrayLength(aCx, events, &length)),
+                 NS_ERROR_INVALID_ARG);
+  NS_ENSURE_TRUE(length, NS_ERROR_INVALID_ARG);
+
+  for (size_t i = 0; i < length; i++) {
+    JS::Rooted<JS::Value> event(aCx);
+    NS_ENSURE_TRUE(CheckJS(aCx, JS_GetElement(aCx, events, i, &event)),
+                   NS_ERROR_INVALID_ARG);
+    NS_ENSURE_TRUE(event.isString(), NS_ERROR_INVALID_ARG);
+
+    const nsresult rv = processEvent(event);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+  return NS_OK;
+}
+
+nsresult EventDispatcher::RegisterEventLocked(
+    const nsAString& aEvent, nsIAndroidEventListener* aListener) {
+  ListenersList* list = mListenersMap.GetOrInsertNew(aEvent);
+
+#ifdef DEBUG
+  for (ssize_t i = 0; i < list->listeners.Count(); i++) {
+    NS_ENSURE_TRUE(list->listeners[i] != aListener,
+                   NS_ERROR_ALREADY_INITIALIZED);
+  }
+#endif
+
+  list->listeners.AppendObject(aListener);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+EventDispatcher::RegisterListener(nsIAndroidEventListener* aListener,
+                                  JS::Handle<JS::Value> aEvents,
+                                  JSContext* aCx) {
+  return IterateEvents(aCx, aEvents, &EventDispatcher::RegisterEventLocked,
+                       aListener);
+}
+
+nsresult EventDispatcher::UnregisterEventLocked(
+    const nsAString& aEvent, nsIAndroidEventListener* aListener) {
+  ListenersList* list = mListenersMap.Get(aEvent);
+#ifdef DEBUG
+  NS_ENSURE_TRUE(list, NS_ERROR_NOT_INITIALIZED);
+#else
+  NS_ENSURE_TRUE(list, NS_OK);
+#endif
+
+  DebugOnly<bool> found = false;
+  for (ssize_t i = list->listeners.Count() - 1; i >= 0; i--) {
+    if (list->listeners[i] != aListener) {
+      continue;
+    }
+    if (list->lockCount) {
+      // Only mark for removal when list is locked.
+      list->listeners.ReplaceObjectAt(nullptr, i);
+      list->unregistering = true;
+    } else {
+      list->listeners.RemoveObjectAt(i);
+    }
+    found = true;
+  }
+#ifdef DEBUG
+  return found ? NS_OK : NS_ERROR_NOT_INITIALIZED;
+#else
+  return NS_OK;
+#endif
+}
+
+NS_IMETHODIMP
+EventDispatcher::UnregisterListener(nsIAndroidEventListener* aListener,
+                                    JS::Handle<JS::Value> aEvents,
+                                    JSContext* aCx) {
+  return IterateEvents(aCx, aEvents, &EventDispatcher::UnregisterEventLocked,
+                       aListener);
+}
+
+void EventDispatcher::Attach(java::EventDispatcher::Param aDispatcher,
+                             nsPIDOMWindowOuter* aDOMWindow) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aDispatcher);
+
+  java::EventDispatcher::LocalRef dispatcher(mDispatcher);
+
+  if (dispatcher) {
+    if (dispatcher == aDispatcher) {
+      // Only need to update the window.
+      mDOMWindow = aDOMWindow;
+      return;
+    }
+    dispatcher->SetAttachedToGecko(java::EventDispatcher::REATTACHING);
+  }
+
+  dispatcher = java::EventDispatcher::LocalRef(aDispatcher);
+  NativesBase::AttachNative(dispatcher, this);
+  mDispatcher = dispatcher;
+  mDOMWindow = aDOMWindow;
+
+  dispatcher->SetAttachedToGecko(java::EventDispatcher::ATTACHED);
+}
+
+void EventDispatcher::Shutdown() {
+  mDispatcher = nullptr;
+  mDOMWindow = nullptr;
+}
+
+void EventDispatcher::Detach() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mDispatcher);
+
+  java::EventDispatcher::GlobalRef dispatcher(mDispatcher);
+
+  // SetAttachedToGecko will call disposeNative for us later on the Gecko
+  // thread to make sure all pending dispatchToGecko calls have completed.
+  if (dispatcher) {
+    dispatcher->SetAttachedToGecko(java::EventDispatcher::DETACHED);
+  }
+
+  Shutdown();
+}
+
+bool EventDispatcher::HasGeckoListener(jni::String::Param aEvent) {
+  // Can be called from any thread.
+  MutexAutoLock lock(mLock);
+  return !!mListenersMap.Get(aEvent->ToString());
+}
+
+void EventDispatcher::DispatchToGecko(jni::String::Param aEvent,
+                                      jni::Object::Param aData,
+                                      jni::Object::Param aCallback) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // Don't need to lock here because we're on the main thread, and we can't
+  // race against Register/UnregisterListener.
+
+  nsString event = aEvent->ToString();
+  ListenersList* list = mListenersMap.Get(event);
+  if (!list || list->listeners.IsEmpty()) {
+    return;
+  }
+
+  // Use the same compartment as the attached window if possible, otherwise
+  // use a default compartment.
+  dom::AutoJSAPI jsapi;
+  NS_ENSURE_TRUE_VOID(jsapi.Init(GetGlobalObject()));
+
+  JS::Rooted<JS::Value> data(jsapi.cx());
+  nsresult rv = UnboxData(aEvent, jsapi.cx(), aData, &data,
+                          /* BundleOnly */ true);
+  NS_ENSURE_SUCCESS_VOID(rv);
+
+  nsCOMPtr<nsIAndroidEventCallback> callback;
+  if (aCallback) {
+    callback =
+        new JavaCallbackDelegate(java::EventCallback::Ref::From(aCallback));
+  }
+
+  DispatchOnGecko(list, event, data, callback);
+}
+
+/* static */
+nsresult EventDispatcher::UnboxBundle(JSContext* aCx, jni::Object::Param aData,
+                                      JS::MutableHandle<JS::Value> aOut) {
+  return detail::UnboxBundle(aCx, aData, aOut);
+}
+
+}  // namespace widget
+}  // namespace mozilla
+
+#if defined(__clang__)
+#  pragma clang diagnostic pop
+#endif
diff --git a/widget/android/EventDispatcher.h b/widget/android/EventDispatcher.h
new file mode 100644
index 0000000000..a7daa18d7d
--- /dev/null
+++ b/widget/android/EventDispatcher.h
@@ -0,0 +1,104 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; indent-tabs-mode: nil; -*-
+ * vim: set sw=2 ts=4 expandtab:
+ * 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_EventDispatcher_h
+#define mozilla_widget_EventDispatcher_h
+
+#include "jsapi.h"
+#include "nsClassHashtable.h"
+#include "nsCOMArray.h"
+#include "nsIAndroidBridge.h"
+#include "nsHashKeys.h"
+#include "nsPIDOMWindow.h"
+
+#include "mozilla/java/EventDispatcherNatives.h"
+#include "mozilla/java/GeckoBundleWrappers.h"
+#include "mozilla/Mutex.h"
+
+namespace mozilla {
+namespace widget {
+
+/**
+ * EventDispatcher is the Gecko counterpart to the Java EventDispatcher class.
+ * Together, they make up a unified event bus. Events dispatched from the Java
+ * side may notify event listeners on the Gecko side, and vice versa.
+ */
+class EventDispatcher final
+    : public nsIAndroidEventDispatcher,
+      public java::EventDispatcher::Natives<EventDispatcher> {
+  using NativesBase = java::EventDispatcher::Natives<EventDispatcher>;
+
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIANDROIDEVENTDISPATCHER
+
+  EventDispatcher() {}
+
+  void Attach(java::EventDispatcher::Param aDispatcher,
+              nsPIDOMWindowOuter* aDOMWindow);
+  void Detach();
+
+  nsresult Dispatch(const char16_t* aEvent,
+                    java::GeckoBundle::Param aData = nullptr,
+                    nsIAndroidEventCallback* aCallback = nullptr);
+
+  bool HasListener(const char16_t* aEvent);
+  bool HasGeckoListener(jni::String::Param aEvent);
+  void DispatchToGecko(jni::String::Param aEvent, jni::Object::Param aData,
+                       jni::Object::Param aCallback);
+
+  static nsresult UnboxBundle(JSContext* aCx, jni::Object::Param aData,
+                              JS::MutableHandle<JS::Value> aOut);
+
+  nsIGlobalObject* GetGlobalObject();
+
+  using NativesBase::DisposeNative;
+
+ private:
+  friend class java::EventDispatcher::Natives<EventDispatcher>;
+
+  java::EventDispatcher::WeakRef mDispatcher;
+  nsCOMPtr<nsPIDOMWindowOuter> mDOMWindow;
+
+  virtual ~EventDispatcher() {}
+
+  void Shutdown();
+
+  struct ListenersList {
+    nsCOMArray<nsIAndroidEventListener> listeners{/* count */ 1};
+    // 0 if the list can be modified
+    uint32_t lockCount{0};
+    // true if this list has a listener that is being unregistered
+    bool unregistering{false};
+  };
+
+  using ListenersMap = nsClassHashtable<nsStringHashKey, ListenersList>;
+
+  Mutex mLock MOZ_UNANNOTATED{"mozilla::widget::EventDispatcher"};
+  ListenersMap mListenersMap;
+
+  using IterateEventsCallback =
+      nsresult (EventDispatcher::*)(const nsAString&, nsIAndroidEventListener*);
+
+  nsresult IterateEvents(JSContext* aCx, JS::Handle<JS::Value> aEvents,
+                         IterateEventsCallback aCallback,
+                         nsIAndroidEventListener* aListener);
+  nsresult RegisterEventLocked(const nsAString&, nsIAndroidEventListener*);
+  nsresult UnregisterEventLocked(const nsAString&, nsIAndroidEventListener*);
+
+  nsresult DispatchOnGecko(ListenersList* list, const nsAString& aEvent,
+                           JS::Handle<JS::Value> aData,
+                           nsIAndroidEventCallback* aCallback);
+
+  java::EventDispatcher::NativeCallbackDelegate::LocalRef WrapCallback(
+      nsIAndroidEventCallback* aCallback,
+      nsIAndroidEventFinalizer* aFinalizer = nullptr);
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_EventDispatcher_h
diff --git a/widget/android/GeckoBatteryManager.h b/widget/android/GeckoBatteryManager.h
new file mode 100644
index 0000000000..d9a171d0d1
--- /dev/null
+++ b/widget/android/GeckoBatteryManager.h
@@ -0,0 +1,28 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 GeckoBatteryManager_h
+#define GeckoBatteryManager_h
+
+#include "nsAppShell.h"
+
+#include "mozilla/Hal.h"
+#include "mozilla/java/GeckoBatteryManagerNatives.h"
+
+namespace mozilla {
+
+class GeckoBatteryManager final
+    : public java::GeckoBatteryManager::Natives<GeckoBatteryManager> {
+ public:
+  static void OnBatteryChange(double aLevel, bool aCharging,
+                              double aRemainingTime) {
+    hal::NotifyBatteryChange(
+        hal::BatteryInformation(aLevel, aCharging, aRemainingTime));
+  }
+};
+
+}  // namespace mozilla
+
+#endif  // GeckoBatteryManager_h
diff --git a/widget/android/GeckoEditableSupport.cpp b/widget/android/GeckoEditableSupport.cpp
new file mode 100644
index 0000000000..fcac5d5399
--- /dev/null
+++ b/widget/android/GeckoEditableSupport.cpp
@@ -0,0 +1,1684 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 4; indent-tabs-mode: nil; -*-
+ * vim: set sw=2 ts=4 expandtab:
+ * 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 "GeckoEditableSupport.h"
+
+#include "AndroidRect.h"
+#include "KeyEvent.h"
+#include "PuppetWidget.h"
+#include "nsIContent.h"
+#include "nsITransferable.h"
+#include "nsStringStream.h"
+
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/IMEStateManager.h"
+#include "mozilla/java/GeckoEditableChildWrappers.h"
+#include "mozilla/java/GeckoServiceChildProcessWrappers.h"
+#include "mozilla/jni/NativesInlines.h"
+#include "mozilla/Logging.h"
+#include "mozilla/MiscEvents.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_intl.h"
+#include "mozilla/TextComposition.h"
+#include "mozilla/TextEventDispatcherListener.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/ToString.h"
+#include "mozilla/dom/BrowserChild.h"
+#include "mozilla/widget/GeckoViewSupport.h"
+
+#include <android/api-level.h>
+#include <android/input.h>
+#include <android/log.h>
+
+#ifdef NIGHTLY_BUILD
+static mozilla::LazyLogModule sGeckoEditableSupportLog("GeckoEditableSupport");
+#  define ALOGIME(...) \
+    MOZ_LOG(sGeckoEditableSupportLog, LogLevel::Debug, (__VA_ARGS__))
+#else
+#  define ALOGIME(args...) \
+    do {                   \
+    } while (0)
+#endif
+
+static uint32_t ConvertAndroidKeyCodeToDOMKeyCode(int32_t androidKeyCode) {
+  // Special-case alphanumeric keycodes because they are most common.
+  if (androidKeyCode >= AKEYCODE_A && androidKeyCode <= AKEYCODE_Z) {
+    return androidKeyCode - AKEYCODE_A + NS_VK_A;
+  }
+
+  if (androidKeyCode >= AKEYCODE_0 && androidKeyCode <= AKEYCODE_9) {
+    return androidKeyCode - AKEYCODE_0 + NS_VK_0;
+  }
+
+  switch (androidKeyCode) {
+    // KEYCODE_UNKNOWN (0) ... KEYCODE_HOME (3)
+    case AKEYCODE_BACK:
+      return NS_VK_ESCAPE;
+    // KEYCODE_CALL (5) ... KEYCODE_POUND (18)
+    case AKEYCODE_DPAD_UP:
+      return NS_VK_UP;
+    case AKEYCODE_DPAD_DOWN:
+      return NS_VK_DOWN;
+    case AKEYCODE_DPAD_LEFT:
+      return NS_VK_LEFT;
+    case AKEYCODE_DPAD_RIGHT:
+      return NS_VK_RIGHT;
+    case AKEYCODE_DPAD_CENTER:
+      return NS_VK_RETURN;
+    case AKEYCODE_VOLUME_UP:
+      return NS_VK_VOLUME_UP;
+    case AKEYCODE_VOLUME_DOWN:
+      return NS_VK_VOLUME_DOWN;
+    // KEYCODE_VOLUME_POWER (26) ... KEYCODE_Z (54)
+    case AKEYCODE_COMMA:
+      return NS_VK_COMMA;
+    case AKEYCODE_PERIOD:
+      return NS_VK_PERIOD;
+    case AKEYCODE_ALT_LEFT:
+      return NS_VK_ALT;
+    case AKEYCODE_ALT_RIGHT:
+      return NS_VK_ALT;
+    case AKEYCODE_SHIFT_LEFT:
+      return NS_VK_SHIFT;
+    case AKEYCODE_SHIFT_RIGHT:
+      return NS_VK_SHIFT;
+    case AKEYCODE_TAB:
+      return NS_VK_TAB;
+    case AKEYCODE_SPACE:
+      return NS_VK_SPACE;
+    // KEYCODE_SYM (63) ... KEYCODE_ENVELOPE (65)
+    case AKEYCODE_ENTER:
+      return NS_VK_RETURN;
+    case AKEYCODE_DEL:
+      return NS_VK_BACK;  // Backspace
+    case AKEYCODE_GRAVE:
+      return NS_VK_BACK_QUOTE;
+    // KEYCODE_MINUS (69)
+    case AKEYCODE_EQUALS:
+      return NS_VK_EQUALS;
+    case AKEYCODE_LEFT_BRACKET:
+      return NS_VK_OPEN_BRACKET;
+    case AKEYCODE_RIGHT_BRACKET:
+      return NS_VK_CLOSE_BRACKET;
+    case AKEYCODE_BACKSLASH:
+      return NS_VK_BACK_SLASH;
+    case AKEYCODE_SEMICOLON:
+      return NS_VK_SEMICOLON;
+    // KEYCODE_APOSTROPHE (75)
+    case AKEYCODE_SLASH:
+      return NS_VK_SLASH;
+    // KEYCODE_AT (77) ... KEYCODE_MEDIA_FAST_FORWARD (90)
+    case AKEYCODE_MUTE:
+      return NS_VK_VOLUME_MUTE;
+    case AKEYCODE_PAGE_UP:
+      return NS_VK_PAGE_UP;
+    case AKEYCODE_PAGE_DOWN:
+      return NS_VK_PAGE_DOWN;
+    // KEYCODE_PICTSYMBOLS (94) ... KEYCODE_BUTTON_MODE (110)
+    case AKEYCODE_ESCAPE:
+      return NS_VK_ESCAPE;
+    case AKEYCODE_FORWARD_DEL:
+      return NS_VK_DELETE;
+    case AKEYCODE_CTRL_LEFT:
+      return NS_VK_CONTROL;
+    case AKEYCODE_CTRL_RIGHT:
+      return NS_VK_CONTROL;
+    case AKEYCODE_CAPS_LOCK:
+      return NS_VK_CAPS_LOCK;
+    case AKEYCODE_SCROLL_LOCK:
+      return NS_VK_SCROLL_LOCK;
+    // KEYCODE_META_LEFT (117) ... KEYCODE_FUNCTION (119)
+    case AKEYCODE_SYSRQ:
+      return NS_VK_PRINTSCREEN;
+    case AKEYCODE_BREAK:
+      return NS_VK_PAUSE;
+    case AKEYCODE_MOVE_HOME:
+      return NS_VK_HOME;
+    case AKEYCODE_MOVE_END:
+      return NS_VK_END;
+    case AKEYCODE_INSERT:
+      return NS_VK_INSERT;
+    // KEYCODE_FORWARD (125) ... KEYCODE_MEDIA_RECORD (130)
+    case AKEYCODE_F1:
+      return NS_VK_F1;
+    case AKEYCODE_F2:
+      return NS_VK_F2;
+    case AKEYCODE_F3:
+      return NS_VK_F3;
+    case AKEYCODE_F4:
+      return NS_VK_F4;
+    case AKEYCODE_F5:
+      return NS_VK_F5;
+    case AKEYCODE_F6:
+      return NS_VK_F6;
+    case AKEYCODE_F7:
+      return NS_VK_F7;
+    case AKEYCODE_F8:
+      return NS_VK_F8;
+    case AKEYCODE_F9:
+      return NS_VK_F9;
+    case AKEYCODE_F10:
+      return NS_VK_F10;
+    case AKEYCODE_F11:
+      return NS_VK_F11;
+    case AKEYCODE_F12:
+      return NS_VK_F12;
+    case AKEYCODE_NUM_LOCK:
+      return NS_VK_NUM_LOCK;
+    case AKEYCODE_NUMPAD_0:
+      return NS_VK_NUMPAD0;
+    case AKEYCODE_NUMPAD_1:
+      return NS_VK_NUMPAD1;
+    case AKEYCODE_NUMPAD_2:
+      return NS_VK_NUMPAD2;
+    case AKEYCODE_NUMPAD_3:
+      return NS_VK_NUMPAD3;
+    case AKEYCODE_NUMPAD_4:
+      return NS_VK_NUMPAD4;
+    case AKEYCODE_NUMPAD_5:
+      return NS_VK_NUMPAD5;
+    case AKEYCODE_NUMPAD_6:
+      return NS_VK_NUMPAD6;
+    case AKEYCODE_NUMPAD_7:
+      return NS_VK_NUMPAD7;
+    case AKEYCODE_NUMPAD_8:
+      return NS_VK_NUMPAD8;
+    case AKEYCODE_NUMPAD_9:
+      return NS_VK_NUMPAD9;
+    case AKEYCODE_NUMPAD_DIVIDE:
+      return NS_VK_DIVIDE;
+    case AKEYCODE_NUMPAD_MULTIPLY:
+      return NS_VK_MULTIPLY;
+    case AKEYCODE_NUMPAD_SUBTRACT:
+      return NS_VK_SUBTRACT;
+    case AKEYCODE_NUMPAD_ADD:
+      return NS_VK_ADD;
+    case AKEYCODE_NUMPAD_DOT:
+      return NS_VK_DECIMAL;
+    case AKEYCODE_NUMPAD_COMMA:
+      return NS_VK_SEPARATOR;
+    case AKEYCODE_NUMPAD_ENTER:
+      return NS_VK_RETURN;
+    case AKEYCODE_NUMPAD_EQUALS:
+      return NS_VK_EQUALS;
+    // KEYCODE_NUMPAD_LEFT_PAREN (162) ... KEYCODE_CALCULATOR (210)
+
+    // Needs to confirm the behavior.  If the key switches the open state
+    // of Japanese IME (or switches input character between Hiragana and
+    // Roman numeric characters), then, it might be better to use
+    // NS_VK_KANJI which is used for Alt+Zenkaku/Hankaku key on Windows.
+    case AKEYCODE_ZENKAKU_HANKAKU:
+      return 0;
+    case AKEYCODE_EISU:
+      return NS_VK_EISU;
+    case AKEYCODE_MUHENKAN:
+      return NS_VK_NONCONVERT;
+    case AKEYCODE_HENKAN:
+      return NS_VK_CONVERT;
+    case AKEYCODE_KATAKANA_HIRAGANA:
+      return 0;
+    case AKEYCODE_YEN:
+      return NS_VK_BACK_SLASH;  // Same as other platforms.
+    case AKEYCODE_RO:
+      return NS_VK_BACK_SLASH;  // Same as other platforms.
+    case AKEYCODE_KANA:
+      return NS_VK_KANA;
+    case AKEYCODE_ASSIST:
+      return NS_VK_HELP;
+
+    // the A key is the action key for gamepad devices.
+    case AKEYCODE_BUTTON_A:
+      return NS_VK_RETURN;
+
+    default:
+      ALOG(
+          "ConvertAndroidKeyCodeToDOMKeyCode: "
+          "No DOM keycode for Android keycode %d",
+          int(androidKeyCode));
+      return 0;
+  }
+}
+
+static KeyNameIndex ConvertAndroidKeyCodeToKeyNameIndex(
+    int32_t keyCode, int32_t action, int32_t domPrintableKeyValue) {
+  // Special-case alphanumeric keycodes because they are most common.
+  if (keyCode >= AKEYCODE_A && keyCode <= AKEYCODE_Z) {
+    return KEY_NAME_INDEX_USE_STRING;
+  }
+
+  if (keyCode >= AKEYCODE_0 && keyCode <= AKEYCODE_9) {
+    return KEY_NAME_INDEX_USE_STRING;
+  }
+
+  switch (keyCode) {
+#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
+
+    // KEYCODE_0 (7) ... KEYCODE_9 (16)
+    case AKEYCODE_STAR:   // '*' key
+    case AKEYCODE_POUND:  // '#' key
+
+      // KEYCODE_A (29) ... KEYCODE_Z (54)
+
+    case AKEYCODE_COMMA:   // ',' key
+    case AKEYCODE_PERIOD:  // '.' key
+    case AKEYCODE_SPACE:
+    case AKEYCODE_GRAVE:          // '`' key
+    case AKEYCODE_MINUS:          // '-' key
+    case AKEYCODE_EQUALS:         // '=' key
+    case AKEYCODE_LEFT_BRACKET:   // '[' key
+    case AKEYCODE_RIGHT_BRACKET:  // ']' key
+    case AKEYCODE_BACKSLASH:      // '\' key
+    case AKEYCODE_SEMICOLON:      // ';' key
+    case AKEYCODE_APOSTROPHE:     // ''' key
+    case AKEYCODE_SLASH:          // '/' key
+    case AKEYCODE_AT:             // '@' key
+    case AKEYCODE_PLUS:           // '+' key
+
+    case AKEYCODE_NUMPAD_0:
+    case AKEYCODE_NUMPAD_1:
+    case AKEYCODE_NUMPAD_2:
+    case AKEYCODE_NUMPAD_3:
+    case AKEYCODE_NUMPAD_4:
+    case AKEYCODE_NUMPAD_5:
+    case AKEYCODE_NUMPAD_6:
+    case AKEYCODE_NUMPAD_7:
+    case AKEYCODE_NUMPAD_8:
+    case AKEYCODE_NUMPAD_9:
+    case AKEYCODE_NUMPAD_DIVIDE:
+    case AKEYCODE_NUMPAD_MULTIPLY:
+    case AKEYCODE_NUMPAD_SUBTRACT:
+    case AKEYCODE_NUMPAD_ADD:
+    case AKEYCODE_NUMPAD_DOT:
+    case AKEYCODE_NUMPAD_COMMA:
+    case AKEYCODE_NUMPAD_EQUALS:
+    case AKEYCODE_NUMPAD_LEFT_PAREN:
+    case AKEYCODE_NUMPAD_RIGHT_PAREN:
+
+    case AKEYCODE_YEN:  // yen sign key
+    case AKEYCODE_RO:   // Japanese Ro key
+      return KEY_NAME_INDEX_USE_STRING;
+
+    case AKEYCODE_NUM:  // XXX Not sure
+    case AKEYCODE_PICTSYMBOLS:
+
+    case AKEYCODE_BUTTON_A:
+    case AKEYCODE_BUTTON_B:
+    case AKEYCODE_BUTTON_C:
+    case AKEYCODE_BUTTON_X:
+    case AKEYCODE_BUTTON_Y:
+    case AKEYCODE_BUTTON_Z:
+    case AKEYCODE_BUTTON_L1:
+    case AKEYCODE_BUTTON_R1:
+    case AKEYCODE_BUTTON_L2:
+    case AKEYCODE_BUTTON_R2:
+    case AKEYCODE_BUTTON_THUMBL:
+    case AKEYCODE_BUTTON_THUMBR:
+    case AKEYCODE_BUTTON_START:
+    case AKEYCODE_BUTTON_SELECT:
+    case AKEYCODE_BUTTON_MODE:
+
+    case AKEYCODE_MEDIA_CLOSE:
+
+    case AKEYCODE_BUTTON_1:
+    case AKEYCODE_BUTTON_2:
+    case AKEYCODE_BUTTON_3:
+    case AKEYCODE_BUTTON_4:
+    case AKEYCODE_BUTTON_5:
+    case AKEYCODE_BUTTON_6:
+    case AKEYCODE_BUTTON_7:
+    case AKEYCODE_BUTTON_8:
+    case AKEYCODE_BUTTON_9:
+    case AKEYCODE_BUTTON_10:
+    case AKEYCODE_BUTTON_11:
+    case AKEYCODE_BUTTON_12:
+    case AKEYCODE_BUTTON_13:
+    case AKEYCODE_BUTTON_14:
+    case AKEYCODE_BUTTON_15:
+    case AKEYCODE_BUTTON_16:
+      return KEY_NAME_INDEX_Unidentified;
+
+    case AKEYCODE_UNKNOWN:
+      MOZ_ASSERT(action != AKEY_EVENT_ACTION_MULTIPLE,
+                 "Don't call this when action is AKEY_EVENT_ACTION_MULTIPLE!");
+      // It's actually an unknown key if the action isn't ACTION_MULTIPLE.
+      // However, it might cause text input.  So, let's check the value.
+      return domPrintableKeyValue ? KEY_NAME_INDEX_USE_STRING
+                                  : KEY_NAME_INDEX_Unidentified;
+
+    default:
+      ALOG(
+          "ConvertAndroidKeyCodeToKeyNameIndex: "
+          "No DOM key name index for Android keycode %d",
+          keyCode);
+      return KEY_NAME_INDEX_Unidentified;
+  }
+}
+
+static CodeNameIndex ConvertAndroidScanCodeToCodeNameIndex(int32_t scanCode) {
+  switch (scanCode) {
+#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;
+  }
+}
+
+static void InitKeyEvent(WidgetKeyboardEvent& aEvent, int32_t aAction,
+                         int32_t aKeyCode, int32_t aScanCode,
+                         int32_t aMetaState, int64_t aTime,
+                         int32_t aDomPrintableKeyValue, int32_t aRepeatCount,
+                         int32_t aFlags) {
+  const uint32_t domKeyCode = ConvertAndroidKeyCodeToDOMKeyCode(aKeyCode);
+
+  aEvent.mModifiers = nsWindow::GetModifiers(aMetaState);
+  aEvent.mKeyCode = domKeyCode;
+
+  aEvent.mIsRepeat =
+      (aEvent.mMessage == eKeyDown || aEvent.mMessage == eKeyPress) &&
+      ((aFlags & java::sdk::KeyEvent::FLAG_LONG_PRESS) || aRepeatCount);
+
+  aEvent.mKeyNameIndex = ConvertAndroidKeyCodeToKeyNameIndex(
+      aKeyCode, aAction, aDomPrintableKeyValue);
+  aEvent.mCodeNameIndex = ConvertAndroidScanCodeToCodeNameIndex(aScanCode);
+
+  if (aEvent.mKeyNameIndex == KEY_NAME_INDEX_USE_STRING &&
+      aDomPrintableKeyValue) {
+    aEvent.mKeyValue = char16_t(aDomPrintableKeyValue);
+  }
+
+  aEvent.mLocation =
+      WidgetKeyboardEvent::ComputeLocationFromCodeValue(aEvent.mCodeNameIndex);
+  aEvent.mTimeStamp = nsWindow::GetEventTimeStamp(aTime);
+}
+
+static nscolor ConvertAndroidColor(uint32_t aArgb) {
+  return NS_RGBA((aArgb & 0x00ff0000) >> 16, (aArgb & 0x0000ff00) >> 8,
+                 (aArgb & 0x000000ff), (aArgb & 0xff000000) >> 24);
+}
+
+static jni::ObjectArray::LocalRef ConvertRectArrayToJavaRectFArray(
+    const nsTArray<LayoutDeviceIntRect>& aRects) {
+  const size_t length = aRects.Length();
+  auto rects = jni::ObjectArray::New<java::sdk::RectF>(length);
+
+  for (size_t i = 0; i < length; i++) {
+    const LayoutDeviceIntRect& tmp = aRects[i];
+
+    auto rect = java::sdk::RectF::New(tmp.x, tmp.y, tmp.XMost(), tmp.YMost());
+    rects->SetElement(i, rect);
+  }
+  return rects;
+}
+
+namespace mozilla {
+namespace widget {
+
+NS_IMPL_ISUPPORTS(GeckoEditableSupport, TextEventDispatcherListener,
+                  nsISupportsWeakReference)
+
+// This is the blocker helper class whether disposing GeckoEditableChild now.
+// During JNI call from GeckoEditableChild, we shouldn't dispose it.
+class MOZ_RAII AutoGeckoEditableBlocker final {
+ public:
+  explicit AutoGeckoEditableBlocker(GeckoEditableSupport* aGeckoEditableSupport)
+      : mGeckoEditable(aGeckoEditableSupport) {
+    mGeckoEditable->AddBlocker();
+  }
+  ~AutoGeckoEditableBlocker() { mGeckoEditable->ReleaseBlocker(); }
+
+ private:
+  RefPtr<GeckoEditableSupport> mGeckoEditable;
+};
+
+RefPtr<TextComposition> GeckoEditableSupport::GetComposition() const {
+  nsCOMPtr<nsIWidget> widget = GetWidget();
+  return widget ? IMEStateManager::GetTextCompositionFor(widget) : nullptr;
+}
+
+bool GeckoEditableSupport::RemoveComposition(RemoveCompositionFlag aFlag) {
+  if (!mDispatcher || !mDispatcher->IsComposing()) {
+    return false;
+  }
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+
+  NS_ENSURE_SUCCESS(BeginInputTransaction(mDispatcher), false);
+  mDispatcher->CommitComposition(
+      status, aFlag == CANCEL_IME_COMPOSITION ? &EmptyString() : nullptr);
+  return true;
+}
+
+void GeckoEditableSupport::OnKeyEvent(int32_t aAction, int32_t aKeyCode,
+                                      int32_t aScanCode, int32_t aMetaState,
+                                      int32_t aKeyPressMetaState, int64_t aTime,
+                                      int32_t aDomPrintableKeyValue,
+                                      int32_t aRepeatCount, int32_t aFlags,
+                                      bool aIsSynthesizedImeKey,
+                                      jni::Object::Param aOriginalEvent) {
+  AutoGeckoEditableBlocker blocker(this);
+
+  nsCOMPtr<nsIWidget> widget = GetWidget();
+  RefPtr<TextEventDispatcher> dispatcher =
+      mDispatcher ? mDispatcher.get()
+      : widget    ? widget->GetTextEventDispatcher()
+                  : nullptr;
+  NS_ENSURE_TRUE_VOID(dispatcher && widget);
+
+  if (!aIsSynthesizedImeKey) {
+    if (nsWindow* window = GetNsWindow()) {
+      window->UserActivity();
+    }
+  } else if (aIsSynthesizedImeKey && mIMEMaskEventsCount > 0) {
+    // Don't synthesize editor keys when not focused.
+    return;
+  }
+
+  EventMessage msg;
+  if (aAction == java::sdk::KeyEvent::ACTION_DOWN) {
+    msg = eKeyDown;
+  } else if (aAction == java::sdk::KeyEvent::ACTION_UP) {
+    msg = eKeyUp;
+  } else if (aAction == java::sdk::KeyEvent::ACTION_MULTIPLE) {
+    // Keys with multiple action are handled in Java,
+    // and we should never see one here
+    MOZ_CRASH("Cannot handle key with multiple action");
+  } else {
+    NS_WARNING("Unknown key action event");
+    return;
+  }
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  WidgetKeyboardEvent event(true, msg, widget);
+  InitKeyEvent(event, aAction, aKeyCode, aScanCode, aMetaState, aTime,
+               aDomPrintableKeyValue, aRepeatCount, aFlags);
+
+  if (nsIWidget::UsePuppetWidgets()) {
+    // Don't use native key bindings.
+    event.PreventNativeKeyBindings();
+  }
+
+  if (aIsSynthesizedImeKey) {
+    // Keys synthesized by Java IME code are saved in the mIMEKeyEvents
+    // array until the next IME_REPLACE_TEXT event, at which point
+    // these keys are dispatched in sequence.
+    mIMEKeyEvents.AppendElement(UniquePtr<WidgetEvent>(event.Duplicate()));
+  } else {
+    NS_ENSURE_SUCCESS_VOID(BeginInputTransaction(dispatcher));
+    dispatcher->DispatchKeyboardEvent(msg, event, status);
+    if (widget->Destroyed() || status == nsEventStatus_eConsumeNoDefault) {
+      // Skip default processing.
+      return;
+    }
+    mEditable->OnDefaultKeyEvent(aOriginalEvent);
+  }
+
+  // Only send keypress after keydown.
+  if (msg != eKeyDown) {
+    return;
+  }
+
+  WidgetKeyboardEvent pressEvent(true, eKeyPress, widget);
+  InitKeyEvent(pressEvent, aAction, aKeyCode, aScanCode, aKeyPressMetaState,
+               aTime, aDomPrintableKeyValue, aRepeatCount, aFlags);
+
+  if (nsIWidget::UsePuppetWidgets()) {
+    // Don't use native key bindings.
+    pressEvent.PreventNativeKeyBindings();
+  }
+
+  if (aIsSynthesizedImeKey) {
+    mIMEKeyEvents.AppendElement(UniquePtr<WidgetEvent>(pressEvent.Duplicate()));
+  } else {
+    dispatcher->MaybeDispatchKeypressEvents(pressEvent, status);
+  }
+}
+
+/*
+ * Send dummy key events for pages that are unaware of input events,
+ * to provide web compatibility for pages that depend on key events.
+ */
+void GeckoEditableSupport::SendIMEDummyKeyEvent(nsIWidget* aWidget,
+                                                EventMessage msg) {
+  AutoGeckoEditableBlocker blocker(this);
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  MOZ_ASSERT(mDispatcher);
+
+  WidgetKeyboardEvent event(true, msg, aWidget);
+  // TODO: If we can know scan code of the key event which caused replacing
+  //       composition string, we should set mCodeNameIndex here.  Then,
+  //       we should rename this method because it becomes not a "dummy"
+  //       keyboard event.
+  event.mKeyCode = NS_VK_PROCESSKEY;
+  event.mKeyNameIndex = KEY_NAME_INDEX_Process;
+  // KeyboardEvents marked as "processed by IME" shouldn't cause any edit
+  // actions.  So, we should set their native key binding to none before
+  // dispatch to avoid crash on PuppetWidget and avoid running redundant
+  // path to look for native key bindings.
+  if (nsIWidget::UsePuppetWidgets()) {
+    event.PreventNativeKeyBindings();
+  }
+  NS_ENSURE_SUCCESS_VOID(BeginInputTransaction(mDispatcher));
+  mDispatcher->DispatchKeyboardEvent(msg, event, status);
+}
+
+void GeckoEditableSupport::AddIMETextChange(
+    const IMENotification::TextChangeDataBase& aChange) {
+  mIMEPendingTextChange.MergeWith(aChange);
+
+  // We may not be in the middle of flushing,
+  // in which case this flag is meaningless.
+  mIMETextChangedDuringFlush = true;
+}
+
+void GeckoEditableSupport::PostFlushIMEChanges() {
+  if (mIMEPendingTextChange.IsValid() || mIMESelectionChanged) {
+    // Already posted
+    return;
+  }
+
+  RefPtr<GeckoEditableSupport> self(this);
+
+  nsAppShell::PostEvent([this, self] {
+    nsCOMPtr<nsIWidget> widget = GetWidget();
+    if (widget && !widget->Destroyed()) {
+      FlushIMEChanges();
+    }
+  });
+}
+
+void GeckoEditableSupport::FlushIMEChanges(FlushChangesFlag aFlags) {
+  // Only send change notifications if we are *not* masking events,
+  // i.e. if we have a focused editor,
+  NS_ENSURE_TRUE_VOID(!mIMEMaskEventsCount);
+
+  if (mIMEDelaySynchronizeReply && mIMEActiveCompositionCount > 0) {
+    // We are still expecting more composition events to be handled. Once
+    // that happens, FlushIMEChanges will be called again.
+    return;
+  }
+
+  nsCOMPtr<nsIWidget> widget = GetWidget();
+  NS_ENSURE_TRUE_VOID(widget);
+
+  struct TextRecord {
+    TextRecord() : start(-1), oldEnd(-1), newEnd(-1) {}
+
+    bool IsValid() const { return start >= 0; }
+
+    nsString text;
+    int32_t start;
+    int32_t oldEnd;
+    int32_t newEnd;
+  };
+  TextRecord textTransaction;
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  bool causedOnlyByComposition = mIMEPendingTextChange.IsValid() &&
+                                 mIMEPendingTextChange.mCausedOnlyByComposition;
+  mIMETextChangedDuringFlush = false;
+
+  auto shouldAbort = [=](bool aForce) -> bool {
+    if (!aForce && !mIMETextChangedDuringFlush) {
+      return false;
+    }
+    // A query event could have triggered more text changes to come in, as
+    // indicated by our flag. If that happens, try flushing IME changes
+    // again.
+    if (aFlags == FLUSH_FLAG_NONE) {
+      FlushIMEChanges(FLUSH_FLAG_RETRY);
+    } else {
+      // Don't retry if already retrying, to avoid infinite loops.
+      __android_log_print(ANDROID_LOG_WARN, "GeckoEditableSupport",
+                          "Already retrying IME flush");
+    }
+    return true;
+  };
+
+  if (mIMEPendingTextChange.IsValid() &&
+      (mIMEPendingTextChange.mStartOffset !=
+           mIMEPendingTextChange.mRemovedEndOffset ||
+       mIMEPendingTextChange.mStartOffset !=
+           mIMEPendingTextChange.mAddedEndOffset)) {
+    WidgetQueryContentEvent queryTextContentEvent(true, eQueryTextContent,
+                                                  widget);
+
+    if (mIMEPendingTextChange.mAddedEndOffset !=
+        mIMEPendingTextChange.mStartOffset) {
+      queryTextContentEvent.InitForQueryTextContent(
+          mIMEPendingTextChange.mStartOffset,
+          mIMEPendingTextChange.mAddedEndOffset -
+              mIMEPendingTextChange.mStartOffset);
+      widget->DispatchEvent(&queryTextContentEvent, status);
+
+      if (shouldAbort(NS_WARN_IF(queryTextContentEvent.Failed()))) {
+        return;
+      }
+
+      textTransaction.text = queryTextContentEvent.mReply->DataRef();
+    }
+
+    textTransaction.start =
+        static_cast<int32_t>(mIMEPendingTextChange.mStartOffset);
+    textTransaction.oldEnd =
+        static_cast<int32_t>(mIMEPendingTextChange.mRemovedEndOffset);
+    textTransaction.newEnd =
+        static_cast<int32_t>(mIMEPendingTextChange.mAddedEndOffset);
+  }
+
+  int32_t selStart = -1;
+  int32_t selEnd = -1;
+
+  if (mIMESelectionChanged) {
+    if (mCachedSelection.IsValid()) {
+      selStart = mCachedSelection.mStartOffset;
+      selEnd = mCachedSelection.mEndOffset;
+    } else {
+      // XXX Unfortunately we don't know current selection via selection
+      //     change notification.
+      //     eQuerySelectedText might be newer data than text change data.
+      //     It means that GeckoEditableChild.onSelectionChange may throw
+      //     IllegalArgumentException since we don't merge with newer text
+      //     change.
+      WidgetQueryContentEvent querySelectedTextEvent(true, eQuerySelectedText,
+                                                     widget);
+      widget->DispatchEvent(&querySelectedTextEvent, status);
+
+      if (shouldAbort(
+              NS_WARN_IF(querySelectedTextEvent.DidNotFindSelection()))) {
+        return;
+      }
+
+      selStart =
+          static_cast<int32_t>(querySelectedTextEvent.mReply->AnchorOffset());
+      selEnd =
+          static_cast<int32_t>(querySelectedTextEvent.mReply->FocusOffset());
+    }
+
+    if (aFlags == FLUSH_FLAG_RECOVER && textTransaction.IsValid()) {
+      // Sometimes we get out-of-bounds selection during recovery.
+      // Limit the offsets so we don't crash.
+      const int32_t end = textTransaction.start + textTransaction.text.Length();
+      selStart = std::min(selStart, end);
+      selEnd = std::min(selEnd, end);
+    }
+  }
+
+  JNIEnv* const env = jni::GetGeckoThreadEnv();
+  auto flushOnException = [=]() -> bool {
+    if (!env->ExceptionCheck()) {
+      return false;
+    }
+    if (aFlags != FLUSH_FLAG_RECOVER) {
+      // First time seeing an exception; try flushing text.
+      env->ExceptionClear();
+      __android_log_print(ANDROID_LOG_WARN, "GeckoEditableSupport",
+                          "Recovering from IME exception");
+      FlushIMEText(FLUSH_FLAG_RECOVER);
+    } else {
+      // Give up because we've already tried.
+#ifdef RELEASE_OR_BETA
+      env->ExceptionClear();
+#else
+      MOZ_CATCH_JNI_EXCEPTION(env);
+#endif
+    }
+    return true;
+  };
+
+  // Commit the text change and selection change transaction.
+  mIMEPendingTextChange.Clear();
+
+  if (textTransaction.IsValid()) {
+    mEditable->OnTextChange(textTransaction.text, textTransaction.start,
+                            textTransaction.oldEnd, textTransaction.newEnd,
+                            causedOnlyByComposition);
+    if (flushOnException()) {
+      return;
+    }
+  }
+
+  while (mIMEDelaySynchronizeReply && mIMEActiveSynchronizeCount) {
+    mIMEActiveSynchronizeCount--;
+    mEditable->NotifyIME(EditableListener::NOTIFY_IME_REPLY_EVENT);
+  }
+  mIMEDelaySynchronizeReply = false;
+  mIMEActiveSynchronizeCount = 0;
+  mIMEActiveCompositionCount = 0;
+
+  if (mIMESelectionChanged) {
+    mIMESelectionChanged = false;
+    if (mDispatcher) {
+      // mCausedOnlyByComposition may be true on committing text.
+      // So even if true, there is no composition.
+      causedOnlyByComposition &= mDispatcher->IsComposing();
+    }
+    mEditable->OnSelectionChange(selStart, selEnd, causedOnlyByComposition);
+    flushOnException();
+  }
+}
+
+void GeckoEditableSupport::FlushIMEText(FlushChangesFlag aFlags) {
+  NS_WARNING_ASSERTION(
+      !mIMEDelaySynchronizeReply || !mIMEActiveCompositionCount,
+      "Cannot synchronize Java text with Gecko text");
+
+  // Notify Java of the newly focused content
+  mIMEPendingTextChange.Clear();
+  mIMESelectionChanged = true;
+
+  // Use 'INT32_MAX / 2' here because subsequent text changes might combine
+  // with this text change, and overflow might occur if we just use
+  // INT32_MAX.
+  IMENotification notification(NOTIFY_IME_OF_TEXT_CHANGE);
+  notification.mTextChangeData.mStartOffset = 0;
+  notification.mTextChangeData.mRemovedEndOffset = INT32_MAX / 2;
+  notification.mTextChangeData.mAddedEndOffset = INT32_MAX / 2;
+  NotifyIME(mDispatcher, notification);
+
+  FlushIMEChanges(aFlags);
+}
+
+void GeckoEditableSupport::UpdateCompositionRects() {
+  nsCOMPtr<nsIWidget> widget = GetWidget();
+  RefPtr<TextComposition> composition(GetComposition());
+  NS_ENSURE_TRUE_VOID(mDispatcher && widget);
+
+  jni::ObjectArray::LocalRef rects;
+  if (composition) {
+    nsEventStatus status = nsEventStatus_eIgnore;
+    uint32_t offset = composition->NativeOffsetOfStartComposition();
+    WidgetQueryContentEvent queryTextRectsEvent(true, eQueryTextRectArray,
+                                                widget);
+    queryTextRectsEvent.InitForQueryTextRectArray(
+        offset, composition->String().Length());
+    widget->DispatchEvent(&queryTextRectsEvent, status);
+    rects = ConvertRectArrayToJavaRectFArray(
+        queryTextRectsEvent.Succeeded()
+            ? queryTextRectsEvent.mReply->mRectArray
+            : CopyableTArray<mozilla::LayoutDeviceIntRect>());
+  } else {
+    rects = ConvertRectArrayToJavaRectFArray(
+        CopyableTArray<mozilla::LayoutDeviceIntRect>());
+  }
+
+  WidgetQueryContentEvent queryCaretRectEvent(true, eQueryCaretRect, widget);
+  WidgetQueryContentEvent::Options options;
+  options.mRelativeToInsertionPoint = true;
+  queryCaretRectEvent.InitForQueryCaretRect(0, options);
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  widget->DispatchEvent(&queryCaretRectEvent, status);
+  auto caretRect =
+      queryCaretRectEvent.Succeeded()
+          ? java::sdk::RectF::New(queryCaretRectEvent.mReply->mRect.x,
+                                  queryCaretRectEvent.mReply->mRect.y,
+                                  queryCaretRectEvent.mReply->mRect.XMost(),
+                                  queryCaretRectEvent.mReply->mRect.YMost())
+          : java::sdk::RectF::New();
+
+  mEditable->UpdateCompositionRects(rects, caretRect);
+}
+
+void GeckoEditableSupport::OnImeSynchronize() {
+  AutoGeckoEditableBlocker blocker(this);
+
+  if (mIMEDelaySynchronizeReply) {
+    // If we are waiting for other events to reply,
+    // queue this reply as well.
+    mIMEActiveSynchronizeCount++;
+    return;
+  }
+  if (!mIMEMaskEventsCount) {
+    FlushIMEChanges();
+  }
+  mEditable->NotifyIME(EditableListener::NOTIFY_IME_REPLY_EVENT);
+}
+
+void GeckoEditableSupport::OnImeReplaceText(int32_t aStart, int32_t aEnd,
+                                            jni::String::Param aText) {
+  AutoGeckoEditableBlocker blocker(this);
+
+  if (DoReplaceText(aStart, aEnd, aText)) {
+    mIMEDelaySynchronizeReply = true;
+  }
+
+  OnImeSynchronize();
+}
+
+bool GeckoEditableSupport::DoReplaceText(int32_t aStart, int32_t aEnd,
+                                         jni::String::Param aText) {
+  ALOGIME("IME: IME_REPLACE_TEXT: text=\"%s\"",
+          NS_ConvertUTF16toUTF8(aText->ToString()).get());
+
+  // Return true if processed and we should reply to the OnImeReplaceText
+  // event later. Return false if _not_ processed and we should reply to the
+  // OnImeReplaceText event now.
+
+  if (mIMEMaskEventsCount > 0) {
+    // Not focused; still reply to events, but don't do anything else.
+    return false;
+  }
+
+  if (nsWindow* window = GetNsWindow()) {
+    window->UserActivity();
+  }
+
+  /*
+      Replace text in Gecko thread from aStart to aEnd with the string text.
+  */
+  nsCOMPtr<nsIWidget> widget = GetWidget();
+  NS_ENSURE_TRUE(mDispatcher && widget, false);
+  NS_ENSURE_SUCCESS(BeginInputTransaction(mDispatcher), false);
+
+  RefPtr<TextComposition> composition(GetComposition());
+  MOZ_ASSERT(!composition || !composition->IsEditorHandlingEvent());
+
+  nsString string(aText->ToString());
+  const bool composing = !mIMERanges->IsEmpty();
+  nsEventStatus status = nsEventStatus_eIgnore;
+  bool textChanged = composing;
+  // Whether deleting content before setting or committing composition text.
+  bool performDeletion = false;
+  // Dispatch composition start to set current composition.
+  bool needDispatchCompositionStart = false;
+
+  if (!mIMEKeyEvents.IsEmpty() || !composition || !mDispatcher->IsComposing() ||
+      uint32_t(aStart) != composition->NativeOffsetOfStartComposition() ||
+      uint32_t(aEnd) != composition->NativeOffsetOfStartComposition() +
+                            composition->String().Length()) {
+    // Only start a new composition if we have key events,
+    // if we don't have an existing composition, or
+    // the replaced text does not match our composition.
+    textChanged |= RemoveComposition();
+
+#ifdef NIGHTLY_BUILD
+    {
+      nsEventStatus status = nsEventStatus_eIgnore;
+      WidgetQueryContentEvent querySelectedTextEvent(true, eQuerySelectedText,
+                                                     widget);
+      widget->DispatchEvent(&querySelectedTextEvent, status);
+      if (querySelectedTextEvent.Succeeded()) {
+        ALOGIME(
+            "IME: Current selection: %s",
+            ToString(querySelectedTextEvent.mReply->mOffsetAndData).c_str());
+      }
+    }
+#endif
+
+    // If aStart or aEnd is negative value, we use current selection instead
+    // of updating the selection.
+    if (aStart >= 0 && aEnd >= 0) {
+      // Use text selection to set target position(s) for
+      // insert, or replace, of text.
+      WidgetSelectionEvent event(true, eSetSelection, widget);
+      event.mOffset = uint32_t(aStart);
+      event.mLength = uint32_t(aEnd - aStart);
+      event.mExpandToClusterBoundary = false;
+      event.mReason = nsISelectionListener::IME_REASON;
+      widget->DispatchEvent(&event, status);
+    }
+
+    if (!mIMEKeyEvents.IsEmpty()) {
+      bool ignoreNextKeyPress = false;
+      for (uint32_t i = 0; i < mIMEKeyEvents.Length(); i++) {
+        const auto event = mIMEKeyEvents[i]->AsKeyboardEvent();
+        // widget for duplicated events is initially nullptr.
+        event->mWidget = widget;
+
+        status = nsEventStatus_eIgnore;
+        if (event->mMessage != eKeyPress) {
+          mDispatcher->DispatchKeyboardEvent(event->mMessage, *event, status);
+          // Skip default processing. It means that next key press shouldn't
+          // be dispatched.
+          ignoreNextKeyPress = event->mMessage == eKeyDown &&
+                               status == nsEventStatus_eConsumeNoDefault;
+        } else {
+          if (ignoreNextKeyPress) {
+            // Don't dispatch key press since previous key down is consumed.
+            ignoreNextKeyPress = false;
+            continue;
+          }
+          mDispatcher->MaybeDispatchKeypressEvents(*event, status);
+          if (status == nsEventStatus_eConsumeNoDefault) {
+            textChanged = true;
+          }
+        }
+        if (!mDispatcher || widget->Destroyed()) {
+          // Don't wait for any text change event.
+          textChanged = false;
+          break;
+        }
+      }
+      mIMEKeyEvents.Clear();
+      return textChanged;
+    }
+
+    if (aStart != aEnd) {
+      if (composing) {
+        // Actually Gecko doesn't start composition, so it is unnecessary to
+        // delete content before setting composition string.
+        needDispatchCompositionStart = true;
+      } else {
+        // Perform a deletion first.
+        performDeletion = true;
+      }
+    }
+  } else if (composition->String().Equals(string)) {
+    // If the new text is the same as the existing composition text,
+    // the NS_COMPOSITION_CHANGE event does not generate a text
+    // change notification. However, the Java side still expects
+    // one, so we manually generate a notification.
+    //
+    // Also, since this is IME change, we have to set mCausedOnlyByComposition.
+    IMENotification::TextChangeData dummyChange(aStart, aEnd, aEnd, true,
+                                                false);
+    PostFlushIMEChanges();
+    mIMESelectionChanged = true;
+    AddIMETextChange(dummyChange);
+    textChanged = true;
+  }
+
+  SendIMEDummyKeyEvent(widget, eKeyDown);
+  if (!mDispatcher || widget->Destroyed()) {
+    return false;
+  }
+
+  if (needDispatchCompositionStart) {
+    // StartComposition sets composition string from selected string.
+    nsEventStatus status = nsEventStatus_eIgnore;
+    mDispatcher->StartComposition(status);
+    if (!mDispatcher || widget->Destroyed()) {
+      return false;
+    }
+  } else if (performDeletion) {
+    WidgetContentCommandEvent event(true, eContentCommandDelete, widget);
+    widget->DispatchEvent(&event, status);
+    if (!mDispatcher || widget->Destroyed()) {
+      return false;
+    }
+    textChanged = true;
+  }
+
+  if (composing) {
+    mDispatcher->SetPendingComposition(string, mIMERanges);
+    mDispatcher->FlushPendingComposition(status);
+    mIMEActiveCompositionCount++;
+    // Ensure IME ranges are empty.
+    mIMERanges->Clear();
+  } else if (!string.IsEmpty() || mDispatcher->IsComposing()) {
+    mDispatcher->CommitComposition(status, &string);
+    mIMEActiveCompositionCount++;
+    textChanged = true;
+  }
+  if (!mDispatcher || widget->Destroyed()) {
+    return false;
+  }
+
+  SendIMEDummyKeyEvent(widget, eKeyUp);
+  // Widget may be destroyed after dispatching the above event.
+
+  return textChanged;
+}
+
+void GeckoEditableSupport::OnImeAddCompositionRange(
+    int32_t aStart, int32_t aEnd, int32_t aRangeType, int32_t aRangeStyle,
+    int32_t aRangeLineStyle, bool aRangeBoldLine, int32_t aRangeForeColor,
+    int32_t aRangeBackColor, int32_t aRangeLineColor) {
+  AutoGeckoEditableBlocker blocker(this);
+
+  if (mIMEMaskEventsCount > 0) {
+    // Not focused.
+    return;
+  }
+
+  TextRange range;
+  range.mStartOffset = aStart;
+  range.mEndOffset = aEnd;
+  range.mRangeType = ToTextRangeType(aRangeType);
+  range.mRangeStyle.mDefinedStyles = aRangeStyle;
+  range.mRangeStyle.mLineStyle = TextRangeStyle::ToLineStyle(aRangeLineStyle);
+  range.mRangeStyle.mIsBoldLine = aRangeBoldLine;
+  range.mRangeStyle.mForegroundColor =
+      ConvertAndroidColor(uint32_t(aRangeForeColor));
+  range.mRangeStyle.mBackgroundColor =
+      ConvertAndroidColor(uint32_t(aRangeBackColor));
+  range.mRangeStyle.mUnderlineColor =
+      ConvertAndroidColor(uint32_t(aRangeLineColor));
+  mIMERanges->AppendElement(range);
+}
+
+void GeckoEditableSupport::OnImeUpdateComposition(int32_t aStart, int32_t aEnd,
+                                                  int32_t aFlags) {
+  AutoGeckoEditableBlocker blocker(this);
+
+  if (DoUpdateComposition(aStart, aEnd, aFlags)) {
+    mIMEDelaySynchronizeReply = true;
+  }
+}
+
+bool GeckoEditableSupport::DoUpdateComposition(int32_t aStart, int32_t aEnd,
+                                               int32_t aFlags) {
+  if (mIMEMaskEventsCount > 0) {
+    // Not focused.
+    return false;
+  }
+
+  nsCOMPtr<nsIWidget> widget = GetWidget();
+  nsEventStatus status = nsEventStatus_eIgnore;
+  NS_ENSURE_TRUE(mDispatcher && widget, false);
+
+  const bool keepCurrent =
+      !!(aFlags & java::GeckoEditableChild::FLAG_KEEP_CURRENT_COMPOSITION);
+
+  // A composition with no ranges means we want to set the selection.
+  if (mIMERanges->IsEmpty()) {
+    if (keepCurrent && mDispatcher->IsComposing()) {
+      // Don't set selection if we want to keep current composition.
+      return false;
+    }
+
+    MOZ_ASSERT(aStart >= 0 && aEnd >= 0);
+    const bool compositionChanged = RemoveComposition();
+
+    WidgetSelectionEvent selEvent(true, eSetSelection, widget);
+    selEvent.mOffset = std::min(aStart, aEnd);
+    selEvent.mLength = std::max(aStart, aEnd) - selEvent.mOffset;
+    selEvent.mReversed = aStart > aEnd;
+    selEvent.mExpandToClusterBoundary = false;
+    widget->DispatchEvent(&selEvent, status);
+    return compositionChanged;
+  }
+
+  /**
+   * Update the composition from aStart to aEnd using information from added
+   * ranges. This is only used for visual indication and does not affect the
+   * text content.  Only the offsets are specified and not the text content
+   * to eliminate the possibility of this event altering the text content
+   * unintentionally.
+   */
+  nsString string;
+  RefPtr<TextComposition> composition(GetComposition());
+  MOZ_ASSERT(!composition || !composition->IsEditorHandlingEvent());
+
+  if (!composition || !mDispatcher->IsComposing() ||
+      uint32_t(aStart) != composition->NativeOffsetOfStartComposition() ||
+      uint32_t(aEnd) != composition->NativeOffsetOfStartComposition() +
+                            composition->String().Length()) {
+    if (keepCurrent) {
+      // Don't start a new composition if we want to keep the current one.
+      mIMERanges->Clear();
+      return false;
+    }
+
+    // Only start new composition if we don't have an existing one,
+    // or if the existing composition doesn't match the new one.
+    RemoveComposition();
+
+    {
+      WidgetSelectionEvent event(true, eSetSelection, widget);
+      event.mOffset = uint32_t(aStart);
+      event.mLength = uint32_t(aEnd - aStart);
+      event.mExpandToClusterBoundary = false;
+      event.mReason = nsISelectionListener::IME_REASON;
+      widget->DispatchEvent(&event, status);
+    }
+
+    {
+      WidgetQueryContentEvent querySelectedTextEvent(true, eQuerySelectedText,
+                                                     widget);
+      widget->DispatchEvent(&querySelectedTextEvent, status);
+      MOZ_ASSERT(querySelectedTextEvent.Succeeded());
+      if (querySelectedTextEvent.FoundSelection()) {
+        string = querySelectedTextEvent.mReply->DataRef();
+      }
+    }
+  } else {
+    // If the new composition matches the existing composition,
+    // reuse the old composition.
+    string = composition->String();
+  }
+
+  ALOGIME("IME: IME_SET_TEXT: text=\"%s\", length=%zu, range=%zu",
+          NS_ConvertUTF16toUTF8(string).get(), string.Length(),
+          mIMERanges->Length());
+
+  if (NS_WARN_IF(NS_FAILED(BeginInputTransaction(mDispatcher)))) {
+    mIMERanges->Clear();
+    return false;
+  }
+  mDispatcher->SetPendingComposition(string, mIMERanges);
+  mDispatcher->FlushPendingComposition(status);
+  mIMEActiveCompositionCount++;
+  mIMERanges->Clear();
+  return true;
+}
+
+void GeckoEditableSupport::OnImeRequestCursorUpdates(int aRequestMode) {
+  AutoGeckoEditableBlocker blocker(this);
+
+  if (aRequestMode == EditableClient::ONE_SHOT) {
+    UpdateCompositionRects();
+    return;
+  }
+
+  mIMEMonitorCursor = (aRequestMode == EditableClient::START_MONITOR);
+}
+
+class MOZ_STACK_CLASS AutoSelectionRestore final {
+ public:
+  explicit AutoSelectionRestore(nsIWidget* widget,
+                                TextEventDispatcher* dispatcher)
+      : mWidget(widget), mDispatcher(dispatcher) {
+    MOZ_ASSERT(widget);
+    if (!dispatcher || !dispatcher->IsComposing()) {
+      mOffset = UINT32_MAX;
+      mLength = UINT32_MAX;
+      return;
+    }
+    WidgetQueryContentEvent querySelectedTextEvent(true, eQuerySelectedText,
+                                                   widget);
+    nsEventStatus status = nsEventStatus_eIgnore;
+    widget->DispatchEvent(&querySelectedTextEvent, status);
+    if (querySelectedTextEvent.DidNotFindSelection()) {
+      mOffset = UINT32_MAX;
+      mLength = UINT32_MAX;
+      return;
+    }
+
+    mOffset = querySelectedTextEvent.mReply->StartOffset();
+    mLength = querySelectedTextEvent.mReply->DataLength();
+  }
+
+  ~AutoSelectionRestore() {
+    if (mWidget->Destroyed() || mOffset == UINT32_MAX) {
+      return;
+    }
+
+    WidgetSelectionEvent selection(true, eSetSelection, mWidget);
+    selection.mOffset = mOffset;
+    selection.mLength = mLength;
+    selection.mExpandToClusterBoundary = false;
+    selection.mReason = nsISelectionListener::IME_REASON;
+    nsEventStatus status = nsEventStatus_eIgnore;
+    mWidget->DispatchEvent(&selection, status);
+  }
+
+ private:
+  nsCOMPtr<nsIWidget> mWidget;
+  RefPtr<TextEventDispatcher> mDispatcher;
+  uint32_t mOffset;
+  uint32_t mLength;
+};
+
+void GeckoEditableSupport::OnImeRequestCommit() {
+  AutoGeckoEditableBlocker blocker(this);
+
+  if (mIMEMaskEventsCount > 0) {
+    // Not focused.
+    return;
+  }
+
+  nsCOMPtr<nsIWidget> widget = GetWidget();
+  if (NS_WARN_IF(!widget)) {
+    return;
+  }
+
+  AutoSelectionRestore restore(widget, mDispatcher);
+
+  RemoveComposition(COMMIT_IME_COMPOSITION);
+}
+
+void GeckoEditableSupport::AsyncNotifyIME(int32_t aNotification) {
+  RefPtr<GeckoEditableSupport> self(this);
+
+  nsAppShell::PostEvent([this, self, aNotification] {
+    if (!mIMEMaskEventsCount) {
+      mEditable->NotifyIME(aNotification);
+    }
+  });
+}
+
+nsresult GeckoEditableSupport::NotifyIME(
+    TextEventDispatcher* aTextEventDispatcher,
+    const IMENotification& aNotification) {
+  MOZ_ASSERT(mEditable);
+
+  switch (aNotification.mMessage) {
+    case REQUEST_TO_COMMIT_COMPOSITION: {
+      ALOGIME("IME: REQUEST_TO_COMMIT_COMPOSITION");
+
+      RemoveComposition(COMMIT_IME_COMPOSITION);
+      AsyncNotifyIME(EditableListener::NOTIFY_IME_TO_COMMIT_COMPOSITION);
+      break;
+    }
+
+    case REQUEST_TO_CANCEL_COMPOSITION: {
+      ALOGIME("IME: REQUEST_TO_CANCEL_COMPOSITION");
+
+      RemoveComposition(CANCEL_IME_COMPOSITION);
+      AsyncNotifyIME(EditableListener::NOTIFY_IME_TO_CANCEL_COMPOSITION);
+      break;
+    }
+
+    case NOTIFY_IME_OF_FOCUS: {
+      ALOGIME("IME: NOTIFY_IME_OF_FOCUS");
+
+      mIMEFocusCount++;
+
+      RefPtr<GeckoEditableSupport> self(this);
+      RefPtr<TextEventDispatcher> dispatcher = aTextEventDispatcher;
+
+      // Post an event because we have to flush the text before sending a
+      // focus event, and we may not be able to flush text during the
+      // NotifyIME call.
+      nsAppShell::PostEvent([this, self, dispatcher] {
+        nsCOMPtr<nsIWidget> widget = dispatcher->GetWidget();
+
+        --mIMEMaskEventsCount;
+        if (!mIMEFocusCount || !widget || widget->Destroyed()) {
+          return;
+        }
+
+        mEditable->NotifyIME(EditableListener::NOTIFY_IME_OF_TOKEN);
+
+        if (mIsRemote) {
+          if (!mEditableAttached) {
+            // Re-attach on focus; see OnRemovedFrom().
+            jni::NativeWeakPtrHolder<GeckoEditableSupport>::AttachExisting(
+                mEditable, do_AddRef(this));
+            mEditableAttached = true;
+          }
+          // Because GeckoEditableSupport in content process doesn't
+          // manage the active input context, we need to retrieve the
+          // input context from the widget, for use by
+          // OnImeReplaceText.
+          mInputContext = widget->GetInputContext();
+        }
+        mDispatcher = dispatcher;
+        mIMEKeyEvents.Clear();
+
+        mCachedSelection.Reset();
+
+        mIMEDelaySynchronizeReply = false;
+        mIMEActiveCompositionCount = 0;
+        FlushIMEText();
+
+        // IME will call requestCursorUpdates after getting context.
+        // So reset cursor update mode before getting context.
+        mIMEMonitorCursor = false;
+
+        mEditable->NotifyIME(EditableListener::NOTIFY_IME_OF_FOCUS);
+      });
+      break;
+    }
+
+    case NOTIFY_IME_OF_BLUR: {
+      ALOGIME("IME: NOTIFY_IME_OF_BLUR");
+
+      mIMEFocusCount--;
+      MOZ_ASSERT(mIMEFocusCount >= 0);
+
+      RefPtr<GeckoEditableSupport> self(this);
+      nsAppShell::PostEvent([this, self] {
+        if (!mIMEFocusCount) {
+          mIMEDelaySynchronizeReply = false;
+          mIMEActiveSynchronizeCount = 0;
+          mIMEActiveCompositionCount = 0;
+          mInputContext.ShutDown();
+          mEditable->NotifyIME(EditableListener::NOTIFY_IME_OF_BLUR);
+          OnRemovedFrom(mDispatcher);
+        }
+      });
+
+      // Mask events because we lost focus. Unmask on the next focus.
+      mIMEMaskEventsCount++;
+      break;
+    }
+
+    case NOTIFY_IME_OF_SELECTION_CHANGE: {
+      ALOGIME("IME: NOTIFY_IME_OF_SELECTION_CHANGE: SelectionChangeData=%s",
+              ToString(aNotification.mSelectionChangeData).c_str());
+
+      if (aNotification.mSelectionChangeData.HasRange()) {
+        mCachedSelection.mStartOffset = static_cast<int32_t>(
+            aNotification.mSelectionChangeData.AnchorOffset());
+        mCachedSelection.mEndOffset = static_cast<int32_t>(
+            aNotification.mSelectionChangeData.FocusOffset());
+      } else {
+        mCachedSelection.Reset();
+      }
+
+      PostFlushIMEChanges();
+      mIMESelectionChanged = true;
+      break;
+    }
+
+    case NOTIFY_IME_OF_TEXT_CHANGE: {
+      ALOGIME("IME: NOTIFY_IME_OF_TEXT_CHANGE: TextChangeData=%s",
+              ToString(aNotification.mTextChangeData).c_str());
+
+      /* Make sure Java's selection is up-to-date */
+      PostFlushIMEChanges();
+      mIMESelectionChanged = true;
+      AddIMETextChange(aNotification.mTextChangeData);
+      break;
+    }
+
+    case NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED: {
+      ALOGIME("IME: NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED");
+
+      // NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED isn't sent per IME call.
+      // Receiving this event means that Gecko has already handled all IME
+      // composing events in queue.
+      //
+      if (mIsRemote) {
+        OnNotifyIMEOfCompositionEventHandled();
+      } else {
+        // Also, when receiving this event, mIMEDelaySynchronizeReply won't
+        // update yet on non-e10s case since IME event is posted before updating
+        // it. So we have to delay handling of this event.
+        RefPtr<GeckoEditableSupport> self(this);
+        nsAppShell::PostEvent(
+            [this, self] { OnNotifyIMEOfCompositionEventHandled(); });
+      }
+      break;
+    }
+
+    default:
+      break;
+  }
+  return NS_OK;
+}
+
+void GeckoEditableSupport::OnNotifyIMEOfCompositionEventHandled() {
+  // NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED may be merged with multiple events,
+  // so reset count.
+  mIMEActiveCompositionCount = 0;
+  if (mIMEDelaySynchronizeReply) {
+    FlushIMEChanges();
+  }
+
+  // Hardware keyboard support requires each string rect.
+  if (mIMEMonitorCursor) {
+    UpdateCompositionRects();
+  }
+}
+
+void GeckoEditableSupport::OnRemovedFrom(
+    TextEventDispatcher* aTextEventDispatcher) {
+  mDispatcher = nullptr;
+
+  if (mIsRemote && mEditable->HasEditableParent()) {
+    // When we're remote, detach every time.
+    OnWeakNonIntrusiveDetach(NS_NewRunnableFunction(
+        "GeckoEditableSupport::OnRemovedFrom",
+        [editable = java::GeckoEditableChild::GlobalRef(mEditable)] {
+          DisposeNative(editable);
+        }));
+  }
+}
+
+void GeckoEditableSupport::WillDispatchKeyboardEvent(
+    TextEventDispatcher* aTextEventDispatcher,
+    WidgetKeyboardEvent& aKeyboardEvent, uint32_t aIndexOfKeypress,
+    void* aData) {}
+
+NS_IMETHODIMP_(IMENotificationRequests)
+GeckoEditableSupport::GetIMENotificationRequests() {
+  return IMENotificationRequests(IMENotificationRequests::NOTIFY_TEXT_CHANGE);
+}
+
+static bool ShouldKeyboardDismiss(const nsAString& aInputType,
+                                  const nsAString& aInputMode) {
+  // Some input type uses the prompt to input value. So it is unnecessary to
+  // show software keyboard.
+  return aInputMode.EqualsLiteral("none") || aInputType.EqualsLiteral("date") ||
+         aInputType.EqualsLiteral("time") ||
+         aInputType.EqualsLiteral("month") ||
+         aInputType.EqualsLiteral("week") ||
+         aInputType.EqualsLiteral("datetime-local");
+}
+
+void GeckoEditableSupport::SetInputContext(const InputContext& aContext,
+                                           const InputContextAction& aAction) {
+  // SetInputContext is called from chrome process only
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(mEditable);
+
+  ALOGIME(
+      "IME: SetInputContext: aContext=%s, "
+      "aAction={mCause=%s, mFocusChange=%s}",
+      ToString(aContext).c_str(), ToString(aAction.mCause).c_str(),
+      ToString(aAction.mFocusChange).c_str());
+
+  mInputContext = aContext;
+
+  if (mInputContext.mIMEState.mEnabled != IMEEnabled::Disabled &&
+      !ShouldKeyboardDismiss(mInputContext.mHTMLInputType,
+                             mInputContext.mHTMLInputMode) &&
+      aAction.UserMightRequestOpenVKB()) {
+    // Don't reset keyboard when we should simply open the vkb
+    mEditable->NotifyIME(EditableListener::NOTIFY_IME_OPEN_VKB);
+    return;
+  }
+
+  // Post an event to keep calls in order relative to NotifyIME.
+  nsAppShell::PostEvent([this, self = RefPtr<GeckoEditableSupport>(this),
+                         context = mInputContext, action = aAction] {
+    nsCOMPtr<nsIWidget> widget = GetWidget();
+
+    if (!widget || widget->Destroyed()) {
+      return;
+    }
+    NotifyIMEContext(context, action);
+  });
+}
+
+void GeckoEditableSupport::NotifyIMEContext(const InputContext& aContext,
+                                            const InputContextAction& aAction) {
+  const bool inPrivateBrowsing = aContext.mInPrivateBrowsing;
+  // isUserAction is used whether opening virtual keyboard. But long press
+  // shouldn't open it.
+  const bool isUserAction =
+      aAction.mCause != InputContextAction::CAUSE_LONGPRESS &&
+      !(aAction.mCause == InputContextAction::CAUSE_UNKNOWN_CHROME &&
+        aContext.mIMEState.mEnabled == IMEEnabled::Enabled) &&
+      (aAction.IsHandlingUserInput() || aContext.mHasHandledUserInput);
+  const int32_t flags =
+      (inPrivateBrowsing ? EditableListener::IME_FLAG_PRIVATE_BROWSING : 0) |
+      (isUserAction ? EditableListener::IME_FLAG_USER_ACTION : 0) |
+      (aAction.mFocusChange == InputContextAction::FOCUS_NOT_CHANGED
+           ? EditableListener::IME_FOCUS_NOT_CHANGED
+           : 0);
+
+  mEditable->NotifyIMEContext(static_cast<int32_t>(aContext.mIMEState.mEnabled),
+                              aContext.mHTMLInputType, aContext.mHTMLInputMode,
+                              aContext.mActionHint, aContext.mAutocapitalize,
+                              flags);
+}
+
+InputContext GeckoEditableSupport::GetInputContext() {
+  // GetInputContext is called from chrome process only
+  MOZ_ASSERT(XRE_IsParentProcess());
+  InputContext context = mInputContext;
+  context.mIMEState.mOpen = IMEState::OPEN_STATE_NOT_SUPPORTED;
+  return context;
+}
+
+void GeckoEditableSupport::TransferParent(jni::Object::Param aEditableParent) {
+  AutoGeckoEditableBlocker blocker(this);
+
+  mEditable->SetParent(aEditableParent);
+
+  // If we are already focused, make sure the new parent has our token
+  // and focus information, so it can accept additional calls from us.
+  if (mIMEFocusCount > 0) {
+    mEditable->NotifyIME(EditableListener::NOTIFY_IME_OF_TOKEN);
+    if (mIsRemote) {
+      // GeckoEditableSupport::SetInputContext is called on chrome process
+      // only, so mInputContext may be still invalid since it is set after
+      // we have gotton focus.
+      RefPtr<GeckoEditableSupport> self(this);
+      nsAppShell::PostEvent([self = std::move(self)] {
+        NS_WARNING_ASSERTION(
+            self->mDispatcher,
+            "Text dispatcher is still null. Why don't we get focus yet?");
+        self->NotifyIMEContext(self->mInputContext, InputContextAction());
+      });
+    } else {
+      NotifyIMEContext(mInputContext, InputContextAction());
+    }
+    mEditable->NotifyIME(EditableListener::NOTIFY_IME_OF_FOCUS);
+    // We have focus, so don't destroy editable child.
+    return;
+  }
+
+  if (mIsRemote && !mDispatcher) {
+    // Detach now if we were only attached temporarily.
+    OnRemovedFrom(/* dispatcher */ nullptr);
+  }
+}
+
+void GeckoEditableSupport::SetOnBrowserChild(dom::BrowserChild* aBrowserChild) {
+  MOZ_ASSERT(!XRE_IsParentProcess());
+  NS_ENSURE_TRUE_VOID(aBrowserChild);
+
+  const dom::ContentChild* const contentChild =
+      dom::ContentChild::GetSingleton();
+  RefPtr<widget::PuppetWidget> widget(aBrowserChild->WebWidget());
+  NS_ENSURE_TRUE_VOID(contentChild && widget);
+
+  // Get the content/tab ID in order to get the correct
+  // IGeckoEditableParent object, which GeckoEditableChild uses to
+  // communicate with the parent process.
+  const uint64_t contentId = contentChild->GetID();
+  const uint64_t tabId = aBrowserChild->GetTabId();
+  NS_ENSURE_TRUE_VOID(contentId && tabId);
+
+  RefPtr<widget::TextEventDispatcherListener> listener =
+      widget->GetNativeTextEventDispatcherListener();
+
+  if (!listener ||
+      listener.get() ==
+          static_cast<widget::TextEventDispatcherListener*>(widget)) {
+    // We need to set a new listener.
+    const auto editableChild = java::GeckoEditableChild::New(
+        /* parent */ nullptr, /* default */ false);
+
+    // Temporarily attach so we can receive the initial editable parent.
+    auto editableSupport =
+        jni::NativeWeakPtrHolder<GeckoEditableSupport>::Attach(editableChild,
+                                                               editableChild);
+    auto accEditableSupport(editableSupport.Access());
+    MOZ_RELEASE_ASSERT(accEditableSupport);
+
+    // Tell PuppetWidget to use our listener for IME operations.
+    widget->SetNativeTextEventDispatcherListener(
+        accEditableSupport.AsRefPtr().get());
+
+    accEditableSupport->mEditableAttached = true;
+
+    // Connect the new child to a parent that corresponds to the BrowserChild.
+    java::GeckoServiceChildProcess::GetEditableParent(editableChild, contentId,
+                                                      tabId);
+    return;
+  }
+
+  // We need to update the existing listener to use the new parent.
+
+  // We expect the existing TextEventDispatcherListener to be a
+  // GeckoEditableSupport object, so we perform a sanity check to make
+  // sure, by comparing their respective vtable pointers.
+  const RefPtr<widget::GeckoEditableSupport> dummy =
+      new widget::GeckoEditableSupport(/* child */ nullptr);
+  NS_ENSURE_TRUE_VOID(*reinterpret_cast<const uintptr_t*>(listener.get()) ==
+                      *reinterpret_cast<const uintptr_t*>(dummy.get()));
+
+  const auto support =
+      static_cast<widget::GeckoEditableSupport*>(listener.get());
+  if (!support->mEditableAttached) {
+    // Temporarily attach so we can receive the initial editable parent.
+    jni::NativeWeakPtrHolder<GeckoEditableSupport>::AttachExisting(
+        support->GetJavaEditable(), do_AddRef(support));
+    support->mEditableAttached = true;
+  }
+
+  // Transfer to a new parent that corresponds to the BrowserChild.
+  java::GeckoServiceChildProcess::GetEditableParent(support->GetJavaEditable(),
+                                                    contentId, tabId);
+}
+
+nsIWidget* GeckoEditableSupport::GetWidget() const {
+  MOZ_ASSERT(NS_IsMainThread());
+  return mDispatcher ? mDispatcher->GetWidget() : GetNsWindow();
+}
+
+nsWindow* GeckoEditableSupport::GetNsWindow() const {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  auto acc(mWindow.Access());
+  if (!acc) {
+    return nullptr;
+  }
+
+  return acc->GetNsWindow();
+}
+
+void GeckoEditableSupport::OnImeInsertImage(jni::ByteArray::Param aData,
+                                            jni::String::Param aMimeType) {
+  AutoGeckoEditableBlocker blocker(this);
+
+  nsCString mimeType(aMimeType->ToCString());
+  nsCOMPtr<nsIInputStream> byteStream;
+
+  nsresult rv = NS_NewByteInputStream(
+      getter_AddRefs(byteStream),
+      mozilla::Span(
+          reinterpret_cast<const char*>(aData->GetElements().Elements()),
+          aData->Length()),
+      NS_ASSIGNMENT_COPY);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return;
+  }
+
+  nsCOMPtr<nsITransferable> trans =
+      do_CreateInstance("@mozilla.org/widget/transferable;1");
+  if (NS_WARN_IF(!trans)) {
+    return;
+  }
+  trans->Init(nullptr);
+  rv = trans->SetTransferData(mimeType.get(), byteStream);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return;
+  }
+
+  nsCOMPtr<nsIWidget> widget = GetWidget();
+  if (NS_WARN_IF(!widget) || NS_WARN_IF(widget->Destroyed())) {
+    return;
+  }
+
+  WidgetContentCommandEvent command(true, eContentCommandPasteTransferable,
+                                    widget);
+  command.mTransferable = trans.forget();
+  nsEventStatus status;
+  widget->DispatchEvent(&command, status);
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/GeckoEditableSupport.h b/widget/android/GeckoEditableSupport.h
new file mode 100644
index 0000000000..90cb2710d3
--- /dev/null
+++ b/widget/android/GeckoEditableSupport.h
@@ -0,0 +1,286 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 mozilla_widget_GeckoEditableSupport_h
+#define mozilla_widget_GeckoEditableSupport_h
+
+#include "nsAppShell.h"
+#include "nsIWidget.h"
+#include "nsTArray.h"
+
+#include "mozilla/java/GeckoEditableChildNatives.h"
+#include "mozilla/java/SessionTextInputWrappers.h"
+#include "mozilla/TextEventDispatcher.h"
+#include "mozilla/TextEventDispatcherListener.h"
+#include "mozilla/UniquePtr.h"
+
+class nsWindow;
+
+namespace mozilla {
+
+class TextComposition;
+
+namespace dom {
+class BrowserChild;
+}
+
+namespace widget {
+
+class GeckoEditableSupport final
+    : public TextEventDispatcherListener,
+      public java::GeckoEditableChild::Natives<GeckoEditableSupport> {
+  /*
+      Rules for managing IME between Gecko and Java:
+
+      * Gecko controls the text content, and Java shadows the Gecko text
+         through text updates
+      * Gecko and Java maintain separate selections, and synchronize when
+         needed through selection updates and set-selection events
+      * Java controls the composition, and Gecko shadows the Java
+         composition through update composition events
+  */
+
+  using EditableBase = java::GeckoEditableChild::Natives<GeckoEditableSupport>;
+  using EditableClient = java::SessionTextInput::EditableClient;
+  using EditableListener = java::SessionTextInput::EditableListener;
+
+  enum FlushChangesFlag {
+    // Not retrying.
+    FLUSH_FLAG_NONE,
+    // Retrying due to IME text changes during flush.
+    FLUSH_FLAG_RETRY,
+    // Retrying due to IME sync exceptions during flush.
+    FLUSH_FLAG_RECOVER
+  };
+
+  enum RemoveCompositionFlag { CANCEL_IME_COMPOSITION, COMMIT_IME_COMPOSITION };
+
+  const bool mIsRemote;
+  jni::NativeWeakPtr<GeckoViewSupport> mWindow;  // Parent only
+  RefPtr<TextEventDispatcher> mDispatcher;
+  java::GeckoEditableChild::GlobalRef mEditable;
+  bool mEditableAttached;
+  InputContext mInputContext;
+  AutoTArray<UniquePtr<mozilla::WidgetEvent>, 4> mIMEKeyEvents;
+  IMENotification::TextChangeData mIMEPendingTextChange;
+  RefPtr<TextRangeArray> mIMERanges;
+  RefPtr<Runnable> mDisposeRunnable;
+  int32_t mIMEMaskEventsCount;         // Mask events when > 0.
+  int32_t mIMEFocusCount;              // We are focused when > 0.
+  bool mIMEDelaySynchronizeReply;      // We reply asynchronously when true.
+  int32_t mIMEActiveSynchronizeCount;  // The number of replies being delayed.
+  int32_t mIMEActiveCompositionCount;  // The number of compositions expected.
+  uint32_t mDisposeBlockCount;
+  bool mIMESelectionChanged;
+  bool mIMETextChangedDuringFlush;
+  bool mIMEMonitorCursor;
+
+  // The cached selection data
+  struct Selection {
+    Selection() : mStartOffset(-1), mEndOffset(-1) {}
+
+    void Reset() {
+      mStartOffset = -1;
+      mEndOffset = -1;
+    }
+
+    bool IsValid() const { return mStartOffset >= 0 && mEndOffset >= 0; }
+
+    int32_t mStartOffset;
+    int32_t mEndOffset;
+  } mCachedSelection;
+
+  nsIWidget* GetWidget() const;
+  nsWindow* GetNsWindow() const;
+
+  nsresult BeginInputTransaction(TextEventDispatcher* aDispatcher) {
+    if (mIsRemote) {
+      return aDispatcher->BeginInputTransaction(this);
+    } else {
+      return aDispatcher->BeginNativeInputTransaction();
+    }
+  }
+
+  virtual ~GeckoEditableSupport() {}
+
+  RefPtr<TextComposition> GetComposition() const;
+  bool RemoveComposition(RemoveCompositionFlag aFlag = COMMIT_IME_COMPOSITION);
+  void SendIMEDummyKeyEvent(nsIWidget* aWidget, EventMessage msg);
+  void AddIMETextChange(const IMENotification::TextChangeDataBase& aChange);
+  void PostFlushIMEChanges();
+  void FlushIMEChanges(FlushChangesFlag aFlags = FLUSH_FLAG_NONE);
+  void FlushIMEText(FlushChangesFlag aFlags = FLUSH_FLAG_NONE);
+  void AsyncNotifyIME(int32_t aNotification);
+  void UpdateCompositionRects();
+  bool DoReplaceText(int32_t aStart, int32_t aEnd, jni::String::Param aText);
+  bool DoUpdateComposition(int32_t aStart, int32_t aEnd, int32_t aFlags);
+  void OnNotifyIMEOfCompositionEventHandled();
+  void NotifyIMEContext(const InputContext& aContext,
+                        const InputContextAction& aAction);
+
+ public:
+  template <typename Functor>
+  static void OnNativeCall(Functor&& aCall) {
+    struct IMEEvent : nsAppShell::LambdaEvent<Functor> {
+      explicit IMEEvent(Functor&& l)
+          : nsAppShell::LambdaEvent<Functor>(std::move(l)) {}
+
+      bool IsUIEvent() const override {
+        using GES = GeckoEditableSupport;
+        if (this->lambda.IsTarget(&GES::OnKeyEvent) ||
+            this->lambda.IsTarget(&GES::OnImeReplaceText) ||
+            this->lambda.IsTarget(&GES::OnImeUpdateComposition)) {
+          return true;
+        }
+        return false;
+      }
+
+      void Run() override {
+        if (NS_WARN_IF(!this->lambda.GetNativeObject())) {
+          // Ignore stale calls after disposal.
+          jni::GetGeckoThreadEnv()->ExceptionClear();
+          return;
+        }
+        nsAppShell::LambdaEvent<Functor>::Run();
+      }
+    };
+    nsAppShell::PostEvent(mozilla::MakeUnique<IMEEvent>(std::move(aCall)));
+  }
+
+  static void SetOnBrowserChild(dom::BrowserChild* aBrowserChild);
+
+  // Constructor for main process GeckoEditableChild.
+  GeckoEditableSupport(jni::NativeWeakPtr<GeckoViewSupport> aWindow,
+                       java::GeckoEditableChild::Param aEditableChild)
+      : mIsRemote(!aWindow.IsAttached()),
+        mWindow(aWindow),
+        mEditable(aEditableChild),
+        mEditableAttached(!mIsRemote),
+        mIMERanges(new TextRangeArray()),
+        mIMEMaskEventsCount(1),  // Mask IME events since there's no focus yet
+        mIMEFocusCount(0),
+        mIMEDelaySynchronizeReply(false),
+        mIMEActiveSynchronizeCount(0),
+        mDisposeBlockCount(0),
+        mIMESelectionChanged(false),
+        mIMETextChangedDuringFlush(false),
+        mIMEMonitorCursor(false) {}
+
+  // Constructor for content process GeckoEditableChild.
+  explicit GeckoEditableSupport(java::GeckoEditableChild::Param aEditableChild)
+      : GeckoEditableSupport(nullptr, aEditableChild) {}
+
+  NS_DECL_ISUPPORTS
+
+  // 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;
+
+  void SetInputContext(const InputContext& aContext,
+                       const InputContextAction& aAction);
+
+  InputContext GetInputContext();
+
+  bool HasIMEFocus() const { return mIMEFocusCount != 0; }
+
+  void AddBlocker() { mDisposeBlockCount++; }
+
+  void ReleaseBlocker() {
+    mDisposeBlockCount--;
+
+    if (!mDisposeBlockCount && mDisposeRunnable) {
+      if (HasIMEFocus()) {
+        // If we have IME focus, GeckoEditableChild is already attached again.
+        // So disposer is unnecessary.
+        mDisposeRunnable = nullptr;
+        return;
+      }
+
+      RefPtr<GeckoEditableSupport> self(this);
+      RefPtr<Runnable> disposer = std::move(mDisposeRunnable);
+
+      nsAppShell::PostEvent(
+          [self = std::move(self), disposer = std::move(disposer)] {
+            self->mEditableAttached = false;
+            disposer->Run();
+          });
+    }
+  }
+
+  bool IsGeckoEditableUsed() const { return mDisposeBlockCount != 0; }
+
+  // GeckoEditableChild methods
+  using EditableBase::AttachNative;
+  using EditableBase::DisposeNative;
+
+  const java::GeckoEditableChild::Ref& GetJavaEditable() { return mEditable; }
+
+  void OnWeakNonIntrusiveDetach(already_AddRefed<Runnable> aDisposer) {
+    RefPtr<GeckoEditableSupport> self(this);
+    nsAppShell::PostEvent(
+        [self = std::move(self), disposer = RefPtr<Runnable>(aDisposer)] {
+          if (self->IsGeckoEditableUsed()) {
+            // Current calling stack uses GeckoEditableChild, so we should
+            // not dispose it now.
+            self->mDisposeRunnable = disposer;
+            return;
+          }
+          self->mEditableAttached = false;
+          disposer->Run();
+        });
+  }
+
+  // Transfer to a new parent.
+  void TransferParent(jni::Object::Param aEditableParent);
+
+  // Handle an Android KeyEvent.
+  void OnKeyEvent(int32_t aAction, int32_t aKeyCode, int32_t aScanCode,
+                  int32_t aMetaState, int32_t aKeyPressMetaState, int64_t aTime,
+                  int32_t aDomPrintableKeyValue, int32_t aRepeatCount,
+                  int32_t aFlags, bool aIsSynthesizedImeKey,
+                  jni::Object::Param originalEvent);
+
+  // Synchronize Gecko thread with the InputConnection thread.
+  void OnImeSynchronize();
+
+  // Replace a range of text with new text.
+  void OnImeReplaceText(int32_t aStart, int32_t aEnd, jni::String::Param aText);
+
+  // Add styling for a range within the active composition.
+  void OnImeAddCompositionRange(int32_t aStart, int32_t aEnd,
+                                int32_t aRangeType, int32_t aRangeStyle,
+                                int32_t aRangeLineStyle, bool aRangeBoldLine,
+                                int32_t aRangeForeColor,
+                                int32_t aRangeBackColor,
+                                int32_t aRangeLineColor);
+
+  // Update styling for the active composition using previous-added ranges.
+  void OnImeUpdateComposition(int32_t aStart, int32_t aEnd, int32_t aFlags);
+
+  // Set cursor mode whether IME requests
+  void OnImeRequestCursorUpdates(int aRequestMode);
+
+  // Commit current composition to sync Gecko text state with Java.
+  void OnImeRequestCommit();
+
+  // Insert image from software keyboard.
+  void OnImeInsertImage(jni::ByteArray::Param aData,
+                        jni::String::Param aMimeType);
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_GeckoEditableSupport_h
diff --git a/widget/android/GeckoNetworkManager.h b/widget/android/GeckoNetworkManager.h
new file mode 100644
index 0000000000..7240821b9e
--- /dev/null
+++ b/widget/android/GeckoNetworkManager.h
@@ -0,0 +1,45 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 GeckoNetworkManager_h
+#define GeckoNetworkManager_h
+
+#include "nsAppShell.h"
+#include "nsCOMPtr.h"
+#include "nsINetworkLinkService.h"
+
+#include "mozilla/java/GeckoNetworkManagerNatives.h"
+#include "mozilla/Services.h"
+
+namespace mozilla {
+
+class GeckoNetworkManager final
+    : public java::GeckoNetworkManager::Natives<GeckoNetworkManager> {
+  GeckoNetworkManager() = delete;
+
+ public:
+  static void OnConnectionChanged(int32_t aType, jni::String::Param aSubType,
+                                  bool aIsWifi, int32_t aGateway) {
+    hal::NotifyNetworkChange(hal::NetworkInformation(aType, aIsWifi, aGateway));
+
+    nsCOMPtr<nsIObserverService> os = services::GetObserverService();
+    if (os) {
+      os->NotifyObservers(nullptr, NS_NETWORK_LINK_TYPE_TOPIC,
+                          aSubType->ToString().get());
+    }
+  }
+
+  static void OnStatusChanged(jni::String::Param aStatus) {
+    nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
+    if (os) {
+      os->NotifyObservers(nullptr, NS_NETWORK_LINK_TOPIC,
+                          aStatus->ToString().get());
+    }
+  }
+};
+
+}  // namespace mozilla
+
+#endif  // GeckoNetworkManager_h
diff --git a/widget/android/GeckoProcessManager.cpp b/widget/android/GeckoProcessManager.cpp
new file mode 100644
index 0000000000..274e92ed9b
--- /dev/null
+++ b/widget/android/GeckoProcessManager.cpp
@@ -0,0 +1,77 @@
+/* -*- 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 "GeckoProcessManager.h"
+
+#include "nsINetworkLinkService.h"
+#include "nsISupportsImpl.h"
+#include "mozilla/Services.h"
+
+namespace mozilla {
+
+/* static */ void GeckoProcessManager::Init() {
+  BaseNatives::Init();
+  ConnectionManager::Init();
+}
+
+NS_IMPL_ISUPPORTS(GeckoProcessManager::ConnectionManager, nsIObserver)
+
+NS_IMETHODIMP GeckoProcessManager::ConnectionManager::Observe(
+    nsISupports* aSubject, const char* aTopic, const char16_t* aData) {
+  java::GeckoProcessManager::ConnectionManager::LocalRef connMgr(mJavaConnMgr);
+  if (!connMgr) {
+    return NS_OK;
+  }
+
+  if (!strcmp("application-foreground", aTopic)) {
+    connMgr->OnForeground();
+    return NS_OK;
+  }
+
+  if (!strcmp("application-background", aTopic)) {
+    connMgr->OnBackground();
+    return NS_OK;
+  }
+
+  if (!strcmp(NS_NETWORK_LINK_TOPIC, aTopic)) {
+    const nsDependentString state(aData);
+    // state can be up, down, or unknown. For the purposes of socket process
+    // prioritization, we treat unknown as being up.
+    const bool isUp = !state.EqualsLiteral(NS_NETWORK_LINK_DATA_DOWN);
+    connMgr->OnNetworkStateChange(isUp);
+    return NS_OK;
+  }
+
+  return NS_OK;
+}
+
+/* static */ void GeckoProcessManager::ConnectionManager::AttachTo(
+    java::GeckoProcessManager::ConnectionManager::Param aInstance) {
+  RefPtr<ConnectionManager> native(new ConnectionManager());
+  BaseNatives::AttachNative(aInstance, native);
+
+  native->mJavaConnMgr = aInstance;
+
+  nsCOMPtr<nsIObserverService> obsServ(services::GetObserverService());
+  obsServ->AddObserver(native, "application-background", false);
+  obsServ->AddObserver(native, "application-foreground", false);
+}
+
+void GeckoProcessManager::ConnectionManager::ObserveNetworkNotifications() {
+  nsCOMPtr<nsIObserverService> obsServ(services::GetObserverService());
+  obsServ->AddObserver(this, NS_NETWORK_LINK_TOPIC, false);
+
+  const bool isUp = java::GeckoAppShell::IsNetworkLinkUp();
+
+  java::GeckoProcessManager::ConnectionManager::LocalRef connMgr(mJavaConnMgr);
+  if (!connMgr) {
+    return;
+  }
+
+  connMgr->OnNetworkStateChange(isUp);
+}
+
+}  // namespace mozilla
diff --git a/widget/android/GeckoProcessManager.h b/widget/android/GeckoProcessManager.h
new file mode 100644
index 0000000000..341cb5f5c5
--- /dev/null
+++ b/widget/android/GeckoProcessManager.h
@@ -0,0 +1,84 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 GeckoProcessManager_h
+#define GeckoProcessManager_h
+
+#include "WidgetUtils.h"
+#include "nsAppShell.h"
+#include "nsContentUtils.h"
+#include "nsIObserver.h"
+#include "nsWindow.h"
+
+#include "mozilla/RefPtr.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/ContentProcessManager.h"
+#include "mozilla/java/GeckoProcessManagerNatives.h"
+
+namespace mozilla {
+
+class GeckoProcessManager final
+    : public java::GeckoProcessManager::Natives<GeckoProcessManager> {
+  using BaseNatives = java::GeckoProcessManager::Natives<GeckoProcessManager>;
+
+  GeckoProcessManager() = delete;
+
+  static already_AddRefed<nsIWidget> GetWidget(int64_t aContentId,
+                                               int64_t aTabId) {
+    using namespace dom;
+    MOZ_ASSERT(NS_IsMainThread());
+
+    ContentProcessManager* const cpm = ContentProcessManager::GetSingleton();
+    NS_ENSURE_TRUE(cpm, nullptr);
+
+    RefPtr<BrowserParent> tab = cpm->GetTopLevelBrowserParentByProcessAndTabId(
+        ContentParentId(aContentId), TabId(aTabId));
+    NS_ENSURE_TRUE(tab, nullptr);
+
+    nsCOMPtr<nsPIDOMWindowOuter> domWin = tab->GetParentWindowOuter();
+    NS_ENSURE_TRUE(domWin, nullptr);
+
+    return widget::WidgetUtils::DOMWindowToWidget(domWin);
+  }
+
+  class ConnectionManager final
+      : public java::GeckoProcessManager::ConnectionManager::Natives<
+            ConnectionManager>,
+        public nsIObserver {
+    using BaseNatives = java::GeckoProcessManager::ConnectionManager::Natives<
+        ConnectionManager>;
+
+    virtual ~ConnectionManager() = default;
+
+   public:
+    ConnectionManager() = default;
+
+    NS_DECL_ISUPPORTS
+    NS_DECL_NSIOBSERVER
+
+    static void AttachTo(
+        java::GeckoProcessManager::ConnectionManager::Param aInstance);
+    void ObserveNetworkNotifications();
+
+   private:
+    java::GeckoProcessManager::ConnectionManager::WeakRef mJavaConnMgr;
+  };
+
+ public:
+  static void Init();
+
+  static void GetEditableParent(jni::Object::Param aEditableChild,
+                                int64_t aContentId, int64_t aTabId) {
+    nsCOMPtr<nsIWidget> widget = GetWidget(aContentId, aTabId);
+    if (RefPtr<nsWindow> window = nsWindow::From(widget)) {
+      java::GeckoProcessManager::SetEditableChildParent(
+          aEditableChild, window->GetEditableParent());
+    }
+  }
+};
+
+}  // namespace mozilla
+
+#endif  // GeckoProcessManager_h
diff --git a/widget/android/GeckoSystemStateListener.h b/widget/android/GeckoSystemStateListener.h
new file mode 100644
index 0000000000..75cb1cd9fe
--- /dev/null
+++ b/widget/android/GeckoSystemStateListener.h
@@ -0,0 +1,31 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 GeckoSystemStateListener_h
+#define GeckoSystemStateListener_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/java/GeckoSystemStateListenerNatives.h"
+
+namespace mozilla {
+
+class GeckoSystemStateListener final
+    : public java::GeckoSystemStateListener::Natives<GeckoSystemStateListener> {
+  GeckoSystemStateListener() = delete;
+
+ public:
+  static void OnDeviceChanged() {
+    MOZ_ASSERT(NS_IsMainThread());
+    // TODO(emilio, bug 1673318): This could become more granular and avoid work
+    // if we get whether these are layout/style-affecting from the caller.
+    mozilla::LookAndFeel::NotifyChangedAllWindows(
+        widget::ThemeChangeKind::StyleAndLayout);
+  }
+};
+
+}  // namespace mozilla
+
+#endif  // GeckoSystemStateListener_h
diff --git a/widget/android/GeckoTelemetryDelegate.h b/widget/android/GeckoTelemetryDelegate.h
new file mode 100644
index 0000000000..43b20d4ad6
--- /dev/null
+++ b/widget/android/GeckoTelemetryDelegate.h
@@ -0,0 +1,100 @@
+/* -*- 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 GeckoTelemetryDelegate_h__
+#define GeckoTelemetryDelegate_h__
+
+#include "geckoview/streaming/GeckoViewStreamingTelemetry.h"
+
+#include <jni.h>
+
+#include "mozilla/java/RuntimeTelemetryNatives.h"
+#include "mozilla/jni/Natives.h"
+
+namespace mozilla {
+namespace widget {
+
+class GeckoTelemetryDelegate final
+    : public GeckoViewStreamingTelemetry::StreamingTelemetryDelegate,
+      public mozilla::java::RuntimeTelemetry::Proxy::Natives<
+          GeckoTelemetryDelegate> {
+ public:
+  // Implement Proxy native.
+  static void RegisterDelegateProxy(
+      mozilla::java::RuntimeTelemetry::Proxy::Param aProxy) {
+    MOZ_ASSERT(aProxy);
+
+    GeckoViewStreamingTelemetry::RegisterDelegate(
+        new GeckoTelemetryDelegate(aProxy));
+  }
+
+  explicit GeckoTelemetryDelegate(
+      mozilla::java::RuntimeTelemetry::Proxy::Param aProxy)
+      : mProxy(aProxy) {}
+
+ private:
+  void DispatchHistogram(bool aIsCategorical, const nsCString& aName,
+                         const nsTArray<uint32_t>& aSamples) {
+    if (!mozilla::jni::IsAvailable() || !mProxy || aSamples.Length() < 1) {
+      return;
+    }
+
+    // Convert aSamples to an array of int64_t. We know |samples| required
+    // capacity needs to match |aSamples.Length()|.
+    nsTArray<int64_t> samples(aSamples.Length());
+    for (size_t i = 0, l = aSamples.Length(); i < l; ++i) {
+      samples.AppendElement(static_cast<int64_t>(aSamples[i]));
+    }
+
+    // LongArray::From *copies* the elements
+    mProxy->DispatchHistogram(aIsCategorical, aName,
+                              mozilla::jni::LongArray::From(samples));
+  }
+
+  // Implement StreamingTelemetryDelegate.
+  void ReceiveHistogramSamples(const nsCString& aName,
+                               const nsTArray<uint32_t>& aSamples) override {
+    DispatchHistogram(/* isCategorical */ false, aName, aSamples);
+  }
+
+  void ReceiveCategoricalHistogramSamples(
+      const nsCString& aName, const nsTArray<uint32_t>& aSamples) override {
+    DispatchHistogram(/* isCategorical */ true, aName, aSamples);
+  }
+
+  void ReceiveBoolScalarValue(const nsCString& aName, bool aValue) override {
+    if (!mozilla::jni::IsAvailable() || !mProxy) {
+      return;
+    }
+
+    mProxy->DispatchBooleanScalar(aName, aValue);
+  }
+
+  void ReceiveStringScalarValue(const nsCString& aName,
+                                const nsCString& aValue) override {
+    if (!mozilla::jni::IsAvailable() || !mProxy) {
+      return;
+    }
+
+    mProxy->DispatchStringScalar(aName, aValue);
+  }
+
+  void ReceiveUintScalarValue(const nsCString& aName,
+                              uint32_t aValue) override {
+    if (!mozilla::jni::IsAvailable() || !mProxy) {
+      return;
+    }
+
+    mProxy->DispatchLongScalar(aName, static_cast<int64_t>(aValue));
+  }
+
+  mozilla::java::RuntimeTelemetry::Proxy::GlobalRef mProxy;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // GeckoTelemetryDelegate_h__
diff --git a/widget/android/GeckoVRManager.h b/widget/android/GeckoVRManager.h
new file mode 100644
index 0000000000..de28c402cd
--- /dev/null
+++ b/widget/android/GeckoVRManager.h
@@ -0,0 +1,24 @@
+/* -*- 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 mozilla_GeckoVRManager_h_
+#define mozilla_GeckoVRManager_h_
+
+#include "mozilla/java/GeckoVRManagerWrappers.h"
+#include "mozilla/jni/Utils.h"
+
+namespace mozilla {
+
+class GeckoVRManager {
+ public:
+  static void* GetExternalContext() {
+    return reinterpret_cast<void*>(
+        mozilla::java::GeckoVRManager::GetExternalContext());
+  }
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_GeckoVRManager_h_
diff --git a/widget/android/GeckoViewSupport.h b/widget/android/GeckoViewSupport.h
new file mode 100644
index 0000000000..c784552824
--- /dev/null
+++ b/widget/android/GeckoViewSupport.h
@@ -0,0 +1,126 @@
+/* -*- 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_GeckoViewSupport_h
+#define mozilla_widget_GeckoViewSupport_h
+
+#include "mozilla/java/GeckoResultWrappers.h"
+#include "mozilla/java/GeckoSessionNatives.h"
+#include "mozilla/java/WebResponseWrappers.h"
+#include "mozilla/dom/CanonicalBrowsingContext.h"
+#include "mozilla/widget/WindowEvent.h"
+
+class nsPIDOMWindowOuter;
+class nsWindow;
+
+namespace mozilla {
+namespace widget {
+
+class GeckoViewSupport final
+    : public java::GeckoSession::Window::Natives<GeckoViewSupport> {
+  RefPtr<nsWindow> mWindow;
+
+  // We hold a WeakRef because we want to allow the
+  // GeckoSession.Window to be garbage collected.
+  // Callers need to create a LocalRef from this
+  // before calling methods.
+  java::GeckoSession::Window::WeakRef mGeckoViewWindow;
+
+ public:
+  typedef java::GeckoSession::Window::Natives<GeckoViewSupport> Base;
+
+  template <typename Functor>
+  static void OnNativeCall(Functor&& aCall) {
+    NS_DispatchToMainThread(new WindowEvent<Functor>(std::move(aCall)));
+  }
+
+  GeckoViewSupport(nsWindow* aWindow,
+                   const java::GeckoSession::Window::LocalRef& aInstance,
+                   nsPIDOMWindowOuter* aDOMWindow)
+      : mWindow(aWindow), mGeckoViewWindow(aInstance), mDOMWindow(aDOMWindow) {}
+
+  ~GeckoViewSupport();
+
+  nsWindow* GetNsWindow() const { return mWindow; }
+
+  using Base::DisposeNative;
+
+  /**
+   * GeckoView methods
+   */
+ private:
+  nsCOMPtr<nsPIDOMWindowOuter> mDOMWindow;
+  bool mIsReady{false};
+  RefPtr<dom::CanonicalBrowsingContext> GetContentCanonicalBrowsingContext();
+  MOZ_CAN_RUN_SCRIPT void CreatePdf(
+      jni::LocalRef<mozilla::java::GeckoResult> aGeckoResult,
+      RefPtr<dom::CanonicalBrowsingContext> aCbc);
+
+ public:
+  // Create and attach a window.
+  static void Open(const jni::Class::LocalRef& aCls,
+                   java::GeckoSession::Window::Param aWindow,
+                   jni::Object::Param aQueue, jni::Object::Param aCompositor,
+                   jni::Object::Param aDispatcher,
+                   jni::Object::Param aSessionAccessibility,
+                   jni::Object::Param aInitData, jni::String::Param aId,
+                   jni::String::Param aChromeURI, bool aPrivateMode);
+
+  // Close and destroy the nsWindow.
+  void Close();
+
+  // Transfer this nsWindow to new GeckoSession objects.
+  void Transfer(const java::GeckoSession::Window::LocalRef& inst,
+                jni::Object::Param aQueue, jni::Object::Param aCompositor,
+                jni::Object::Param aDispatcher,
+                jni::Object::Param aSessionAccessibility,
+                jni::Object::Param aInitData);
+
+  void AttachEditable(const java::GeckoSession::Window::LocalRef& inst,
+                      jni::Object::Param aEditableParent);
+
+  void AttachAccessibility(const java::GeckoSession::Window::LocalRef& inst,
+                           jni::Object::Param aSessionAccessibility);
+
+  void OnReady(jni::Object::Param aQueue = nullptr);
+
+  auto OnLoadRequest(mozilla::jni::String::Param aUri, int32_t aWindowType,
+                     int32_t aFlags, mozilla::jni::String::Param aTriggeringUri,
+                     bool aHasUserGesture, bool aIsTopLevel) const
+      -> java::GeckoResult::LocalRef;
+
+  void OnShowDynamicToolbar() const;
+
+  void OnUpdateSessionStore(mozilla::jni::Object::Param aBundle);
+
+  void PassExternalResponse(java::WebResponse::Param aResponse);
+
+  void AttachMediaSessionController(
+      const java::GeckoSession::Window::LocalRef& inst,
+      jni::Object::Param aController, const int64_t aId);
+
+  void DetachMediaSessionController(
+      const java::GeckoSession::Window::LocalRef& inst,
+      jni::Object::Param aController);
+
+  void OnWeakNonIntrusiveDetach(already_AddRefed<Runnable> aDisposer) {
+    RefPtr<Runnable> disposer(aDisposer);
+    disposer->Run();
+  }
+
+  MOZ_CAN_RUN_SCRIPT void PrintToPdf(
+      const java::GeckoSession::Window::LocalRef& inst,
+      jni::Object::Param aStream, int64_t aBcId);
+
+  MOZ_CAN_RUN_SCRIPT void PrintToPdf(
+      const java::GeckoSession::Window::LocalRef& inst,
+      jni::Object::Param aStream);
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_GeckoViewSupport_h
diff --git a/widget/android/GfxInfo.cpp b/widget/android/GfxInfo.cpp
new file mode 100644
index 0000000000..e4f8d5d88b
--- /dev/null
+++ b/widget/android/GfxInfo.cpp
@@ -0,0 +1,866 @@
+/* -*- 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 "GfxInfo.h"
+#include "AndroidBuild.h"
+#include "GLContext.h"
+#include "GLContextProvider.h"
+#include "nsUnicharUtils.h"
+#include "prenv.h"
+#include "nsExceptionHandler.h"
+#include "nsHashKeys.h"
+#include "nsVersionComparator.h"
+#include "nsServiceManagerUtils.h"
+
+#include "mozilla/Preferences.h"
+#include "mozilla/java/GeckoAppShellWrappers.h"
+#include "mozilla/java/HardwareCodecCapabilityUtilsWrappers.h"
+
+namespace mozilla {
+namespace widget {
+
+class GfxInfo::GLStrings {
+  nsCString mVendor;
+  nsCString mRenderer;
+  nsCString mVersion;
+  nsTArray<nsCString> mExtensions;
+  bool mReady;
+
+ public:
+  GLStrings() : mReady(false) {}
+
+  const nsCString& Vendor() {
+    EnsureInitialized();
+    return mVendor;
+  }
+
+  // This spoofed value wins, even if the environment variable
+  // MOZ_GFX_SPOOF_GL_VENDOR was set.
+  void SpoofVendor(const nsCString& s) { mVendor = s; }
+
+  const nsCString& Renderer() {
+    EnsureInitialized();
+    return mRenderer;
+  }
+
+  // This spoofed value wins, even if the environment variable
+  // MOZ_GFX_SPOOF_GL_RENDERER was set.
+  void SpoofRenderer(const nsCString& s) { mRenderer = s; }
+
+  const nsCString& Version() {
+    EnsureInitialized();
+    return mVersion;
+  }
+
+  // This spoofed value wins, even if the environment variable
+  // MOZ_GFX_SPOOF_GL_VERSION was set.
+  void SpoofVersion(const nsCString& s) { mVersion = s; }
+
+  const nsTArray<nsCString>& Extensions() {
+    EnsureInitialized();
+    return mExtensions;
+  }
+
+  void EnsureInitialized() {
+    if (mReady) {
+      return;
+    }
+
+    RefPtr<gl::GLContext> gl;
+    nsCString discardFailureId;
+    gl = gl::GLContextProvider::CreateHeadless(
+        {gl::CreateContextFlags::REQUIRE_COMPAT_PROFILE}, &discardFailureId);
+
+    if (!gl) {
+      // Setting mReady to true here means that we won't retry. Everything will
+      // remain blocklisted forever. Ideally, we would like to update that once
+      // any GLContext is successfully created, like the compositor's GLContext.
+      mReady = true;
+      return;
+    }
+
+    gl->MakeCurrent();
+
+    if (mVendor.IsEmpty()) {
+      const char* spoofedVendor = PR_GetEnv("MOZ_GFX_SPOOF_GL_VENDOR");
+      if (spoofedVendor) {
+        mVendor.Assign(spoofedVendor);
+      } else {
+        mVendor.Assign((const char*)gl->fGetString(LOCAL_GL_VENDOR));
+      }
+    }
+
+    if (mRenderer.IsEmpty()) {
+      const char* spoofedRenderer = PR_GetEnv("MOZ_GFX_SPOOF_GL_RENDERER");
+      if (spoofedRenderer) {
+        mRenderer.Assign(spoofedRenderer);
+      } else {
+        mRenderer.Assign((const char*)gl->fGetString(LOCAL_GL_RENDERER));
+      }
+    }
+
+    if (mVersion.IsEmpty()) {
+      const char* spoofedVersion = PR_GetEnv("MOZ_GFX_SPOOF_GL_VERSION");
+      if (spoofedVersion) {
+        mVersion.Assign(spoofedVersion);
+      } else {
+        mVersion.Assign((const char*)gl->fGetString(LOCAL_GL_VERSION));
+      }
+    }
+
+    if (mExtensions.IsEmpty()) {
+      nsCString rawExtensions;
+      rawExtensions.Assign((const char*)gl->fGetString(LOCAL_GL_EXTENSIONS));
+      rawExtensions.Trim(" ");
+
+      for (auto extension : rawExtensions.Split(' ')) {
+        mExtensions.AppendElement(extension);
+      }
+    }
+
+    mReady = true;
+  }
+};
+
+#ifdef DEBUG
+NS_IMPL_ISUPPORTS_INHERITED(GfxInfo, GfxInfoBase, nsIGfxInfoDebug)
+#endif
+
+GfxInfo::GfxInfo()
+    : mInitialized(false),
+      mGLStrings(new GLStrings),
+      mOSVersionInteger(0),
+      mSDKVersion(0) {}
+
+GfxInfo::~GfxInfo() {}
+
+/* GetD2DEnabled and GetDwriteEnabled shouldn't be called until after
+ * gfxPlatform initialization has occurred because they depend on it for
+ * information. (See bug 591561) */
+nsresult GfxInfo::GetD2DEnabled(bool* aEnabled) { return NS_ERROR_FAILURE; }
+
+nsresult GfxInfo::GetDWriteEnabled(bool* aEnabled) { return NS_ERROR_FAILURE; }
+
+nsresult GfxInfo::GetHasBattery(bool* aHasBattery) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetDWriteVersion(nsAString& aDwriteVersion) {
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetEmbeddedInFirefoxReality(bool* aEmbeddedInFirefoxReality) {
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetCleartypeParameters(nsAString& aCleartypeParams) {
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetWindowProtocol(nsAString& aWindowProtocol) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetTestType(nsAString& aTestType) { return NS_ERROR_NOT_IMPLEMENTED; }
+
+void GfxInfo::EnsureInitialized() {
+  if (mInitialized) return;
+
+  if (!jni::IsAvailable()) {
+    gfxWarning() << "JNI missing during initialization";
+    return;
+  }
+
+  jni::String::LocalRef model = java::sdk::Build::MODEL();
+  mModel = model->ToString();
+  mAdapterDescription.AppendPrintf("Model: %s",
+                                   NS_LossyConvertUTF16toASCII(mModel).get());
+
+  jni::String::LocalRef product = java::sdk::Build::PRODUCT();
+  mProduct = product->ToString();
+  mAdapterDescription.AppendPrintf(", Product: %s",
+                                   NS_LossyConvertUTF16toASCII(mProduct).get());
+
+  jni::String::LocalRef manufacturer =
+      mozilla::java::sdk::Build::MANUFACTURER();
+  mManufacturer = manufacturer->ToString();
+  mAdapterDescription.AppendPrintf(
+      ", Manufacturer: %s", NS_LossyConvertUTF16toASCII(mManufacturer).get());
+
+  mSDKVersion = java::sdk::Build::VERSION::SDK_INT();
+  // the HARDWARE field isn't available on Android SDK < 8, but we require 9+
+  // anyway.
+  MOZ_ASSERT(mSDKVersion >= 8);
+  jni::String::LocalRef hardware = java::sdk::Build::HARDWARE();
+  mHardware = hardware->ToString();
+  mAdapterDescription.AppendPrintf(
+      ", Hardware: %s", NS_LossyConvertUTF16toASCII(mHardware).get());
+
+  jni::String::LocalRef release = java::sdk::Build::VERSION::RELEASE();
+  mOSVersion = release->ToCString();
+
+  mOSVersionInteger = 0;
+  char a[5], b[5], c[5], d[5];
+  SplitDriverVersion(mOSVersion.get(), a, b, c, d);
+  uint8_t na = atoi(a);
+  uint8_t nb = atoi(b);
+  uint8_t nc = atoi(c);
+  uint8_t nd = atoi(d);
+
+  mOSVersionInteger = (uint32_t(na) << 24) | (uint32_t(nb) << 16) |
+                      (uint32_t(nc) << 8) | uint32_t(nd);
+
+  mAdapterDescription.AppendPrintf(
+      ", OpenGL: %s -- %s -- %s", mGLStrings->Vendor().get(),
+      mGLStrings->Renderer().get(), mGLStrings->Version().get());
+
+  AddCrashReportAnnotations();
+  mInitialized = true;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDescription(nsAString& aAdapterDescription) {
+  EnsureInitialized();
+  aAdapterDescription = NS_ConvertASCIItoUTF16(mAdapterDescription);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDescription2(nsAString& aAdapterDescription) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterRAM(uint32_t* aAdapterRAM) {
+  EnsureInitialized();
+  *aAdapterRAM = 0;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterRAM2(uint32_t* aAdapterRAM) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriver(nsAString& aAdapterDriver) {
+  EnsureInitialized();
+  aAdapterDriver.Truncate();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriver2(nsAString& aAdapterDriver) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverVendor(nsAString& aAdapterDriverVendor) {
+  EnsureInitialized();
+  aAdapterDriverVendor.Truncate();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverVendor2(nsAString& aAdapterDriverVendor) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverVersion(nsAString& aAdapterDriverVersion) {
+  EnsureInitialized();
+  aAdapterDriverVersion = NS_ConvertASCIItoUTF16(mGLStrings->Version());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverVersion2(nsAString& aAdapterDriverVersion) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverDate(nsAString& aAdapterDriverDate) {
+  EnsureInitialized();
+  aAdapterDriverDate.Truncate();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDriverDate2(nsAString& aAdapterDriverDate) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterVendorID(nsAString& aAdapterVendorID) {
+  EnsureInitialized();
+  aAdapterVendorID = NS_ConvertASCIItoUTF16(mGLStrings->Vendor());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterVendorID2(nsAString& aAdapterVendorID) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDeviceID(nsAString& aAdapterDeviceID) {
+  EnsureInitialized();
+  aAdapterDeviceID = NS_ConvertASCIItoUTF16(mGLStrings->Renderer());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterDeviceID2(nsAString& aAdapterDeviceID) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterSubsysID(nsAString& aAdapterSubsysID) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetAdapterSubsysID2(nsAString& aAdapterSubsysID) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetIsGPU2Active(bool* aIsGPU2Active) {
+  EnsureInitialized();
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+GfxInfo::GetDrmRenderDevice(nsACString& aDrmRenderDevice) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+void GfxInfo::AddCrashReportAnnotations() {
+  CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::AdapterVendorID,
+                                     mGLStrings->Vendor());
+  CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::AdapterDeviceID,
+                                     mGLStrings->Renderer());
+  CrashReporter::AnnotateCrashReport(
+      CrashReporter::Annotation::AdapterDriverVersion, mGLStrings->Version());
+}
+
+const nsTArray<GfxDriverInfo>& GfxInfo::GetGfxDriverInfo() {
+  if (sDriverInfo->IsEmpty()) {
+    APPEND_TO_DRIVER_BLOCKLIST2(
+        OperatingSystem::Android, DeviceFamily::All,
+        nsIGfxInfo::FEATURE_OPENGL_LAYERS, nsIGfxInfo::FEATURE_STATUS_OK,
+        DRIVER_COMPARISON_IGNORED, GfxDriverInfo::allDriverVersions,
+        "FEATURE_OK_FORCE_OPENGL");
+  }
+
+  return *sDriverInfo;
+}
+
+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 = OperatingSystem::Android;
+  if (aOS) *aOS = os;
+
+  if (sShutdownOccurred) {
+    return NS_OK;
+  }
+
+  // OpenGL layers are never blocklisted on Android.
+  // This early return is so we avoid potentially slow
+  // GLStrings initialization on startup when we initialize GL layers.
+  if (aFeature == nsIGfxInfo::FEATURE_OPENGL_LAYERS) {
+    *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+    return NS_OK;
+  }
+
+  EnsureInitialized();
+
+  if (mGLStrings->Vendor().IsEmpty() || mGLStrings->Renderer().IsEmpty()) {
+    *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+    return NS_OK;
+  }
+
+  // Don't evaluate special cases when evaluating the downloaded blocklist.
+  if (aDriverInfo.IsEmpty()) {
+    if (aFeature == nsIGfxInfo::FEATURE_CANVAS2D_ACCELERATION) {
+      if (mSDKVersion < 11) {
+        // It's slower than software due to not having a compositing fast path
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_OS_VERSION;
+        aFailureId = "FEATURE_FAILURE_CANVAS_2D_SDK";
+      } else if (mGLStrings->Renderer().Find("Vivante GC1000") != -1) {
+        // Blocklist Vivante GC1000. See bug 1248183.
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILED_CANVAS_2D_HW";
+      } else {
+        *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+      }
+      return NS_OK;
+    }
+
+    if (aFeature == FEATURE_WEBGL_OPENGL) {
+      if (mGLStrings->Renderer().Find("Adreno 200") != -1 ||
+          mGLStrings->Renderer().Find("Adreno 205") != -1) {
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_ADRENO_20x";
+        return NS_OK;
+      }
+
+      if (mSDKVersion <= 17) {
+        if (mGLStrings->Renderer().Find("Adreno (TM) 3") != -1) {
+          *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+          aFailureId = "FEATURE_FAILURE_ADRENO_3xx";
+        }
+        return NS_OK;
+      }
+
+      if (mHardware.EqualsLiteral("ville")) {
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_VILLE";
+        return NS_OK;
+      }
+    }
+
+    if (aFeature == FEATURE_STAGEFRIGHT) {
+      NS_LossyConvertUTF16toASCII cManufacturer(mManufacturer);
+      NS_LossyConvertUTF16toASCII cModel(mModel);
+      NS_LossyConvertUTF16toASCII cHardware(mHardware);
+
+      if (cHardware.EqualsLiteral("antares") ||
+          cHardware.EqualsLiteral("harmony") ||
+          cHardware.EqualsLiteral("picasso") ||
+          cHardware.EqualsLiteral("picasso_e") ||
+          cHardware.EqualsLiteral("ventana") ||
+          cHardware.EqualsLiteral("rk30board")) {
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_STAGE_HW";
+        return NS_OK;
+      }
+
+      if (CompareVersions(mOSVersion.get(), "4.1.0") < 0) {
+        // Whitelist:
+        //   All Samsung ICS devices, except for:
+        //     Samsung SGH-I717 (Bug 845729)
+        //     Samsung SGH-I727 (Bug 845729)
+        //     Samsung SGH-I757 (Bug 845729)
+        //   All Galaxy nexus ICS devices
+        //   Sony Xperia Ion (LT28) ICS devices
+        bool isWhitelisted =
+            cModel.Equals("LT28h", nsCaseInsensitiveCStringComparator) ||
+            cManufacturer.Equals("samsung",
+                                 nsCaseInsensitiveCStringComparator) ||
+            cModel.Equals(
+                "galaxy nexus",
+                nsCaseInsensitiveCStringComparator);  // some Galaxy Nexus
+                                                      // have
+                                                      // manufacturer=amazon
+
+        if (cModel.LowerCaseFindASCII("sgh-i717") != -1 ||
+            cModel.LowerCaseFindASCII("sgh-i727") != -1 ||
+            cModel.LowerCaseFindASCII("sgh-i757") != -1) {
+          isWhitelisted = false;
+        }
+
+        if (!isWhitelisted) {
+          *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+          aFailureId = "FEATURE_FAILURE_4_1_HW";
+          return NS_OK;
+        }
+      } else if (CompareVersions(mOSVersion.get(), "4.2.0") < 0) {
+        // Whitelist:
+        //   All JB phones except for those in blocklist below
+        // Blocklist:
+        //   Samsung devices from bug 812881 and 853522.
+        //   Motorola XT890 from bug 882342.
+        bool isBlocklisted = cModel.LowerCaseFindASCII("gt-p3100") != -1 ||
+                             cModel.LowerCaseFindASCII("gt-p3110") != -1 ||
+                             cModel.LowerCaseFindASCII("gt-p3113") != -1 ||
+                             cModel.LowerCaseFindASCII("gt-p5100") != -1 ||
+                             cModel.LowerCaseFindASCII("gt-p5110") != -1 ||
+                             cModel.LowerCaseFindASCII("gt-p5113") != -1 ||
+                             cModel.LowerCaseFindASCII("xt890") != -1;
+
+        if (isBlocklisted) {
+          *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+          aFailureId = "FEATURE_FAILURE_4_2_HW";
+          return NS_OK;
+        }
+      } else if (CompareVersions(mOSVersion.get(), "4.3.0") < 0) {
+        // Blocklist all Sony devices
+        if (cManufacturer.LowerCaseFindASCII("sony") != -1) {
+          *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+          aFailureId = "FEATURE_FAILURE_4_3_SONY";
+          return NS_OK;
+        }
+      }
+    }
+
+    if (aFeature == FEATURE_WEBRTC_HW_ACCELERATION_ENCODE) {
+      if (jni::IsAvailable()) {
+        *aStatus = WebRtcHwVp8EncodeSupported();
+        aFailureId = "FEATURE_FAILURE_WEBRTC_ENCODE";
+        return NS_OK;
+      }
+    }
+    if (aFeature == FEATURE_WEBRTC_HW_ACCELERATION_DECODE) {
+      if (jni::IsAvailable()) {
+        *aStatus = WebRtcHwVp8DecodeSupported();
+        aFailureId = "FEATURE_FAILURE_WEBRTC_DECODE";
+        return NS_OK;
+      }
+    }
+    if (aFeature == FEATURE_WEBRTC_HW_ACCELERATION_H264) {
+      if (jni::IsAvailable()) {
+        *aStatus = WebRtcHwH264Supported();
+        aFailureId = "FEATURE_FAILURE_WEBRTC_H264";
+        return NS_OK;
+      }
+    }
+    if (aFeature == FEATURE_VP8_HW_DECODE ||
+        aFeature == FEATURE_VP9_HW_DECODE) {
+      NS_LossyConvertUTF16toASCII model(mModel);
+      bool isBlocked =
+          // GIFV crash, see bug 1232911.
+          model.Equals("GT-N8013", nsCaseInsensitiveCStringComparator);
+
+      if (isBlocked) {
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_VPx";
+      } else {
+        *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+      }
+      return NS_OK;
+    }
+
+    if (aFeature == FEATURE_WEBRENDER) {
+      const bool isMali4xx =
+          mGLStrings->Renderer().LowerCaseFindASCII("mali-4") >= 0;
+
+      const bool isPowerVrG6110 =
+          mGLStrings->Renderer().LowerCaseFindASCII("powervr rogue g6110") >= 0;
+
+      const bool isVivanteGC7000UL =
+          mGLStrings->Renderer().LowerCaseFindASCII("vivante gc7000ul") >= 0;
+
+      const bool isPowerVrFenceSyncCrash =
+          (mGLStrings->Renderer().LowerCaseFindASCII("powervr rogue g6200") >=
+               0 ||
+           mGLStrings->Renderer().LowerCaseFindASCII("powervr rogue g6430") >=
+               0 ||
+           mGLStrings->Renderer().LowerCaseFindASCII("powervr rogue gx6250") >=
+               0) &&
+          (mGLStrings->Version().Find("3283119") >= 0 ||
+           mGLStrings->Version().Find("3443629") >= 0 ||
+           mGLStrings->Version().Find("3573678") >= 0 ||
+           mGLStrings->Version().Find("3830101") >= 0);
+
+      if (isMali4xx) {
+        // Mali 4xx does not support GLES 3.
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_NO_GLES_3";
+      } else if (isPowerVrG6110) {
+        // Blocked on PowerVR Rogue G6110 due to bug 1742986 and bug 1717863.
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_POWERVR_G6110";
+      } else if (isVivanteGC7000UL) {
+        // Blocked on Vivante GC7000UL due to bug 1719327.
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_VIVANTE_GC7000UL";
+      } else if (isPowerVrFenceSyncCrash) {
+        // Blocked on various PowerVR GPUs due to bug 1773128.
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_POWERVR_FENCE_SYNC_CRASH";
+      } else {
+        *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+      }
+      return NS_OK;
+    }
+
+    if (aFeature == FEATURE_WEBRENDER_SCISSORED_CACHE_CLEARS) {
+      // Emulator with SwiftShader is buggy when attempting to clear picture
+      // cache textures with a scissor rect set.
+      const bool isEmulatorSwiftShader =
+          mGLStrings->Renderer().Find(
+              "Android Emulator OpenGL ES Translator (Google SwiftShader)") >=
+          0;
+      if (isEmulatorSwiftShader) {
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_BUG_1603515";
+      } else {
+        *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+      }
+      return NS_OK;
+    }
+
+    if (aFeature == FEATURE_WEBRENDER_SHADER_CACHE) {
+      // Program binaries are known to be buggy on Adreno 3xx. While we haven't
+      // encountered any correctness or stability issues with them, loading them
+      // fails more often than not, so is a waste of time. Better to just not
+      // even attempt to cache them. See bug 1615574.
+      const bool isAdreno3xx =
+          mGLStrings->Renderer().LowerCaseFindASCII("adreno (tm) 3") >= 0;
+      if (isAdreno3xx) {
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_ADRENO_3XX";
+      } else {
+        *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+      }
+    }
+
+    if (aFeature == FEATURE_WEBRENDER_OPTIMIZED_SHADERS) {
+      // Optimized shaders result in completely broken rendering on some Mali-T
+      // devices. We have seen this on T6xx, T7xx, and T8xx on android versions
+      // up to 5.1, and on T6xx on versions up to android 7.1. As a precaution
+      // disable for all Mali-T regardless of version. See bug 1689064 and bug
+      // 1707283 for details.
+      const bool isMaliT =
+          mGLStrings->Renderer().LowerCaseFindASCII("mali-t") >= 0;
+      if (isMaliT) {
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_BUG_1689064";
+      } else {
+        *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+      }
+      return NS_OK;
+    }
+
+    if (aFeature == FEATURE_WEBRENDER_PARTIAL_PRESENT) {
+      // Block partial present on some devices due to rendering issues.
+      // On Mali-Txxx due to bug 1680087 and bug 1707815.
+      // On Adreno 3xx GPUs due to bug 1695771.
+      const bool isMaliT =
+          mGLStrings->Renderer().LowerCaseFindASCII("mali-t") >= 0;
+      const bool isAdreno3xx =
+          mGLStrings->Renderer().LowerCaseFindASCII("adreno (tm) 3") >= 0;
+      if (isMaliT || isAdreno3xx) {
+        *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+        aFailureId = "FEATURE_FAILURE_BUG_1680087_1695771_1707815";
+      } else {
+        *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+      }
+      return NS_OK;
+    }
+  }
+
+  if (aFeature == FEATURE_GL_SWIZZLE) {
+    // Swizzling appears to be buggy on PowerVR Rogue devices with webrender.
+    // See bug 1704783.
+    const bool isPowerVRRogue =
+        mGLStrings->Renderer().LowerCaseFindASCII("powervr rogue") >= 0;
+    if (isPowerVRRogue) {
+      *aStatus = nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+      aFailureId = "FEATURE_FAILURE_POWERVR_ROGUE";
+    } else {
+      *aStatus = nsIGfxInfo::FEATURE_STATUS_OK;
+    }
+    return NS_OK;
+  }
+
+  return GfxInfoBase::GetFeatureStatusImpl(
+      aFeature, aStatus, aSuggestedDriverVersion, aDriverInfo, aFailureId, &os);
+}
+
+static nsCString FeatureCacheOsVerPrefName(int32_t aFeature) {
+  nsCString osPrefName;
+  osPrefName.AppendASCII("gfxinfo.cache.");
+  osPrefName.AppendInt(aFeature);
+  osPrefName.AppendASCII(".osver");
+  return osPrefName;
+}
+
+static nsCString FeatureCacheAppVerPrefName(int32_t aFeature) {
+  nsCString osPrefName;
+  osPrefName.AppendASCII("gfxinfo.cache.");
+  osPrefName.AppendInt(aFeature);
+  osPrefName.AppendASCII(".appver");
+  return osPrefName;
+}
+
+static nsCString FeatureCacheValuePrefName(int32_t aFeature) {
+  nsCString osPrefName;
+  osPrefName.AppendASCII("gfxinfo.cache.");
+  osPrefName.AppendInt(aFeature);
+  osPrefName.AppendASCII(".value");
+  return osPrefName;
+}
+
+static bool GetCachedFeatureVal(int32_t aFeature, uint32_t aExpectedOsVer,
+                                const nsCString& aCurrentAppVer,
+                                int32_t& aOutStatus) {
+  uint32_t osVer = 0;
+  nsresult rv =
+      Preferences::GetUint(FeatureCacheOsVerPrefName(aFeature).get(), &osVer);
+  if (NS_FAILED(rv) || osVer != aExpectedOsVer) {
+    return false;
+  }
+  // Bug 1804287 requires we invalidate cached values for new builds to allow
+  // for code changes to modify the features support.
+  nsAutoCString cachedAppVersion;
+  rv = Preferences::GetCString(FeatureCacheAppVerPrefName(aFeature).get(),
+                               cachedAppVersion);
+  if (NS_FAILED(rv) || !aCurrentAppVer.Equals(cachedAppVersion)) {
+    return false;
+  }
+  int32_t status = 0;
+  rv = Preferences::GetInt(FeatureCacheValuePrefName(aFeature).get(), &status);
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+  aOutStatus = status;
+  return true;
+}
+
+static void SetCachedFeatureVal(int32_t aFeature, uint32_t aOsVer,
+                                const nsCString& aCurrentAppVer,
+                                int32_t aStatus) {
+  // Ignore failures; not much we can do anyway.
+  Preferences::SetUint(FeatureCacheOsVerPrefName(aFeature).get(), aOsVer);
+  Preferences::SetCString(FeatureCacheAppVerPrefName(aFeature).get(),
+                          aCurrentAppVer);
+  Preferences::SetInt(FeatureCacheValuePrefName(aFeature).get(), aStatus);
+}
+
+int32_t GfxInfo::WebRtcHwVp8EncodeSupported() {
+  MOZ_ASSERT(jni::IsAvailable());
+
+  // The Android side of this calculation is very slow, so we cache the result
+  // in preferences, invalidating if the OS version changes.
+
+  int32_t status = 0;
+  const auto& currentAppVersion = GfxInfoBase::GetApplicationVersion();
+  if (GetCachedFeatureVal(FEATURE_WEBRTC_HW_ACCELERATION_ENCODE,
+                          mOSVersionInteger, currentAppVersion, status)) {
+    return status;
+  }
+
+  status = java::GeckoAppShell::HasHWVP8Encoder()
+               ? nsIGfxInfo::FEATURE_STATUS_OK
+               : nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+
+  SetCachedFeatureVal(FEATURE_WEBRTC_HW_ACCELERATION_ENCODE, mOSVersionInteger,
+                      currentAppVersion, status);
+
+  return status;
+}
+
+int32_t GfxInfo::WebRtcHwVp8DecodeSupported() {
+  MOZ_ASSERT(jni::IsAvailable());
+
+  // The Android side of this caclulation is very slow, so we cache the result
+  // in preferences, invalidating if the OS version changes.
+
+  int32_t status = 0;
+  const auto& appVersion = GfxInfoBase::GetApplicationVersion();
+  if (GetCachedFeatureVal(FEATURE_WEBRTC_HW_ACCELERATION_DECODE,
+                          mOSVersionInteger, appVersion, status)) {
+    return status;
+  }
+
+  status = java::GeckoAppShell::HasHWVP8Decoder()
+               ? nsIGfxInfo::FEATURE_STATUS_OK
+               : nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+
+  SetCachedFeatureVal(FEATURE_WEBRTC_HW_ACCELERATION_DECODE, mOSVersionInteger,
+                      appVersion, status);
+
+  return status;
+}
+
+int32_t GfxInfo::WebRtcHwH264Supported() {
+  MOZ_ASSERT(jni::IsAvailable());
+
+  // The Android side of this calculation is very slow, so we cache the result
+  // in preferences, invalidating if the OS version changes.
+
+  int32_t status = 0;
+  const auto& currentAppVersion = GfxInfoBase::GetApplicationVersion();
+  if (GetCachedFeatureVal(FEATURE_WEBRTC_HW_ACCELERATION_H264,
+                          mOSVersionInteger, currentAppVersion, status)) {
+    return status;
+  }
+
+  status = java::HardwareCodecCapabilityUtils::HasHWH264()
+               ? nsIGfxInfo::FEATURE_STATUS_OK
+               : nsIGfxInfo::FEATURE_BLOCKED_DEVICE;
+
+  SetCachedFeatureVal(FEATURE_WEBRTC_HW_ACCELERATION_H264, mOSVersionInteger,
+                      currentAppVersion, status);
+
+  return status;
+}
+
+#ifdef DEBUG
+
+// Implement nsIGfxInfoDebug
+
+NS_IMETHODIMP GfxInfo::SpoofVendorID(const nsAString& aVendorID) {
+  mGLStrings->SpoofVendor(NS_LossyConvertUTF16toASCII(aVendorID));
+  return NS_OK;
+}
+
+NS_IMETHODIMP GfxInfo::SpoofDeviceID(const nsAString& aDeviceID) {
+  mGLStrings->SpoofRenderer(NS_LossyConvertUTF16toASCII(aDeviceID));
+  return NS_OK;
+}
+
+NS_IMETHODIMP GfxInfo::SpoofDriverVersion(const nsAString& aDriverVersion) {
+  mGLStrings->SpoofVersion(NS_LossyConvertUTF16toASCII(aDriverVersion));
+  return NS_OK;
+}
+
+NS_IMETHODIMP GfxInfo::SpoofOSVersion(uint32_t aVersion) {
+  EnsureInitialized();
+  mOSVersion = aVersion;
+  return NS_OK;
+}
+
+#endif
+
+nsString GfxInfo::Model() {
+  EnsureInitialized();
+  return mModel;
+}
+
+nsString GfxInfo::Hardware() {
+  EnsureInitialized();
+  return mHardware;
+}
+
+nsString GfxInfo::Product() {
+  EnsureInitialized();
+  return mProduct;
+}
+
+nsString GfxInfo::Manufacturer() {
+  EnsureInitialized();
+  return mManufacturer;
+}
+
+uint32_t GfxInfo::OperatingSystemVersion() {
+  EnsureInitialized();
+  return mOSVersionInteger;
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/GfxInfo.h b/widget/android/GfxInfo.h
new file mode 100644
index 0000000000..7a963b0275
--- /dev/null
+++ b/widget/android/GfxInfo.h
@@ -0,0 +1,109 @@
+/* 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 "GfxDriverInfo.h"
+
+#include "nsString.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla {
+
+namespace widget {
+
+class GfxInfo : public GfxInfoBase {
+ private:
+  ~GfxInfo();
+
+ 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 GetCleartypeParameters(nsAString& aCleartypeParams) override;
+  NS_IMETHOD GetWindowProtocol(nsAString& aWindowProtocol) override;
+  NS_IMETHOD GetTestType(nsAString& aTestType) 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;
+
+  void EnsureInitialized();
+
+  virtual nsString Model() override;
+  virtual nsString Hardware() override;
+  virtual nsString Product() override;
+  virtual nsString Manufacturer() override;
+
+#ifdef DEBUG
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIGFXINFODEBUG
+#endif
+
+  virtual uint32_t OperatingSystemVersion() override;
+
+ protected:
+  OperatingSystem GetOperatingSystem() override {
+    return OperatingSystem::Android;
+  }
+  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 AddCrashReportAnnotations();
+  int32_t WebRtcHwVp8EncodeSupported();
+  int32_t WebRtcHwVp8DecodeSupported();
+  int32_t WebRtcHwH264Supported();
+
+  bool mInitialized;
+
+  class GLStrings;
+  UniquePtr<GLStrings> mGLStrings;
+
+  nsCString mAdapterDescription;
+
+  nsString mModel, mHardware, mManufacturer, mProduct;
+  nsCString mOSVersion;
+  uint32_t mOSVersionInteger;
+  int32_t mSDKVersion;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif /* __mozilla_widget_GfxInfo_h__ */
diff --git a/widget/android/ImageDecoderSupport.cpp b/widget/android/ImageDecoderSupport.cpp
new file mode 100644
index 0000000000..f3e1c3e444
--- /dev/null
+++ b/widget/android/ImageDecoderSupport.cpp
@@ -0,0 +1,185 @@
+/* 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 "ImageDecoderSupport.h"
+
+#include "imgINotificationObserver.h"
+#include "imgITools.h"
+#include "imgINotificationObserver.h"
+#include "gfxUtils.h"
+#include "AndroidGraphics.h"
+#include "JavaExceptions.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/gfx/Swizzle.h"
+#include "mozilla/java/ImageWrappers.h"
+#include "nsNetUtil.h"
+
+using namespace mozilla::gfx;
+
+namespace mozilla {
+namespace widget {
+
+namespace {
+
+class ImageCallbackHelper;
+
+HashSet<RefPtr<ImageCallbackHelper>, PointerHasher<ImageCallbackHelper*>>
+    gDecodeRequests;
+
+class ImageCallbackHelper : public imgIContainerCallback,
+                            public imgINotificationObserver {
+ public:
+  NS_DECL_ISUPPORTS
+
+  void CompleteExceptionally(nsresult aRv) {
+    nsPrintfCString error("Could not process image: 0x%08X", aRv);
+    mResult->CompleteExceptionally(
+        java::Image::ImageProcessingException::New(error.get())
+            .Cast<jni::Throwable>());
+    gDecodeRequests.remove(this);
+  }
+
+  void Complete(DataSourceSurface::ScopedMap& aSourceSurface, int32_t width,
+                int32_t height) {
+    auto pixels = mozilla::jni::ByteBuffer::New(
+        reinterpret_cast<int8_t*>(aSourceSurface.GetData()),
+        aSourceSurface.GetStride() * height);
+    auto bitmap = java::sdk::Bitmap::CreateBitmap(
+        width, height, java::sdk::Bitmap::Config::ARGB_8888());
+    bitmap->CopyPixelsFromBuffer(pixels);
+    mResult->Complete(bitmap);
+    gDecodeRequests.remove(this);
+  }
+
+  ImageCallbackHelper(java::GeckoResult::Param aResult, int32_t aDesiredLength)
+      : mResult(aResult), mDesiredLength(aDesiredLength), mImage(nullptr) {
+    MOZ_ASSERT(mResult);
+  }
+
+  NS_IMETHOD
+  OnImageReady(imgIContainer* aImage, nsresult aStatus) override {
+    // Let's make sure we are alive until the request completes
+    MOZ_ALWAYS_TRUE(gDecodeRequests.putNew(this));
+
+    if (NS_FAILED(aStatus)) {
+      CompleteExceptionally(aStatus);
+      return aStatus;
+    }
+
+    mImage = aImage;
+    return mImage->StartDecoding(
+        imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY,
+        imgIContainer::FRAME_FIRST);
+  }
+
+  // This method assumes that the image is ready to be processed
+  nsresult SendBitmap() {
+    RefPtr<gfx::SourceSurface> surface;
+
+    NS_ENSURE_TRUE(mImage, NS_ERROR_FAILURE);
+    if (mDesiredLength > 0) {
+      surface = mImage->GetFrameAtSize(
+          gfx::IntSize(mDesiredLength, mDesiredLength),
+          imgIContainer::FRAME_FIRST,
+          imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
+    } else {
+      surface = mImage->GetFrame(
+          imgIContainer::FRAME_FIRST,
+          imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
+    }
+
+    NS_ENSURE_TRUE(surface, NS_ERROR_FAILURE);
+    RefPtr<DataSourceSurface> dataSurface = surface->GetDataSurface();
+
+    NS_ENSURE_TRUE(dataSurface, NS_ERROR_FAILURE);
+    int32_t width = dataSurface->GetSize().width;
+    int32_t height = dataSurface->GetSize().height;
+
+    DataSourceSurface::ScopedMap sourceMap(dataSurface,
+                                           DataSourceSurface::READ);
+
+    // Android's Bitmap only supports R8G8B8A8, so we need to convert the
+    // data to the right format
+    RefPtr<DataSourceSurface> destDataSurface =
+        Factory::CreateDataSourceSurfaceWithStride(dataSurface->GetSize(),
+                                                   SurfaceFormat::R8G8B8A8,
+                                                   sourceMap.GetStride());
+    NS_ENSURE_TRUE(destDataSurface, NS_ERROR_FAILURE);
+
+    DataSourceSurface::ScopedMap destMap(destDataSurface,
+                                         DataSourceSurface::READ_WRITE);
+
+    SwizzleData(sourceMap.GetData(), sourceMap.GetStride(),
+                surface->GetFormat(), destMap.GetData(), destMap.GetStride(),
+                SurfaceFormat::R8G8B8A8, destDataSurface->GetSize());
+
+    Complete(destMap, width, height);
+
+    return NS_OK;
+  }
+
+  void Notify(imgIRequest* aRequest, int32_t aType,
+              const nsIntRect* aData) override {
+    if (aType == imgINotificationObserver::DECODE_COMPLETE) {
+      nsresult status = SendBitmap();
+      if (NS_FAILED(status)) {
+        CompleteExceptionally(status);
+      }
+
+      // Breack the cyclic reference between `ImageDecoderListener` (which is a
+      // `imgIContainer`) and `ImageCallbackHelper`.
+      mImage = nullptr;
+    }
+  }
+
+ private:
+  const java::GeckoResult::GlobalRef mResult;
+  int32_t mDesiredLength;
+  nsCOMPtr<imgIContainer> mImage;
+  virtual ~ImageCallbackHelper() {}
+};
+
+NS_IMPL_ISUPPORTS(ImageCallbackHelper, imgIContainerCallback,
+                  imgINotificationObserver)
+
+}  // namespace
+
+/* static */ void ImageDecoderSupport::Decode(jni::String::Param aUri,
+                                              int32_t aDesiredLength,
+                                              jni::Object::Param aResult) {
+  auto result = java::GeckoResult::LocalRef(aResult);
+  RefPtr<ImageCallbackHelper> helper =
+      new ImageCallbackHelper(result, aDesiredLength);
+
+  nsresult rv = DecodeInternal(aUri->ToString(), helper, helper);
+  if (NS_FAILED(rv)) {
+    helper->OnImageReady(nullptr, rv);
+  }
+}
+
+/* static */ nsresult ImageDecoderSupport::DecodeInternal(
+    const nsAString& aUri, imgIContainerCallback* aCallback,
+    imgINotificationObserver* aObserver) {
+  nsCOMPtr<imgITools> imgTools = do_GetService("@mozilla.org/image/tools;1");
+  if (NS_WARN_IF(!imgTools)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIURI> uri;
+  nsresult rv = NS_NewURI(getter_AddRefs(uri), aUri);
+  NS_ENSURE_SUCCESS(rv, NS_ERROR_MALFORMED_URI);
+
+  nsCOMPtr<nsIChannel> channel;
+  rv = NS_NewChannel(getter_AddRefs(channel), uri,
+                     nsContentUtils::GetSystemPrincipal(),
+                     nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+                     nsIContentPolicy::TYPE_IMAGE);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return imgTools->DecodeImageFromChannelAsync(uri, channel, aCallback,
+                                               aObserver);
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/ImageDecoderSupport.h b/widget/android/ImageDecoderSupport.h
new file mode 100644
index 0000000000..d38b3e7e1b
--- /dev/null
+++ b/widget/android/ImageDecoderSupport.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 ImageDecoderSupport_h__
+#define ImageDecoderSupport_h__
+
+#include "mozilla/java/ImageDecoderNatives.h"
+
+class imgIContainerCallback;
+
+namespace mozilla {
+namespace widget {
+
+class ImageDecoderSupport final
+    : public java::ImageDecoder::Natives<ImageDecoderSupport> {
+ public:
+  static void Decode(jni::String::Param aUri, int32_t aDesiredLength,
+                     jni::Object::Param aResult);
+
+ private:
+  static nsresult DecodeInternal(const nsAString& aUri,
+                                 imgIContainerCallback* aCallback,
+                                 imgINotificationObserver* aObserver);
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // ImageDecoderSupport_h__
diff --git a/widget/android/InProcessAndroidCompositorWidget.cpp b/widget/android/InProcessAndroidCompositorWidget.cpp
new file mode 100644
index 0000000000..1ae221acb9
--- /dev/null
+++ b/widget/android/InProcessAndroidCompositorWidget.cpp
@@ -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/. */
+
+#include "HeadlessCompositorWidget.h"
+#include "HeadlessWidget.h"
+#include "mozilla/widget/PlatformWidgetTypes.h"
+
+#include "InProcessAndroidCompositorWidget.h"
+#include "nsWindow.h"
+
+namespace mozilla {
+namespace widget {
+
+/* static */
+RefPtr<CompositorWidget> CompositorWidget::CreateLocal(
+    const CompositorWidgetInitData& aInitData,
+    const layers::CompositorOptions& aOptions, nsIWidget* aWidget) {
+  if (aInitData.type() ==
+      CompositorWidgetInitData::THeadlessCompositorWidgetInitData) {
+    return new HeadlessCompositorWidget(
+        aInitData.get_HeadlessCompositorWidgetInitData(), aOptions,
+        static_cast<HeadlessWidget*>(aWidget));
+  } else {
+    return new InProcessAndroidCompositorWidget(
+        aInitData.get_AndroidCompositorWidgetInitData(), aOptions,
+        static_cast<nsWindow*>(aWidget));
+  }
+}
+
+InProcessAndroidCompositorWidget::InProcessAndroidCompositorWidget(
+    const AndroidCompositorWidgetInitData& aInitData,
+    const layers::CompositorOptions& aOptions, nsWindow* aWindow)
+    : AndroidCompositorWidget(aInitData, aOptions), mWindow(aWindow) {}
+
+void InProcessAndroidCompositorWidget::ObserveVsync(VsyncObserver* aObserver) {
+  if (RefPtr<CompositorVsyncDispatcher> cvd =
+          mWindow->GetCompositorVsyncDispatcher()) {
+    cvd->SetCompositorVsyncObserver(aObserver);
+  }
+}
+
+nsIWidget* InProcessAndroidCompositorWidget::RealWidget() { return mWindow; }
+
+void InProcessAndroidCompositorWidget::OnCompositorSurfaceChanged() {
+  mSurface = java::sdk::Surface::Ref::From(
+      static_cast<jobject>(mWindow->GetNativeData(NS_JAVA_SURFACE)));
+}
+
+void InProcessAndroidCompositorWidget::NotifyClientSizeChanged(
+    const LayoutDeviceIntSize& aClientSize) {
+  AndroidCompositorWidget::NotifyClientSizeChanged(aClientSize);
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/InProcessAndroidCompositorWidget.h b/widget/android/InProcessAndroidCompositorWidget.h
new file mode 100644
index 0000000000..b7ba280d5c
--- /dev/null
+++ b/widget/android/InProcessAndroidCompositorWidget.h
@@ -0,0 +1,45 @@
+/* -*- 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_android_InProcessAndroidCompositorWidget_h
+#define widget_android_InProcessAndroidCompositorWidget_h
+
+#include "AndroidCompositorWidget.h"
+#include "CompositorWidget.h"
+
+class nsWindow;
+
+namespace mozilla {
+namespace widget {
+
+class InProcessAndroidCompositorWidget final
+    : public AndroidCompositorWidget,
+      public PlatformCompositorWidgetDelegate {
+ public:
+  InProcessAndroidCompositorWidget(
+      const AndroidCompositorWidgetInitData& aInitData,
+      const layers::CompositorOptions& aOptions, nsWindow* aWidget);
+
+  // CompositorWidget overrides
+
+  void ObserveVsync(VsyncObserver* aObserver) override;
+  nsIWidget* RealWidget() override;
+  CompositorWidgetDelegate* AsDelegate() override { return this; }
+
+  // PlatformCompositorWidgetDelegate overrides
+
+  void NotifyClientSizeChanged(const LayoutDeviceIntSize& aClientSize) override;
+
+ private:
+  // AndroidCompositorWidget overrides
+  void OnCompositorSurfaceChanged() override;
+
+  nsWindow* mWindow;
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // widget_android_InProcessAndroidCompositorWidget_h
diff --git a/widget/android/MediaKeysEventSourceFactory.cpp b/widget/android/MediaKeysEventSourceFactory.cpp
new file mode 100644
index 0000000000..b52919d4cc
--- /dev/null
+++ b/widget/android/MediaKeysEventSourceFactory.cpp
@@ -0,0 +1,17 @@
+/* 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"
+
+namespace mozilla {
+namespace widget {
+
+mozilla::dom::MediaControlKeySource* CreateMediaControlKeySource() {
+  // GeckoView uses MediaController.webidl for media session events and control,
+  // see bug 1623715.
+  return nullptr;
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/PCompositorWidget.ipdl b/widget/android/PCompositorWidget.ipdl
new file mode 100644
index 0000000000..35a150cbba
--- /dev/null
+++ b/widget/android/PCompositorWidget.ipdl
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=99: */
+/* 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 protocol PCompositorBridge;
+
+using mozilla::LayoutDeviceIntSize from "Units.h";
+
+namespace mozilla {
+namespace widget {
+
+[ManualDealloc, ChildImpl=virtual, ParentImpl=virtual]
+sync protocol PCompositorWidget
+{
+  manager PCompositorBridge;
+
+parent:
+  async __delete__();
+
+  async NotifyClientSizeChanged(LayoutDeviceIntSize aClientSize);
+
+child:
+  async ObserveVsync();
+  async UnobserveVsync();
+};
+
+} // namespace widget
+} // namespace mozilla
diff --git a/widget/android/PlatformWidgetTypes.ipdlh b/widget/android/PlatformWidgetTypes.ipdlh
new file mode 100644
index 0000000000..62ac0df9ff
--- /dev/null
+++ b/widget/android/PlatformWidgetTypes.ipdlh
@@ -0,0 +1,29 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=99: */
+/* 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 HeadlessWidgetTypes;
+
+include "mozilla/GfxMessageUtils.h";
+
+using mozilla::LayoutDeviceIntSize from "Units.h";
+
+namespace mozilla {
+namespace widget {
+
+struct AndroidCompositorWidgetInitData
+{
+  int32_t widgetId;
+  LayoutDeviceIntSize clientSize;
+};
+
+union CompositorWidgetInitData
+{
+  AndroidCompositorWidgetInitData;
+  HeadlessCompositorWidgetInitData;
+};
+
+} // namespace widget
+} // namespace mozilla
diff --git a/widget/android/ScreenHelperAndroid.cpp b/widget/android/ScreenHelperAndroid.cpp
new file mode 100644
index 0000000000..33c91fe6e0
--- /dev/null
+++ b/widget/android/ScreenHelperAndroid.cpp
@@ -0,0 +1,70 @@
+/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set sw=2 ts=4 expandtab:
+ * 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 "ScreenHelperAndroid.h"
+#include "AndroidRect.h"
+#include "nsThreadUtils.h"
+
+#include <mozilla/jni/Refs.h>
+
+#include "AndroidVsync.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/java/GeckoAppShellWrappers.h"
+#include "mozilla/java/ScreenManagerHelperNatives.h"
+#include "mozilla/widget/ScreenManager.h"
+#include "nsXULAppAPI.h"
+
+using namespace mozilla;
+using namespace mozilla::widget;
+
+static ScreenHelperAndroid* gHelper = nullptr;
+
+class ScreenHelperAndroid::ScreenHelperSupport final
+    : public java::ScreenManagerHelper::Natives<ScreenHelperSupport> {
+ public:
+  typedef java::ScreenManagerHelper::Natives<ScreenHelperSupport> Base;
+
+  static void RefreshScreenInfo() { gHelper->Refresh(); }
+};
+
+static already_AddRefed<Screen> MakePrimaryScreen() {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  java::sdk::Rect::LocalRef rect = java::GeckoAppShell::GetScreenSize();
+  LayoutDeviceIntRect bounds = LayoutDeviceIntRect(
+      rect->Left(), rect->Top(), rect->Width(), rect->Height());
+  uint32_t depth = java::GeckoAppShell::GetScreenDepth();
+  float density = java::GeckoAppShell::GetDensity();
+  float dpi = java::GeckoAppShell::GetDpi();
+  auto orientation =
+      hal::ScreenOrientation(java::GeckoAppShell::GetScreenOrientation());
+  uint16_t angle = java::GeckoAppShell::GetScreenAngle();
+  float refreshRate = java::GeckoAppShell::GetScreenRefreshRate();
+  return MakeAndAddRef<Screen>(bounds, bounds, depth, depth, refreshRate,
+                               DesktopToLayoutDeviceScale(density),
+                               CSSToLayoutDeviceScale(1.0f), dpi,
+                               Screen::IsPseudoDisplay::No, orientation, angle);
+}
+
+ScreenHelperAndroid::ScreenHelperAndroid() {
+  MOZ_ASSERT(!gHelper);
+  gHelper = this;
+
+  ScreenHelperSupport::Base::Init();
+
+  Refresh();
+}
+
+ScreenHelperAndroid::~ScreenHelperAndroid() { gHelper = nullptr; }
+
+void ScreenHelperAndroid::Refresh() {
+  AutoTArray<RefPtr<Screen>, 1> screens;
+  screens.AppendElement(MakePrimaryScreen());
+  ScreenManager::Refresh(std::move(screens));
+
+  if (RefPtr<AndroidVsync> vsync = AndroidVsync::GetInstance()) {
+    vsync->OnMaybeUpdateRefreshRate();
+  }
+}
diff --git a/widget/android/ScreenHelperAndroid.h b/widget/android/ScreenHelperAndroid.h
new file mode 100644
index 0000000000..c7015ee873
--- /dev/null
+++ b/widget/android/ScreenHelperAndroid.h
@@ -0,0 +1,29 @@
+/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: ts=4 sw=2 expandtab:
+ * 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 ScreenHelperAndroid_h___
+#define ScreenHelperAndroid_h___
+
+#include "mozilla/widget/ScreenManager.h"
+#include "nsTHashMap.h"
+
+namespace mozilla {
+namespace widget {
+
+class ScreenHelperAndroid final : public ScreenManager::Helper {
+ public:
+  class ScreenHelperSupport;
+
+  ScreenHelperAndroid();
+  ~ScreenHelperAndroid();
+
+  void Refresh();
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif /* ScreenHelperAndroid_h___ */
diff --git a/widget/android/Telemetry.h b/widget/android/Telemetry.h
new file mode 100644
index 0000000000..9936b13367
--- /dev/null
+++ b/widget/android/Telemetry.h
@@ -0,0 +1,31 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 mozilla_widget_Telemetry_h__
+#define mozilla_widget_Telemetry_h__
+
+#include "mozilla/java/TelemetryUtilsNatives.h"
+#include "nsAppShell.h"
+#include "nsIAndroidBridge.h"
+
+#include "mozilla/Telemetry.h"
+
+namespace mozilla {
+namespace widget {
+
+class Telemetry final : public java::TelemetryUtils::Natives<Telemetry> {
+  Telemetry() = delete;
+
+ public:
+  static void AddHistogram(jni::String::Param aName, int32_t aValue) {
+    MOZ_ASSERT(aName);
+    mozilla::Telemetry::Accumulate(aName->ToCString().get(), aValue);
+  }
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_Telemetry_h__
diff --git a/widget/android/WebExecutorSupport.cpp b/widget/android/WebExecutorSupport.cpp
new file mode 100644
index 0000000000..eca9790aad
--- /dev/null
+++ b/widget/android/WebExecutorSupport.cpp
@@ -0,0 +1,469 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 <algorithm>
+
+#include "GeckoViewStreamListener.h"
+#include "InetAddress.h"  // for java::sdk::InetAddress and java::sdk::UnknownHostException
+#include "ReferrerInfo.h"
+#include "WebExecutorSupport.h"
+
+#include "nsIAsyncVerifyRedirectCallback.h"
+#include "nsIHttpChannel.h"
+#include "nsIHttpChannelInternal.h"
+#include "nsIHttpHeaderVisitor.h"
+#include "nsIDNSService.h"
+#include "nsIDNSListener.h"
+#include "nsIDNSRecord.h"
+#include "nsINSSErrorsService.h"
+#include "nsNetUtil.h"  // for NS_NewURI, NS_NewChannel, NS_NewStreamLoader
+#include "nsIPrivateBrowsingChannel.h"
+#include "nsIUploadChannel2.h"
+#include "nsIX509Cert.h"
+
+#include "mozilla/Preferences.h"
+#include "mozilla/net/CookieJarSettings.h"
+#include "mozilla/net/DNS.h"  // for NetAddr
+#include "mozilla/java/GeckoWebExecutorWrappers.h"
+#include "mozilla/java/WebMessageWrappers.h"
+#include "mozilla/java/WebRequestErrorWrappers.h"
+#include "mozilla/java/WebResponseWrappers.h"
+
+namespace mozilla {
+using namespace net;
+
+namespace widget {
+
+static void CompleteWithError(java::GeckoResult::Param aResult,
+                              nsresult aStatus, nsIChannel* aChannel) {
+  nsCOMPtr<nsINSSErrorsService> errSvc =
+      do_GetService("@mozilla.org/nss_errors_service;1");
+  MOZ_ASSERT(errSvc);
+
+  uint32_t errorClass;
+  nsresult rv = errSvc->GetErrorClass(aStatus, &errorClass);
+  if (NS_FAILED(rv)) {
+    errorClass = 0;
+  }
+
+  jni::ByteArray::LocalRef certBytes;
+  if (aChannel) {
+    std::tie(certBytes, std::ignore) =
+        GeckoViewStreamListener::CertificateFromChannel(aChannel);
+  }
+
+  java::WebRequestError::LocalRef error = java::WebRequestError::FromGeckoError(
+      int64_t(aStatus), NS_ERROR_GET_MODULE(aStatus), errorClass, certBytes);
+
+  aResult->CompleteExceptionally(error.Cast<jni::Throwable>());
+}
+
+static void CompleteWithError(java::GeckoResult::Param aResult,
+                              nsresult aStatus) {
+  CompleteWithError(aResult, aStatus, nullptr);
+}
+
+class ByteBufferStream final : public nsIInputStream {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  explicit ByteBufferStream(jni::ByteBuffer::Param buffer)
+      : mBuffer(buffer), mPosition(0), mClosed(false) {
+    MOZ_ASSERT(mBuffer);
+    MOZ_ASSERT(mBuffer->Address());
+  }
+
+  NS_IMETHOD
+  Close() override {
+    mClosed = true;
+    return NS_OK;
+  }
+
+  NS_IMETHOD
+  Available(uint64_t* aResult) override {
+    if (mClosed) {
+      return NS_BASE_STREAM_CLOSED;
+    }
+
+    *aResult = (mBuffer->Capacity() - mPosition);
+    return NS_OK;
+  }
+
+  NS_IMETHOD
+  StreamStatus() override { return mClosed ? NS_BASE_STREAM_CLOSED : NS_OK; }
+
+  NS_IMETHOD
+  Read(char* aBuf, uint32_t aCount, uint32_t* aCountRead) override {
+    if (mClosed) {
+      return NS_BASE_STREAM_CLOSED;
+    }
+
+    *aCountRead = uint32_t(
+        std::min(uint64_t(mBuffer->Capacity() - mPosition), uint64_t(aCount)));
+
+    if (*aCountRead > 0) {
+      memcpy(aBuf, (char*)mBuffer->Address() + mPosition, *aCountRead);
+      mPosition += *aCountRead;
+    }
+
+    return NS_OK;
+  }
+
+  NS_IMETHOD
+  ReadSegments(nsWriteSegmentFun aWriter, void* aClosure, uint32_t aCount,
+               uint32_t* aResult) override {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  NS_IMETHOD
+  IsNonBlocking(bool* aResult) override {
+    *aResult = false;
+    return NS_OK;
+  }
+
+ protected:
+  virtual ~ByteBufferStream() {}
+
+  const jni::ByteBuffer::GlobalRef mBuffer;
+  uint64_t mPosition;
+  bool mClosed;
+};
+
+NS_IMPL_ISUPPORTS(ByteBufferStream, nsIInputStream)
+
+class LoaderListener final : public GeckoViewStreamListener {
+ public:
+  explicit LoaderListener(java::GeckoResult::Param aResult,
+                          bool aAllowRedirects, bool testStreamFailure)
+      : GeckoViewStreamListener(),
+        mResult(aResult),
+        mTestStreamFailure(testStreamFailure),
+        mAllowRedirects(aAllowRedirects) {
+    MOZ_ASSERT(mResult);
+  }
+
+  NS_IMETHOD
+  OnDataAvailable(nsIRequest* aRequest, nsIInputStream* aInputStream,
+                  uint64_t aOffset, uint32_t aCount) override {
+    MOZ_ASSERT(mStream);
+
+    if (mTestStreamFailure) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    // We only need this for the ReadSegments call, the value is unused.
+    uint32_t countRead;
+    nsresult rv =
+        aInputStream->ReadSegments(WriteSegment, this, aCount, &countRead);
+    NS_ENSURE_SUCCESS(rv, rv);
+    return rv;
+  }
+
+  NS_IMETHOD
+  AsyncOnChannelRedirect(nsIChannel* aOldChannel, nsIChannel* aNewChannel,
+                         uint32_t flags,
+                         nsIAsyncVerifyRedirectCallback* callback) override {
+    if (!mAllowRedirects) {
+      return NS_ERROR_ABORT;
+    }
+
+    callback->OnRedirectVerifyCallback(NS_OK);
+    return NS_OK;
+  }
+
+  void SendWebResponse(java::WebResponse::Param aResponse) override {
+    mResult->Complete(aResponse);
+  }
+
+  void CompleteWithError(nsresult aStatus, nsIChannel* aChannel) override {
+    ::CompleteWithError(mResult, aStatus, aChannel);
+  }
+
+  virtual ~LoaderListener() {}
+
+  const java::GeckoResult::GlobalRef mResult;
+  const bool mTestStreamFailure;
+  bool mAllowRedirects;
+};
+
+class DNSListener final : public nsIDNSListener {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  DNSListener(const nsCString& aHost, java::GeckoResult::Param aResult)
+      : mHost(aHost), mResult(aResult) {}
+
+  NS_IMETHOD
+  OnLookupComplete(nsICancelable* aRequest, nsIDNSRecord* aRecord,
+                   nsresult aStatus) override {
+    if (NS_FAILED(aStatus)) {
+      CompleteUnknownHostError();
+      return NS_OK;
+    }
+
+    nsresult rv = CompleteWithRecord(aRecord);
+    if (NS_FAILED(rv)) {
+      CompleteUnknownHostError();
+      return NS_OK;
+    }
+
+    return NS_OK;
+  }
+
+  void CompleteUnknownHostError() {
+    java::sdk::UnknownHostException::LocalRef error =
+        java::sdk::UnknownHostException::New();
+    mResult->CompleteExceptionally(error.Cast<jni::Throwable>());
+  }
+
+ private:
+  nsresult CompleteWithRecord(nsIDNSRecord* aRecord) {
+    nsTArray<NetAddr> addrs;
+    nsCOMPtr<nsIDNSAddrRecord> rec = do_QueryInterface(aRecord);
+    if (!rec) {
+      return NS_ERROR_UNEXPECTED;
+    }
+    nsresult rv = rec->GetAddresses(addrs);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    jni::ByteArray::LocalRef bytes;
+    auto objects =
+        jni::ObjectArray::New<java::sdk::InetAddress>(addrs.Length());
+    for (size_t i = 0; i < addrs.Length(); i++) {
+      const auto& addr = addrs[i];
+      if (addr.raw.family == AF_INET) {
+        bytes = jni::ByteArray::New(
+            reinterpret_cast<const int8_t*>(&addr.inet.ip), 4);
+      } else if (addr.raw.family == AF_INET6) {
+        bytes = jni::ByteArray::New(
+            reinterpret_cast<const int8_t*>(&addr.inet6.ip), 16);
+      } else {
+        // We don't handle this, skip it.
+        continue;
+      }
+
+      objects->SetElement(i,
+                          java::sdk::InetAddress::GetByAddress(mHost, bytes));
+    }
+
+    mResult->Complete(objects);
+    return NS_OK;
+  }
+
+  virtual ~DNSListener() {}
+
+  const nsCString mHost;
+  const java::GeckoResult::GlobalRef mResult;
+};
+
+NS_IMPL_ISUPPORTS(DNSListener, nsIDNSListener)
+
+static nsresult ConvertCacheMode(int32_t mode, int32_t& result) {
+  switch (mode) {
+    case java::WebRequest::CACHE_MODE_DEFAULT:
+      result = nsIHttpChannelInternal::FETCH_CACHE_MODE_DEFAULT;
+      break;
+    case java::WebRequest::CACHE_MODE_NO_STORE:
+      result = nsIHttpChannelInternal::FETCH_CACHE_MODE_NO_STORE;
+      break;
+    case java::WebRequest::CACHE_MODE_RELOAD:
+      result = nsIHttpChannelInternal::FETCH_CACHE_MODE_RELOAD;
+      break;
+    case java::WebRequest::CACHE_MODE_NO_CACHE:
+      result = nsIHttpChannelInternal::FETCH_CACHE_MODE_NO_CACHE;
+      break;
+    case java::WebRequest::CACHE_MODE_FORCE_CACHE:
+      result = nsIHttpChannelInternal::FETCH_CACHE_MODE_FORCE_CACHE;
+      break;
+    case java::WebRequest::CACHE_MODE_ONLY_IF_CACHED:
+      result = nsIHttpChannelInternal::FETCH_CACHE_MODE_ONLY_IF_CACHED;
+      break;
+    default:
+      return NS_ERROR_UNEXPECTED;
+  }
+
+  return NS_OK;
+}
+
+static nsresult SetupHttpChannel(nsIHttpChannel* aHttpChannel,
+                                 nsIChannel* aChannel,
+                                 java::WebRequest::Param aRequest) {
+  const auto req = java::WebRequest::LocalRef(aRequest);
+  const auto reqBase = java::WebMessage::LocalRef(req.Cast<java::WebMessage>());
+
+  // Method
+  nsresult rv = aHttpChannel->SetRequestMethod(aRequest->Method()->ToCString());
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Headers
+  const auto keys = reqBase->GetHeaderKeys();
+  const auto values = reqBase->GetHeaderValues();
+  nsCString contentType;
+  for (size_t i = 0; i < keys->Length(); i++) {
+    const auto key = jni::String::LocalRef(keys->GetElement(i))->ToCString();
+    const auto value =
+        jni::String::LocalRef(values->GetElement(i))->ToCString();
+
+    if (key.LowerCaseEqualsASCII("content-type")) {
+      contentType = value;
+    }
+
+    // We clobber any duplicate keys here because we've already merged them
+    // in the upstream WebRequest.
+    rv = aHttpChannel->SetRequestHeader(key, value, false /* merge */);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  // Body
+  const auto body = req->Body();
+  if (body) {
+    nsCOMPtr<nsIInputStream> stream = new ByteBufferStream(body);
+
+    nsCOMPtr<nsIUploadChannel2> uploadChannel(do_QueryInterface(aChannel, &rv));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = uploadChannel->ExplicitSetUploadStream(
+        stream, contentType, -1, aRequest->Method()->ToCString(), false);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  // Referrer
+  RefPtr<nsIURI> referrerUri;
+  const auto referrer = req->Referrer();
+  if (referrer) {
+    rv = NS_NewURI(getter_AddRefs(referrerUri), referrer->ToString());
+    NS_ENSURE_SUCCESS(rv, NS_ERROR_MALFORMED_URI);
+  }
+
+  nsCOMPtr<nsIReferrerInfo> referrerInfo = new dom::ReferrerInfo(referrerUri);
+  rv = aHttpChannel->SetReferrerInfoWithoutClone(referrerInfo);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Cache mode
+  nsCOMPtr<nsIHttpChannelInternal> internalChannel(
+      do_QueryInterface(aChannel, &rv));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  int32_t cacheMode;
+  rv = ConvertCacheMode(req->CacheMode(), cacheMode);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = internalChannel->SetFetchCacheMode(cacheMode);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (req->BeConservative()) {
+    rv = internalChannel->SetBeConservative(true);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  // We don't have any UI
+  rv = internalChannel->SetBlockAuthPrompt(true);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return NS_OK;
+}
+
+nsresult WebExecutorSupport::CreateStreamLoader(
+    java::WebRequest::Param aRequest, int32_t aFlags,
+    java::GeckoResult::Param aResult) {
+  const auto req = java::WebRequest::LocalRef(aRequest);
+  const auto reqBase = java::WebMessage::LocalRef(req.Cast<java::WebMessage>());
+
+  nsCOMPtr<nsIURI> uri;
+  nsresult rv = NS_NewURI(getter_AddRefs(uri), reqBase->Uri()->ToString());
+  NS_ENSURE_SUCCESS(rv, NS_ERROR_MALFORMED_URI);
+
+  nsCOMPtr<nsIChannel> channel;
+  rv = NS_NewChannel(getter_AddRefs(channel), uri,
+                     nsContentUtils::GetSystemPrincipal(),
+                     nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+                     nsIContentPolicy::TYPE_OTHER);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (aFlags & java::GeckoWebExecutor::FETCH_FLAGS_ANONYMOUS) {
+    channel->SetLoadFlags(nsIRequest::LOAD_ANONYMOUS);
+  }
+
+  bool shouldResistFingerprinting =
+      nsContentUtils::ShouldResistFingerprinting(channel);
+  nsCOMPtr<nsICookieJarSettings> cookieJarSettings;
+  if (aFlags & java::GeckoWebExecutor::FETCH_FLAGS_PRIVATE) {
+    nsCOMPtr<nsIPrivateBrowsingChannel> pbChannel = do_QueryInterface(channel);
+    NS_ENSURE_TRUE(pbChannel, NS_ERROR_FAILURE);
+    pbChannel->SetPrivate(true);
+    cookieJarSettings = CookieJarSettings::Create(CookieJarSettings::ePrivate,
+                                                  shouldResistFingerprinting);
+  } else {
+    cookieJarSettings = CookieJarSettings::Create(CookieJarSettings::eRegular,
+                                                  shouldResistFingerprinting);
+  }
+  MOZ_ASSERT(cookieJarSettings);
+
+  nsCOMPtr<nsILoadInfo> loadInfo = channel->LoadInfo();
+  loadInfo->SetCookieJarSettings(cookieJarSettings);
+
+  // setup http/https specific things
+  nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(channel, &rv));
+  if (httpChannel) {
+    rv = SetupHttpChannel(httpChannel, channel, aRequest);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  // set up the listener
+  const bool allowRedirects =
+      !(aFlags & java::GeckoWebExecutor::FETCH_FLAGS_NO_REDIRECTS);
+  const bool testStreamFailure =
+      (aFlags & java::GeckoWebExecutor::FETCH_FLAGS_STREAM_FAILURE_TEST);
+
+  RefPtr<LoaderListener> listener =
+      new LoaderListener(aResult, allowRedirects, testStreamFailure);
+
+  rv = channel->SetNotificationCallbacks(listener);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Finally, open the channel
+  return channel->AsyncOpen(listener);
+}
+
+void WebExecutorSupport::Fetch(jni::Object::Param aRequest, int32_t aFlags,
+                               jni::Object::Param aResult) {
+  const auto request = java::WebRequest::LocalRef(aRequest);
+  auto result = java::GeckoResult::LocalRef(aResult);
+
+  nsresult rv = CreateStreamLoader(request, aFlags, result);
+  if (NS_FAILED(rv)) {
+    CompleteWithError(result, rv);
+  }
+}
+
+static nsresult ResolveHost(nsCString& host, java::GeckoResult::Param result) {
+  nsresult rv;
+  nsCOMPtr<nsIDNSService> dns = do_GetService(NS_DNSSERVICE_CONTRACTID, &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsICancelable> cancelable;
+  RefPtr<DNSListener> listener = new DNSListener(host, result);
+  rv = dns->AsyncResolveNative(host, nsIDNSService::RESOLVE_TYPE_DEFAULT,
+                               nsIDNSService::RESOLVE_DEFAULT_FLAGS, nullptr,
+                               listener, nullptr /* aListenerTarget */,
+                               OriginAttributes(), getter_AddRefs(cancelable));
+  return rv;
+}
+
+void WebExecutorSupport::Resolve(jni::String::Param aUri,
+                                 jni::Object::Param aResult) {
+  auto result = java::GeckoResult::LocalRef(aResult);
+
+  nsCString uri = aUri->ToCString();
+  nsresult rv = ResolveHost(uri, result);
+  if (NS_FAILED(rv)) {
+    java::sdk::UnknownHostException::LocalRef error =
+        java::sdk::UnknownHostException::New();
+    result->CompleteExceptionally(error.Cast<jni::Throwable>());
+  }
+}
+
+}  // namespace widget
+}  // namespace mozilla
diff --git a/widget/android/WebExecutorSupport.h b/widget/android/WebExecutorSupport.h
new file mode 100644
index 0000000000..65a68fcc40
--- /dev/null
+++ b/widget/android/WebExecutorSupport.h
@@ -0,0 +1,32 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 WebExecutorSupport_h__
+#define WebExecutorSupport_h__
+
+#include "mozilla/java/GeckoWebExecutorNatives.h"
+#include "mozilla/java/GeckoResultWrappers.h"
+#include "mozilla/java/WebRequestWrappers.h"
+
+namespace mozilla {
+namespace widget {
+
+class WebExecutorSupport final
+    : public java::GeckoWebExecutor::Natives<WebExecutorSupport> {
+ public:
+  static void Fetch(jni::Object::Param request, int32_t flags,
+                    jni::Object::Param result);
+  static void Resolve(jni::String::Param aUri, jni::Object::Param result);
+
+ protected:
+  static nsresult CreateStreamLoader(java::WebRequest::Param aRequest,
+                                     int32_t aFlags,
+                                     java::GeckoResult::Param aResult);
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // WebExecutorSupport_h__
diff --git a/widget/android/WindowEvent.h b/widget/android/WindowEvent.h
new file mode 100644
index 0000000000..fdb73bf692
--- /dev/null
+++ b/widget/android/WindowEvent.h
@@ -0,0 +1,57 @@
+/* -*- 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_WindowEvent_h
+#define mozilla_widget_WindowEvent_h
+
+#include "nsThreadUtils.h"
+#include "mozilla/jni/Natives.h"
+
+namespace mozilla {
+namespace widget {
+
+// An Event subclass that guards against stale events.
+// (See the implmentation of mozilla::jni::detail::ProxyNativeCall for info
+//  about the default template parameters for this class)
+template <typename Lambda, bool IsStatic = Lambda::isStatic,
+          typename InstanceType = typename Lambda::ThisArgType,
+          class Impl = typename Lambda::TargetClass>
+class WindowEvent : public Runnable {
+  bool IsStaleCall() {
+    if (IsStatic) {
+      // Static calls are never stale.
+      return false;
+    }
+
+    return jni::NativePtrTraits<Impl>::IsStale(mInstance);
+  }
+
+  Lambda mLambda;
+  const InstanceType mInstance;
+
+ public:
+  WindowEvent(Lambda&& aLambda, InstanceType&& aInstance)
+      : Runnable("mozilla::widget::WindowEvent"),
+        mLambda(std::move(aLambda)),
+        mInstance(std::forward<InstanceType>(aInstance)) {}
+
+  explicit WindowEvent(Lambda&& aLambda)
+      : Runnable("mozilla::widget::WindowEvent"),
+        mLambda(std::move(aLambda)),
+        mInstance(mLambda.GetThisArg()) {}
+
+  NS_IMETHOD Run() override {
+    if (!IsStaleCall()) {
+      mLambda();
+    }
+    return NS_OK;
+  }
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_WindowEvent_h
diff --git a/widget/android/bindings/AccessibilityEvent-classes.txt b/widget/android/bindings/AccessibilityEvent-classes.txt
new file mode 100644
index 0000000000..b54e3ce105
--- /dev/null
+++ b/widget/android/bindings/AccessibilityEvent-classes.txt
@@ -0,0 +1,3 @@
+# We only use constants from AccessibilityEvent
+[android.view.accessibility.AccessibilityEvent = skip:true]
+<field> = skip:false
diff --git a/widget/android/bindings/AndroidBuild-classes.txt b/widget/android/bindings/AndroidBuild-classes.txt
new file mode 100644
index 0000000000..a76aa12c66
--- /dev/null
+++ b/widget/android/bindings/AndroidBuild-classes.txt
@@ -0,0 +1,5 @@
+[android.os.Build]
+<field> = noLiteral:true
+
+[android.os.Build$VERSION]
+<field> = noLiteral:true
diff --git a/widget/android/bindings/AndroidGraphics-classes.txt b/widget/android/bindings/AndroidGraphics-classes.txt
new file mode 100644
index 0000000000..452ba404e8
--- /dev/null
+++ b/widget/android/bindings/AndroidGraphics-classes.txt
@@ -0,0 +1,10 @@
+[android.graphics.Bitmap = skip:true]
+copyPixelsFromBuffer(Ljava/nio/Buffer;)V =
+createBitmap(IILandroid/graphics/Bitmap$Config;)Landroid/graphics/Bitmap; =
+
+[android.graphics.Bitmap$Config = skip:true]
+valueOf(Ljava/lang/String;)Landroid/graphics/Bitmap$Config; =
+ALPHA_8 =
+ARGB_8888 =
+RGBA_F16 =
+RGB_565 =
\ No newline at end of file
diff --git a/widget/android/bindings/AndroidInputType-classes.txt b/widget/android/bindings/AndroidInputType-classes.txt
new file mode 100644
index 0000000000..fa1138dce4
--- /dev/null
+++ b/widget/android/bindings/AndroidInputType-classes.txt
@@ -0,0 +1,3 @@
+# We only use constants from InputType
+[android.text.InputType = skip:true]
+<field> = skip:false
diff --git a/widget/android/bindings/AndroidProcess-classes.txt b/widget/android/bindings/AndroidProcess-classes.txt
new file mode 100644
index 0000000000..a6929ac5bc
--- /dev/null
+++ b/widget/android/bindings/AndroidProcess-classes.txt
@@ -0,0 +1,5 @@
+[android.os.Process = skip:true]
+setThreadPriority =
+getThreadPriority =
+myTid =
+THREAD_PRIORITY_URGENT_AUDIO =
diff --git a/widget/android/bindings/AndroidRect-classes.txt b/widget/android/bindings/AndroidRect-classes.txt
new file mode 100644
index 0000000000..76d3094a9f
--- /dev/null
+++ b/widget/android/bindings/AndroidRect-classes.txt
@@ -0,0 +1,2 @@
+[android.graphics.Rect]
+[android.graphics.RectF]
diff --git a/widget/android/bindings/InetAddress-classes.txt b/widget/android/bindings/InetAddress-classes.txt
new file mode 100644
index 0000000000..65788be252
--- /dev/null
+++ b/widget/android/bindings/InetAddress-classes.txt
@@ -0,0 +1,6 @@
+# We only want getByAddress(String, byte[])
+[java.net.InetAddress = skip:true]
+getByAddress(Ljava/lang/String;[B)Ljava/net/InetAddress; = skip:false
+
+[java.net.UnknownHostException = skip:true]
+<init>()V =
diff --git a/widget/android/bindings/JavaBuiltins-classes.txt b/widget/android/bindings/JavaBuiltins-classes.txt
new file mode 100644
index 0000000000..c6be5dde34
--- /dev/null
+++ b/widget/android/bindings/JavaBuiltins-classes.txt
@@ -0,0 +1,25 @@
+[java.lang.Boolean = skip:true]
+# Use static fields for boxing boolean.
+TRUE =
+FALSE =
+booleanValue =
+
+[java.lang.Double = skip:true]
+<init>(D)V =
+
+[java.lang.Integer = skip:true]
+# Use valueOf() for boxing int; don't use constructor
+# because some Integer values are cached.
+valueOf(I)Ljava/lang/Integer; =
+
+[java.lang.Long = skip:true]
+valueOf(J)Ljava/lang/Long; =
+
+[java.lang.Number = skip:true]
+# Use doubleValue() for unboxing Double/Float/Long.
+doubleValue =
+# Use intValue() for unboxing Byte/Int/Short.
+intValue =
+
+[java.lang.String = skip:true]
+valueOf(Ljava/lang/Object;)Ljava/lang/String; =
diff --git a/widget/android/bindings/JavaExceptions-classes.txt b/widget/android/bindings/JavaExceptions-classes.txt
new file mode 100644
index 0000000000..ebaff375d5
--- /dev/null
+++ b/widget/android/bindings/JavaExceptions-classes.txt
@@ -0,0 +1,8 @@
+[java.lang.IllegalStateException = skip:true]
+<init>(Ljava/lang/String;)V =
+
+[java.lang.IllegalArgumentException = skip:true]
+<init>(Ljava/lang/String;)V =
+
+[java.lang.Throwable = skip:true]
+getMessage()Ljava/lang/String; =
diff --git a/widget/android/bindings/KeyEvent-classes.txt b/widget/android/bindings/KeyEvent-classes.txt
new file mode 100644
index 0000000000..6001a5025b
--- /dev/null
+++ b/widget/android/bindings/KeyEvent-classes.txt
@@ -0,0 +1,3 @@
+# We only use constants from KeyEvent
+[android.view.KeyEvent = skip:true]
+<field> = skip:false
diff --git a/widget/android/bindings/MediaCodec-classes.txt b/widget/android/bindings/MediaCodec-classes.txt
new file mode 100644
index 0000000000..8830c11ccf
--- /dev/null
+++ b/widget/android/bindings/MediaCodec-classes.txt
@@ -0,0 +1,13 @@
+[android.media.MediaCodec = exceptionMode:nsresult]
+[android.media.MediaCodec$BufferInfo = exceptionMode:nsresult]
+[android.media.MediaCodec$CryptoInfo = exceptionMode:nsresult]
+
+# We only use constants from CodecCapabilities
+[android.media.MediaCodecInfo$CodecCapabilities = skip:true]
+<field> = skip:false
+
+# We only use constants from KeyStatus
+[android.media.MediaDrm$KeyStatus = skip:true]
+<field> = skip:false
+
+[android.media.MediaFormat = exceptionMode:nsresult]
diff --git a/widget/android/bindings/MotionEvent-classes.txt b/widget/android/bindings/MotionEvent-classes.txt
new file mode 100644
index 0000000000..17874a16af
--- /dev/null
+++ b/widget/android/bindings/MotionEvent-classes.txt
@@ -0,0 +1,3 @@
+# We only use constants from MotionEvent
+[android.view.MotionEvent = skip:true]
+<field> = skip:false
diff --git a/widget/android/bindings/SurfaceTexture-classes.txt b/widget/android/bindings/SurfaceTexture-classes.txt
new file mode 100644
index 0000000000..554c8e7c3f
--- /dev/null
+++ b/widget/android/bindings/SurfaceTexture-classes.txt
@@ -0,0 +1,5 @@
+[android.graphics.SurfaceTexture = exceptionMode:nsresult]
+[android.view.Surface = exceptionMode:nsresult]
+<init>(Landroid/view/SurfaceControl;)V = stubName:FromSurfaceControl, exceptionMode:abort
+[android.view.SurfaceControl = exceptionMode:nsresult]
+isValid()Z = exceptionMode:abort
diff --git a/widget/android/bindings/ViewConfiguration-classes.txt b/widget/android/bindings/ViewConfiguration-classes.txt
new file mode 100644
index 0000000000..cf8689f25a
--- /dev/null
+++ b/widget/android/bindings/ViewConfiguration-classes.txt
@@ -0,0 +1 @@
+[android.view.ViewConfiguration = exceptionMode:nsresult]
diff --git a/widget/android/bindings/moz.build b/widget/android/bindings/moz.build
new file mode 100644
index 0000000000..49a7dbd9e0
--- /dev/null
+++ b/widget/android/bindings/moz.build
@@ -0,0 +1,54 @@
+# -*- 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 = ("GeckoView", "General")
+
+# List of stems to generate .cpp and .h files for.  To add a stem, add it to
+# this list and ensure that $(stem)-classes.txt exists in this directory.
+generated = [
+    "AccessibilityEvent",
+    "AndroidBuild",
+    "AndroidGraphics",
+    "AndroidInputType",
+    "AndroidProcess",
+    "AndroidRect",
+    "InetAddress",
+    "JavaBuiltins",
+    "JavaExceptions",
+    "KeyEvent",
+    "MediaCodec",
+    "MotionEvent",
+    "SurfaceTexture",
+    "ViewConfiguration",
+]
+
+SOURCES += ["!%s.cpp" % stem for stem in generated]
+
+EXPORTS += ["!%s.h" % stem for stem in generated]
+
+# The recursive make backend treats the first output specially: it's passed as
+# an open FileAvoidWrite to the invoked script.  That doesn't work well with
+# the Gradle task that generates all of the outputs, so we add a dummy first
+# output.
+t = tuple(
+    ["sdk_bindings"]
+    + ["%s.cpp" % stem for stem in generated]
+    + ["%s.h" % stem for stem in generated]
+)
+
+GeneratedFile(
+    *t,
+    script="/mobile/android/gradle.py",
+    entry_point="generate_sdk_bindings",
+    inputs=["%s-classes.txt" % stem for stem in generated]
+)
+
+FINAL_LIBRARY = "xul"
+
+LOCAL_INCLUDES += [
+    "/widget/android",
+]
diff --git a/widget/android/components.conf b/widget/android/components.conf
new file mode 100644
index 0000000000..3b926771f3
--- /dev/null
+++ b/widget/android/components.conf
@@ -0,0 +1,100 @@
+# -*- 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/android/nsWidgetFactory.h',
+]
+
+InitFunc = 'nsWidgetAndroidModuleCtor'
+UnloadFunc = 'nsWidgetAndroidModuleDtor'
+
+Classes = [
+    {
+        'cid': '{2d96b3df-c051-11d1-a827-0040959a28c9}',
+        'contract_ids': ['@mozilla.org/widget/appshell/android;1'],
+        'legacy_constructor': 'nsAppShellConstructor',
+        'headers': ['/widget/android/nsWidgetFactory.h'],
+        'processes': ProcessSelector.ALLOW_IN_GPU_RDD_VR_SOCKET_AND_UTILITY_PROCESS,
+    },
+    {
+        'cid': '{d594094c-28b6-466b-97d7-66c039c3dea9}',
+        'contract_ids': ['@mozilla.org/gfx/parent/screenmanager;1'],
+        'singleton': True,
+        'type': 'mozilla::widget::ScreenManager',
+        'headers': ['mozilla/widget/ScreenManager.h'],
+        'constructor': 'mozilla::widget::ScreenManager::GetAddRefedSingleton',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'cid': '{6987230e-0098-4e78-bc5f-1493ee7519fa}',
+        'contract_ids': ['@mozilla.org/widget/useridleservice;1'],
+        'singleton': True,
+        'type': 'nsUserIdleServiceAndroid',
+        'headers': ['/widget/android/nsUserIdleServiceAndroid.h'],
+        'constructor': 'nsUserIdleServiceAndroid::GetInstance',
+    },
+    {
+        'cid': '{8b5314bc-db01-11d2-96ce-0060b0fb9956}',
+        'contract_ids': ['@mozilla.org/widget/transferable;1'],
+        'type': 'nsTransferable',
+        'headers': ['/widget/nsTransferable.h'],
+    },
+    {
+        'cid': '{9d5adbb9-1da4-4162-acba-b373fe3ae837}',
+        'contract_ids': ['@mozilla.org/widget/parent/clipboard;1'],
+        'interfaces': ['nsIClipboard'],
+        'type': 'nsClipboard',
+        'headers': ['/widget/android/nsClipboard.h'],
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+    {
+        'cid': '{77221d5a-1dd2-11b2-8c69-c710f15d2ed5}',
+        'contract_ids': ['@mozilla.org/widget/clipboardhelper;1'],
+        'type': 'nsClipboardHelper',
+        'headers': ['/widget/nsClipboardHelper.h'],
+    },
+    {
+        'cid': '{841387c8-72e6-484b-9296-bf6eea80d58a}',
+        'contract_ids': ['@mozilla.org/gfx/printsettings-service;1'],
+        'type': 'nsPrintSettingsServiceAndroid',
+        'headers': ['/widget/android/nsPrintSettingsServiceAndroid.h'],
+        'init_method': 'Init',
+    },
+    {
+        'cid': '{d3f69889-e13a-4321-980c-a39332e21f34}',
+        'contract_ids': ['@mozilla.org/gfx/devicecontextspec;1'],
+        'type': 'nsDeviceContextSpecAndroid',
+        'headers': ['/widget/android/nsDeviceContextAndroid.h'],
+    },
+    {
+        'cid': '{948a0023-e3a7-11d2-96cf-0060b0fb9956}',
+        'contract_ids': ['@mozilla.org/widget/htmlformatconverter;1'],
+        'type': 'nsHTMLFormatConverter',
+        'headers': ['/widget/nsHTMLFormatConverter.h'],
+    },
+    {
+        'name': 'GfxInfo',
+        'cid': '{d755a760-9f27-11df-0800-200c9a664242}',
+        'contract_ids': ['@mozilla.org/gfx/info;1'],
+        'type': 'mozilla::widget::GfxInfo',
+        'headers': ['/widget/android/GfxInfo.h'],
+        'init_method': 'Init',
+    },
+    {
+        'js_name': 'androidBridge',
+        'cid': '{0fe2321d-ebd9-467d-a743-03a68d40599e}',
+        'contract_ids': ['@mozilla.org/android/bridge;1'],
+        'interfaces': ['nsIAndroidBridge'],
+        'type': 'nsAndroidBridge',
+        'headers': ['/widget/android/AndroidBridge.h'],
+    },
+    {
+        'cid': '{84e11f80-ca55-11dd-ad8b-0800200c9a66}',
+        'contract_ids': ['@mozilla.org/system-alerts-service;1'],
+        'type': 'mozilla::widget::AndroidAlerts',
+        'headers': ['/widget/android/AndroidAlerts.h'],
+    },
+]
diff --git a/widget/android/jni/Accessors.h b/widget/android/jni/Accessors.h
new file mode 100644
index 0000000000..7496cbcb5a
--- /dev/null
+++ b/widget/android/jni/Accessors.h
@@ -0,0 +1,251 @@
+/* -*- 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_jni_Accessors_h__
+#define mozilla_jni_Accessors_h__
+
+#include <jni.h>
+
+#include "mozilla/jni/Refs.h"
+#include "mozilla/jni/Types.h"
+#include "mozilla/jni/Utils.h"
+#include "AndroidBridge.h"
+
+namespace mozilla {
+namespace jni {
+
+namespace detail {
+
+// Helper class to convert an arbitrary type to a jvalue, e.g. Value(123).val.
+struct Value {
+  explicit Value(jboolean z) { val.z = z; }
+  explicit Value(jbyte b) { val.b = b; }
+  explicit Value(jchar c) { val.c = c; }
+  explicit Value(jshort s) { val.s = s; }
+  explicit Value(jint i) { val.i = i; }
+  explicit Value(jlong j) { val.j = j; }
+  explicit Value(jfloat f) { val.f = f; }
+  explicit Value(jdouble d) { val.d = d; }
+  explicit Value(jobject l) { val.l = l; }
+
+  jvalue val;
+};
+
+}  // namespace detail
+
+using namespace detail;
+
+// Base class for Method<>, Field<>, and Constructor<>.
+class Accessor {
+  static void GetNsresult(JNIEnv* env, nsresult* rv) {
+    if (env->ExceptionCheck()) {
+#ifdef MOZ_CHECK_JNI
+      env->ExceptionDescribe();
+#endif
+      env->ExceptionClear();
+      *rv = NS_ERROR_FAILURE;
+    } else {
+      *rv = NS_OK;
+    }
+  }
+
+ protected:
+  // Called after making a JNIEnv call.
+  template <class Traits>
+  static void EndAccess(const typename Traits::Owner::Context& ctx,
+                        nsresult* rv) {
+    if (Traits::exceptionMode == ExceptionMode::ABORT) {
+      MOZ_CATCH_JNI_EXCEPTION(ctx.Env());
+
+    } else if (Traits::exceptionMode == ExceptionMode::NSRESULT) {
+      GetNsresult(ctx.Env(), rv);
+    }
+  }
+};
+
+// Member<> is used to call a JNI method given a traits class.
+template <class Traits, typename ReturnType = typename Traits::ReturnType>
+class Method : public Accessor {
+  typedef Accessor Base;
+  typedef typename Traits::Owner::Context Context;
+
+ protected:
+  static jmethodID sID;
+
+  static void BeginAccess(const Context& ctx) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+    static_assert(Traits::dispatchTarget == DispatchTarget::CURRENT,
+                  "Dispatching not supported for method call");
+
+    if (sID) {
+      return;
+    }
+
+    if (Traits::isStatic) {
+      MOZ_ALWAYS_TRUE(
+          sID = AndroidBridge::GetStaticMethodID(
+              ctx.Env(), ctx.ClassRef(), Traits::name, Traits::signature));
+    } else {
+      MOZ_ALWAYS_TRUE(
+          sID = AndroidBridge::GetMethodID(ctx.Env(), ctx.ClassRef(),
+                                           Traits::name, Traits::signature));
+    }
+  }
+
+  static void EndAccess(const Context& ctx, nsresult* rv) {
+    return Base::EndAccess<Traits>(ctx, rv);
+  }
+
+ public:
+  template <typename... Args>
+  static ReturnType Call(const Context& ctx, nsresult* rv,
+                         const Args&... args) {
+    JNIEnv* const env = ctx.Env();
+    BeginAccess(ctx);
+
+    jvalue jargs[] = {Value(TypeAdapter<Args>::FromNative(env, args)).val...};
+
+    auto result = TypeAdapter<ReturnType>::ToNative(
+        env, Traits::isStatic ? (env->*TypeAdapter<ReturnType>::StaticCall)(
+                                    ctx.ClassRef(), sID, jargs)
+                              : (env->*TypeAdapter<ReturnType>::Call)(
+                                    ctx.Get(), sID, jargs));
+
+    EndAccess(ctx, rv);
+    return result;
+  }
+};
+
+// Define sID member.
+template <class T, typename R>
+jmethodID Method<T, R>::sID;
+
+// Specialize void because C++ forbids us from
+// using a "void" temporary result variable.
+template <class Traits>
+class Method<Traits, void> : public Method<Traits, bool> {
+  typedef Method<Traits, bool> Base;
+  typedef typename Traits::Owner::Context Context;
+
+ public:
+  template <typename... Args>
+  static void Call(const Context& ctx, nsresult* rv, const Args&... args) {
+    JNIEnv* const env = ctx.Env();
+    Base::BeginAccess(ctx);
+
+    jvalue jargs[] = {Value(TypeAdapter<Args>::FromNative(env, args)).val...};
+
+    if (Traits::isStatic) {
+      env->CallStaticVoidMethodA(ctx.ClassRef(), Base::sID, jargs);
+    } else {
+      env->CallVoidMethodA(ctx.Get(), Base::sID, jargs);
+    }
+
+    Base::EndAccess(ctx, rv);
+  }
+};
+
+// Constructor<> is used to construct a JNI instance given a traits class.
+template <class Traits>
+class Constructor : protected Method<Traits, typename Traits::ReturnType> {
+  typedef typename Traits::Owner::Context Context;
+  typedef typename Traits::ReturnType ReturnType;
+  typedef Method<Traits, ReturnType> Base;
+
+ public:
+  template <typename... Args>
+  static ReturnType Call(const Context& ctx, nsresult* rv,
+                         const Args&... args) {
+    JNIEnv* const env = ctx.Env();
+    Base::BeginAccess(ctx);
+
+    jvalue jargs[] = {Value(TypeAdapter<Args>::FromNative(env, args)).val...};
+
+    auto result = TypeAdapter<ReturnType>::ToNative(
+        env, env->NewObjectA(ctx.ClassRef(), Base::sID, jargs));
+
+    Base::EndAccess(ctx, rv);
+    return result;
+  }
+};
+
+// Field<> is used to access a JNI field given a traits class.
+template <class Traits>
+class Field : public Accessor {
+  typedef Accessor Base;
+  typedef typename Traits::Owner::Context Context;
+  typedef typename Traits::ReturnType GetterType;
+  typedef typename Traits::SetterType SetterType;
+
+ private:
+  static jfieldID sID;
+
+  static void BeginAccess(const Context& ctx) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+    static_assert(Traits::dispatchTarget == DispatchTarget::CURRENT,
+                  "Dispatching not supported for field access");
+
+    if (sID) {
+      return;
+    }
+
+    if (Traits::isStatic) {
+      MOZ_ALWAYS_TRUE(
+          sID = AndroidBridge::GetStaticFieldID(
+              ctx.Env(), ctx.ClassRef(), Traits::name, Traits::signature));
+    } else {
+      MOZ_ALWAYS_TRUE(sID = AndroidBridge::GetFieldID(ctx.Env(), ctx.ClassRef(),
+                                                      Traits::name,
+                                                      Traits::signature));
+    }
+  }
+
+  static void EndAccess(const Context& ctx, nsresult* rv) {
+    return Base::EndAccess<Traits>(ctx, rv);
+  }
+
+ public:
+  static GetterType Get(const Context& ctx, nsresult* rv) {
+    JNIEnv* const env = ctx.Env();
+    BeginAccess(ctx);
+
+    auto result = TypeAdapter<GetterType>::ToNative(
+        env, Traits::isStatic
+                 ?
+
+                 (env->*TypeAdapter<GetterType>::StaticGet)(ctx.ClassRef(), sID)
+                 :
+
+                 (env->*TypeAdapter<GetterType>::Get)(ctx.Get(), sID));
+
+    EndAccess(ctx, rv);
+    return result;
+  }
+
+  static void Set(const Context& ctx, nsresult* rv, SetterType val) {
+    JNIEnv* const env = ctx.Env();
+    BeginAccess(ctx);
+
+    if (Traits::isStatic) {
+      (env->*TypeAdapter<SetterType>::StaticSet)(
+          ctx.ClassRef(), sID, TypeAdapter<SetterType>::FromNative(env, val));
+    } else {
+      (env->*TypeAdapter<SetterType>::Set)(
+          ctx.Get(), sID, TypeAdapter<SetterType>::FromNative(env, val));
+    }
+
+    EndAccess(ctx, rv);
+  }
+};
+
+// Define sID member.
+template <class T>
+jfieldID Field<T>::sID;
+
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_Accessors_h__
diff --git a/widget/android/jni/Conversions.cpp b/widget/android/jni/Conversions.cpp
new file mode 100644
index 0000000000..f7742b9535
--- /dev/null
+++ b/widget/android/jni/Conversions.cpp
@@ -0,0 +1,115 @@
+/* -*- 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 "Conversions.h"
+#include "JavaBuiltins.h"
+
+#include "mozilla/ipc/GeckoChildProcessHost.h"
+
+namespace mozilla {
+namespace jni {
+
+template <class T>
+jfieldID GetValueFieldID(JNIEnv* aEnv, const char* aType) {
+  const jfieldID id = aEnv->GetFieldID(
+      typename T::Context(aEnv, nullptr).ClassRef(), "value", aType);
+  aEnv->ExceptionClear();
+  return id;
+}
+
+// Cached locations of the primitive types within their standard boxed objects
+// to skip doing that lookup on every get.
+static jfieldID gBooleanValueField;
+static jfieldID gIntValueField;
+static jfieldID gDoubleValueField;
+
+void InitConversionStatics() {
+  MOZ_ASSERT(NS_IsMainThread());
+  JNIEnv* const env = jni::GetGeckoThreadEnv();
+  gBooleanValueField = GetValueFieldID<java::sdk::Boolean>(env, "Z");
+  gIntValueField = GetValueFieldID<java::sdk::Integer>(env, "I");
+  gDoubleValueField = GetValueFieldID<java::sdk::Double>(env, "D");
+}
+
+template <>
+bool Java2Native(mozilla::jni::Object::Param aData, JNIEnv* aEnv) {
+  MOZ_ASSERT(aData.IsInstanceOf<jni::Boolean>());
+
+  bool result = false;
+  if (gBooleanValueField) {
+    if (!aEnv) {
+      aEnv = jni::GetEnvForThread();
+    }
+    result =
+        aEnv->GetBooleanField(aData.Get(), gBooleanValueField) != JNI_FALSE;
+    MOZ_CATCH_JNI_EXCEPTION(aEnv);
+  } else {
+    result = java::sdk::Boolean::Ref::From(aData)->BooleanValue();
+  }
+
+  return result;
+}
+
+template <>
+int Java2Native(mozilla::jni::Object::Param aData, JNIEnv* aEnv) {
+  MOZ_ASSERT(aData.IsInstanceOf<jni::Integer>());
+
+  int result = 0;
+  if (gIntValueField) {
+    if (!aEnv) {
+      aEnv = jni::GetEnvForThread();
+    }
+    result = aEnv->GetIntField(aData.Get(), gIntValueField);
+    MOZ_CATCH_JNI_EXCEPTION(aEnv);
+  } else {
+    result = java::sdk::Number::Ref::From(aData)->IntValue();
+  }
+
+  return result;
+}
+
+template <>
+double Java2Native(mozilla::jni::Object::Param aData, JNIEnv* aEnv) {
+  MOZ_ASSERT(aData.IsInstanceOf<jni::Double>());
+
+  double result = 0;
+  if (gDoubleValueField) {
+    if (!aEnv) {
+      aEnv = jni::GetEnvForThread();
+    }
+    result = aEnv->GetDoubleField(aData.Get(), gDoubleValueField);
+    MOZ_CATCH_JNI_EXCEPTION(aEnv);
+  } else {
+    result = java::sdk::Number::Ref::From(aData)->DoubleValue();
+  }
+
+  return result;
+}
+
+template <>
+ipc::LaunchError Java2Native(mozilla::jni::Object::Param aData, JNIEnv* aEnv) {
+  // Bug 1819311: there is not much we can really catch due to how Android
+  // services are started, so for now we just expose it this way.
+  return ipc::LaunchError("Java2Native");
+}
+
+template <>
+nsString Java2Native(mozilla::jni::Object::Param aData, JNIEnv* aEnv) {
+  nsString result;
+  if (aData != NULL && aData.IsInstanceOf<jni::String>()) {
+    result = jni::String::Ref::From(aData)->ToString();
+  }
+  return result;
+}
+
+template <>
+nsresult Java2Native(mozilla::jni::Object::Param aData, JNIEnv* aEnv) {
+  MOZ_ASSERT(aData.IsInstanceOf<jni::Throwable>());
+  return NS_ERROR_FAILURE;
+}
+
+}  // namespace jni
+}  // namespace mozilla
diff --git a/widget/android/jni/Conversions.h b/widget/android/jni/Conversions.h
new file mode 100644
index 0000000000..1d9e20acc7
--- /dev/null
+++ b/widget/android/jni/Conversions.h
@@ -0,0 +1,23 @@
+/* -*- 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_jni_Conversions_h__
+#define mozilla_jni_Conversions_h__
+
+#include "mozilla/jni/Refs.h"
+
+namespace mozilla {
+namespace jni {
+
+template <typename ArgType>
+ArgType Java2Native(mozilla::jni::Object::Param, JNIEnv* aEnv = nullptr);
+
+void InitConversionStatics();
+
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_Conversions_h__
diff --git a/widget/android/jni/GeckoBundleUtils.cpp b/widget/android/jni/GeckoBundleUtils.cpp
new file mode 100644
index 0000000000..310f284093
--- /dev/null
+++ b/widget/android/jni/GeckoBundleUtils.cpp
@@ -0,0 +1,309 @@
+/* -*- 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 "mozilla/jni/GeckoBundleUtils.h"
+
+#include "JavaBuiltins.h"
+#include "js/Warnings.h"
+#include "nsJSUtils.h"
+
+#include "js/Array.h"
+#include "js/experimental/TypedData.h"
+
+namespace mozilla::jni {
+namespace detail {
+bool CheckJS(JSContext* aCx, bool aResult) {
+  if (!aResult) {
+    JS_ClearPendingException(aCx);
+  }
+  return aResult;
+}
+
+nsresult BoxString(JSContext* aCx, JS::Handle<JS::Value> aData,
+                   jni::Object::LocalRef& aOut) {
+  if (aData.isNullOrUndefined()) {
+    aOut = nullptr;
+    return NS_OK;
+  }
+
+  MOZ_ASSERT(aData.isString());
+
+  JS::Rooted<JSString*> str(aCx, aData.toString());
+
+  if (JS::StringHasLatin1Chars(str)) {
+    nsAutoJSString autoStr;
+    NS_ENSURE_TRUE(CheckJS(aCx, autoStr.init(aCx, str)), NS_ERROR_FAILURE);
+
+    // StringParam can automatically convert a nsString to jstring.
+    aOut = jni::StringParam(autoStr, aOut.Env(), fallible);
+    if (!aOut) {
+      return NS_ERROR_FAILURE;
+    }
+    return NS_OK;
+  }
+
+  // Two-byte string
+  JNIEnv* const env = aOut.Env();
+  const char16_t* chars;
+  {
+    JS::AutoCheckCannotGC nogc;
+    size_t len = 0;
+    chars = JS_GetTwoByteStringCharsAndLength(aCx, nogc, str, &len);
+    if (chars) {
+      aOut = jni::String::LocalRef::Adopt(
+          env, env->NewString(reinterpret_cast<const jchar*>(chars), len));
+    }
+  }
+  if (NS_WARN_IF(!CheckJS(aCx, !!chars) || !aOut)) {
+    env->ExceptionClear();
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+nsresult BoxObject(JSContext* aCx, JS::Handle<JS::Value> aData,
+                   jni::Object::LocalRef& aOut);
+
+template <typename Type, bool (JS::Value::*IsType)() const,
+          Type (JS::Value::*ToType)() const, class ArrayType,
+          typename ArrayType::LocalRef (*NewArray)(const Type*, size_t)>
+nsresult BoxArrayPrimitive(JSContext* aCx, JS::Handle<JSObject*> aData,
+                           jni::Object::LocalRef& aOut, size_t aLength,
+                           JS::Handle<JS::Value> aElement) {
+  JS::Rooted<JS::Value> element(aCx);
+  auto data = MakeUnique<Type[]>(aLength);
+  data[0] = (aElement.get().*ToType)();
+
+  for (size_t i = 1; i < aLength; i++) {
+    NS_ENSURE_TRUE(CheckJS(aCx, JS_GetElement(aCx, aData, i, &element)),
+                   NS_ERROR_FAILURE);
+    NS_ENSURE_TRUE((element.get().*IsType)(), NS_ERROR_INVALID_ARG);
+
+    data[i] = (element.get().*ToType)();
+  }
+  aOut = (*NewArray)(data.get(), aLength);
+  return NS_OK;
+}
+
+nsresult BoxByteArray(JSContext* aCx, JS::Handle<JSObject*> aData,
+                      jni::Object::LocalRef& aOut) {
+  JS::AutoCheckCannotGC nogc;
+  bool isShared = false;
+  const void* data = JS_GetArrayBufferViewData(aData, &isShared, nogc);
+  size_t length = JS_GetArrayBufferViewByteLength(aData);
+
+  aOut = jni::ByteArray::New(reinterpret_cast<const int8_t*>(data), length);
+  if (!aOut) {
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+template <class Type,
+          nsresult (*Box)(JSContext*, JS::Handle<JS::Value>,
+                          jni::Object::LocalRef&),
+          typename IsType>
+nsresult BoxArrayObject(JSContext* aCx, JS::Handle<JSObject*> aData,
+                        jni::Object::LocalRef& aOut, size_t aLength,
+                        JS::Handle<JS::Value> aElement, IsType&& aIsType) {
+  auto out = jni::ObjectArray::New<Type>(aLength);
+  JS::Rooted<JS::Value> element(aCx);
+  jni::Object::LocalRef jniElement(aOut.Env());
+
+  nsresult rv = (*Box)(aCx, aElement, jniElement);
+  NS_ENSURE_SUCCESS(rv, rv);
+  out->SetElement(0, jniElement);
+
+  for (size_t i = 1; i < aLength; i++) {
+    NS_ENSURE_TRUE(CheckJS(aCx, JS_GetElement(aCx, aData, i, &element)),
+                   NS_ERROR_FAILURE);
+    NS_ENSURE_TRUE(element.isNullOrUndefined() || aIsType(element),
+                   NS_ERROR_INVALID_ARG);
+
+    rv = (*Box)(aCx, element, jniElement);
+    NS_ENSURE_SUCCESS(rv, rv);
+    out->SetElement(i, jniElement);
+  }
+  aOut = out;
+  return NS_OK;
+}
+
+nsresult BoxArray(JSContext* aCx, JS::Handle<JSObject*> aData,
+                  jni::Object::LocalRef& aOut) {
+  uint32_t length = 0;
+  NS_ENSURE_TRUE(CheckJS(aCx, JS::GetArrayLength(aCx, aData, &length)),
+                 NS_ERROR_FAILURE);
+
+  if (!length) {
+    // Always represent empty arrays as an empty boolean array.
+    aOut = java::GeckoBundle::EMPTY_BOOLEAN_ARRAY();
+    return NS_OK;
+  }
+
+  // We only check the first element's type. If the array has mixed types,
+  // we'll throw an error during actual conversion.
+  JS::Rooted<JS::Value> element(aCx);
+  NS_ENSURE_TRUE(CheckJS(aCx, JS_GetElement(aCx, aData, 0, &element)),
+                 NS_ERROR_FAILURE);
+
+  if (element.isBoolean()) {
+    return BoxArrayPrimitive<bool, &JS::Value::isBoolean, &JS::Value::toBoolean,
+                             jni::BooleanArray, &jni::BooleanArray::New>(
+        aCx, aData, aOut, length, element);
+  }
+
+  if (element.isInt32()) {
+    nsresult rv =
+        BoxArrayPrimitive<int32_t, &JS::Value::isInt32, &JS::Value::toInt32,
+                          jni::IntArray, &jni::IntArray::New>(aCx, aData, aOut,
+                                                              length, element);
+    if (rv != NS_ERROR_INVALID_ARG) {
+      return rv;
+    }
+    // Not int32, but we can still try a double array.
+  }
+
+  if (element.isNumber()) {
+    return BoxArrayPrimitive<double, &JS::Value::isNumber, &JS::Value::toNumber,
+                             jni::DoubleArray, &jni::DoubleArray::New>(
+        aCx, aData, aOut, length, element);
+  }
+
+  if (element.isNullOrUndefined() || element.isString()) {
+    const auto isString = [](JS::Handle<JS::Value> val) -> bool {
+      return val.isString();
+    };
+    nsresult rv = BoxArrayObject<jni::String, &BoxString>(
+        aCx, aData, aOut, length, element, isString);
+    if (element.isString() || rv != NS_ERROR_INVALID_ARG) {
+      return rv;
+    }
+    // First element was null/undefined, so it may still be an object array.
+  }
+
+  const auto isObject = [aCx](JS::Handle<JS::Value> val) -> bool {
+    if (!val.isObject()) {
+      return false;
+    }
+    bool array = false;
+    JS::Rooted<JSObject*> obj(aCx, &val.toObject());
+    // We don't support array of arrays.
+    return CheckJS(aCx, JS::IsArrayObject(aCx, obj, &array)) && !array;
+  };
+
+  if (element.isNullOrUndefined() || isObject(element)) {
+    return BoxArrayObject<java::GeckoBundle, &BoxObject>(
+        aCx, aData, aOut, length, element, isObject);
+  }
+
+  NS_WARNING("Unknown type");
+  return NS_ERROR_INVALID_ARG;
+}
+
+nsresult BoxValue(JSContext* aCx, JS::Handle<JS::Value> aData,
+                  jni::Object::LocalRef& aOut);
+
+nsresult BoxObject(JSContext* aCx, JS::Handle<JS::Value> aData,
+                   jni::Object::LocalRef& aOut) {
+  if (aData.isNullOrUndefined()) {
+    aOut = nullptr;
+    return NS_OK;
+  }
+
+  MOZ_ASSERT(aData.isObject());
+
+  JS::Rooted<JS::IdVector> ids(aCx, JS::IdVector(aCx));
+  JS::Rooted<JSObject*> obj(aCx, &aData.toObject());
+
+  bool isArray = false;
+  if (CheckJS(aCx, JS::IsArrayObject(aCx, obj, &isArray)) && isArray) {
+    return BoxArray(aCx, obj, aOut);
+  }
+
+  if (JS_IsTypedArrayObject(obj)) {
+    return BoxByteArray(aCx, obj, aOut);
+  }
+
+  NS_ENSURE_TRUE(CheckJS(aCx, JS_Enumerate(aCx, obj, &ids)), NS_ERROR_FAILURE);
+
+  const size_t length = ids.length();
+  auto keys = jni::ObjectArray::New<jni::String>(length);
+  auto values = jni::ObjectArray::New<jni::Object>(length);
+
+  // Iterate through each property of the JS object.
+  for (size_t i = 0; i < ids.length(); i++) {
+    const JS::RootedId id(aCx, ids[i]);
+    JS::Rooted<JS::Value> idVal(aCx);
+    JS::Rooted<JS::Value> val(aCx);
+    jni::Object::LocalRef key(aOut.Env());
+    jni::Object::LocalRef value(aOut.Env());
+
+    NS_ENSURE_TRUE(CheckJS(aCx, JS_IdToValue(aCx, id, &idVal)),
+                   NS_ERROR_FAILURE);
+
+    JS::Rooted<JSString*> idStr(aCx, JS::ToString(aCx, idVal));
+    NS_ENSURE_TRUE(CheckJS(aCx, !!idStr), NS_ERROR_FAILURE);
+
+    idVal.setString(idStr);
+    NS_ENSURE_SUCCESS(BoxString(aCx, idVal, key), NS_ERROR_FAILURE);
+    NS_ENSURE_TRUE(CheckJS(aCx, JS_GetPropertyById(aCx, obj, id, &val)),
+                   NS_ERROR_FAILURE);
+
+    nsresult rv = BoxValue(aCx, val, value);
+    if (rv == NS_ERROR_INVALID_ARG && !JS_IsExceptionPending(aCx)) {
+      nsAutoJSString autoStr;
+      if (CheckJS(aCx, autoStr.init(aCx, idVal.toString()))) {
+        JS_ReportErrorUTF8(aCx, "Invalid event data property %s",
+                           NS_ConvertUTF16toUTF8(autoStr).get());
+      }
+    }
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    keys->SetElement(i, key);
+    values->SetElement(i, value);
+  }
+
+  aOut = java::GeckoBundle::New(keys, values);
+  return NS_OK;
+}
+
+nsresult BoxValue(JSContext* aCx, JS::Handle<JS::Value> aData,
+                  jni::Object::LocalRef& aOut) {
+  if (aData.isNullOrUndefined()) {
+    aOut = nullptr;
+  } else if (aData.isBoolean()) {
+    aOut = aData.toBoolean() ? java::sdk::Boolean::TRUE()
+                             : java::sdk::Boolean::FALSE();
+  } else if (aData.isInt32()) {
+    aOut = java::sdk::Integer::ValueOf(aData.toInt32());
+  } else if (aData.isNumber()) {
+    aOut = java::sdk::Double::New(aData.toNumber());
+  } else if (aData.isString()) {
+    return BoxString(aCx, aData, aOut);
+  } else if (aData.isObject()) {
+    return BoxObject(aCx, aData, aOut);
+  } else {
+    NS_WARNING("Unknown type");
+    return NS_ERROR_INVALID_ARG;
+  }
+  return NS_OK;
+}
+
+}  // namespace detail
+
+nsresult BoxData(JSContext* aCx, JS::Handle<JS::Value> aData,
+                 jni::Object::LocalRef& aOut, bool aObjectOnly) {
+  nsresult rv = NS_ERROR_INVALID_ARG;
+
+  if (!aObjectOnly) {
+    rv = detail::BoxValue(aCx, aData, aOut);
+  } else if (aData.isObject() || aData.isNullOrUndefined()) {
+    rv = detail::BoxObject(aCx, aData, aOut);
+  }
+
+  return rv;
+}
+}  // namespace mozilla::jni
diff --git a/widget/android/jni/GeckoBundleUtils.h b/widget/android/jni/GeckoBundleUtils.h
new file mode 100644
index 0000000000..a92a27abc3
--- /dev/null
+++ b/widget/android/jni/GeckoBundleUtils.h
@@ -0,0 +1,46 @@
+/* -*- 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_jni_GeckoBundleUtils_h
+#define mozilla_jni_GeckoBundleUtils_h
+
+#include "mozilla/java/GeckoBundleWrappers.h"
+
+#include "jsapi.h"
+
+namespace mozilla {
+namespace jni {
+
+#define GECKOBUNDLE_START(name)                   \
+  nsTArray<jni::String::LocalRef> _##name##_keys; \
+  nsTArray<jni::Object::LocalRef> _##name##_values;
+
+#define GECKOBUNDLE_PUT(name, key, value)                     \
+  _##name##_keys.AppendElement(                               \
+      jni::StringParam(NS_LITERAL_STRING_FROM_CSTRING(key))); \
+  _##name##_values.AppendElement(value);
+
+#define GECKOBUNDLE_FINISH(name)                                            \
+  MOZ_ASSERT(_##name##_keys.Length() == _##name##_values.Length());         \
+  auto _##name##_jkeys =                                                    \
+      jni::ObjectArray::New<jni::String>(_##name##_keys.Length());          \
+  auto _##name##_jvalues =                                                  \
+      jni::ObjectArray::New<jni::Object>(_##name##_values.Length());        \
+  for (size_t i = 0;                                                        \
+       i < _##name##_keys.Length() && i < _##name##_values.Length(); i++) { \
+    _##name##_jkeys->SetElement(i, _##name##_keys.ElementAt(i));            \
+    _##name##_jvalues->SetElement(i, _##name##_values.ElementAt(i));        \
+  }                                                                         \
+  auto name =                                                               \
+      mozilla::java::GeckoBundle::New(_##name##_jkeys, _##name##_jvalues);
+
+nsresult BoxData(JSContext* aCx, JS::Handle<JS::Value> aData,
+                 jni::Object::LocalRef& aOut, bool aObjectOnly);
+
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_GeckoBundleUtils_h
diff --git a/widget/android/jni/GeckoResultUtils.h b/widget/android/jni/GeckoResultUtils.h
new file mode 100644
index 0000000000..da103f35ee
--- /dev/null
+++ b/widget/android/jni/GeckoResultUtils.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 mozilla_jni_GeckoResultUtils_h
+#define mozilla_jni_GeckoResultUtils_h
+
+#include "mozilla/java/GeckoResultNatives.h"
+#include "mozilla/jni/Conversions.h"
+
+namespace mozilla {
+namespace jni {
+
+// C++-side object bound to Java's GeckoResult.GeckoCallback.
+//
+// Note that we can't template this class because that breaks JNI dispatch
+// (surprisingly: it compiles, but selects the wrong method specialization
+// during dispatch). So instead we use a templated factory function, which
+// bundles the per-ArgType conversion logic into the callback.
+class GeckoResultCallback final
+    : public java::GeckoResult::GeckoCallback::Natives<GeckoResultCallback> {
+ public:
+  typedef java::GeckoResult::GeckoCallback::Natives<GeckoResultCallback> Base;
+  typedef std::function<void(mozilla::jni::Object::Param)> OuterCallback;
+
+  void Call(mozilla::jni::Object::Param aArg) { mCallback(aArg); }
+
+  template <typename ArgType>
+  static java::GeckoResult::GeckoCallback::LocalRef CreateAndAttach(
+      std::function<void(ArgType)>&& aInnerCallback) {
+    auto java = java::GeckoResult::GeckoCallback::New();
+    OuterCallback outerCallback =
+        [inner{std::move(aInnerCallback)}](mozilla::jni::Object::Param aParam) {
+          ArgType converted = Java2Native<ArgType>(aParam);
+          inner(std::move(converted));
+        };
+    auto native = MakeUnique<GeckoResultCallback>(std::move(outerCallback));
+    Base::AttachNative(java, std::move(native));
+    return java;
+  }
+
+  explicit GeckoResultCallback(OuterCallback&& aCallback)
+      : mCallback(std::move(aCallback)) {}
+
+ private:
+  OuterCallback mCallback;
+};
+
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_GeckoResultUtils_h
diff --git a/widget/android/jni/Natives.h b/widget/android/jni/Natives.h
new file mode 100644
index 0000000000..45b351ba21
--- /dev/null
+++ b/widget/android/jni/Natives.h
@@ -0,0 +1,1540 @@
+/* -*- 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_jni_Natives_h__
+#define mozilla_jni_Natives_h__
+
+#include <jni.h>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+#include "mozilla/RefPtr.h"
+#include "mozilla/RWLock.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/jni/Accessors.h"
+#include "mozilla/jni/Refs.h"
+#include "mozilla/jni/Types.h"
+#include "mozilla/jni/Utils.h"
+#include "nsThreadUtils.h"
+
+#if defined(_MSC_VER)  // MSVC
+#  define FUNCTION_SIGNATURE __FUNCSIG__
+#elif defined(__GNUC__)  // GCC, Clang
+#  define FUNCTION_SIGNATURE __PRETTY_FUNCTION__
+#endif
+
+struct NativeException {
+  const char* str;
+};
+
+template <class T>
+static NativeException NullHandle() {
+  return {FUNCTION_SIGNATURE};
+}
+
+template <class T>
+static NativeException NullWeakPtr() {
+  return {FUNCTION_SIGNATURE};
+}
+
+namespace mozilla {
+
+template <typename ResolveValueT, typename RejectValueT, bool IsExclusive>
+class MozPromise;
+
+namespace jni {
+
+/**
+ * C++ classes implementing instance (non-static) native methods can choose
+ * from one of two ownership models, when associating a C++ object with a Java
+ * instance.
+ *
+ * * If the C++ class inherits from mozilla::SupportsWeakPtr, weak pointers
+ *   will be used. The Java instance will store and own the pointer to a
+ *   WeakPtr object. The C++ class itself is otherwise not owned or directly
+ *   referenced. Note that mozilla::SupportsWeakPtr only supports being used on
+ *   a single thread. To attach a Java instance to a C++ instance, pass in a
+ *   mozilla::SupportsWeakPtr pointer to the C++ class (i.e. MyClass*).
+ *
+ *   class MyClass : public SupportsWeakPtr
+ *                 , public MyJavaClass::Natives<MyClass>
+ *   {
+ *       // ...
+ *
+ *   public:
+ *       using MyJavaClass::Natives<MyClass>::DisposeNative;
+ *
+ *       void AttachTo(const MyJavaClass::LocalRef& instance)
+ *       {
+ *           MyJavaClass::Natives<MyClass>::AttachNative(
+ *                   instance, static_cast<SupportsWeakPtr*>(this));
+ *
+ *           // "instance" does NOT own "this", so the C++ object
+ *           // lifetime is separate from the Java object lifetime.
+ *       }
+ *   };
+ *
+ * * If the C++ class contains public members AddRef() and Release(), the Java
+ *   instance will store and own the pointer to a RefPtr object, which holds a
+ *   strong reference on the C++ instance. Normal ref-counting considerations
+ *   apply in this case; for example, disposing may cause the C++ instance to
+ *   be deleted and the destructor to be run on the current thread, which may
+ *   not be desirable. To attach a Java instance to a C++ instance, pass in a
+ *   pointer to the C++ class (i.e. MyClass*).
+ *
+ *   class MyClass : public RefCounted<MyClass>
+ *                 , public MyJavaClass::Natives<MyClass>
+ *   {
+ *       // ...
+ *
+ *   public:
+ *       using MyJavaClass::Natives<MyClass>::DisposeNative;
+ *
+ *       void AttachTo(const MyJavaClass::LocalRef& instance)
+ *       {
+ *           MyJavaClass::Natives<MyClass>::AttachNative(instance, this);
+ *
+ *           // "instance" owns "this" through the RefPtr, so the C++ object
+ *           // may be destroyed as soon as instance.disposeNative() is called.
+ *       }
+ *   };
+ *
+ * * In other cases, the Java instance will store and own a pointer to the C++
+ *   object itself. This pointer must not be stored or deleted elsewhere. To
+ *   attach a Java instance to a C++ instance, pass in a reference to a
+ *   UniquePtr of the C++ class (i.e. UniquePtr<MyClass>).
+ *
+ *   class MyClass : public MyJavaClass::Natives<MyClass>
+ *   {
+ *       // ...
+ *
+ *   public:
+ *       using MyJavaClass::Natives<MyClass>::DisposeNative;
+ *
+ *       static void AttachTo(const MyJavaClass::LocalRef& instance)
+ *       {
+ *           MyJavaClass::Natives<MyClass>::AttachNative(
+ *                   instance, mozilla::MakeUnique<MyClass>());
+ *
+ *           // "instance" owns the newly created C++ object, so the C++
+ *           // object is destroyed as soon as instance.disposeNative() is
+ *           // called.
+ *       }
+ *   };
+ */
+
+namespace detail {
+
+/**
+ * Type trait that determines whether a given class has a member named
+ * T::OnWeakNonIntrusiveDetach.
+ *
+ * Example usage:
+ * class Foo {};
+ * class Bar {
+ *  public:
+ *   void OnWeakNonIntrusiveDetach(already_AddRefed<nsIRunnable> aRunnable);
+ * };
+ *
+ * constexpr bool foo = HasWeakNonIntrusiveDetach<Foo>::value; // Expect false
+ * constexpr bool bar = HasWeakNonIntrusiveDetach<Bar>::value; // Expect true
+ */
+template <typename, typename = std::void_t<>>
+struct HasWeakNonIntrusiveDetach : std::false_type {};
+
+template <typename T>
+struct HasWeakNonIntrusiveDetach<
+    T, std::void_t<decltype(std::declval<T>().OnWeakNonIntrusiveDetach(
+           std::declval<already_AddRefed<nsIRunnable>>()))>> : std::true_type {
+};
+
+/**
+ * Type trait that determines whether a given class is refcounted, ie. it has
+ * both T::AddRef and T::Release methods.
+ *
+ * Example usage:
+ * class Foo {};
+ * class Bar {
+ *  public:
+ *   void AddRef();
+ *   void Release();
+ * };
+ *
+ * constexpr bool foo = IsRefCounted<Foo>::value; // Expect false
+ * constexpr bool bar = IsRefCounted<Bar>::value; // Expect true
+ */
+template <typename, typename = std::void_t<>>
+struct IsRefCounted : std::false_type {};
+
+template <typename T>
+struct IsRefCounted<T, std::void_t<decltype(std::declval<T>().AddRef(),
+                                            std::declval<T>().Release())>>
+    : std::true_type {};
+
+/**
+ * This enum is used for classifying the type of pointer that is stored
+ * within a NativeWeakPtr. This classification is different from the one used
+ * for normal native pointers.
+ */
+enum class NativePtrInternalType : size_t {
+  OWNING = 1,
+  WEAK = 2,
+  REFPTR = 3,
+};
+
+/**
+ * NativePtrInternalPicker uses some C++ SFINAE template-fu to figure out
+ * what type of pointer the class specified by Impl needs to be.
+ *
+ * It does this by supplying multiple overloads of a method named Test.
+ * Various overloads are enabled or disabled depending on whether or not Impl
+ * can possibly support them.
+ *
+ * Each overload "returns" a reference to an array whose size corresponds to the
+ * value of each enum in NativePtrInternalType. That size is then converted back
+ * to the enum value, yielding the right type.
+ */
+template <class Impl>
+class NativePtrInternalPicker {
+  // Enable if Impl derives from SupportsWeakPtr, yielding type WEAK
+  template <class I>
+  static std::enable_if_t<
+      std::is_base_of<SupportsWeakPtr, I>::value,
+      char (&)[static_cast<size_t>(NativePtrInternalType::WEAK)]>
+  Test(char);
+
+  // Enable if Impl implements AddRef and Release, yielding type REFPTR
+  template <class I, typename = decltype(&I::AddRef, &I::Release)>
+  static char (&Test(int))[static_cast<size_t>(NativePtrInternalType::REFPTR)];
+
+  // This overload uses '...' as its param to make its arguments less specific;
+  // the compiler prefers more-specific overloads to less-specific ones.
+  // OWNING is the fallback type.
+  template <class>
+  static char (&Test(...))[static_cast<size_t>(NativePtrInternalType::OWNING)];
+
+ public:
+  // Given a hypothetical function call Test<Impl>, convert the size of its
+  // resulting array back into a NativePtrInternalType enum value.
+  static const NativePtrInternalType value = static_cast<NativePtrInternalType>(
+      sizeof(Test<Impl>('\0')) / sizeof(char));
+};
+
+/**
+ * This enum is used for classifying the type of pointer that is stored in a
+ * JNIObject's handle.
+ *
+ * We have two different weak pointer types:
+ *   * WEAK_INTRUSIVE is a pointer to a class that derives from
+ *     mozilla::SupportsWeakPtr.
+ *   * WEAK_NON_INTRUSIVE is a pointer to a class that does not have any
+ *     internal support for weak pointers, but does supply a
+ *     OnWeakNonIntrusiveDetach method.
+ */
+enum class NativePtrType : size_t {
+  OWNING = 1,
+  WEAK_INTRUSIVE = 2,
+  WEAK_NON_INTRUSIVE = 3,
+  REFPTR = 4,
+};
+
+/**
+ * NativePtrPicker uses some C++ SFINAE template-fu to figure out what type of
+ * pointer the class specified by Impl needs to be.
+ *
+ * It does this by supplying multiple overloads of a method named Test.
+ * Various overloads are enabled or disabled depending on whether or not Impl
+ * can possibly support them.
+ *
+ * Each overload "returns" a reference to an array whose size corresponds to the
+ * value of each enum in NativePtrInternalType. That size is then converted back
+ * to the enum value, yielding the right type.
+ */
+template <class Impl>
+class NativePtrPicker {
+  // Just shorthand for each overload's return type
+  template <NativePtrType PtrType>
+  using ResultTypeT = char (&)[static_cast<size_t>(PtrType)];
+
+  // Enable if Impl derives from SupportsWeakPtr, yielding type WEAK_INTRUSIVE
+  template <typename I>
+  static auto Test(void*)
+      -> std::enable_if_t<std::is_base_of<SupportsWeakPtr, I>::value,
+                          ResultTypeT<NativePtrType::WEAK_INTRUSIVE>>;
+
+  // Enable if Impl implements OnWeakNonIntrusiveDetach, yielding type
+  // WEAK_NON_INTRUSIVE
+  template <typename I>
+  static auto Test(void*)
+      -> std::enable_if_t<HasWeakNonIntrusiveDetach<I>::value,
+                          ResultTypeT<NativePtrType::WEAK_NON_INTRUSIVE>>;
+
+  // We want the WEAK_NON_INTRUSIVE overload to take precedence over this one,
+  // so we only enable this overload if Impl is refcounted AND it does not
+  // implement OnWeakNonIntrusiveDetach. Yields type REFPTR.
+  template <typename I>
+  static auto Test(void*) -> std::enable_if_t<
+      std::conjunction_v<IsRefCounted<I>,
+                         std::negation<HasWeakNonIntrusiveDetach<I>>>,
+      ResultTypeT<NativePtrType::REFPTR>>;
+
+  // This overload uses '...' as its param to make its arguments less specific;
+  // the compiler prefers more-specific overloads to less-specific ones.
+  // OWNING is the fallback type.
+  template <typename>
+  static char (&Test(...))[static_cast<size_t>(NativePtrType::OWNING)];
+
+ public:
+  // Given a hypothetical function call Test<Impl>, convert the size of its
+  // resulting array back into a NativePtrType enum value.
+  static const NativePtrType value =
+      static_cast<NativePtrType>(sizeof(Test<Impl>(nullptr)));
+};
+
+template <class Impl>
+inline uintptr_t CheckNativeHandle(JNIEnv* env, uintptr_t handle) {
+  if (!handle) {
+    if (!env->ExceptionCheck()) {
+      ThrowException(env, "java/lang/NullPointerException",
+                     NullHandle<Impl>().str);
+    }
+    return 0;
+  }
+  return handle;
+}
+
+/**
+ * This struct is used to describe various traits of a native pointer of type
+ * Impl that will be attached to a JNIObject.
+ *
+ * See the definition of the NativePtrType::OWNING specialization for comments
+ * describing the required fields.
+ */
+template <class Impl, NativePtrType Type = NativePtrPicker<Impl>::value>
+struct NativePtrTraits;
+
+template <class Impl>
+struct NativePtrTraits<Impl, /* Type = */ NativePtrType::OWNING> {
+  using AccessorType =
+      Impl*;  // Pointer-like type returned by Access() (an actual pointer in
+              // this case, but this is not strictly necessary)
+  using HandleType = Impl*;  // Type of the pointer stored in JNIObject.mHandle
+  using RefType = Impl*;     // Type of the pointer returned by Get()
+
+  /**
+   * Returns a RefType to the native implementation belonging to
+   * the given Java object.
+   */
+  static RefType Get(JNIEnv* env, jobject instance) {
+    static_assert(
+        std::is_same<HandleType, RefType>::value,
+        "HandleType and RefType must be identical for owning pointers");
+    return reinterpret_cast<HandleType>(
+        CheckNativeHandle<Impl>(env, GetNativeHandle(env, instance)));
+  }
+
+  /**
+   * Returns a RefType to the native implementation belonging to
+   * the given Java object.
+   */
+  template <class LocalRef>
+  static RefType Get(const LocalRef& instance) {
+    return Get(instance.Env(), instance.Get());
+  }
+
+  /**
+   * Given a RefType, returns the pointer-like AccessorType used for
+   * manipulating the native object.
+   */
+  static AccessorType Access(RefType aImpl, JNIEnv* aEnv = nullptr) {
+    static_assert(
+        std::is_same<AccessorType, RefType>::value,
+        "AccessorType and RefType must be identical for owning pointers");
+    return aImpl;
+  }
+
+  /**
+   * Set the JNIObject's handle to the provided pointer, clearing any previous
+   * handle if necessary.
+   */
+  template <class LocalRef>
+  static void Set(const LocalRef& instance, UniquePtr<Impl>&& ptr) {
+    Clear(instance);
+    SetNativeHandle(instance.Env(), instance.Get(),
+                    reinterpret_cast<uintptr_t>(ptr.release()));
+    MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+  }
+
+  /**
+   * Clear the JNIObject's handle.
+   */
+  template <class LocalRef>
+  static void Clear(const LocalRef& instance) {
+    UniquePtr<Impl> ptr(reinterpret_cast<RefType>(
+        GetNativeHandle(instance.Env(), instance.Get())));
+    MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+
+    if (ptr) {
+      SetNativeHandle(instance.Env(), instance.Get(), 0);
+      MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+    }
+  }
+};
+
+template <class Impl>
+struct NativePtrTraits<Impl, /* Type = */ NativePtrType::WEAK_INTRUSIVE> {
+  using AccessorType = Impl*;
+  using HandleType = WeakPtr<Impl>*;
+  using RefType = WeakPtr<Impl>;
+
+  static RefType Get(JNIEnv* env, jobject instance) {
+    const auto ptr = reinterpret_cast<HandleType>(
+        CheckNativeHandle<Impl>(env, GetNativeHandle(env, instance)));
+    return *ptr;
+  }
+
+  template <class LocalRef>
+  static RefType Get(const LocalRef& instance) {
+    return Get(instance.Env(), instance.Get());
+  }
+
+  static AccessorType Access(RefType aPtr, JNIEnv* aEnv = nullptr) {
+    AccessorType const impl = *aPtr;
+    if (!impl) {
+      JNIEnv* env = aEnv ? aEnv : mozilla::jni::GetEnvForThread();
+      ThrowException(env, "java/lang/NullPointerException",
+                     NullWeakPtr<Impl>().str);
+    }
+
+    return impl;
+  }
+
+  template <class LocalRef>
+  static void Set(const LocalRef& instance, Impl* ptr) {
+    // Create the new handle first before clearing any old handle, so the
+    // new handle is guaranteed to have different value than any old handle.
+    const uintptr_t handle =
+        reinterpret_cast<uintptr_t>(new WeakPtr<Impl>(ptr));
+    Clear(instance);
+    SetNativeHandle(instance.Env(), instance.Get(), handle);
+    MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+  }
+
+  template <class LocalRef>
+  static void Clear(const LocalRef& instance) {
+    const auto ptr = reinterpret_cast<HandleType>(
+        GetNativeHandle(instance.Env(), instance.Get()));
+    MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+
+    if (ptr) {
+      SetNativeHandle(instance.Env(), instance.Get(), 0);
+      MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+      delete ptr;
+    }
+  }
+};
+
+template <class Impl>
+struct NativePtrTraits<Impl, /* Type = */ NativePtrType::REFPTR> {
+  using AccessorType = Impl*;
+  using HandleType = RefPtr<Impl>*;
+  using RefType = Impl*;
+
+  static RefType Get(JNIEnv* env, jobject instance) {
+    const auto ptr = reinterpret_cast<HandleType>(
+        CheckNativeHandle<Impl>(env, GetNativeHandle(env, instance)));
+    if (!ptr) {
+      return nullptr;
+    }
+
+    MOZ_ASSERT(*ptr);
+    return *ptr;
+  }
+
+  template <class LocalRef>
+  static RefType Get(const LocalRef& instance) {
+    return Get(instance.Env(), instance.Get());
+  }
+
+  static AccessorType Access(RefType aImpl, JNIEnv* aEnv = nullptr) {
+    static_assert(std::is_same<AccessorType, RefType>::value,
+                  "AccessorType and RefType must be identical for refpointers");
+    return aImpl;
+  }
+
+  template <class LocalRef>
+  static void Set(const LocalRef& instance, RefType ptr) {
+    // Create the new handle first before clearing any old handle, so the
+    // new handle is guaranteed to have different value than any old handle.
+    const uintptr_t handle = reinterpret_cast<uintptr_t>(new RefPtr<Impl>(ptr));
+    Clear(instance);
+    SetNativeHandle(instance.Env(), instance.Get(), handle);
+    MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+  }
+
+  template <class LocalRef>
+  static void Clear(const LocalRef& instance) {
+    const auto ptr = reinterpret_cast<HandleType>(
+        GetNativeHandle(instance.Env(), instance.Get()));
+    MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+
+    if (ptr) {
+      SetNativeHandle(instance.Env(), instance.Get(), 0);
+      MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+      delete ptr;
+    }
+  }
+};
+
+}  // namespace detail
+
+// Forward declarations
+template <typename NativeImpl>
+class NativeWeakPtr;
+template <typename NativeImpl>
+class NativeWeakPtrHolder;
+
+namespace detail {
+
+/**
+ * Given the class of a native implementation, as well as its
+ * NativePtrInternalType, resolve traits for that type that will be used by
+ * the NativeWeakPtrControlBlock.
+ *
+ * Note that we only implement specializations for OWNING and REFPTR types,
+ * as a WEAK_INTRUSIVE type should not be using NativeWeakPtr anyway. The build
+ * will fail if such an attempt is made.
+ *
+ * Traits need to implement two things:
+ * 1. A |Type| field that resolves to a pointer type to be stored in the
+ *    JNIObject's handle. It is assumed that setting a |Type| object to nullptr
+ *    is sufficient to delete the underlying object.
+ * 2. A static |AsRaw| method that converts a pointer of |Type| into a raw
+ *    pointer.
+ */
+template <
+    typename NativeImpl,
+    NativePtrInternalType PtrType =
+        ::mozilla::jni::detail::NativePtrInternalPicker<NativeImpl>::value>
+struct NativeWeakPtrControlBlockStorageTraits;
+
+template <typename NativeImpl>
+struct NativeWeakPtrControlBlockStorageTraits<
+    NativeImpl, ::mozilla::jni::detail::NativePtrInternalType::OWNING> {
+  using Type = UniquePtr<NativeImpl>;
+
+  static NativeImpl* AsRaw(const Type& aStorage) { return aStorage.get(); }
+};
+
+template <typename NativeImpl>
+struct NativeWeakPtrControlBlockStorageTraits<
+    NativeImpl, ::mozilla::jni::detail::NativePtrInternalType::REFPTR> {
+  using Type = RefPtr<NativeImpl>;
+
+  static NativeImpl* AsRaw(const Type& aStorage) { return aStorage.get(); }
+};
+
+// Forward Declaration
+template <typename NativeImpl>
+class Accessor;
+
+/**
+ * This class contains the shared data that is referenced by all NativeWeakPtr
+ * objects that reference the same object.
+ *
+ * It retains a WeakRef to the Java object that owns this native object.
+ * It uses a RWLock to control access to the native pointer itself.
+ * Read locks are used when accessing the pointer (even when calling non-const
+ * methods on the native object).
+ * A write lock is only used when it is time to destroy the native object and
+ * we need to clear the value of mNativeImpl.
+ */
+template <typename NativeImpl>
+class MOZ_HEAP_CLASS NativeWeakPtrControlBlock final {
+ public:
+  using StorageTraits = NativeWeakPtrControlBlockStorageTraits<NativeImpl>;
+  using StorageType = typename StorageTraits::Type;
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(NativeWeakPtrControlBlock)
+
+  NativeWeakPtrControlBlock(const NativeWeakPtrControlBlock&) = delete;
+  NativeWeakPtrControlBlock(NativeWeakPtrControlBlock&&) = delete;
+  NativeWeakPtrControlBlock& operator=(const NativeWeakPtrControlBlock&) =
+      delete;
+  NativeWeakPtrControlBlock& operator=(NativeWeakPtrControlBlock&&) = delete;
+
+  // This is safe to call on any thread because mJavaOwner is immutable.
+  mozilla::jni::Object::WeakRef GetJavaOwner() const { return mJavaOwner; }
+
+ private:
+  NativeWeakPtrControlBlock(::mozilla::jni::Object::Param aJavaOwner,
+                            StorageType&& aNativeImpl)
+      : mJavaOwner(aJavaOwner),
+        mLock("mozilla::jni::detail::NativeWeakPtrControlBlock"),
+        mNativeImpl(std::move(aNativeImpl)) {}
+
+  ~NativeWeakPtrControlBlock() {
+    // Make sure that somebody, somewhere, has detached us before destroying.
+    MOZ_ASSERT(!(*this));
+  }
+
+  /**
+   * Clear the native pointer so that subsequent accesses to the native pointer
+   * via this control block are no longer available.
+   *
+   * We return the native pointer to the caller so that it may proceed with
+   * cleaning up its resources.
+   */
+  StorageType Clear() {
+    StorageType nativeImpl(nullptr);
+
+    {  // Scope for lock
+      AutoWriteLock lock(mLock);
+      std::swap(mNativeImpl, nativeImpl);
+    }
+
+    return nativeImpl;
+  }
+
+  MOZ_PUSH_IGNORE_THREAD_SAFETY
+  void Lock() const { mLock.ReadLock(); }
+
+  void Unlock() const { mLock.ReadUnlock(); }
+  MOZ_POP_THREAD_SAFETY
+
+#if defined(DEBUG)
+  // This is kind of expensive, so we only support it in debug builds.
+  explicit operator bool() const {
+    AutoReadLock lock(mLock);
+    return !!mNativeImpl;
+  }
+#endif  // defined(DEBUG)
+
+ private:
+  friend class Accessor<NativeImpl>;
+  friend class NativeWeakPtr<NativeImpl>;
+  friend class NativeWeakPtrHolder<NativeImpl>;
+
+ private:
+  const mozilla::jni::Object::WeakRef mJavaOwner;
+  mutable RWLock mLock MOZ_UNANNOTATED;  // Protects mNativeImpl
+  StorageType mNativeImpl;
+};
+
+/**
+ * If you want to temporarily access the object held by a NativeWeakPtr, you
+ * must obtain one of these Accessor objects from the pointer. Access must
+ * be done _exclusively_ using once of these objects!
+ */
+template <typename NativeImpl>
+class MOZ_STACK_CLASS Accessor final {
+ public:
+  ~Accessor() {
+    if (mCtlBlock) {
+      mCtlBlock->Unlock();
+    }
+  }
+
+  // Check whether the object is still valid before doing anything else
+  explicit operator bool() const { return mCtlBlock && mCtlBlock->mNativeImpl; }
+
+  // Normal member access
+  NativeImpl* operator->() const {
+    return NativeWeakPtrControlBlockStorageTraits<NativeImpl>::AsRaw(
+        mCtlBlock->mNativeImpl);
+  }
+
+  // This allows us to support calling a pointer to a member function
+  template <typename Member>
+  auto operator->*(Member aMember) const {
+    NativeImpl* impl =
+        NativeWeakPtrControlBlockStorageTraits<NativeImpl>::AsRaw(
+            mCtlBlock->mNativeImpl);
+    return [impl, member = aMember](auto&&... aArgs) {
+      return (impl->*member)(std::forward<decltype(aArgs)>(aArgs)...);
+    };
+  }
+
+  // Only available for NativeImpl types that actually use refcounting.
+  // The idea here is that it should be possible to obtain a strong ref from
+  // a NativeWeakPtr if and only if NativeImpl supports refcounting.
+  template <typename I = NativeImpl>
+  auto AsRefPtr() const -> std::enable_if_t<IsRefCounted<I>::value, RefPtr<I>> {
+    MOZ_ASSERT(I::HasThreadSafeRefCnt::value || NS_IsMainThread());
+    return mCtlBlock->mNativeImpl;
+  }
+
+  Accessor(const Accessor&) = delete;
+  Accessor(Accessor&&) = delete;
+  Accessor& operator=(const Accessor&) = delete;
+  Accessor& operator=(Accessor&&) = delete;
+
+ private:
+  explicit Accessor(
+      const RefPtr<detail::NativeWeakPtrControlBlock<NativeImpl>>& aCtlBlock)
+      : mCtlBlock(aCtlBlock) {
+    if (aCtlBlock) {
+      aCtlBlock->Lock();
+    }
+  }
+
+ private:
+  friend class NativeWeakPtr<NativeImpl>;
+  friend class NativeWeakPtrHolder<NativeImpl>;
+
+ private:
+  const RefPtr<NativeWeakPtrControlBlock<NativeImpl>> mCtlBlock;
+};
+
+}  // namespace detail
+
+using DetachPromise = mozilla::MozPromise<bool, nsresult, true>;
+
+/**
+ * This class implements support for thread-safe weak pointers to native objects
+ * that are owned by Java objects deriving from JNIObject.
+ *
+ * Any code that wants to access such a native object must have a copy of
+ * a NativeWeakPtr to that object.
+ */
+template <typename NativeImpl>
+class NativeWeakPtr {
+ public:
+  using Accessor = detail::Accessor<NativeImpl>;
+
+  /**
+   * Call this method to access the underlying object referenced by this
+   * NativeWeakPtr.
+   *
+   * Always check the returned Accessor object for availability before calling
+   * methods on it.
+   *
+   * For example, given:
+   *
+   * NativeWeakPtr<Foo> foo;
+   * auto accessor = foo.Access();
+   * if (accessor) {
+   *   // Okay, safe to work with
+   *   accessor->DoStuff();
+   * } else {
+   *   // The object's strong reference was cleared and is no longer available!
+   * }
+   */
+  Accessor Access() const { return Accessor(mCtlBlock); }
+
+  /**
+   * Detach the underlying object's strong reference from its owning Java object
+   * and clean it up.
+   */
+  RefPtr<DetachPromise> Detach();
+
+  /**
+   * This method does not indicate whether or not the weak pointer is still
+   * valid; it only indicates whether we're actually attached to one.
+   */
+  bool IsAttached() const { return !!mCtlBlock; }
+
+  /**
+   * Does this pointer reference the same object as the one referenced by the
+   * provided Accessor?
+   */
+  bool IsSame(const Accessor& aAccessor) const {
+    return mCtlBlock == aAccessor.mCtlBlock;
+  }
+
+  /**
+   * Does this pointer reference the same object as the one referenced by the
+   * provided Control Block?
+   */
+  bool IsSame(const RefPtr<detail::NativeWeakPtrControlBlock<NativeImpl>>&
+                  aOther) const {
+    return mCtlBlock == aOther;
+  }
+
+  NativeWeakPtr() = default;
+  MOZ_IMPLICIT NativeWeakPtr(decltype(nullptr)) {}
+  NativeWeakPtr(const NativeWeakPtr& aOther) = default;
+  NativeWeakPtr(NativeWeakPtr&& aOther) = default;
+  NativeWeakPtr& operator=(const NativeWeakPtr& aOther) = default;
+  NativeWeakPtr& operator=(NativeWeakPtr&& aOther) = default;
+
+  NativeWeakPtr& operator=(decltype(nullptr)) {
+    mCtlBlock = nullptr;
+    return *this;
+  }
+
+ protected:
+  // Construction of initial NativeWeakPtr for aCtlBlock
+  explicit NativeWeakPtr(
+      already_AddRefed<detail::NativeWeakPtrControlBlock<NativeImpl>> aCtlBlock)
+      : mCtlBlock(aCtlBlock) {}
+
+ private:
+  // Construction of subsequent NativeWeakPtrs for aCtlBlock
+  explicit NativeWeakPtr(
+      const RefPtr<detail::NativeWeakPtrControlBlock<NativeImpl>>& aCtlBlock)
+      : mCtlBlock(aCtlBlock) {}
+
+  friend class NativeWeakPtrHolder<NativeImpl>;
+
+ protected:
+  RefPtr<detail::NativeWeakPtrControlBlock<NativeImpl>> mCtlBlock;
+};
+
+/**
+ * A pointer to an instance of this class should be stored in a Java object's
+ * JNIObject handle. New instances of native objects wrapped by NativeWeakPtr
+ * are created using the static methods of this class.
+ *
+ * Why do we have distinct methods here instead of using AttachNative like other
+ * pointer types that may be stored in JNIObject?
+ *
+ * Essentially, we want the creation and use of NativeWeakPtr to be as
+ * deliberate as possible. Forcing a different creation mechanism is part of
+ * that emphasis.
+ *
+ * Example:
+ *
+ * class NativeFoo {
+ *  public:
+ *   NativeFoo();
+ *   void Bar();
+ *   // The following method is required to be used with NativeWeakPtr
+ *   void OnWeakNonIntrusiveDetach(already_AddRefed<Runnable> aDisposer);
+ * };
+ *
+ * java::Object::LocalRef javaObj(...);
+ *
+ * // Create a new Foo that is attached to javaObj
+ * auto weakFoo = NativeWeakPtrHolder<NativeFoo>::Attach(javaObj);
+ *
+ * // Now I can save weakFoo, access it, do whatever I want
+ * if (auto accWeakFoo = weakFoo.Access()) {
+ *   accWeakFoo->Bar();
+ * }
+ *
+ * // Detach from javaObj and clean up
+ * weakFoo.Detach();
+ */
+template <typename NativeImpl>
+class MOZ_HEAP_CLASS NativeWeakPtrHolder final
+    : public NativeWeakPtr<NativeImpl> {
+  using Base = NativeWeakPtr<NativeImpl>;
+
+ public:
+  using Accessor = typename Base::Accessor;
+  using StorageTraits =
+      typename detail::NativeWeakPtrControlBlock<NativeImpl>::StorageTraits;
+  using StorageType = typename StorageTraits::Type;
+
+  /**
+   * Create a new NativeImpl object, wrap it in a NativeWeakPtr, and store it
+   * in the Java object's JNIObject handle.
+   *
+   * @return A NativeWeakPtr object that references the newly-attached object.
+   */
+  template <typename Cls, typename JNIType, typename... Args>
+  static NativeWeakPtr<NativeImpl> Attach(const Ref<Cls, JNIType>& aJavaObject,
+                                          Args&&... aArgs) {
+    MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+    StorageType nativeImpl(new NativeImpl(std::forward<Args>(aArgs)...));
+    return AttachInternal(aJavaObject, std::move(nativeImpl));
+  }
+
+  /**
+   * Given a new NativeImpl object, wrap it in a NativeWeakPtr, and store it
+   * in the Java object's JNIObject handle.
+   *
+   * @return A NativeWeakPtr object that references the newly-attached object.
+   */
+  template <typename Cls, typename JNIType>
+  static NativeWeakPtr<NativeImpl> AttachExisting(
+      const Ref<Cls, JNIType>& aJavaObject,
+      already_AddRefed<NativeImpl> aNativeImpl) {
+    MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+    StorageType nativeImpl(aNativeImpl);
+    return AttachInternal(aJavaObject, std::move(nativeImpl));
+  }
+
+  ~NativeWeakPtrHolder() = default;
+
+  MOZ_IMPLICIT NativeWeakPtrHolder(decltype(nullptr)) = delete;
+  NativeWeakPtrHolder(const NativeWeakPtrHolder&) = delete;
+  NativeWeakPtrHolder(NativeWeakPtrHolder&&) = delete;
+  NativeWeakPtrHolder& operator=(const NativeWeakPtrHolder&) = delete;
+  NativeWeakPtrHolder& operator=(NativeWeakPtrHolder&&) = delete;
+  NativeWeakPtrHolder& operator=(decltype(nullptr)) = delete;
+
+ private:
+  template <typename Cls>
+  NativeWeakPtrHolder(const LocalRef<Cls>& aJavaObject,
+                      StorageType&& aNativeImpl)
+      : NativeWeakPtr<NativeImpl>(
+            do_AddRef(new NativeWeakPtrControlBlock<NativeImpl>(
+                aJavaObject, std::move(aNativeImpl)))) {}
+
+  /**
+   * Internal function that actually wraps the native pointer, binds it to the
+   * JNIObject, and then returns the NativeWeakPtr result.
+   */
+  template <typename Cls, typename JNIType>
+  static NativeWeakPtr<NativeImpl> AttachInternal(
+      const Ref<Cls, JNIType>& aJavaObject, StorageType&& aPtr) {
+    auto localJavaObject = ToLocalRef(aJavaObject);
+    NativeWeakPtrHolder<NativeImpl>* holder =
+        new NativeWeakPtrHolder<NativeImpl>(localJavaObject, std::move(aPtr));
+    static_assert(
+        NativePtrPicker<NativeImpl>::value == NativePtrType::WEAK_NON_INTRUSIVE,
+        "This type is not compatible with mozilla::jni::NativeWeakPtr");
+    NativePtrTraits<NativeImpl>::Set(localJavaObject, holder);
+    return NativeWeakPtr<NativeImpl>(holder->mCtlBlock);
+  }
+};
+
+namespace detail {
+
+/**
+ * NativePtrTraits for the WEAK_NON_INTRUSIVE pointer type.
+ */
+template <class Impl>
+struct NativePtrTraits<Impl, /* Type = */ NativePtrType::WEAK_NON_INTRUSIVE> {
+  using AccessorType = typename NativeWeakPtrHolder<Impl>::Accessor;
+  using HandleType = NativeWeakPtrHolder<Impl>*;
+  using RefType = NativeWeakPtrHolder<Impl>* const;
+
+  static RefType Get(JNIEnv* env, jobject instance) {
+    return GetHandle(env, instance);
+  }
+
+  template <typename Cls>
+  static RefType Get(const LocalRef<Cls>& instance) {
+    return GetHandle(instance.Env(), instance.Get());
+  }
+
+  static AccessorType Access(RefType aPtr) { return aPtr->Access(); }
+
+  template <typename Cls>
+  static void Set(const LocalRef<Cls>& instance, HandleType ptr) {
+    MOZ_RELEASE_ASSERT(NS_IsMainThread());
+    const uintptr_t handle = reinterpret_cast<uintptr_t>(ptr);
+    Clear(instance);
+    SetNativeHandle(instance.Env(), instance.Get(), handle);
+    MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+  }
+
+  template <typename Cls>
+  static void Clear(const LocalRef<Cls>& instance) {
+    auto ptr = reinterpret_cast<HandleType>(
+        GetNativeHandle(instance.Env(), instance.Get()));
+    MOZ_CATCH_JNI_EXCEPTION(instance.Env());
+
+    if (!ptr) {
+      return;
+    }
+
+    ptr->Detach();
+  }
+
+  // This call is not safe to do unless we know for sure that instance's
+  // native handle has not changed. It is up to NativeWeakPtrDetachRunnable
+  // to perform this check.
+  template <typename Cls>
+  static void ClearFinish(const LocalRef<Cls>& instance) {
+    MOZ_RELEASE_ASSERT(NS_IsMainThread());
+    JNIEnv* const env = instance.Env();
+    auto ptr =
+        reinterpret_cast<HandleType>(GetNativeHandle(env, instance.Get()));
+    MOZ_CATCH_JNI_EXCEPTION(env);
+    MOZ_RELEASE_ASSERT(!!ptr);
+
+    SetNativeHandle(env, instance.Get(), 0);
+    MOZ_CATCH_JNI_EXCEPTION(env);
+    // Deletion of ptr is done by the caller
+  }
+
+  // The call is stale if the native object has been destroyed on the
+  // Gecko side, but the Java object is still attached to it through
+  // a weak pointer. Stale calls should be discarded. Note that it's
+  // an error if holder is nullptr here; we return false but the
+  // native call will throw an error.
+  template <class LocalRef>
+  static bool IsStale(const LocalRef& instance) {
+    JNIEnv* const env = mozilla::jni::GetEnvForThread();
+
+    // We cannot use Get here because that method throws an exception when the
+    // object is null, which is a valid state for a stale call.
+    const auto holder =
+        reinterpret_cast<HandleType>(GetNativeHandle(env, instance.Get()));
+    MOZ_CATCH_JNI_EXCEPTION(env);
+
+    if (!holder || !holder->IsAttached()) {
+      return true;
+    }
+
+    auto acc(holder->Access());
+    return !acc;
+  }
+
+ private:
+  static HandleType GetHandle(JNIEnv* env, jobject instance) {
+    return reinterpret_cast<HandleType>(
+        CheckNativeHandle<Impl>(env, GetNativeHandle(env, instance)));
+  }
+
+  template <typename Cls>
+  static HandleType GetHandle(const LocalRef<Cls>& instance) {
+    return GetHandle(instance.Env(), instance.Get());
+  }
+
+  friend class NativeWeakPtrHolder<Impl>;
+};
+
+}  // namespace detail
+
+using namespace detail;
+
+/**
+ * For JNI native methods that are dispatched to a proxy, i.e. using
+ * @WrapForJNI(dispatchTo = "proxy"), the implementing C++ class must provide a
+ * OnNativeCall member. Subsequently, every native call is automatically
+ * wrapped in a functor object, and the object is passed to OnNativeCall. The
+ * OnNativeCall implementation can choose to invoke the call, save it, dispatch
+ * it to a different thread, etc. Each copy of functor may only be invoked
+ * once.
+ *
+ * class MyClass : public MyJavaClass::Natives<MyClass>
+ * {
+ *     // ...
+ *
+ *     template<class Functor>
+ *     class ProxyRunnable final : public Runnable
+ *     {
+ *         Functor mCall;
+ *     public:
+ *         ProxyRunnable(Functor&& call) : mCall(std::move(call)) {}
+ *         virtual void run() override { mCall(); }
+ *     };
+ *
+ * public:
+ *     template<class Functor>
+ *     static void OnNativeCall(Functor&& call)
+ *     {
+ *         RunOnAnotherThread(new ProxyRunnable(std::move(call)));
+ *     }
+ * };
+ */
+
+namespace detail {
+
+// ProxyArg is used to handle JNI ref arguments for proxies. Because a proxied
+// call may happen outside of the original JNI native call, we must save all
+// JNI ref arguments as global refs to avoid the arguments going out of scope.
+template <typename T>
+struct ProxyArg {
+  static_assert(std::is_trivial_v<T> && std::is_standard_layout_v<T>,
+                "T must be primitive type");
+
+  // Primitive types can be saved by value.
+  typedef T Type;
+  typedef typename TypeAdapter<T>::JNIType JNIType;
+
+  static void Clear(JNIEnv* env, Type&) {}
+
+  static Type From(JNIEnv* env, JNIType val) {
+    return TypeAdapter<T>::ToNative(env, val);
+  }
+};
+
+template <class C, typename T>
+struct ProxyArg<Ref<C, T>> {
+  // Ref types need to be saved by global ref.
+  typedef typename C::GlobalRef Type;
+  typedef typename TypeAdapter<Ref<C, T>>::JNIType JNIType;
+
+  static void Clear(JNIEnv* env, Type& ref) { ref.Clear(env); }
+
+  static Type From(JNIEnv* env, JNIType val) {
+    return Type(env, C::Ref::From(val));
+  }
+};
+
+template <typename C>
+struct ProxyArg<const C&> : ProxyArg<C> {};
+template <>
+struct ProxyArg<StringParam> : ProxyArg<String::Ref> {};
+template <class C>
+struct ProxyArg<LocalRef<C>> : ProxyArg<typename C::Ref> {};
+
+// ProxyNativeCall implements the functor object that is passed to OnNativeCall
+template <class Impl, class Owner, bool IsStatic,
+          bool HasThisArg /* has instance/class local ref in the call */,
+          typename... Args>
+class ProxyNativeCall {
+  // "this arg" refers to the Class::LocalRef (for static methods) or
+  // Owner::LocalRef (for instance methods) that we optionally (as indicated
+  // by HasThisArg) pass into the destination C++ function.
+  using ThisArgClass = std::conditional_t<IsStatic, Class, Owner>;
+  using ThisArgJNIType = std::conditional_t<IsStatic, jclass, jobject>;
+
+  // Type signature of the destination C++ function, which matches the
+  // Method template parameter in NativeStubImpl::Wrap.
+  using NativeCallType = std::conditional_t<
+      IsStatic,
+      std::conditional_t<HasThisArg, void (*)(const Class::LocalRef&, Args...),
+                         void (*)(Args...)>,
+      std::conditional_t<
+          HasThisArg, void (Impl::*)(const typename Owner::LocalRef&, Args...),
+          void (Impl::*)(Args...)>>;
+
+  // Destination C++ function.
+  NativeCallType mNativeCall;
+  // Saved this arg.
+  typename ThisArgClass::GlobalRef mThisArg;
+  // Saved arguments.
+  std::tuple<typename ProxyArg<Args>::Type...> mArgs;
+
+  // We cannot use IsStatic and HasThisArg directly (without going through
+  // extra hoops) because GCC complains about invalid overloads, so we use
+  // another pair of template parameters, Static and ThisArg.
+
+  template <bool Static, bool ThisArg, size_t... Indices>
+  std::enable_if_t<Static && ThisArg, void> Call(
+      const Class::LocalRef& cls, std::index_sequence<Indices...>) const {
+    (*mNativeCall)(cls, std::get<Indices>(mArgs)...);
+  }
+
+  template <bool Static, bool ThisArg, size_t... Indices>
+  std::enable_if_t<Static && !ThisArg, void> Call(
+      const Class::LocalRef& cls, std::index_sequence<Indices...>) const {
+    (*mNativeCall)(std::get<Indices>(mArgs)...);
+  }
+
+  template <bool Static, bool ThisArg, size_t... Indices>
+  std::enable_if_t<!Static && ThisArg, void> Call(
+      const typename Owner::LocalRef& inst,
+      std::index_sequence<Indices...>) const {
+    auto impl = NativePtrTraits<Impl>::Access(NativePtrTraits<Impl>::Get(inst));
+    MOZ_CATCH_JNI_EXCEPTION(inst.Env());
+    (impl->*mNativeCall)(inst, std::get<Indices>(mArgs)...);
+  }
+
+  template <bool Static, bool ThisArg, size_t... Indices>
+  std::enable_if_t<!Static && !ThisArg, void> Call(
+      const typename Owner::LocalRef& inst,
+      std::index_sequence<Indices...>) const {
+    auto impl = NativePtrTraits<Impl>::Access(NativePtrTraits<Impl>::Get(inst));
+    MOZ_CATCH_JNI_EXCEPTION(inst.Env());
+    (impl->*mNativeCall)(std::get<Indices>(mArgs)...);
+  }
+
+  template <size_t... Indices>
+  void Clear(JNIEnv* env, std::index_sequence<Indices...>) {
+    int dummy[] = {
+        (ProxyArg<Args>::Clear(env, std::get<Indices>(mArgs)), 0)...};
+    mozilla::Unused << dummy;
+  }
+
+  static decltype(auto) GetNativeObject(Class::Param thisArg) {
+    return nullptr;
+  }
+
+  static decltype(auto) GetNativeObject(typename Owner::Param thisArg) {
+    return NativePtrTraits<Impl>::Access(
+        NativePtrTraits<Impl>::Get(GetEnvForThread(), thisArg.Get()));
+  }
+
+ public:
+  // The class that implements the call target.
+  typedef Impl TargetClass;
+  typedef typename ThisArgClass::Param ThisArgType;
+
+  static const bool isStatic = IsStatic;
+
+  ProxyNativeCall(ThisArgJNIType thisArg, NativeCallType nativeCall,
+                  JNIEnv* env, typename ProxyArg<Args>::JNIType... args)
+      : mNativeCall(nativeCall),
+        mThisArg(env, ThisArgClass::Ref::From(thisArg)),
+        mArgs(ProxyArg<Args>::From(env, args)...) {}
+
+  ProxyNativeCall(ProxyNativeCall&&) = default;
+  ProxyNativeCall(const ProxyNativeCall&) = default;
+
+  // Get class ref for static calls or object ref for instance calls.
+  typename ThisArgClass::Param GetThisArg() const { return mThisArg; }
+
+  // Get the native object targeted by this call.
+  // Returns nullptr for static calls.
+  decltype(auto) GetNativeObject() const { return GetNativeObject(mThisArg); }
+
+  // Return if target is the given function pointer / pointer-to-member.
+  // Because we can only compare pointers of the same type, we use a
+  // templated overload that is chosen only if given a different type of
+  // pointer than our target pointer type.
+  bool IsTarget(NativeCallType call) const { return call == mNativeCall; }
+  template <typename T>
+  bool IsTarget(T&&) const {
+    return false;
+  }
+
+  // Redirect the call to another function / class member with the same
+  // signature as the original target. Crash if given a wrong signature.
+  void SetTarget(NativeCallType call) { mNativeCall = call; }
+  template <typename T>
+  void SetTarget(T&&) const {
+    MOZ_CRASH();
+  }
+
+  void operator()() {
+    JNIEnv* const env = GetEnvForThread();
+    typename ThisArgClass::LocalRef thisArg(env, mThisArg);
+    Call<IsStatic, HasThisArg>(thisArg, std::index_sequence_for<Args...>{});
+
+    // Clear all saved global refs. We do this after the call is invoked,
+    // and not inside the destructor because we already have a JNIEnv here,
+    // so it's more efficient to clear out the saved args here. The
+    // downside is that the call can only be invoked once.
+    Clear(env, std::index_sequence_for<Args...>{});
+    mThisArg.Clear(env);
+  }
+};
+
+template <class Impl, bool HasThisArg, typename... Args>
+struct Dispatcher {
+  template <class Traits, bool IsStatic = Traits::isStatic,
+            typename... ProxyArgs>
+  static std::enable_if_t<Traits::dispatchTarget == DispatchTarget::PROXY, void>
+  Run(ProxyArgs&&... args) {
+    Impl::OnNativeCall(
+        ProxyNativeCall<Impl, typename Traits::Owner, IsStatic, HasThisArg,
+                        Args...>(std::forward<ProxyArgs>(args)...));
+  }
+
+  template <class Traits, bool IsStatic = Traits::isStatic, typename ThisArg,
+            typename... ProxyArgs>
+  static std::enable_if_t<
+      Traits::dispatchTarget == DispatchTarget::GECKO_PRIORITY, void>
+  Run(ThisArg thisArg, ProxyArgs&&... args) {
+    // For a static method, do not forward the "this arg" (i.e. the class
+    // local ref) if the implementation does not request it. This saves us
+    // a pair of calls to add/delete global ref.
+    auto proxy =
+        ProxyNativeCall<Impl, typename Traits::Owner, IsStatic, HasThisArg,
+                        Args...>((HasThisArg || !IsStatic) ? thisArg : nullptr,
+                                 std::forward<ProxyArgs>(args)...);
+    DispatchToGeckoPriorityQueue(
+        NS_NewRunnableFunction("PriorityNativeCall", std::move(proxy)));
+  }
+
+  template <class Traits, bool IsStatic = Traits::isStatic, typename ThisArg,
+            typename... ProxyArgs>
+  static std::enable_if_t<Traits::dispatchTarget == DispatchTarget::GECKO, void>
+  Run(ThisArg thisArg, ProxyArgs&&... args) {
+    // For a static method, do not forward the "this arg" (i.e. the class
+    // local ref) if the implementation does not request it. This saves us
+    // a pair of calls to add/delete global ref.
+    auto proxy =
+        ProxyNativeCall<Impl, typename Traits::Owner, IsStatic, HasThisArg,
+                        Args...>((HasThisArg || !IsStatic) ? thisArg : nullptr,
+                                 std::forward<ProxyArgs>(args)...);
+    NS_DispatchToMainThread(
+        NS_NewRunnableFunction("GeckoNativeCall", std::move(proxy)));
+  }
+
+  template <class Traits, bool IsStatic = false, typename... ProxyArgs>
+  static std::enable_if_t<Traits::dispatchTarget == DispatchTarget::CURRENT,
+                          void>
+  Run(ProxyArgs&&... args) {
+    MOZ_CRASH("Unreachable code");
+  }
+};
+
+}  // namespace detail
+
+// Wrapper methods that convert arguments from the JNI types to the native
+// types, e.g. from jobject to jni::Object::Ref. For instance methods, the
+// wrapper methods also convert calls to calls on objects.
+//
+// We need specialization for static/non-static because the two have different
+// signatures (jobject vs jclass and Impl::*Method vs *Method).
+// We need specialization for return type, because void return type requires
+// us to not deal with the return value.
+
+// Bug 1207642 - Work around Dalvik bug by realigning stack on JNI entry
+#ifdef __i386__
+#  define MOZ_JNICALL JNICALL __attribute__((force_align_arg_pointer))
+#else
+#  define MOZ_JNICALL JNICALL
+#endif
+
+template <class Traits, class Impl, class Args = typename Traits::Args>
+class NativeStub;
+
+template <class Traits, class Impl, typename... Args>
+class NativeStub<Traits, Impl, jni::Args<Args...>> {
+  using Owner = typename Traits::Owner;
+  using ReturnType = typename Traits::ReturnType;
+
+  static constexpr bool isStatic = Traits::isStatic;
+  static constexpr bool isVoid = std::is_void_v<ReturnType>;
+
+  struct VoidType {
+    using JNIType = void;
+  };
+  using ReturnJNIType =
+      typename std::conditional_t<isVoid, VoidType,
+                                  TypeAdapter<ReturnType>>::JNIType;
+
+  using ReturnTypeForNonVoidInstance =
+      std::conditional_t<!isStatic && !isVoid, ReturnType, VoidType>;
+  using ReturnTypeForVoidInstance =
+      std::conditional_t<!isStatic && isVoid, ReturnType, VoidType&>;
+  using ReturnTypeForNonVoidStatic =
+      std::conditional_t<isStatic && !isVoid, ReturnType, VoidType>;
+  using ReturnTypeForVoidStatic =
+      std::conditional_t<isStatic && isVoid, ReturnType, VoidType&>;
+
+  static_assert(Traits::dispatchTarget == DispatchTarget::CURRENT || isVoid,
+                "Dispatched calls must have void return type");
+
+ public:
+  // Non-void instance method
+  template <ReturnTypeForNonVoidInstance (Impl::*Method)(Args...)>
+  static MOZ_JNICALL ReturnJNIType
+  Wrap(JNIEnv* env, jobject instance,
+       typename TypeAdapter<Args>::JNIType... args) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+
+    auto impl = NativePtrTraits<Impl>::Access(
+        NativePtrTraits<Impl>::Get(env, instance));
+    if (!impl) {
+      // There is a pending JNI exception at this point.
+      return ReturnJNIType();
+    }
+    return TypeAdapter<ReturnType>::FromNative(
+        env, (impl->*Method)(TypeAdapter<Args>::ToNative(env, args)...));
+  }
+
+  // Non-void instance method with instance reference
+  template <ReturnTypeForNonVoidInstance (Impl::*Method)(
+      const typename Owner::LocalRef&, Args...)>
+  static MOZ_JNICALL ReturnJNIType
+  Wrap(JNIEnv* env, jobject instance,
+       typename TypeAdapter<Args>::JNIType... args) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+
+    auto impl = NativePtrTraits<Impl>::Access(
+        NativePtrTraits<Impl>::Get(env, instance));
+    if (!impl) {
+      // There is a pending JNI exception at this point.
+      return ReturnJNIType();
+    }
+    auto self = Owner::LocalRef::Adopt(env, instance);
+    const auto res = TypeAdapter<ReturnType>::FromNative(
+        env, (impl->*Method)(self, TypeAdapter<Args>::ToNative(env, args)...));
+    self.Forget();
+    return res;
+  }
+
+  // Void instance method
+  template <ReturnTypeForVoidInstance (Impl::*Method)(Args...)>
+  static MOZ_JNICALL void Wrap(JNIEnv* env, jobject instance,
+                               typename TypeAdapter<Args>::JNIType... args) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+
+    if (Traits::dispatchTarget != DispatchTarget::CURRENT) {
+      Dispatcher<Impl, /* HasThisArg */ false, Args...>::template Run<Traits>(
+          instance, Method, env, args...);
+      return;
+    }
+
+    auto impl = NativePtrTraits<Impl>::Access(
+        NativePtrTraits<Impl>::Get(env, instance));
+    if (!impl) {
+      // There is a pending JNI exception at this point.
+      return;
+    }
+    (impl->*Method)(TypeAdapter<Args>::ToNative(env, args)...);
+  }
+
+  // Void instance method with instance reference
+  template <ReturnTypeForVoidInstance (Impl::*Method)(
+      const typename Owner::LocalRef&, Args...)>
+  static MOZ_JNICALL void Wrap(JNIEnv* env, jobject instance,
+                               typename TypeAdapter<Args>::JNIType... args) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+
+    if (Traits::dispatchTarget != DispatchTarget::CURRENT) {
+      Dispatcher<Impl, /* HasThisArg */ true, Args...>::template Run<Traits>(
+          instance, Method, env, args...);
+      return;
+    }
+
+    auto impl = NativePtrTraits<Impl>::Access(
+        NativePtrTraits<Impl>::Get(env, instance));
+    if (!impl) {
+      // There is a pending JNI exception at this point.
+      return;
+    }
+    auto self = Owner::LocalRef::Adopt(env, instance);
+    (impl->*Method)(self, TypeAdapter<Args>::ToNative(env, args)...);
+    self.Forget();
+  }
+
+  // Overload for DisposeNative
+  template <ReturnTypeForVoidInstance (*DisposeNative)(
+      const typename Owner::LocalRef&)>
+  static MOZ_JNICALL void Wrap(JNIEnv* env, jobject instance) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+
+    if (Traits::dispatchTarget != DispatchTarget::CURRENT) {
+      using LocalRef = typename Owner::LocalRef;
+      Dispatcher<Impl, /* HasThisArg */ false, const LocalRef&>::template Run<
+          Traits, /* IsStatic */ true>(
+          /* ThisArg */ nullptr, DisposeNative, env, instance);
+      return;
+    }
+
+    auto self = Owner::LocalRef::Adopt(env, instance);
+    DisposeNative(self);
+    self.Forget();
+  }
+
+  // Non-void static method
+  template <ReturnTypeForNonVoidStatic (*Method)(Args...)>
+  static MOZ_JNICALL ReturnJNIType
+  Wrap(JNIEnv* env, jclass, typename TypeAdapter<Args>::JNIType... args) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+
+    return TypeAdapter<ReturnType>::FromNative(
+        env, (*Method)(TypeAdapter<Args>::ToNative(env, args)...));
+  }
+
+  // Non-void static method with class reference
+  template <ReturnTypeForNonVoidStatic (*Method)(const Class::LocalRef&,
+                                                 Args...)>
+  static MOZ_JNICALL ReturnJNIType
+  Wrap(JNIEnv* env, jclass cls, typename TypeAdapter<Args>::JNIType... args) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+
+    auto clazz = Class::LocalRef::Adopt(env, cls);
+    const auto res = TypeAdapter<ReturnType>::FromNative(
+        env, (*Method)(clazz, TypeAdapter<Args>::ToNative(env, args)...));
+    clazz.Forget();
+    return res;
+  }
+
+  // Void static method
+  template <ReturnTypeForVoidStatic (*Method)(Args...)>
+  static MOZ_JNICALL void Wrap(JNIEnv* env, jclass cls,
+                               typename TypeAdapter<Args>::JNIType... args) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+
+    if (Traits::dispatchTarget != DispatchTarget::CURRENT) {
+      Dispatcher<Impl, /* HasThisArg */ false, Args...>::template Run<Traits>(
+          cls, Method, env, args...);
+      return;
+    }
+
+    (*Method)(TypeAdapter<Args>::ToNative(env, args)...);
+  }
+
+  // Void static method with class reference
+  template <ReturnTypeForVoidStatic (*Method)(const Class::LocalRef&, Args...)>
+  static MOZ_JNICALL void Wrap(JNIEnv* env, jclass cls,
+                               typename TypeAdapter<Args>::JNIType... args) {
+    MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+
+    if (Traits::dispatchTarget != DispatchTarget::CURRENT) {
+      Dispatcher<Impl, /* HasThisArg */ true, Args...>::template Run<Traits>(
+          cls, Method, env, args...);
+      return;
+    }
+
+    auto clazz = Class::LocalRef::Adopt(env, cls);
+    (*Method)(clazz, TypeAdapter<Args>::ToNative(env, args)...);
+    clazz.Forget();
+  }
+};
+
+// Generate a JNINativeMethod from a native
+// method's traits class and a wrapped stub.
+template <class Traits, typename Ret, typename... Args>
+constexpr JNINativeMethod MakeNativeMethod(MOZ_JNICALL Ret (*stub)(JNIEnv*,
+                                                                   Args...)) {
+  return {Traits::name, Traits::signature, reinterpret_cast<void*>(stub)};
+}
+
+// Class inherited by implementing class.
+template <class Cls, class Impl>
+class NativeImpl {
+  typedef typename Cls::template Natives<Impl> Natives;
+
+  static bool sInited;
+
+ public:
+  static void Init() {
+    if (sInited) {
+      return;
+    }
+    const auto& ctx = typename Cls::Context();
+    ctx.Env()->RegisterNatives(
+        ctx.ClassRef(), Natives::methods,
+        sizeof(Natives::methods) / sizeof(Natives::methods[0]));
+    MOZ_CATCH_JNI_EXCEPTION(ctx.Env());
+    sInited = true;
+  }
+
+ protected:
+  // Associate a C++ instance with a Java instance.
+  static void AttachNative(const typename Cls::LocalRef& instance,
+                           SupportsWeakPtr* ptr) {
+    static_assert(NativePtrPicker<Impl>::value == NativePtrType::WEAK_INTRUSIVE,
+                  "Use another AttachNative for non-WeakPtr usage");
+    return NativePtrTraits<Impl>::Set(instance, static_cast<Impl*>(ptr));
+  }
+
+  static void AttachNative(const typename Cls::LocalRef& instance,
+                           UniquePtr<Impl>&& ptr) {
+    static_assert(NativePtrPicker<Impl>::value == NativePtrType::OWNING,
+                  "Use another AttachNative for WeakPtr or RefPtr usage");
+    return NativePtrTraits<Impl>::Set(instance, std::move(ptr));
+  }
+
+  static void AttachNative(const typename Cls::LocalRef& instance, Impl* ptr) {
+    static_assert(NativePtrPicker<Impl>::value == NativePtrType::REFPTR,
+                  "Use another AttachNative for non-RefPtr usage");
+    return NativePtrTraits<Impl>::Set(instance, ptr);
+  }
+
+  // Get the C++ instance associated with a Java instance.
+  // There is always a pending exception if the return value is nullptr.
+  static decltype(auto) GetNative(const typename Cls::LocalRef& instance) {
+    return NativePtrTraits<Impl>::Get(instance);
+  }
+
+  static void DisposeNative(const typename Cls::LocalRef& instance) {
+    NativePtrTraits<Impl>::Clear(instance);
+  }
+
+  NativeImpl() {
+    // Initialize on creation if not already initialized.
+    Init();
+  }
+};
+
+// Define static member.
+template <class C, class I>
+bool NativeImpl<C, I>::sInited;
+
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_Natives_h__
diff --git a/widget/android/jni/NativesInlines.h b/widget/android/jni/NativesInlines.h
new file mode 100644
index 0000000000..858b677715
--- /dev/null
+++ b/widget/android/jni/NativesInlines.h
@@ -0,0 +1,116 @@
+/* -*- 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 "Natives.h"
+
+#include "mozilla/MozPromise.h"
+
+namespace mozilla::jni {
+
+namespace details {
+
+/**
+ * When a NativeWeakPtr is detached from its owning Java object, the calling
+ * thread invokes the implementation's OnWeakNonIntrusiveDetach to perform
+ * cleanup. We complete the remainder of the cleanup sequence on the Gecko
+ * main thread by expecting OnWeakNonIntrusiveDetach implementations to invoke
+ * this Runnable before exiting. It will move itself to the main thread if it
+ * is not already there.
+ */
+template <typename NativeImpl>
+class NativeWeakPtrDetachRunnable final : public Runnable {
+ public:
+  NativeWeakPtrDetachRunnable(
+      already_AddRefed<detail::NativeWeakPtrControlBlock<NativeImpl>> aCtlBlock,
+      const Object::LocalRef& aOwner,
+      typename NativeWeakPtrControlBlockStorageTraits<NativeImpl>::Type
+          aNativeImpl)
+      : Runnable("mozilla::jni::detail::NativeWeakPtrDetachRunnable"),
+        mCtlBlock(aCtlBlock),
+        mOwner(aOwner),
+        mNativeImpl(std::move(aNativeImpl)),
+        mHasRun(false) {
+    MOZ_RELEASE_ASSERT(!!mCtlBlock);
+    MOZ_RELEASE_ASSERT(!!mNativeImpl);
+  }
+
+  NS_INLINE_DECL_REFCOUNTING_INHERITED(NativeWeakPtrDetachRunnable, Runnable)
+
+  NS_IMETHOD Run() override {
+    mHasRun = true;
+
+    if (!NS_IsMainThread()) {
+      NS_DispatchToMainThread(this);
+      return NS_OK;
+    }
+
+    // Get the owner object's native implementation
+    auto owner = ToLocalRef(mOwner);
+    auto attachedNativeImpl = NativePtrTraits<NativeImpl>::Get(owner);
+    MOZ_RELEASE_ASSERT(!!attachedNativeImpl);
+
+    // NativePtrTraits::ClearFinish cleans out the JNIObject's handle, which
+    // obviously we don't want to attempt unless that handle still points to
+    // our native implementation.
+    if (attachedNativeImpl->IsSame(mCtlBlock)) {
+      NativePtrTraits<NativeImpl>::ClearFinish(owner);
+    }
+
+    // Now we destroy that native object.
+    mNativeImpl = nullptr;
+    mHolder.Resolve(true, __func__);
+    return NS_OK;
+  }
+
+  RefPtr<DetachPromise> GetPromise() { return mHolder.Ensure(__func__); }
+
+ private:
+  ~NativeWeakPtrDetachRunnable() {
+    // Guard against somebody forgetting to call this runnable.
+    MOZ_RELEASE_ASSERT(mHasRun, "You must run/dispatch this runnable!");
+  }
+
+ private:
+  RefPtr<detail::NativeWeakPtrControlBlock<NativeImpl>> mCtlBlock;
+  Object::GlobalRef mOwner;
+  MozPromiseHolder<DetachPromise> mHolder;
+  typename NativeWeakPtrControlBlockStorageTraits<NativeImpl>::Type mNativeImpl;
+  bool mHasRun;
+};
+
+}  // namespace details
+
+template <typename NativeImpl>
+RefPtr<DetachPromise> NativeWeakPtr<NativeImpl>::Detach() {
+  if (!IsAttached()) {
+    // Never attached to begin with; no-op
+    return DetachPromise::CreateAndResolve(true, __func__);
+  }
+
+  auto native = mCtlBlock->Clear();
+  if (!native) {
+    // Detach already in progress
+    return DetachPromise::CreateAndResolve(true, __func__);
+  }
+
+  Object::LocalRef owner(mCtlBlock->GetJavaOwner());
+  MOZ_RELEASE_ASSERT(!!owner);
+
+  // Save the raw pointer before we move native into the runnable so that we
+  // may call OnWeakNonIntrusiveDetach on it even after moving native into
+  // the runnable.
+  NativeImpl* rawImpl =
+      detail::NativeWeakPtrControlBlock<NativeImpl>::StorageTraits::AsRaw(
+          native);
+  RefPtr<details::NativeWeakPtrDetachRunnable<NativeImpl>> runnable =
+      new details::NativeWeakPtrDetachRunnable<NativeImpl>(
+          mCtlBlock.forget(), owner, std::move(native));
+  RefPtr<DetachPromise> promise = runnable->GetPromise();
+  rawImpl->OnWeakNonIntrusiveDetach(runnable.forget());
+  return promise;
+}
+
+}  // namespace mozilla::jni
diff --git a/widget/android/jni/Refs.h b/widget/android/jni/Refs.h
new file mode 100644
index 0000000000..9b50703491
--- /dev/null
+++ b/widget/android/jni/Refs.h
@@ -0,0 +1,1117 @@
+/* -*- 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_jni_Refs_h__
+#define mozilla_jni_Refs_h__
+
+#include <jni.h>
+
+#include <utility>
+
+#include "mozilla/fallible.h"
+#include "mozilla/jni/Utils.h"
+#include "mozilla/jni/TypeAdapter.h"
+#include "nsError.h"  // for nsresult
+#include "nsString.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace jni {
+
+// Wrapped object reference (e.g. jobject, jclass, etc...)
+template <class Cls, typename JNIType>
+class Ref;
+// Represents a calling context for JNI methods.
+template <class Cls, typename JNIType>
+class Context;
+// Wrapped local reference that inherits from Ref.
+template <class Cls>
+class LocalRef;
+// Wrapped global reference that inherits from Ref.
+template <class Cls>
+class GlobalRef;
+// Wrapped weak reference that inherits from Ref.
+template <class Cls>
+class WeakRef;
+// Wrapped dangling reference that's owned by someone else.
+template <class Cls>
+class DependentRef;
+
+// Class to hold the native types of a method's arguments.
+// For example, if a method has signature (ILjava/lang/String;)V,
+// its arguments class would be jni::Args<int32_t, jni::String::Param>
+template <typename...>
+struct Args {};
+
+class Object;
+
+// Base class for Ref and its specializations.
+template <class Cls, typename Type>
+class Ref {
+  template <class C, typename T>
+  friend class Ref;
+
+  using Self = Ref<Cls, Type>;
+  using bool_type = void (Self::*)() const;
+  void non_null_reference() const {}
+
+  // A Cls-derivative that allows copying
+  // (e.g. when acting as a return value).
+  struct CopyableCtx : public Context<Cls, Type> {
+    CopyableCtx(JNIEnv* env, Type instance)
+        : Context<Cls, Type>(env, instance) {}
+
+    CopyableCtx(const CopyableCtx& cls)
+        : Context<Cls, Type>(cls.Env(), cls.Get()) {}
+  };
+
+  // Private copy constructor so that there's no danger of assigning a
+  // temporary LocalRef/GlobalRef to a Ref, and potentially use the Ref
+  // after the source had been freed.
+  Ref(const Ref&) = default;
+
+ protected:
+  static JNIEnv* FindEnv() {
+    return Cls::callingThread == CallingThread::GECKO ? GetGeckoThreadEnv()
+                                                      : GetEnvForThread();
+  }
+
+  Type mInstance;
+
+  // Protected jobject constructor because outside code should be using
+  // Ref::From. Using Ref::From makes it very easy to see which code is using
+  // raw JNI types for future refactoring.
+  explicit Ref(Type instance) : mInstance(instance) {}
+
+ public:
+  using JNIType = Type;
+
+  class AutoLock {
+    friend class Ref<Cls, Type>;
+
+    JNIEnv* const mEnv;
+    Type mInstance;
+
+    explicit AutoLock(Type aInstance)
+        : mEnv(FindEnv()), mInstance(mEnv->NewLocalRef(aInstance)) {
+      mEnv->MonitorEnter(mInstance);
+      MOZ_CATCH_JNI_EXCEPTION(mEnv);
+    }
+
+   public:
+    AutoLock(AutoLock&& aOther)
+        : mEnv(aOther.mEnv), mInstance(aOther.mInstance) {
+      aOther.mInstance = nullptr;
+    }
+
+    ~AutoLock() { Unlock(); }
+
+    void Unlock() {
+      if (mInstance) {
+        mEnv->MonitorExit(mInstance);
+        mEnv->DeleteLocalRef(mInstance);
+        MOZ_CATCH_JNI_EXCEPTION(mEnv);
+        mInstance = nullptr;
+      }
+    }
+  };
+
+  // Construct a Ref form a raw JNI reference.
+  static Ref<Cls, Type> From(JNIType obj) { return Ref<Cls, Type>(obj); }
+
+  // Construct a Ref form a generic object reference.
+  static Ref<Cls, Type> From(const Ref<Object, jobject>& obj) {
+    return Ref<Cls, Type>(JNIType(obj.Get()));
+  }
+
+  MOZ_IMPLICIT Ref(decltype(nullptr)) : mInstance(nullptr) {}
+
+  // Get the raw JNI reference.
+  JNIType Get() const { return mInstance; }
+
+  template <class T>
+  bool IsInstanceOf() const {
+    return FindEnv()->IsInstanceOf(mInstance, typename T::Context().ClassRef());
+  }
+
+  template <class T>
+  typename T::Ref Cast() const {
+#ifdef MOZ_CHECK_JNI
+    MOZ_RELEASE_ASSERT(FindEnv()->IsAssignableFrom(
+        Context<Cls, Type>().ClassRef(), typename T::Context().ClassRef()));
+#endif
+    return T::Ref::From(*this);
+  }
+
+  AutoLock Lock() const { return AutoLock(mInstance); }
+
+  bool operator==(const Ref& other) const {
+    // Treat two references of the same object as being the same.
+    return mInstance == other.mInstance ||
+           JNI_FALSE != FindEnv()->IsSameObject(mInstance, other.mInstance);
+  }
+
+  bool operator!=(const Ref& other) const { return !operator==(other); }
+
+  bool operator==(decltype(nullptr)) const { return !mInstance; }
+
+  bool operator!=(decltype(nullptr)) const { return !!mInstance; }
+
+  CopyableCtx operator->() const { return CopyableCtx(FindEnv(), mInstance); }
+
+  CopyableCtx operator*() const { return operator->(); }
+
+  // Any ref can be cast to an object ref.
+  operator Ref<Object, jobject>() const {
+    return Ref<Object, jobject>(mInstance);
+  }
+
+  // Null checking (e.g. !!ref) using the safe-bool idiom.
+  operator bool_type() const {
+    return mInstance ? &Self::non_null_reference : nullptr;
+  }
+
+  // We don't allow implicit conversion to jobject because that can lead
+  // to easy mistakes such as assigning a temporary LocalRef to a jobject,
+  // and using the jobject after the LocalRef has been freed.
+
+  // We don't allow explicit conversion, to make outside code use Ref::Get.
+  // Using Ref::Get makes it very easy to see which code is using raw JNI
+  // types to make future refactoring easier.
+
+  // operator JNIType() const = delete;
+};
+
+// Represents a calling context for JNI methods.
+template <class Cls, typename Type>
+class Context : public Ref<Cls, Type> {
+  using Ref = jni::Ref<Cls, Type>;
+
+  static jclass sClassRef;  // global reference
+
+ protected:
+  JNIEnv* const mEnv;
+
+ public:
+  Context() : Ref(nullptr), mEnv(Ref::FindEnv()) {}
+
+  Context(JNIEnv* env, Type instance) : Ref(instance), mEnv(env) {}
+
+  jclass ClassRef() const {
+    if (!sClassRef) {
+      const jclass cls = GetClassRef(mEnv, Cls::name);
+      sClassRef = jclass(mEnv->NewGlobalRef(cls));
+      mEnv->DeleteLocalRef(cls);
+    }
+    return sClassRef;
+  }
+
+  JNIEnv* Env() const { return mEnv; }
+
+  template <class T>
+  bool IsInstanceOf() const {
+    return mEnv->IsInstanceOf(Ref::mInstance,
+                              typename T::Context(mEnv, nullptr).ClassRef());
+  }
+
+  bool operator==(const Ref& other) const {
+    // Treat two references of the same object as being the same.
+    return Ref::mInstance == other.Get() ||
+           JNI_FALSE != mEnv->IsSameObject(Ref::mInstance, other.Get());
+  }
+
+  bool operator!=(const Ref& other) const { return !operator==(other); }
+
+  bool operator==(decltype(nullptr)) const { return !Ref::mInstance; }
+
+  bool operator!=(decltype(nullptr)) const { return !!Ref::mInstance; }
+
+  Cls operator->() const {
+    MOZ_ASSERT(Ref::mInstance, "Null jobject");
+    return Cls(*this);
+  }
+
+  const Context<Cls, Type>& operator*() const { return *this; }
+};
+
+template <class C, typename T>
+jclass Context<C, T>::sClassRef;
+
+template <class Cls, typename Type = jobject>
+class ObjectBase {
+ protected:
+  const jni::Context<Cls, Type>& mCtx;
+
+  jclass ClassRef() const { return mCtx.ClassRef(); }
+  JNIEnv* Env() const { return mCtx.Env(); }
+  Type Instance() const { return mCtx.Get(); }
+
+ public:
+  using Ref = jni::Ref<Cls, Type>;
+  using Context = jni::Context<Cls, Type>;
+  using LocalRef = jni::LocalRef<Cls>;
+  using GlobalRef = jni::GlobalRef<Cls>;
+  using WeakRef = jni::WeakRef<Cls>;
+  using Param = const Ref&;
+
+  static const CallingThread callingThread = CallingThread::ANY;
+  static const char name[];
+
+  explicit ObjectBase(const Context& ctx) : mCtx(ctx) {}
+
+  Cls* operator->() { return static_cast<Cls*>(this); }
+};
+
+// Binding for a plain jobject.
+class Object : public ObjectBase<Object, jobject> {
+ public:
+  explicit Object(const Context& ctx) : ObjectBase<Object, jobject>(ctx) {}
+};
+
+// Binding for a built-in object reference other than jobject.
+template <typename T>
+class TypedObject : public ObjectBase<TypedObject<T>, T> {
+ public:
+  explicit TypedObject(const Context<TypedObject<T>, T>& ctx)
+      : ObjectBase<TypedObject<T>, T>(ctx) {}
+};
+
+// Binding for a boxed primitive object.
+template <typename T>
+class BoxedObject : public ObjectBase<BoxedObject<T>, jobject> {
+ public:
+  explicit BoxedObject(const Context<BoxedObject<T>, jobject>& ctx)
+      : ObjectBase<BoxedObject<T>, jobject>(ctx) {}
+};
+
+template <>
+const char ObjectBase<Object, jobject>::name[];
+template <>
+const char ObjectBase<TypedObject<jstring>, jstring>::name[];
+template <>
+const char ObjectBase<TypedObject<jclass>, jclass>::name[];
+template <>
+const char ObjectBase<TypedObject<jthrowable>, jthrowable>::name[];
+template <>
+const char ObjectBase<BoxedObject<jboolean>, jobject>::name[];
+template <>
+const char ObjectBase<BoxedObject<jbyte>, jobject>::name[];
+template <>
+const char ObjectBase<BoxedObject<jchar>, jobject>::name[];
+template <>
+const char ObjectBase<BoxedObject<jshort>, jobject>::name[];
+template <>
+const char ObjectBase<BoxedObject<jint>, jobject>::name[];
+template <>
+const char ObjectBase<BoxedObject<jlong>, jobject>::name[];
+template <>
+const char ObjectBase<BoxedObject<jfloat>, jobject>::name[];
+template <>
+const char ObjectBase<BoxedObject<jdouble>, jobject>::name[];
+template <>
+const char ObjectBase<TypedObject<jbooleanArray>, jbooleanArray>::name[];
+template <>
+const char ObjectBase<TypedObject<jbyteArray>, jbyteArray>::name[];
+template <>
+const char ObjectBase<TypedObject<jcharArray>, jcharArray>::name[];
+template <>
+const char ObjectBase<TypedObject<jshortArray>, jshortArray>::name[];
+template <>
+const char ObjectBase<TypedObject<jintArray>, jintArray>::name[];
+template <>
+const char ObjectBase<TypedObject<jlongArray>, jlongArray>::name[];
+template <>
+const char ObjectBase<TypedObject<jfloatArray>, jfloatArray>::name[];
+template <>
+const char ObjectBase<TypedObject<jdoubleArray>, jdoubleArray>::name[];
+template <>
+const char ObjectBase<TypedObject<jobjectArray>, jobjectArray>::name[];
+
+// Define bindings for built-in types.
+using String = TypedObject<jstring>;
+using Class = TypedObject<jclass>;
+using Throwable = TypedObject<jthrowable>;
+
+using Boolean = BoxedObject<jboolean>;
+using Byte = BoxedObject<jbyte>;
+using Character = BoxedObject<jchar>;
+using Short = BoxedObject<jshort>;
+using Integer = BoxedObject<jint>;
+using Long = BoxedObject<jlong>;
+using Float = BoxedObject<jfloat>;
+using Double = BoxedObject<jdouble>;
+
+using BooleanArray = TypedObject<jbooleanArray>;
+using ByteArray = TypedObject<jbyteArray>;
+using CharArray = TypedObject<jcharArray>;
+using ShortArray = TypedObject<jshortArray>;
+using IntArray = TypedObject<jintArray>;
+using LongArray = TypedObject<jlongArray>;
+using FloatArray = TypedObject<jfloatArray>;
+using DoubleArray = TypedObject<jdoubleArray>;
+using ObjectArray = TypedObject<jobjectArray>;
+
+namespace detail {
+
+// See explanation in LocalRef.
+template <class Cls>
+struct GenericObject {
+  using Type = Object;
+};
+template <>
+struct GenericObject<Object> {
+  struct Type {
+    using Ref = jni::Ref<Type, jobject>;
+    using Context = jni::Context<Type, jobject>;
+  };
+};
+template <class Cls>
+struct GenericLocalRef {
+  template <class C>
+  struct Type : jni::Object {};
+};
+template <>
+struct GenericLocalRef<Object> {
+  template <class C>
+  using Type = jni::LocalRef<C>;
+};
+
+}  // namespace detail
+
+template <class Cls>
+class LocalRef : public Cls::Context {
+  template <class C>
+  friend class LocalRef;
+
+  using Ctx = typename Cls::Context;
+  using Ref = typename Cls::Ref;
+  using JNIType = typename Ref::JNIType;
+
+  // In order to be able to convert LocalRef<Object> to LocalRef<Cls>, we
+  // need constructors and copy assignment operators that take in a
+  // LocalRef<Object> argument. However, if Cls *is* Object, we would have
+  // duplicated constructors and operators with LocalRef<Object> arguments. To
+  // avoid this conflict, we use GenericObject, which is defined as Object for
+  // LocalRef<non-Object> and defined as a dummy class for LocalRef<Object>.
+  using GenericObject = typename detail::GenericObject<Cls>::Type;
+
+  // Similarly, GenericLocalRef is useed to convert LocalRef<Cls> to,
+  // LocalRef<Object>. It's defined as LocalRef<C> for Cls == Object,
+  // and defined as a dummy template class for Cls != Object.
+  template <class C>
+  using GenericLocalRef =
+      typename detail::GenericLocalRef<Cls>::template Type<C>;
+
+  static JNIType NewLocalRef(JNIEnv* env, JNIType obj) {
+    return JNIType(obj ? env->NewLocalRef(obj) : nullptr);
+  }
+
+  LocalRef(JNIEnv* env, JNIType instance) : Ctx(env, instance) {}
+
+  LocalRef& swap(LocalRef& other) {
+    auto instance = other.mInstance;
+    other.mInstance = Ctx::mInstance;
+    Ctx::mInstance = instance;
+    return *this;
+  }
+
+ public:
+  // Construct a LocalRef from a raw JNI local reference. Unlike Ref::From,
+  // LocalRef::Adopt returns a LocalRef that will delete the local reference
+  // when going out of scope.
+  static LocalRef Adopt(JNIType instance) {
+    return LocalRef(Ref::FindEnv(), instance);
+  }
+
+  static LocalRef Adopt(JNIEnv* env, JNIType instance) {
+    return LocalRef(env, instance);
+  }
+
+  // Copy constructor.
+  LocalRef(const LocalRef<Cls>& ref)
+      : Ctx(ref.mEnv, NewLocalRef(ref.mEnv, ref.mInstance)) {}
+
+  // Move constructor.
+  LocalRef(LocalRef<Cls>&& ref) : Ctx(ref.mEnv, ref.mInstance) {
+    ref.mInstance = nullptr;
+  }
+
+  explicit LocalRef(JNIEnv* env = Ref::FindEnv()) : Ctx(env, nullptr) {}
+
+  // Construct a LocalRef from any Ref,
+  // which means creating a new local reference.
+  MOZ_IMPLICIT LocalRef(const Ref& ref) : Ctx(Ref::FindEnv(), nullptr) {
+    Ctx::mInstance = NewLocalRef(Ctx::mEnv, ref.Get());
+  }
+
+  LocalRef(JNIEnv* env, const Ref& ref)
+      : Ctx(env, NewLocalRef(env, ref.Get())) {}
+
+  // Move a LocalRef<Object> into a LocalRef<Cls> without
+  // creating/deleting local references.
+  MOZ_IMPLICIT LocalRef(LocalRef<GenericObject>&& ref)
+      : Ctx(ref.mEnv, JNIType(ref.mInstance)) {
+    ref.mInstance = nullptr;
+  }
+
+  template <class C>
+  MOZ_IMPLICIT LocalRef(GenericLocalRef<C>&& ref)
+      : Ctx(ref.mEnv, ref.mInstance) {
+    ref.mInstance = nullptr;
+  }
+
+  // Implicitly converts nullptr to LocalRef.
+  MOZ_IMPLICIT LocalRef(decltype(nullptr)) : Ctx(Ref::FindEnv(), nullptr) {}
+
+  ~LocalRef() {
+    if (Ctx::mInstance) {
+      Ctx::mEnv->DeleteLocalRef(Ctx::mInstance);
+      Ctx::mInstance = nullptr;
+    }
+  }
+
+  // Get the raw JNI reference that can be used as a return value.
+  // Returns the same JNI type (jobject, jstring, etc.) as the underlying Ref.
+  typename Ref::JNIType Forget() {
+    const auto obj = Ctx::Get();
+    Ctx::mInstance = nullptr;
+    return obj;
+  }
+
+  LocalRef<Cls>& operator=(LocalRef<Cls> ref) & { return swap(ref); }
+
+  LocalRef<Cls>& operator=(const Ref& ref) & {
+    LocalRef<Cls> newRef(Ctx::mEnv, ref);
+    return swap(newRef);
+  }
+
+  LocalRef<Cls>& operator=(LocalRef<GenericObject>&& ref) & {
+    LocalRef<Cls> newRef(std::move(ref));
+    return swap(newRef);
+  }
+
+  template <class C>
+  LocalRef<Cls>& operator=(GenericLocalRef<C>&& ref) & {
+    LocalRef<Cls> newRef(std::move(ref));
+    return swap(newRef);
+  }
+
+  LocalRef<Cls>& operator=(decltype(nullptr)) & {
+    LocalRef<Cls> newRef(Ctx::mEnv, nullptr);
+    return swap(newRef);
+  }
+};
+
+template <class Cls>
+class GlobalRef : public Cls::Ref {
+  using Ref = typename Cls::Ref;
+  using JNIType = typename Ref::JNIType;
+
+  static JNIType NewGlobalRef(JNIEnv* env, JNIType instance) {
+    return JNIType(instance ? env->NewGlobalRef(instance) : nullptr);
+  }
+
+  GlobalRef& swap(GlobalRef& other) {
+    auto instance = other.mInstance;
+    other.mInstance = Ref::mInstance;
+    Ref::mInstance = instance;
+    return *this;
+  }
+
+ public:
+  GlobalRef() : Ref(nullptr) {}
+
+  // Copy constructor
+  GlobalRef(const GlobalRef& ref)
+      : Ref(NewGlobalRef(GetEnvForThread(), ref.mInstance)) {}
+
+  // Move constructor
+  GlobalRef(GlobalRef&& ref) : Ref(ref.mInstance) { ref.mInstance = nullptr; }
+
+  MOZ_IMPLICIT GlobalRef(const Ref& ref)
+      : Ref(NewGlobalRef(GetEnvForThread(), ref.Get())) {}
+
+  GlobalRef(JNIEnv* env, const Ref& ref) : Ref(NewGlobalRef(env, ref.Get())) {}
+
+  MOZ_IMPLICIT GlobalRef(const LocalRef<Cls>& ref)
+      : Ref(NewGlobalRef(ref.Env(), ref.Get())) {}
+
+  // Implicitly converts nullptr to GlobalRef.
+  MOZ_IMPLICIT GlobalRef(decltype(nullptr)) : Ref(nullptr) {}
+
+  ~GlobalRef() {
+    if (Ref::mInstance) {
+      Clear(GetEnvForThread());
+    }
+  }
+
+  // Get the raw JNI reference that can be used as a return value.
+  // Returns the same JNI type (jobject, jstring, etc.) as the underlying Ref.
+  typename Ref::JNIType Forget() {
+    const auto obj = Ref::Get();
+    Ref::mInstance = nullptr;
+    return obj;
+  }
+
+  void Clear(JNIEnv* env) {
+    if (Ref::mInstance) {
+      env->DeleteGlobalRef(Ref::mInstance);
+      Ref::mInstance = nullptr;
+    }
+  }
+
+  GlobalRef<Cls>& operator=(GlobalRef<Cls> ref) & { return swap(ref); }
+
+  GlobalRef<Cls>& operator=(const Ref& ref) & {
+    GlobalRef<Cls> newRef(ref);
+    return swap(newRef);
+  }
+
+  GlobalRef<Cls>& operator=(const LocalRef<Cls>& ref) & {
+    GlobalRef<Cls> newRef(ref);
+    return swap(newRef);
+  }
+
+  GlobalRef<Cls>& operator=(decltype(nullptr)) & {
+    GlobalRef<Cls> newRef(nullptr);
+    return swap(newRef);
+  }
+};
+
+template <class Cls>
+class WeakRef : public Ref<Cls, jweak> {
+  using Ref = Ref<Cls, jweak>;
+  using JNIType = typename Ref::JNIType;
+
+  static JNIType NewWeakRef(JNIEnv* env, JNIType instance) {
+    return JNIType(instance ? env->NewWeakGlobalRef(instance) : nullptr);
+  }
+
+  WeakRef& swap(WeakRef& other) {
+    auto instance = other.mInstance;
+    other.mInstance = Ref::mInstance;
+    Ref::mInstance = instance;
+    return *this;
+  }
+
+ public:
+  WeakRef() : Ref(nullptr) {}
+
+  // Copy constructor
+  WeakRef(const WeakRef& ref)
+      : Ref(NewWeakRef(GetEnvForThread(), ref.mInstance)) {}
+
+  // Move constructor
+  WeakRef(WeakRef&& ref) : Ref(ref.mInstance) { ref.mInstance = nullptr; }
+
+  MOZ_IMPLICIT WeakRef(const Ref& ref)
+      : Ref(NewWeakRef(GetEnvForThread(), ref.Get())) {}
+
+  WeakRef(JNIEnv* env, const Ref& ref) : Ref(NewWeakRef(env, ref.Get())) {}
+
+  MOZ_IMPLICIT WeakRef(const LocalRef<Cls>& ref)
+      : Ref(NewWeakRef(ref.Env(), ref.Get())) {}
+
+  // Implicitly converts nullptr to WeakRef.
+  MOZ_IMPLICIT WeakRef(decltype(nullptr)) : Ref(nullptr) {}
+
+  ~WeakRef() {
+    if (Ref::mInstance) {
+      Clear(GetEnvForThread());
+    }
+  }
+
+  // Get the raw JNI reference that can be used as a return value.
+  // Returns the same JNI type (jobject, jstring, etc.) as the underlying Ref.
+  typename Ref::JNIType Forget() {
+    const auto obj = Ref::Get();
+    Ref::mInstance = nullptr;
+    return obj;
+  }
+
+  void Clear(JNIEnv* env) {
+    if (Ref::mInstance) {
+      env->DeleteWeakGlobalRef(Ref::mInstance);
+      Ref::mInstance = nullptr;
+    }
+  }
+
+  WeakRef<Cls>& operator=(WeakRef<Cls> ref) & { return swap(ref); }
+
+  WeakRef<Cls>& operator=(const Ref& ref) & {
+    WeakRef<Cls> newRef(ref);
+    return swap(newRef);
+  }
+
+  WeakRef<Cls>& operator=(const LocalRef<Cls>& ref) & {
+    WeakRef<Cls> newRef(ref);
+    return swap(newRef);
+  }
+
+  WeakRef<Cls>& operator=(decltype(nullptr)) & {
+    WeakRef<Cls> newRef(nullptr);
+    return swap(newRef);
+  }
+
+  void operator->() const = delete;
+  void operator*() const = delete;
+};
+
+template <class Cls>
+class DependentRef : public Cls::Ref {
+  using Ref = typename Cls::Ref;
+
+ public:
+  explicit DependentRef(typename Ref::JNIType instance) : Ref(instance) {}
+
+  DependentRef(const DependentRef& ref) : Ref(ref.Get()) {}
+};
+
+class StringParam;
+
+template <>
+class TypedObject<jstring> : public ObjectBase<TypedObject<jstring>, jstring> {
+  using Base = ObjectBase<TypedObject<jstring>, jstring>;
+
+ public:
+  using Param = const StringParam&;
+
+  explicit TypedObject(const Context& ctx) : Base(ctx) {}
+
+  size_t Length() const {
+    const size_t ret = Base::Env()->GetStringLength(Base::Instance());
+    MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+    return ret;
+  }
+
+  nsString ToString() const {
+    const jchar* const str =
+        Base::Env()->GetStringChars(Base::Instance(), nullptr);
+    const jsize len = Base::Env()->GetStringLength(Base::Instance());
+
+    nsString result(reinterpret_cast<const char16_t*>(str), len);
+    Base::Env()->ReleaseStringChars(Base::Instance(), str);
+    return result;
+  }
+
+  nsCString ToCString() const { return NS_ConvertUTF16toUTF8(ToString()); }
+
+  // Convert jstring to a nsString.
+  operator nsString() const { return ToString(); }
+
+  // Convert jstring to a nsCString.
+  operator nsCString() const { return ToCString(); }
+};
+
+// Define a custom parameter type for String,
+// which accepts both String::Ref and nsAString/nsACString
+class StringParam : public String::Ref {
+  using Ref = String::Ref;
+
+ private:
+  // Not null if we should delete ref on destruction.
+  JNIEnv* const mEnv;
+
+  static jstring GetString(JNIEnv* env, const nsAString& str) {
+    const jstring result = env->NewString(
+        reinterpret_cast<const jchar*>(str.BeginReading()), str.Length());
+    if (!result) {
+      NS_ABORT_OOM(str.Length() * sizeof(char16_t));
+    }
+    MOZ_CATCH_JNI_EXCEPTION(env);
+    return result;
+  }
+
+  static jstring GetString(JNIEnv* env, const nsAString& str,
+                           const fallible_t&) {
+    const jstring result = env->NewString(
+        reinterpret_cast<const jchar*>(str.BeginReading()), str.Length());
+    if (env->ExceptionCheck()) {
+#ifdef MOZ_CHECK_JNI
+      env->ExceptionDescribe();
+#endif
+      env->ExceptionClear();
+    }
+    return result;
+  }
+
+  static jstring GetString(JNIEnv* env, const nsACString& str,
+                           const fallible_t& aFallible) {
+    nsAutoString utf16;
+    if (!CopyUTF8toUTF16(str, utf16, aFallible)) {
+      return nullptr;
+    }
+    return GetString(env, utf16, aFallible);
+  }
+
+ public:
+  MOZ_IMPLICIT StringParam(decltype(nullptr)) : Ref(nullptr), mEnv(nullptr) {}
+
+  MOZ_IMPLICIT StringParam(const Ref& ref) : Ref(ref.Get()), mEnv(nullptr) {}
+
+  MOZ_IMPLICIT StringParam(const nsAString& str, JNIEnv* env = Ref::FindEnv())
+      : Ref(GetString(env, str)), mEnv(env) {}
+
+  MOZ_IMPLICIT StringParam(const nsAString& str, JNIEnv* env,
+                           const fallible_t& aFallible)
+      : Ref(GetString(env, str, aFallible)), mEnv(env) {}
+
+  MOZ_IMPLICIT StringParam(const nsLiteralString& str,
+                           JNIEnv* env = Ref::FindEnv())
+      : Ref(GetString(env, str)), mEnv(env) {}
+
+  MOZ_IMPLICIT StringParam(const char16_t* str, JNIEnv* env = Ref::FindEnv())
+      : Ref(GetString(env, nsDependentString(str))), mEnv(env) {}
+
+  MOZ_IMPLICIT StringParam(const nsACString& str, JNIEnv* env = Ref::FindEnv())
+      : Ref(GetString(env, NS_ConvertUTF8toUTF16(str))), mEnv(env) {}
+
+  MOZ_IMPLICIT StringParam(const nsACString& str, JNIEnv* env,
+                           const fallible_t& aFallible)
+      : Ref(GetString(env, str, aFallible)), mEnv(env) {}
+
+  MOZ_IMPLICIT StringParam(const nsLiteralCString& str,
+                           JNIEnv* env = Ref::FindEnv())
+      : Ref(GetString(env, NS_ConvertUTF8toUTF16(str))), mEnv(env) {}
+
+  MOZ_IMPLICIT StringParam(const char* str, JNIEnv* env = Ref::FindEnv())
+      : Ref(GetString(env, NS_ConvertUTF8toUTF16(str))), mEnv(env) {}
+
+  StringParam(StringParam&& other) : Ref(other.Get()), mEnv(other.mEnv) {
+    other.mInstance = nullptr;
+  }
+
+  ~StringParam() {
+    if (mEnv && Get()) {
+      mEnv->DeleteLocalRef(Get());
+    }
+  }
+
+  operator String::LocalRef() const {
+    // We can't return our existing ref because the returned
+    // LocalRef could be freed first, so we need a new local ref.
+    return String::LocalRef(mEnv ? mEnv : Ref::FindEnv(), *this);
+  }
+};
+
+namespace detail {
+template <typename T>
+struct TypeAdapter;
+}
+
+// Ref specialization for arrays.
+template <typename JNIType, class ElementType>
+class ArrayRefBase : public ObjectBase<TypedObject<JNIType>, JNIType> {
+ protected:
+  using Base = ObjectBase<TypedObject<JNIType>, JNIType>;
+
+ public:
+  explicit ArrayRefBase(const Context<TypedObject<JNIType>, JNIType>& ctx)
+      : Base(ctx) {}
+
+  static typename Base::LocalRef New(const ElementType* data, size_t length) {
+    using JNIElemType = typename detail::TypeAdapter<ElementType>::JNIType;
+    static_assert(sizeof(ElementType) == sizeof(JNIElemType),
+                  "Size of native type must match size of JNI type");
+    JNIEnv* const jenv = mozilla::jni::GetEnvForThread();
+    auto result = (jenv->*detail::TypeAdapter<ElementType>::NewArray)(length);
+    MOZ_CATCH_JNI_EXCEPTION(jenv);
+    (jenv->*detail::TypeAdapter<ElementType>::SetArray)(
+        result, jsize(0), length, reinterpret_cast<const JNIElemType*>(data));
+    MOZ_CATCH_JNI_EXCEPTION(jenv);
+    return Base::LocalRef::Adopt(jenv, result);
+  }
+
+  static typename Base::LocalRef New(const ElementType* data, size_t length,
+                                     const fallible_t&) {
+    using JNIElemType = typename detail::TypeAdapter<ElementType>::JNIType;
+    static_assert(sizeof(ElementType) == sizeof(JNIElemType),
+                  "Size of native type must match size of JNI type");
+    JNIEnv* const jenv = mozilla::jni::GetEnvForThread();
+    auto result = (jenv->*detail::TypeAdapter<ElementType>::NewArray)(length);
+    if (jenv->ExceptionCheck()) {
+      if (!IsOOMException(jenv)) {
+        // This exception isn't excepted due not to OOM. This is unrecoverable
+        // error.
+        MOZ_CATCH_JNI_EXCEPTION(jenv);
+      }
+#ifdef MOZ_CHECK_JNI
+      jenv->ExceptionDescribe();
+#endif
+      jenv->ExceptionClear();
+      return Base::LocalRef::Adopt(jenv, nullptr);
+    }
+    (jenv->*detail::TypeAdapter<ElementType>::SetArray)(
+        result, jsize(0), length, reinterpret_cast<const JNIElemType*>(data));
+    if (jenv->ExceptionCheck()) {
+      if (!IsOOMException(jenv)) {
+        // This exception isn't excepted due not to OOM. This is unrecoverable
+        // error.
+        MOZ_CATCH_JNI_EXCEPTION(jenv);
+      }
+#ifdef MOZ_CHECK_JNI
+      jenv->ExceptionDescribe();
+#endif
+      jenv->ExceptionClear();
+      jenv->DeleteLocalRef(result);
+      return Base::LocalRef::Adopt(jenv, nullptr);
+    }
+    return Base::LocalRef::Adopt(jenv, result);
+  }
+
+  size_t Length() const {
+    const size_t ret = Base::Env()->GetArrayLength(Base::Instance());
+    MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+    return ret;
+  }
+
+  ElementType GetElement(size_t index) const {
+    using JNIElemType = typename detail::TypeAdapter<ElementType>::JNIType;
+    static_assert(sizeof(ElementType) == sizeof(JNIElemType),
+                  "Size of native type must match size of JNI type");
+
+    ElementType ret;
+    (Base::Env()->*detail::TypeAdapter<ElementType>::GetArray)(
+        Base::Instance(), jsize(index), 1,
+        reinterpret_cast<JNIElemType*>(&ret));
+    MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+    return ret;
+  }
+
+  nsTArray<ElementType> GetElements() const {
+    using JNIElemType = typename detail::TypeAdapter<ElementType>::JNIType;
+    static_assert(sizeof(ElementType) == sizeof(JNIElemType),
+                  "Size of native type must match size of JNI type");
+
+    const size_t len = size_t(Base::Env()->GetArrayLength(Base::Instance()));
+
+    nsTArray<ElementType> array(len);
+    array.SetLength(len);
+    CopyTo(array.Elements(), len);
+    return array;
+  }
+
+  // returns number of elements copied
+  size_t CopyTo(ElementType* buffer, size_t size) const {
+    using JNIElemType = typename detail::TypeAdapter<ElementType>::JNIType;
+    static_assert(sizeof(ElementType) == sizeof(JNIElemType),
+                  "Size of native type must match size of JNI type");
+
+    const size_t len = size_t(Base::Env()->GetArrayLength(Base::Instance()));
+    const size_t amountToCopy = (len > size ? size : len);
+    (Base::Env()->*detail::TypeAdapter<ElementType>::GetArray)(
+        Base::Instance(), 0, jsize(amountToCopy),
+        reinterpret_cast<JNIElemType*>(buffer));
+    return amountToCopy;
+  }
+
+  ElementType operator[](size_t index) const { return GetElement(index); }
+
+  operator nsTArray<ElementType>() const { return GetElements(); }
+};
+
+#define DEFINE_PRIMITIVE_ARRAY_REF_HEADER(JNIType, ElementType)                \
+  template <>                                                                  \
+  class TypedObject<JNIType> : public ArrayRefBase<JNIType, ElementType> {     \
+   public:                                                                     \
+    explicit TypedObject(const Context& ctx)                                   \
+        : ArrayRefBase<JNIType, ElementType>(ctx) {}                           \
+    static typename Base::LocalRef From(const nsTArray<ElementType>& aArray) { \
+      return New(aArray.Elements(), aArray.Length());                          \
+    }
+
+#define DEFINE_PRIMITIVE_ARRAY_REF_FOOTER }
+
+#define DEFINE_PRIMITIVE_ARRAY_REF_FROM_IMPLICIT_CONVERSION(ElementType,     \
+                                                            ConvertFromType) \
+  static typename Base::LocalRef From(                                       \
+      const nsTArray<ConvertFromType>& aArray) {                             \
+    return New(reinterpret_cast<const ElementType*>(aArray.Elements()),      \
+               aArray.Length());                                             \
+  }
+
+#define DEFINE_PRIMITIVE_ARRAY_REF(JNIType, ElementType)  \
+  DEFINE_PRIMITIVE_ARRAY_REF_HEADER(JNIType, ElementType) \
+  DEFINE_PRIMITIVE_ARRAY_REF_FOOTER
+
+#define DEFINE_PRIMITIVE_ARRAY_REF_WITH_IMPLICIT_CONVERSION(           \
+    JNIType, ElementType, ConvertFromType)                             \
+  DEFINE_PRIMITIVE_ARRAY_REF_HEADER(JNIType, ElementType)              \
+  DEFINE_PRIMITIVE_ARRAY_REF_FROM_IMPLICIT_CONVERSION(ElementType,     \
+                                                      ConvertFromType) \
+  DEFINE_PRIMITIVE_ARRAY_REF_FOOTER
+
+DEFINE_PRIMITIVE_ARRAY_REF(jbooleanArray, bool);
+DEFINE_PRIMITIVE_ARRAY_REF_WITH_IMPLICIT_CONVERSION(jbyteArray, int8_t,
+                                                    uint8_t);
+DEFINE_PRIMITIVE_ARRAY_REF(jcharArray, char16_t);
+DEFINE_PRIMITIVE_ARRAY_REF_WITH_IMPLICIT_CONVERSION(jshortArray, int16_t,
+                                                    uint16_t);
+DEFINE_PRIMITIVE_ARRAY_REF_WITH_IMPLICIT_CONVERSION(jintArray, int32_t,
+                                                    uint32_t);
+DEFINE_PRIMITIVE_ARRAY_REF(jfloatArray, float);
+DEFINE_PRIMITIVE_ARRAY_REF_WITH_IMPLICIT_CONVERSION(jlongArray, int64_t,
+                                                    uint64_t);
+DEFINE_PRIMITIVE_ARRAY_REF(jdoubleArray, double);
+
+#undef DEFINE_PRIMITIVE_ARRAY_REF
+#undef DEFINE_PRIMITIVE_ARRAY_REF_WITH_IMPLICIT_CONVERSION
+#undef DEFINE_PRIMITIVE_ARRAY_HEADER
+#undef DEFINE_PRIMITIVE_ARRAY_FROM_IMPLICIT_CONVERSION
+#undef DEFINE_PRIMITIVE_ARRAY_FOOTER
+
+class ByteBuffer : public ObjectBase<ByteBuffer, jobject> {
+ public:
+  explicit ByteBuffer(const Context& ctx)
+      : ObjectBase<ByteBuffer, jobject>(ctx) {}
+
+  static LocalRef New(void* data, size_t capacity) {
+    JNIEnv* const env = GetEnvForThread();
+    const auto ret =
+        LocalRef::Adopt(env, env->NewDirectByteBuffer(data, jlong(capacity)));
+    MOZ_CATCH_JNI_EXCEPTION(env);
+    return ret;
+  }
+
+  void* Address() {
+    void* const ret = Env()->GetDirectBufferAddress(Instance());
+    MOZ_CATCH_JNI_EXCEPTION(Env());
+    return ret;
+  }
+
+  size_t Capacity() {
+    const size_t ret = size_t(Env()->GetDirectBufferCapacity(Instance()));
+    MOZ_CATCH_JNI_EXCEPTION(Env());
+    return ret;
+  }
+};
+
+template <>
+const char ObjectBase<ByteBuffer, jobject>::name[];
+
+template <>
+class TypedObject<jobjectArray>
+    : public ObjectBase<TypedObject<jobjectArray>, jobjectArray> {
+  using Base = ObjectBase<TypedObject<jobjectArray>, jobjectArray>;
+
+ public:
+  template <class Cls = Object>
+  static Base::LocalRef New(size_t length,
+                            typename Cls::Param initialElement = nullptr) {
+    JNIEnv* const env = GetEnvForThread();
+    jobjectArray array = env->NewObjectArray(
+        jsize(length), typename Cls::Context(env, nullptr).ClassRef(),
+        initialElement.Get());
+    MOZ_CATCH_JNI_EXCEPTION(env);
+    return Base::LocalRef::Adopt(env, array);
+  }
+
+  explicit TypedObject(const Context& ctx) : Base(ctx) {}
+
+  size_t Length() const {
+    const size_t ret = Base::Env()->GetArrayLength(Base::Instance());
+    MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+    return ret;
+  }
+
+  Object::LocalRef GetElement(size_t index) const {
+    auto ret = Object::LocalRef::Adopt(
+        Base::Env(),
+        Base::Env()->GetObjectArrayElement(Base::Instance(), jsize(index)));
+    MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+    return ret;
+  }
+
+  nsTArray<Object::LocalRef> GetElements() const {
+    const jsize len = size_t(Base::Env()->GetArrayLength(Base::Instance()));
+
+    nsTArray<Object::LocalRef> array((size_t(len)));
+    for (jsize i = 0; i < len; i++) {
+      array.AppendElement(Object::LocalRef::Adopt(
+          Base::Env(),
+          Base::Env()->GetObjectArrayElement(Base::Instance(), i)));
+      MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+    }
+    return array;
+  }
+
+  Object::LocalRef operator[](size_t index) const { return GetElement(index); }
+
+  operator nsTArray<Object::LocalRef>() const { return GetElements(); }
+
+  void SetElement(size_t index, Object::Param element) const {
+    Base::Env()->SetObjectArrayElement(Base::Instance(), jsize(index),
+                                       element.Get());
+    MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+  }
+};
+
+// Support conversion from LocalRef<T>* to LocalRef<Object>*:
+//   LocalRef<Foo> foo;
+//   Foo::GetFoo(&foo); // error because parameter type is LocalRef<Object>*.
+//   Foo::GetFoo(ReturnTo(&foo)); // OK because ReturnTo converts the argument.
+template <class Cls>
+class ReturnToLocal {
+ private:
+  LocalRef<Cls>* const localRef;
+  LocalRef<Object> objRef;
+
+ public:
+  explicit ReturnToLocal(LocalRef<Cls>* ref) : localRef(ref) {}
+  operator LocalRef<Object>*() { return &objRef; }
+
+  ~ReturnToLocal() {
+    if (objRef) {
+      *localRef = std::move(objRef);
+    }
+  }
+};
+
+template <class Cls>
+ReturnToLocal<Cls> ReturnTo(LocalRef<Cls>* ref) {
+  return ReturnToLocal<Cls>(ref);
+}
+
+// Support conversion from GlobalRef<T>* to LocalRef<Object/T>*:
+//   GlobalRef<Foo> foo;
+//   Foo::GetFoo(&foo); // error because parameter type is LocalRef<Foo>*.
+//   Foo::GetFoo(ReturnTo(&foo)); // OK because ReturnTo converts the argument.
+template <class Cls>
+class ReturnToGlobal {
+ private:
+  GlobalRef<Cls>* const globalRef;
+  LocalRef<Object> objRef;
+  LocalRef<Cls> clsRef;
+
+ public:
+  explicit ReturnToGlobal(GlobalRef<Cls>* ref) : globalRef(ref) {}
+  operator LocalRef<Object>*() { return &objRef; }
+  operator LocalRef<Cls>*() { return &clsRef; }
+
+  ~ReturnToGlobal() {
+    if (objRef) {
+      *globalRef = (clsRef = std::move(objRef));
+    } else if (clsRef) {
+      *globalRef = clsRef;
+    }
+  }
+};
+
+template <class Cls>
+ReturnToGlobal<Cls> ReturnTo(GlobalRef<Cls>* ref) {
+  return ReturnToGlobal<Cls>(ref);
+}
+
+// Make a LocalRef<T> from any other Ref<T>
+template <typename Cls, typename JNIType>
+LocalRef<Cls> ToLocalRef(const Ref<Cls, JNIType>& aRef) {
+  return LocalRef<Cls>(aRef);
+}
+
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_Refs_h__
diff --git a/widget/android/jni/TypeAdapter.h b/widget/android/jni/TypeAdapter.h
new file mode 100644
index 0000000000..5ab1e14bf5
--- /dev/null
+++ b/widget/android/jni/TypeAdapter.h
@@ -0,0 +1,71 @@
+/* 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_jni_TypeAdapter_h__
+#define mozilla_jni_TypeAdapter_h__
+
+#include <jni.h>
+
+#include "mozilla/jni/Refs.h"
+
+namespace mozilla {
+namespace jni {
+namespace detail {
+
+// TypeAdapter specializations are the interfaces between native/C++ types such
+// as int32_t and JNI types such as jint. The template parameter T is the native
+// type, and each TypeAdapter specialization can have the following members:
+//
+//  * Call: JNIEnv member pointer for making a method call that returns T.
+//  * StaticCall: JNIEnv member pointer for making a static call that returns T.
+//  * Get: JNIEnv member pointer for getting a field of type T.
+//  * StaticGet: JNIEnv member pointer for getting a static field of type T.
+//  * Set: JNIEnv member pointer for setting a field of type T.
+//  * StaticGet: JNIEnv member pointer for setting a static field of type T.
+//  * ToNative: static function that converts the JNI type to the native type.
+//  * FromNative: static function that converts the native type to the JNI type.
+
+template <typename T>
+struct TypeAdapter;
+
+#define DEFINE_PRIMITIVE_TYPE_ADAPTER(NativeType, JNIType, JNIName)           \
+                                                                              \
+  template <>                                                                 \
+  struct TypeAdapter<NativeType> {                                            \
+    using JNI##Type = JNIType;                                                \
+                                                                              \
+    static constexpr auto Call = &JNIEnv::Call##JNIName##MethodA;             \
+    static constexpr auto StaticCall = &JNIEnv::CallStatic##JNIName##MethodA; \
+    static constexpr auto Get = &JNIEnv::Get##JNIName##Field;                 \
+    static constexpr auto StaticGet = &JNIEnv::GetStatic##JNIName##Field;     \
+    static constexpr auto Set = &JNIEnv::Set##JNIName##Field;                 \
+    static constexpr auto StaticSet = &JNIEnv::SetStatic##JNIName##Field;     \
+    static constexpr auto GetArray = &JNIEnv::Get##JNIName##ArrayRegion;      \
+    static constexpr auto SetArray = &JNIEnv::Set##JNIName##ArrayRegion;      \
+    static constexpr auto NewArray = &JNIEnv::New##JNIName##Array;            \
+                                                                              \
+    static JNIType FromNative(JNIEnv*, NativeType val) {                      \
+      return static_cast<JNIType>(val);                                       \
+    }                                                                         \
+    static NativeType ToNative(JNIEnv*, JNIType val) {                        \
+      return static_cast<NativeType>(val);                                    \
+    }                                                                         \
+  }
+
+DEFINE_PRIMITIVE_TYPE_ADAPTER(bool, jboolean, Boolean);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(int8_t, jbyte, Byte);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(char16_t, jchar, Char);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(int16_t, jshort, Short);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(int32_t, jint, Int);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(int64_t, jlong, Long);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(float, jfloat, Float);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(double, jdouble, Double);
+
+#undef DEFINE_PRIMITIVE_TYPE_ADAPTER
+
+}  // namespace detail
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_Types_h__
diff --git a/widget/android/jni/Types.h b/widget/android/jni/Types.h
new file mode 100644
index 0000000000..1fe5fa4400
--- /dev/null
+++ b/widget/android/jni/Types.h
@@ -0,0 +1,123 @@
+/* -*- 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_jni_Types_h__
+#define mozilla_jni_Types_h__
+
+#include <jni.h>
+
+#include "mozilla/jni/Refs.h"
+#include "mozilla/jni/TypeAdapter.h"
+
+namespace mozilla {
+namespace jni {
+namespace detail {
+
+// TypeAdapter specializations are the interfaces between native/C++ types such
+// as int32_t and JNI types such as jint. The template parameter T is the native
+// type, and each TypeAdapter specialization can have the following members:
+//
+//  * Call: JNIEnv member pointer for making a method call that returns T.
+//  * StaticCall: JNIEnv member pointer for making a static call that returns T.
+//  * Get: JNIEnv member pointer for getting a field of type T.
+//  * StaticGet: JNIEnv member pointer for getting a static field of type T.
+//  * Set: JNIEnv member pointer for setting a field of type T.
+//  * StaticGet: JNIEnv member pointer for setting a static field of type T.
+//  * ToNative: static function that converts the JNI type to the native type.
+//  * FromNative: static function that converts the native type to the JNI type.
+
+// TypeAdapter<LocalRef<Cls>> applies when jobject is a return value.
+template <class Cls>
+struct TypeAdapter<LocalRef<Cls>> {
+  using JNIType = typename Cls::Ref::JNIType;
+
+  static constexpr auto Call = &JNIEnv::CallObjectMethodA;
+  static constexpr auto StaticCall = &JNIEnv::CallStaticObjectMethodA;
+  static constexpr auto Get = &JNIEnv::GetObjectField;
+  static constexpr auto StaticGet = &JNIEnv::GetStaticObjectField;
+
+  // Declare instance as jobject because JNI methods return
+  // jobject even if the return value is really jstring, etc.
+  static LocalRef<Cls> ToNative(JNIEnv* env, jobject instance) {
+    return LocalRef<Cls>::Adopt(env, JNIType(instance));
+  }
+
+  static JNIType FromNative(JNIEnv*, LocalRef<Cls>&& instance) {
+    return instance.Forget();
+  }
+};
+
+// clang is picky about function types, including attributes that modify the
+// calling convention, lining up.  GCC appears to be somewhat less so.
+#ifdef __clang__
+#  define MOZ_JNICALL_ABI JNICALL
+#else
+#  define MOZ_JNICALL_ABI
+#endif
+
+// NDK r18 made jvalue* method parameters const. We detect the change directly
+// instead of using ndk-version.h in order to remain compatible with r15 for
+// now, which doesn't include those headers.
+class CallArgs {
+  static const jvalue* test(void (JNIEnv::*)(jobject, jmethodID,
+                                             const jvalue*));
+  static jvalue* test(void (JNIEnv::*)(jobject, jmethodID, jvalue*));
+
+ public:
+  using JValueType = decltype(test(&JNIEnv::CallVoidMethodA));
+};
+
+template <class Cls>
+constexpr jobject (JNIEnv::*TypeAdapter<LocalRef<Cls>>::Call)(
+    jobject, jmethodID, CallArgs::JValueType) MOZ_JNICALL_ABI;
+template <class Cls>
+constexpr jobject (JNIEnv::*TypeAdapter<LocalRef<Cls>>::StaticCall)(
+    jclass, jmethodID, CallArgs::JValueType) MOZ_JNICALL_ABI;
+template <class Cls>
+constexpr jobject (JNIEnv::*TypeAdapter<LocalRef<Cls>>::Get)(jobject, jfieldID);
+template <class Cls>
+constexpr jobject (JNIEnv::*TypeAdapter<LocalRef<Cls>>::StaticGet)(jclass,
+                                                                   jfieldID);
+
+// TypeAdapter<Ref<Cls>> applies when jobject is a parameter value.
+template <class Cls, typename T>
+struct TypeAdapter<Ref<Cls, T>> {
+  using JNIType = typename Ref<Cls, T>::JNIType;
+
+  static constexpr auto Set = &JNIEnv::SetObjectField;
+  static constexpr auto StaticSet = &JNIEnv::SetStaticObjectField;
+
+  static DependentRef<Cls> ToNative(JNIEnv* env, JNIType instance) {
+    return DependentRef<Cls>(instance);
+  }
+
+  static JNIType FromNative(JNIEnv*, const Ref<Cls, T>& instance) {
+    return instance.Get();
+  }
+};
+
+template <class Cls, typename T>
+constexpr void (JNIEnv::*TypeAdapter<Ref<Cls, T>>::Set)(jobject, jfieldID,
+                                                        jobject);
+template <class Cls, typename T>
+constexpr void (JNIEnv::*TypeAdapter<Ref<Cls, T>>::StaticSet)(jclass, jfieldID,
+                                                              jobject);
+
+// jstring has its own Param type.
+template <>
+struct TypeAdapter<StringParam> : public TypeAdapter<String::Ref> {};
+
+template <class Cls>
+struct TypeAdapter<const Cls&> : public TypeAdapter<Cls> {};
+
+}  // namespace detail
+
+using namespace detail;
+
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_Types_h__
diff --git a/widget/android/jni/Utils.cpp b/widget/android/jni/Utils.cpp
new file mode 100644
index 0000000000..08164e4950
--- /dev/null
+++ b/widget/android/jni/Utils.cpp
@@ -0,0 +1,348 @@
+/* -*- 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 "Utils.h"
+#include "Types.h"
+
+#include <android/log.h>
+#include <pthread.h>
+
+#include "mozilla/Assertions.h"
+#include "mozilla/java/GeckoAppShellWrappers.h"
+#include "mozilla/java/GeckoThreadWrappers.h"
+
+#include "AndroidBuild.h"
+#include "nsAppShell.h"
+#include "nsExceptionHandler.h"
+
+namespace mozilla {
+namespace jni {
+
+namespace detail {
+
+#define DEFINE_PRIMITIVE_TYPE_ADAPTER(NativeType, JNIType, JNIName, ABIName)   \
+                                                                               \
+  constexpr JNIType (JNIEnv::*TypeAdapter<NativeType>::Call)(                  \
+      jobject, jmethodID, CallArgs::JValueType) MOZ_JNICALL_ABI;               \
+  constexpr JNIType (JNIEnv::*TypeAdapter<NativeType>::StaticCall)(            \
+      jclass, jmethodID, CallArgs::JValueType) MOZ_JNICALL_ABI;                \
+  constexpr JNIType (JNIEnv::*TypeAdapter<NativeType>::Get)(jobject, jfieldID) \
+      ABIName;                                                                 \
+  constexpr JNIType (JNIEnv::*TypeAdapter<NativeType>::StaticGet)(             \
+      jclass, jfieldID) ABIName;                                               \
+  constexpr void (JNIEnv::*TypeAdapter<NativeType>::Set)(jobject, jfieldID,    \
+                                                         JNIType) ABIName;     \
+  constexpr void (JNIEnv::*TypeAdapter<NativeType>::StaticSet)(                \
+      jclass, jfieldID, JNIType) ABIName;                                      \
+  constexpr void (JNIEnv::*TypeAdapter<NativeType>::GetArray)(                 \
+      JNIType##Array, jsize, jsize, JNIType*)
+
+DEFINE_PRIMITIVE_TYPE_ADAPTER(bool, jboolean, Boolean, /*nothing*/);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(int8_t, jbyte, Byte, /*nothing*/);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(char16_t, jchar, Char, /*nothing*/);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(int16_t, jshort, Short, /*nothing*/);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(int32_t, jint, Int, /*nothing*/);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(int64_t, jlong, Long, /*nothing*/);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(float, jfloat, Float, MOZ_JNICALL_ABI);
+DEFINE_PRIMITIVE_TYPE_ADAPTER(double, jdouble, Double, MOZ_JNICALL_ABI);
+
+#undef DEFINE_PRIMITIVE_TYPE_ADAPTER
+
+}  // namespace detail
+
+template <>
+const char ObjectBase<Object, jobject>::name[] = "java/lang/Object";
+template <>
+const char ObjectBase<TypedObject<jstring>, jstring>::name[] =
+    "java/lang/String";
+template <>
+const char ObjectBase<TypedObject<jclass>, jclass>::name[] = "java/lang/Class";
+template <>
+const char ObjectBase<TypedObject<jthrowable>, jthrowable>::name[] =
+    "java/lang/Throwable";
+template <>
+const char ObjectBase<BoxedObject<jboolean>, jobject>::name[] =
+    "java/lang/Boolean";
+template <>
+const char ObjectBase<BoxedObject<jbyte>, jobject>::name[] = "java/lang/Byte";
+template <>
+const char ObjectBase<BoxedObject<jchar>, jobject>::name[] =
+    "java/lang/Character";
+template <>
+const char ObjectBase<BoxedObject<jshort>, jobject>::name[] = "java/lang/Short";
+template <>
+const char ObjectBase<BoxedObject<jint>, jobject>::name[] = "java/lang/Integer";
+template <>
+const char ObjectBase<BoxedObject<jlong>, jobject>::name[] = "java/lang/Long";
+template <>
+const char ObjectBase<BoxedObject<jfloat>, jobject>::name[] = "java/lang/Float";
+template <>
+const char ObjectBase<BoxedObject<jdouble>, jobject>::name[] =
+    "java/lang/Double";
+template <>
+const char ObjectBase<TypedObject<jbooleanArray>, jbooleanArray>::name[] = "[Z";
+template <>
+const char ObjectBase<TypedObject<jbyteArray>, jbyteArray>::name[] = "[B";
+template <>
+const char ObjectBase<TypedObject<jcharArray>, jcharArray>::name[] = "[C";
+template <>
+const char ObjectBase<TypedObject<jshortArray>, jshortArray>::name[] = "[S";
+template <>
+const char ObjectBase<TypedObject<jintArray>, jintArray>::name[] = "[I";
+template <>
+const char ObjectBase<TypedObject<jlongArray>, jlongArray>::name[] = "[J";
+template <>
+const char ObjectBase<TypedObject<jfloatArray>, jfloatArray>::name[] = "[F";
+template <>
+const char ObjectBase<TypedObject<jdoubleArray>, jdoubleArray>::name[] = "[D";
+template <>
+const char ObjectBase<TypedObject<jobjectArray>, jobjectArray>::name[] =
+    "[Ljava/lang/Object;";
+template <>
+const char ObjectBase<ByteBuffer, jobject>::name[] = "java/nio/ByteBuffer";
+
+JavaVM* sJavaVM;
+JNIEnv* sGeckoThreadEnv;
+
+namespace {
+
+pthread_key_t sThreadEnvKey;
+jclass sOOMErrorClass;
+jobject sClassLoader;
+jmethodID sClassLoaderLoadClass;
+
+void UnregisterThreadEnv(void* env) {
+  if (!env) {
+    // We were never attached.
+    return;
+  }
+  // The thread may have already been detached. In that case, it's still
+  // okay to call DetachCurrentThread(); it'll simply return an error.
+  // However, we must not access | env | because it may be invalid.
+  MOZ_ASSERT(sJavaVM);
+  sJavaVM->DetachCurrentThread();
+}
+
+}  // namespace
+
+void SetGeckoThreadEnv(JNIEnv* aEnv) {
+  MOZ_ASSERT(aEnv);
+  MOZ_ASSERT(!sGeckoThreadEnv || sGeckoThreadEnv == aEnv);
+
+  if (!sGeckoThreadEnv &&
+      pthread_key_create(&sThreadEnvKey, UnregisterThreadEnv)) {
+    MOZ_CRASH("Failed to initialize required TLS");
+  }
+
+  sGeckoThreadEnv = aEnv;
+  MOZ_ALWAYS_TRUE(!pthread_setspecific(sThreadEnvKey, aEnv));
+
+  MOZ_ALWAYS_TRUE(!aEnv->GetJavaVM(&sJavaVM));
+  MOZ_ASSERT(sJavaVM);
+
+  sOOMErrorClass =
+      Class::GlobalRef(
+          Class::LocalRef::Adopt(aEnv->FindClass("java/lang/OutOfMemoryError")))
+          .Forget();
+  aEnv->ExceptionClear();
+
+  sClassLoader = Object::GlobalRef(java::GeckoThread::ClsLoader()).Forget();
+  sClassLoaderLoadClass = aEnv->GetMethodID(
+      Class::LocalRef::Adopt(aEnv->GetObjectClass(sClassLoader)).Get(),
+      "loadClass", "(Ljava/lang/String;)Ljava/lang/Class;");
+  MOZ_ASSERT(sClassLoader && sClassLoaderLoadClass);
+}
+
+JNIEnv* GetEnvForThread() {
+  MOZ_ASSERT(sGeckoThreadEnv);
+
+  JNIEnv* env = static_cast<JNIEnv*>(pthread_getspecific(sThreadEnvKey));
+  if (env) {
+    return env;
+  }
+
+  // We don't have a saved JNIEnv, so try to get one.
+  // AttachCurrentThread() does the same thing as GetEnv() when a thread is
+  // already attached, so we don't have to call GetEnv() at all.
+  if (!sJavaVM->AttachCurrentThread(&env, nullptr)) {
+    MOZ_ASSERT(env);
+    MOZ_ALWAYS_TRUE(!pthread_setspecific(sThreadEnvKey, env));
+    return env;
+  }
+
+  MOZ_CRASH("Failed to get JNIEnv for thread");
+  return nullptr;  // unreachable
+}
+
+bool ThrowException(JNIEnv* aEnv, const char* aClass, const char* aMessage) {
+  MOZ_ASSERT(aEnv, "Invalid thread JNI env");
+
+  Class::LocalRef cls = Class::LocalRef::Adopt(aEnv->FindClass(aClass));
+  MOZ_ASSERT(cls, "Cannot find exception class");
+
+  return !aEnv->ThrowNew(cls.Get(), aMessage);
+}
+
+bool HandleUncaughtException(JNIEnv* aEnv) {
+  MOZ_ASSERT(aEnv, "Invalid thread JNI env");
+
+  if (!aEnv->ExceptionCheck()) {
+    return false;
+  }
+
+#ifdef MOZ_CHECK_JNI
+  aEnv->ExceptionDescribe();
+#endif
+
+  Throwable::LocalRef e =
+      Throwable::LocalRef::Adopt(aEnv, aEnv->ExceptionOccurred());
+  MOZ_ASSERT(e);
+  aEnv->ExceptionClear();
+
+  String::LocalRef stack = java::GeckoAppShell::GetExceptionStackTrace(e);
+  if (stack && ReportException(aEnv, e.Get(), stack.Get())) {
+    return true;
+  }
+
+  aEnv->ExceptionClear();
+  java::GeckoAppShell::HandleUncaughtException(e);
+
+  if (NS_WARN_IF(aEnv->ExceptionCheck())) {
+    aEnv->ExceptionDescribe();
+    aEnv->ExceptionClear();
+  }
+
+  return true;
+}
+
+bool ReportException(JNIEnv* aEnv, jthrowable aExc, jstring aStack) {
+  bool result = true;
+
+  result &= NS_SUCCEEDED(CrashReporter::AnnotateCrashReport(
+      CrashReporter::Annotation::JavaStackTrace,
+      String::Ref::From(aStack)->ToCString()));
+
+  auto appNotes = java::GeckoAppShell::GetAppNotes();
+  if (NS_WARN_IF(aEnv->ExceptionCheck())) {
+    aEnv->ExceptionDescribe();
+    aEnv->ExceptionClear();
+  } else if (appNotes) {
+    CrashReporter::AppendAppNotesToCrashReport("\n"_ns + appNotes->ToCString());
+  }
+
+  if (sOOMErrorClass && aEnv->IsInstanceOf(aExc, sOOMErrorClass)) {
+    NS_ABORT_OOM(0);  // Unknown OOM size
+  }
+  return result;
+}
+
+namespace {
+
+jclass sJNIObjectClass;
+jfieldID sJNIObjectHandleField;
+
+bool EnsureJNIObject(JNIEnv* env, jobject instance) {
+  if (!sJNIObjectClass) {
+    sJNIObjectClass =
+        Class::GlobalRef(Class::LocalRef::Adopt(GetClassRef(
+                             env, "org/mozilla/gecko/mozglue/JNIObject")))
+            .Forget();
+
+    sJNIObjectHandleField = env->GetFieldID(sJNIObjectClass, "mHandle", "J");
+  }
+
+  MOZ_ASSERT(env->IsInstanceOf(instance, sJNIObjectClass),
+             "Java class is not derived from JNIObject");
+  return true;
+}
+
+}  // namespace
+
+uintptr_t GetNativeHandle(JNIEnv* env, jobject instance) {
+  if (!EnsureJNIObject(env, instance)) {
+    return 0;
+  }
+
+  return static_cast<uintptr_t>(
+      env->GetLongField(instance, sJNIObjectHandleField));
+}
+
+void SetNativeHandle(JNIEnv* env, jobject instance, uintptr_t handle) {
+  if (!EnsureJNIObject(env, instance)) {
+    return;
+  }
+
+  env->SetLongField(instance, sJNIObjectHandleField,
+                    static_cast<jlong>(handle));
+}
+
+jclass GetClassRef(JNIEnv* aEnv, const char* aClassName) {
+  // First try the default class loader.
+  auto classRef = Class::LocalRef::Adopt(aEnv, aEnv->FindClass(aClassName));
+
+  if ((!classRef || aEnv->ExceptionCheck()) && sClassLoader) {
+    // If the default class loader failed but we have an app class loader, try
+    // that. Clear the pending exception from failed FindClass call above.
+    aEnv->ExceptionClear();
+    classRef = Class::LocalRef::Adopt(
+        aEnv,
+        jclass(aEnv->CallObjectMethod(sClassLoader, sClassLoaderLoadClass,
+                                      StringParam(aClassName, aEnv).Get())));
+  }
+
+  if (classRef && !aEnv->ExceptionCheck()) {
+    return classRef.Forget();
+  }
+
+  __android_log_print(
+      ANDROID_LOG_ERROR, "Gecko",
+      ">>> FATAL JNI ERROR! FindClass(\"%s\") failed. "
+      "Does the class require a newer API version? "
+      "Or did ProGuard optimize away something it shouldn't have?",
+      aClassName);
+  aEnv->ExceptionDescribe();
+  MOZ_CRASH("Cannot find JNI class");
+  return nullptr;
+}
+
+void DispatchToGeckoPriorityQueue(already_AddRefed<nsIRunnable> aCall) {
+  class RunnableEvent : public nsAppShell::Event {
+    nsCOMPtr<nsIRunnable> mCall;
+
+   public:
+    explicit RunnableEvent(already_AddRefed<nsIRunnable> aCall)
+        : mCall(aCall) {}
+    void Run() override { NS_ENSURE_SUCCESS_VOID(mCall->Run()); }
+  };
+
+  nsAppShell::PostEvent(MakeUnique<RunnableEvent>(std::move(aCall)));
+}
+
+int GetAPIVersion() {
+  static int32_t apiVersion = 0;
+  if (!apiVersion && IsAvailable()) {
+    apiVersion = java::sdk::Build::VERSION::SDK_INT();
+  }
+  return apiVersion;
+}
+
+pid_t GetUIThreadId() {
+  static pid_t uiThreadId;
+  if (!uiThreadId) {
+    uiThreadId = pid_t(java::GeckoThread::UiThreadId());
+  }
+  return uiThreadId;
+}
+
+bool IsOOMException(JNIEnv* aEnv) {
+  MOZ_ASSERT(aEnv->ExceptionCheck());
+  Throwable::LocalRef e =
+      Throwable::LocalRef::Adopt(aEnv, aEnv->ExceptionOccurred());
+  return sOOMErrorClass && aEnv->IsInstanceOf(e.Get(), sOOMErrorClass);
+}
+
+}  // namespace jni
+}  // namespace mozilla
diff --git a/widget/android/jni/Utils.h b/widget/android/jni/Utils.h
new file mode 100644
index 0000000000..adcafeb44e
--- /dev/null
+++ b/widget/android/jni/Utils.h
@@ -0,0 +1,150 @@
+/* -*- 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_jni_Utils_h__
+#define mozilla_jni_Utils_h__
+
+#include <jni.h>
+
+#include "nsIRunnable.h"
+
+#include "mozilla/UniquePtr.h"
+
+#if defined(DEBUG) || !defined(RELEASE_OR_BETA)
+#  define MOZ_CHECK_JNI
+#endif
+
+#ifdef MOZ_CHECK_JNI
+#  include <unistd.h>
+#  include "mozilla/Assertions.h"
+#  include "APKOpen.h"
+#  include "MainThreadUtils.h"
+#endif
+
+namespace mozilla {
+namespace jni {
+
+// How exception during a JNI call should be treated.
+enum class ExceptionMode {
+  // Abort on unhandled excepion (default).
+  ABORT,
+  // Ignore the exception and return to caller.
+  IGNORE,
+  // Catch any exception and return a nsresult.
+  NSRESULT,
+};
+
+// Thread that a particular JNI call is allowed on.
+enum class CallingThread {
+  // Can be called from any thread (default).
+  ANY,
+  // Can be called from the Gecko thread.
+  GECKO,
+  // Can be called from the Java UI thread.
+  UI,
+};
+
+// If and where a JNI call will be dispatched.
+enum class DispatchTarget {
+  // Call happens synchronously on the calling thread (default).
+  CURRENT,
+  // Call happens synchronously on the calling thread, but the call is
+  // wrapped in a function object and is passed thru UsesNativeCallProxy.
+  // Method must return void.
+  PROXY,
+  // Call is dispatched asynchronously on the Gecko thread to the XPCOM
+  // (nsThread) event queue. Method must return void.
+  GECKO,
+  // Call is dispatched asynchronously on the Gecko thread to the widget
+  // (nsAppShell) event queue. In most cases, events in the widget event
+  // queue (aka native event queue) are favored over events in the XPCOM
+  // event queue. Method must return void.
+  GECKO_PRIORITY,
+};
+
+extern JavaVM* sJavaVM;
+extern JNIEnv* sGeckoThreadEnv;
+
+inline bool IsAvailable() { return !!sGeckoThreadEnv; }
+
+inline JavaVM* GetVM() {
+#ifdef MOZ_CHECK_JNI
+  MOZ_ASSERT(sJavaVM);
+#endif
+  return sJavaVM;
+}
+
+inline JNIEnv* GetGeckoThreadEnv() {
+#ifdef MOZ_CHECK_JNI
+  MOZ_RELEASE_ASSERT(NS_IsMainThread(), "Must be on Gecko thread");
+  MOZ_RELEASE_ASSERT(sGeckoThreadEnv, "Must have a JNIEnv");
+#endif
+  return sGeckoThreadEnv;
+}
+
+void SetGeckoThreadEnv(JNIEnv* aEnv);
+
+JNIEnv* GetEnvForThread();
+
+#ifdef MOZ_CHECK_JNI
+#  define MOZ_ASSERT_JNI_THREAD(thread)                            \
+    do {                                                           \
+      if ((thread) == mozilla::jni::CallingThread::GECKO) {        \
+        MOZ_RELEASE_ASSERT(::NS_IsMainThread());                   \
+      } else if ((thread) == mozilla::jni::CallingThread::UI) {    \
+        const bool isOnUiThread = (GetUIThreadId() == ::gettid()); \
+        MOZ_RELEASE_ASSERT(isOnUiThread);                          \
+      }                                                            \
+    } while (0)
+#else
+#  define MOZ_ASSERT_JNI_THREAD(thread) \
+    do {                                \
+    } while (0)
+#endif
+
+bool ThrowException(JNIEnv* aEnv, const char* aClass, const char* aMessage);
+
+inline bool ThrowException(JNIEnv* aEnv, const char* aMessage) {
+  return ThrowException(aEnv, "java/lang/Exception", aMessage);
+}
+
+inline bool ThrowException(const char* aClass, const char* aMessage) {
+  return ThrowException(GetEnvForThread(), aClass, aMessage);
+}
+
+inline bool ThrowException(const char* aMessage) {
+  return ThrowException(GetEnvForThread(), aMessage);
+}
+
+bool HandleUncaughtException(JNIEnv* aEnv);
+
+bool ReportException(JNIEnv* aEnv, jthrowable aExc, jstring aStack);
+
+#define MOZ_CATCH_JNI_EXCEPTION(env)                    \
+  do {                                                  \
+    if (mozilla::jni::HandleUncaughtException((env))) { \
+      MOZ_CRASH("JNI exception");                       \
+    }                                                   \
+  } while (0)
+
+uintptr_t GetNativeHandle(JNIEnv* env, jobject instance);
+
+void SetNativeHandle(JNIEnv* env, jobject instance, uintptr_t handle);
+
+jclass GetClassRef(JNIEnv* aEnv, const char* aClassName);
+
+void DispatchToGeckoPriorityQueue(already_AddRefed<nsIRunnable> aCall);
+
+int GetAPIVersion();
+
+pid_t GetUIThreadId();
+
+bool IsOOMException(JNIEnv* aEnv);
+
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_Utils_h__
diff --git a/widget/android/jni/moz.build b/widget/android/jni/moz.build
new file mode 100644
index 0000000000..53bef6663f
--- /dev/null
+++ b/widget/android/jni/moz.build
@@ -0,0 +1,36 @@
+# -*- 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 = ("GeckoView", "General")
+
+EXPORTS.mozilla.jni += [
+    "Accessors.h",
+    "Conversions.h",
+    "GeckoBundleUtils.h",
+    "GeckoResultUtils.h",
+    "Natives.h",
+    "NativesInlines.h",
+    "Refs.h",
+    "TypeAdapter.h",
+    "Types.h",
+    "Utils.h",
+]
+
+UNIFIED_SOURCES += [
+    "Conversions.cpp",
+    "GeckoBundleUtils.cpp",
+    "Utils.cpp",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"
+
+LOCAL_INCLUDES += [
+    "/widget",
+    "/widget/android",
+]
diff --git a/widget/android/moz.build b/widget/android/moz.build
new file mode 100644
index 0000000000..ca05de848b
--- /dev/null
+++ b/widget/android/moz.build
@@ -0,0 +1,201 @@
+# -*- 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 = ("GeckoView", "General")
+    SCHEDULES.exclusive = ["android"]
+
+with Files("*CompositorWidget*"):
+    BUG_COMPONENT = ("Core", "Graphics")
+
+DIRS += [
+    "bindings",
+    "jni",
+]
+
+XPIDL_SOURCES += [
+    "nsIAndroidBridge.idl",
+]
+
+XPIDL_MODULE = "widget_android"
+
+EXPORTS += [
+    "AndroidBridge.h",
+]
+
+classes_with_WrapForJNI = [
+    "AndroidGamepadManager",
+    "AndroidVsync",
+    "Base64Utils",
+    "Clipboard",
+    "CodecProxy",
+    "CompositorSurfaceManager",
+    "EnterpriseRoots",
+    "EventCallback",
+    "EventDispatcher",
+    "GeckoAppShell",
+    "GeckoAudioInfo",
+    "GeckoBatteryManager",
+    "GeckoBundle",
+    "GeckoEditableChild",
+    "GeckoHLSDemuxerWrapper",
+    "GeckoHLSResourceWrapper",
+    "GeckoHLSSample",
+    "GeckoInputStream",
+    "GeckoJavaSampler",
+    "GeckoNetworkManager",
+    "GeckoProcessManager",
+    "GeckoProcessType",
+    "GeckoResult",
+    "GeckoRuntime",
+    "GeckoServiceChildProcess",
+    "GeckoServiceGpuProcess",
+    "GeckoSession",
+    "GeckoSurface",
+    "GeckoSurfaceTexture",
+    "GeckoSystemStateListener",
+    "GeckoThread",
+    "GeckoVRManager",
+    "GeckoVideoInfo",
+    "GeckoWebExecutor",
+    "HardwareCodecCapabilityUtils",
+    "Image",
+    "ImageDecoder",
+    "MediaDrmProxy",
+    "PanZoomController",
+    "RuntimeTelemetry",
+    "Sample",
+    "SampleBuffer",
+    "ScreenManagerHelper",
+    "ServiceAllocator",
+    "SessionAccessibility",
+    "SessionKeyInfo",
+    "SessionTextInput",
+    "SpeechSynthesisService",
+    "SurfaceAllocator",
+    "SurfaceControlManager",
+    "SurfaceTextureListener",
+    "TelemetryUtils",
+    "WebAuthnTokenManager",
+    "WebMessage",
+    "WebNotification",
+    "WebNotificationDelegate",
+    "WebRequest",
+    "WebRequestError",
+    "WebResponse",
+    "XPCOMEventTarget",
+]
+
+natives_from_WrapForJNI = sorted(
+    ["GeneratedJNI/{}Natives.h".format(c) for c in classes_with_WrapForJNI]
+)
+
+wrappers_from_WrapForJNI = sorted(
+    ["GeneratedJNI/{}Wrappers.h".format(c) for c in classes_with_WrapForJNI]
+)
+
+sources_from_WrapForJNI = sorted(
+    "GeneratedJNI{}Wrappers.cpp".format(c) for c in classes_with_WrapForJNI
+)
+
+EXPORTS.mozilla.widget += [
+    "AndroidCompositorWidget.h",
+    "AndroidUiThread.h",
+    "AndroidView.h",
+    "AndroidVsync.h",
+    "CompositorWidgetChild.h",
+    "CompositorWidgetParent.h",
+    "EventDispatcher.h",
+    "GeckoViewSupport.h",
+    "InProcessAndroidCompositorWidget.h",
+    "nsWindow.h",
+    "WindowEvent.h",
+]
+
+EXPORTS.mozilla.java += ["!{}".format(c) for c in natives_from_WrapForJNI]
+
+EXPORTS.mozilla.java += ["!{}".format(c) for c in wrappers_from_WrapForJNI]
+
+SOURCES += ["!{}".format(c) for c in sources_from_WrapForJNI]
+
+SOURCES += [
+    "MediaKeysEventSourceFactory.cpp",
+]
+
+UNIFIED_SOURCES += [
+    "AndroidAlerts.cpp",
+    "AndroidBridge.cpp",
+    "AndroidCompositorWidget.cpp",
+    "AndroidContentController.cpp",
+    "AndroidUiThread.cpp",
+    "AndroidVsync.cpp",
+    "CompositorWidgetChild.cpp",
+    "CompositorWidgetParent.cpp",
+    "EventDispatcher.cpp",
+    "GeckoEditableSupport.cpp",
+    "GeckoProcessManager.cpp",
+    "GfxInfo.cpp",
+    "ImageDecoderSupport.cpp",
+    "InProcessAndroidCompositorWidget.cpp",
+    "nsAppShell.cpp",
+    "nsClipboard.cpp",
+    "nsDeviceContextAndroid.cpp",
+    "nsLookAndFeel.cpp",
+    "nsPrintSettingsServiceAndroid.cpp",
+    "nsUserIdleServiceAndroid.cpp",
+    "nsWidgetFactory.cpp",
+    "nsWindow.cpp",
+    "ScreenHelperAndroid.cpp",
+    "WebExecutorSupport.cpp",
+]
+
+XPCOM_MANIFESTS += [
+    "components.conf",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+# The recursive make backend treats the first output specially: it's passed as
+# an open FileAvoidWrite to the invoked script.  That doesn't work well with
+# the Gradle task that generates all of the outputs, so we add a dummy first
+# output.
+
+t = tuple(
+    ["generated_jni_wrappers"]
+    + natives_from_WrapForJNI
+    + sources_from_WrapForJNI
+    + wrappers_from_WrapForJNI
+)
+
+GeneratedFile(
+    *t,
+    script="/mobile/android/gradle.py",
+    entry_point="generate_generated_jni_wrappers"
+)
+
+FINAL_LIBRARY = "xul"
+
+LOCAL_INCLUDES += [
+    "/docshell/base",
+    "/dom/base",
+    "/dom/system/android",
+    "/gfx/2d",
+    "/gfx/vr",
+    "/layout/forms",
+    "/layout/painting",
+    "/netwerk/base",
+    "/toolkit/components/telemetry",
+    "/widget",
+    "/widget/headless",
+    "/xpcom/threads",
+]
+
+OS_LIBS += ["android"]
+
+if CONFIG["MOZ_NATIVE_DEVICES"]:
+    DEFINES["MOZ_NATIVE_DEVICES"] = True
+
+# DEFINES['DEBUG_WIDGETS'] = True
diff --git a/widget/android/nsAppShell.cpp b/widget/android/nsAppShell.cpp
new file mode 100644
index 0000000000..28389184a0
--- /dev/null
+++ b/widget/android/nsAppShell.cpp
@@ -0,0 +1,753 @@
+/* -*- 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 "nsAppShell.h"
+
+#include "base/basictypes.h"
+#include "base/message_loop.h"
+#include "base/task.h"
+#include "mozilla/Hal.h"
+#include "gfxConfig.h"
+#include "nsExceptionHandler.h"
+#include "nsIScreen.h"
+#include "nsWindow.h"
+#include "nsThreadUtils.h"
+#include "nsIObserverService.h"
+#include "nsIAppStartup.h"
+#include "nsIGeolocationProvider.h"
+#include "nsIDOMWakeLockListener.h"
+#include "nsIPowerManagerService.h"
+#include "nsISpeculativeConnect.h"
+#include "nsIURIFixup.h"
+#include "nsCategoryManagerUtils.h"
+#include "mozilla/dom/GeolocationPosition.h"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/AppShutdown.h"
+#include "mozilla/Components.h"
+#include "mozilla/Services.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/Hal.h"
+#include "mozilla/dom/BrowserChild.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/intl/OSPreferences.h"
+#include "mozilla/ipc/GeckoChildProcessHost.h"
+#include "mozilla/java/GeckoAppShellNatives.h"
+#include "mozilla/java/GeckoResultWrappers.h"
+#include "mozilla/java/GeckoThreadNatives.h"
+#include "mozilla/java/XPCOMEventTargetNatives.h"
+#include "mozilla/widget/ScreenManager.h"
+#include "prenv.h"
+#include "prtime.h"
+
+#include "AndroidBridge.h"
+#include "AndroidBridgeUtilities.h"
+#include "AndroidSurfaceTexture.h"
+#include <android/log.h>
+#include <pthread.h>
+#include <wchar.h>
+
+#ifdef MOZ_ANDROID_HISTORY
+#  include "nsNetUtil.h"
+#  include "nsIURI.h"
+#  include "IHistory.h"
+#endif
+
+#ifdef MOZ_LOGGING
+#  include "mozilla/Logging.h"
+#endif
+
+#include "AndroidAlerts.h"
+#include "AndroidUiThread.h"
+#include "GeckoBatteryManager.h"
+#include "GeckoEditableSupport.h"
+#include "GeckoNetworkManager.h"
+#include "GeckoProcessManager.h"
+#include "GeckoSystemStateListener.h"
+#include "GeckoTelemetryDelegate.h"
+#include "GeckoVRManager.h"
+#include "ImageDecoderSupport.h"
+#include "JavaBuiltins.h"
+#include "ScreenHelperAndroid.h"
+#include "Telemetry.h"
+#include "WebExecutorSupport.h"
+#include "Base64UtilsSupport.h"
+
+#ifdef DEBUG_ANDROID_EVENTS
+#  define EVLOG(args...) ALOG(args)
+#else
+#  define EVLOG(args...) \
+    do {                 \
+    } while (0)
+#endif
+
+using namespace mozilla;
+using namespace mozilla::widget;
+
+nsIGeolocationUpdate* gLocationCallback = nullptr;
+
+nsAppShell* nsAppShell::sAppShell;
+StaticAutoPtr<Mutex> nsAppShell::sAppShellLock;
+
+NS_IMPL_ISUPPORTS_INHERITED(nsAppShell, nsBaseAppShell, nsIObserver)
+
+class WakeLockListener final : public nsIDOMMozWakeLockListener {
+ private:
+  ~WakeLockListener() {}
+
+ public:
+  NS_DECL_ISUPPORTS;
+
+  nsresult Callback(const nsAString& topic, const nsAString& state) override {
+    java::GeckoAppShell::NotifyWakeLockChanged(topic, state);
+    return NS_OK;
+  }
+};
+
+NS_IMPL_ISUPPORTS(WakeLockListener, nsIDOMMozWakeLockListener)
+nsCOMPtr<nsIPowerManagerService> sPowerManagerService = nullptr;
+StaticRefPtr<WakeLockListener> sWakeLockListener;
+
+class GeckoThreadSupport final
+    : public java::GeckoThread::Natives<GeckoThreadSupport> {
+  // When this number goes above 0, the app is paused. When less than or
+  // equal to zero, the app is resumed.
+  static int32_t sPauseCount;
+
+ public:
+  static void SpeculativeConnect(jni::String::Param aUriStr) {
+    if (!NS_IsMainThread()) {
+      // We will be on the main thread if the call was queued on the Java
+      // side during startup. Otherwise, the call was not queued, which
+      // means Gecko is already sufficiently loaded, and we don't really
+      // care about speculative connections at this point.
+      return;
+    }
+
+    nsCOMPtr<nsIIOService> ioServ = do_GetIOService();
+    nsCOMPtr<nsISpeculativeConnect> specConn = do_QueryInterface(ioServ);
+    if (!specConn) {
+      return;
+    }
+
+    nsCOMPtr<nsIURI> uri = nsAppShell::ResolveURI(aUriStr->ToCString());
+    if (!uri) {
+      return;
+    }
+
+    OriginAttributes attrs;
+    nsCOMPtr<nsIPrincipal> principal =
+        BasePrincipal::CreateContentPrincipal(uri, attrs);
+    specConn->SpeculativeConnect(uri, principal, nullptr, false);
+  }
+
+  static void OnPause() {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    sPauseCount++;
+    // If sPauseCount is now 1, we just crossed the threshold from "resumed"
+    // "paused". so we should notify observers and so on.
+    if (sPauseCount != 1) {
+      return;
+    }
+
+    nsCOMPtr<nsIObserverService> obsServ =
+        mozilla::services::GetObserverService();
+    obsServ->NotifyObservers(nullptr, "application-background", nullptr);
+
+    obsServ->NotifyObservers(nullptr, "memory-pressure", u"heap-minimize");
+
+    // We really want to send a notification like profile-before-change,
+    // but profile-before-change ends up shutting some things down instead
+    // of flushing data
+    Preferences* prefs = static_cast<Preferences*>(Preferences::GetService());
+    if (prefs) {
+      // Force a main thread blocking save
+      prefs->SavePrefFileBlocking();
+    }
+  }
+
+  static void OnResume() {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    sPauseCount--;
+    // If sPauseCount is now 0, we just crossed the threshold from "paused"
+    // to "resumed", so we should notify observers and so on.
+    if (sPauseCount != 0) {
+      return;
+    }
+
+    // We didn't return from one of our own activities, so restore
+    // to foreground status
+    nsCOMPtr<nsIObserverService> obsServ =
+        mozilla::services::GetObserverService();
+    obsServ->NotifyObservers(nullptr, "application-foreground", nullptr);
+  }
+
+  static void CreateServices(jni::String::Param aCategory,
+                             jni::String::Param aData) {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    nsCString category(aCategory->ToCString());
+
+    NS_CreateServicesFromCategory(category.get(),
+                                  nullptr,  // aOrigin
+                                  category.get(),
+                                  aData ? aData->ToString().get() : nullptr);
+  }
+
+  static int64_t RunUiThreadCallback() { return RunAndroidUiTasks(); }
+
+  static void ForceQuit() {
+    nsCOMPtr<nsIAppStartup> appStartup = components::AppStartup::Service();
+
+    if (appStartup) {
+      bool userAllowedQuit = true;
+      appStartup->Quit(nsIAppStartup::eForceQuit, 0, &userAllowedQuit);
+    }
+  }
+
+  static void Crash() {
+    printf_stderr("Intentionally crashing...\n");
+    MOZ_CRASH("intentional crash");
+  }
+};
+
+int32_t GeckoThreadSupport::sPauseCount;
+
+class GeckoAppShellSupport final
+    : public java::GeckoAppShell::Natives<GeckoAppShellSupport> {
+ public:
+  static void ReportJavaCrash(const jni::Class::LocalRef& aCls,
+                              jni::Throwable::Param aException,
+                              jni::String::Param aStack) {
+    if (!jni::ReportException(aCls.Env(), aException.Get(), aStack.Get())) {
+      // Only crash below if crash reporter is initialized and annotation
+      // succeeded. Otherwise try other means of reporting the crash in
+      // Java.
+      return;
+    }
+
+    MOZ_CRASH("Uncaught Java exception");
+  }
+
+  static void NotifyObservers(jni::String::Param aTopic,
+                              jni::String::Param aData) {
+    MOZ_ASSERT(NS_IsMainThread());
+    MOZ_ASSERT(aTopic);
+
+    nsCOMPtr<nsIObserverService> obsServ = services::GetObserverService();
+    if (!obsServ) {
+      return;
+    }
+
+    obsServ->NotifyObservers(nullptr, aTopic->ToCString().get(),
+                             aData ? aData->ToString().get() : nullptr);
+  }
+
+  static void AppendAppNotesToCrashReport(jni::String::Param aNotes) {
+    MOZ_ASSERT(NS_IsMainThread());
+    MOZ_ASSERT(aNotes);
+    CrashReporter::AppendAppNotesToCrashReport(aNotes->ToCString());
+  }
+
+  static void OnSensorChanged(int32_t aType, float aX, float aY, float aZ,
+                              float aW, int64_t aTime) {
+    AutoTArray<float, 4> values;
+
+    switch (aType) {
+      // Bug 938035, transfer HAL data for orientation sensor to meet w3c
+      // spec, ex: HAL report alpha=90 means East but alpha=90 means West
+      // in w3c spec
+      case hal::SENSOR_ORIENTATION:
+        values.AppendElement(360.0f - aX);
+        values.AppendElement(-aY);
+        values.AppendElement(-aZ);
+        break;
+
+      case hal::SENSOR_LINEAR_ACCELERATION:
+      case hal::SENSOR_ACCELERATION:
+      case hal::SENSOR_GYROSCOPE:
+        values.AppendElement(aX);
+        values.AppendElement(aY);
+        values.AppendElement(aZ);
+        break;
+
+      case hal::SENSOR_LIGHT:
+        values.AppendElement(aX);
+        break;
+
+      case hal::SENSOR_ROTATION_VECTOR:
+      case hal::SENSOR_GAME_ROTATION_VECTOR:
+        values.AppendElement(aX);
+        values.AppendElement(aY);
+        values.AppendElement(aZ);
+        values.AppendElement(aW);
+        break;
+
+      default:
+        __android_log_print(ANDROID_LOG_ERROR, "Gecko",
+                            "Unknown sensor type %d", aType);
+    }
+
+    hal::SensorData sdata(hal::SensorType(aType), aTime, values);
+    hal::NotifySensorChange(sdata);
+  }
+
+  static void OnLocationChanged(double aLatitude, double aLongitude,
+                                double aAltitude, float aAccuracy,
+                                float aAltitudeAccuracy, float aHeading,
+                                float aSpeed) {
+    if (!gLocationCallback) {
+      return;
+    }
+
+    static constexpr float kEpsilon = 0.0001f;
+    double heading = (aHeading >= kEpsilon && aHeading < (360.0f - kEpsilon) &&
+                      aSpeed > kEpsilon)
+                         ? aHeading
+                         : UnspecifiedNaN<double>();
+
+    RefPtr<nsIDOMGeoPosition> geoPosition(new nsGeoPosition(
+        aLatitude, aLongitude, aAltitude, aAccuracy, aAltitudeAccuracy, heading,
+        aSpeed, PR_Now() / PR_USEC_PER_MSEC));
+    gLocationCallback->Update(geoPosition);
+  }
+
+  static void NotifyAlertListener(jni::String::Param aName,
+                                  jni::String::Param aTopic,
+                                  jni::String::Param aCookie) {
+    if (!aName || !aTopic || !aCookie) {
+      return;
+    }
+
+    widget::AndroidAlerts::NotifyListener(aName->ToString(),
+                                          aTopic->ToCString().get(),
+                                          aCookie->ToString().get());
+  }
+
+  static bool IsParentProcess() { return XRE_IsParentProcess(); }
+
+  static jni::Object::LocalRef IsGpuProcessEnabled() {
+    java::GeckoResult::GlobalRef result = java::GeckoResult::New();
+
+    NS_DispatchToMainThread(NS_NewRunnableFunction(
+        "GeckoAppShellSupport::IsGpuProcessEnabled", [result]() {
+          result->Complete(gfx::gfxConfig::IsEnabled(gfx::Feature::GPU_PROCESS)
+                               ? java::sdk::Boolean::TRUE()
+                               : java::sdk::Boolean::FALSE());
+        }));
+
+    return jni::Object::Ref::From(result);
+  }
+};
+
+class XPCOMEventTargetWrapper final
+    : public java::XPCOMEventTarget::Natives<XPCOMEventTargetWrapper> {
+ public:
+  // Wraps a java runnable into an XPCOM runnable and dispatches it to mTarget.
+  void DispatchNative(mozilla::jni::Object::Param aJavaRunnable) {
+    if (AppShutdown::GetCurrentShutdownPhase() >=
+        ShutdownPhase::XPCOMShutdownThreads) {
+      // No point in trying to dispatch this if we're already shutting down.
+      return;
+    }
+    java::XPCOMEventTarget::JNIRunnable::GlobalRef r =
+        java::XPCOMEventTarget::JNIRunnable::Ref::From(aJavaRunnable);
+    mTarget->Dispatch(NS_NewRunnableFunction(
+        "XPCOMEventTargetWrapper::DispatchNative",
+        [runnable = std::move(r)]() { runnable->Run(); }));
+  }
+
+  bool IsOnCurrentThread() { return mTarget->IsOnCurrentThread(); }
+
+  static void Init() {
+    java::XPCOMEventTarget::Natives<XPCOMEventTargetWrapper>::Init();
+    CreateWrapper(u"main"_ns, do_GetMainThread());
+    if (XRE_IsParentProcess()) {
+      CreateWrapper(u"launcher"_ns, ipc::GetIPCLauncher());
+    }
+  }
+
+  static void CreateWrapper(mozilla::jni::String::Param aName,
+                            nsCOMPtr<nsIEventTarget> aTarget) {
+    auto java = java::XPCOMEventTarget::New();
+    auto native = MakeUnique<XPCOMEventTargetWrapper>(aTarget.forget());
+    AttachNative(java, std::move(native));
+
+    java::XPCOMEventTarget::SetTarget(aName, java);
+  }
+
+  static void ResolveAndDispatchNative(mozilla::jni::String::Param aName,
+                                       mozilla::jni::Object::Param aRunnable) {
+    java::XPCOMEventTarget::ResolveAndDispatch(aName, aRunnable);
+  }
+
+  explicit XPCOMEventTargetWrapper(already_AddRefed<nsIEventTarget> aTarget)
+      : mTarget(aTarget) {}
+
+ private:
+  nsCOMPtr<nsIEventTarget> mTarget;
+};
+
+nsAppShell::nsAppShell()
+    : mSyncRunFinished(*(sAppShellLock = new Mutex("nsAppShell")),
+                       "nsAppShell.SyncRun"),
+      mSyncRunQuit(false) {
+  {
+    MutexAutoLock lock(*sAppShellLock);
+    sAppShell = this;
+  }
+
+  hal::Init();
+
+  if (!XRE_IsParentProcess()) {
+    if (jni::IsAvailable()) {
+      GeckoThreadSupport::Init();
+      GeckoAppShellSupport::Init();
+      XPCOMEventTargetWrapper::Init();
+      mozilla::widget::Telemetry::Init();
+      mozilla::widget::GeckoTelemetryDelegate::Init();
+
+      if (XRE_IsGPUProcess()) {
+        mozilla::gl::AndroidSurfaceTexture::Init();
+      }
+
+      // Set the corresponding state in GeckoThread.
+      java::GeckoThread::SetState(java::GeckoThread::State::RUNNING());
+    }
+    return;
+  }
+
+  if (jni::IsAvailable()) {
+    ScreenManager& screenManager = ScreenManager::GetSingleton();
+    screenManager.SetHelper(mozilla::MakeUnique<ScreenHelperAndroid>());
+
+    // Initialize JNI and Set the corresponding state in GeckoThread.
+    AndroidBridge::ConstructBridge();
+    GeckoAppShellSupport::Init();
+    GeckoThreadSupport::Init();
+    XPCOMEventTargetWrapper::Init();
+    mozilla::GeckoBatteryManager::Init();
+    mozilla::GeckoNetworkManager::Init();
+    mozilla::GeckoProcessManager::Init();
+    mozilla::GeckoSystemStateListener::Init();
+    mozilla::widget::Telemetry::Init();
+    mozilla::widget::ImageDecoderSupport::Init();
+    mozilla::widget::WebExecutorSupport::Init();
+    mozilla::widget::Base64UtilsSupport::Init();
+    nsWindow::InitNatives();
+    mozilla::gl::AndroidSurfaceTexture::Init();
+    mozilla::widget::GeckoTelemetryDelegate::Init();
+
+    java::GeckoThread::SetState(java::GeckoThread::State::JNI_READY());
+
+    CreateAndroidUiThread();
+  }
+
+  sPowerManagerService = do_GetService(POWERMANAGERSERVICE_CONTRACTID);
+
+  if (sPowerManagerService) {
+    sWakeLockListener = new WakeLockListener();
+  } else {
+    NS_WARNING(
+        "Failed to retrieve PowerManagerService, wakelocks will be broken!");
+  }
+}
+
+nsAppShell::~nsAppShell() {
+  {
+    // Release any thread waiting for a sync call to finish.
+    MutexAutoLock lock(*sAppShellLock);
+    sAppShell = nullptr;
+    mSyncRunFinished.NotifyAll();
+  }
+
+  while (mEventQueue.Pop(/* mayWait */ false)) {
+    NS_WARNING("Discarded event on shutdown");
+  }
+
+  if (sPowerManagerService) {
+    sPowerManagerService->RemoveWakeLockListener(sWakeLockListener);
+
+    sPowerManagerService = nullptr;
+    sWakeLockListener = nullptr;
+  }
+
+  hal::Shutdown();
+
+  if (jni::IsAvailable() && XRE_IsParentProcess()) {
+    DestroyAndroidUiThread();
+    AndroidBridge::DeconstructBridge();
+  }
+}
+
+void nsAppShell::NotifyNativeEvent() { mEventQueue.Signal(); }
+
+nsresult nsAppShell::Init() {
+  nsresult rv = nsBaseAppShell::Init();
+  nsCOMPtr<nsIObserverService> obsServ =
+      mozilla::services::GetObserverService();
+  if (obsServ) {
+    obsServ->AddObserver(this, "browser-delayed-startup-finished", false);
+    obsServ->AddObserver(this, "geckoview-startup-complete", false);
+    obsServ->AddObserver(this, "profile-after-change", false);
+    obsServ->AddObserver(this, "quit-application", false);
+    obsServ->AddObserver(this, "quit-application-granted", false);
+
+    if (XRE_IsParentProcess()) {
+      obsServ->AddObserver(this, "chrome-document-loaded", false);
+    } else {
+      obsServ->AddObserver(this, "content-document-global-created", false);
+      obsServ->AddObserver(this, "geckoview-content-global-transferred", false);
+    }
+  }
+
+  if (sPowerManagerService)
+    sPowerManagerService->AddWakeLockListener(sWakeLockListener);
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsAppShell::Exit(void) {
+  {
+    // Release any thread waiting for a sync call to finish.
+    mozilla::MutexAutoLock shellLock(*sAppShellLock);
+    mSyncRunQuit = true;
+    mSyncRunFinished.NotifyAll();
+  }
+  // We need to ensure no observers stick around after XPCOM shuts down
+  // or we'll see crashes, as the app shell outlives XPConnect.
+  mObserversHash.Clear();
+  return nsBaseAppShell::Exit();
+}
+
+NS_IMETHODIMP
+nsAppShell::Observe(nsISupports* aSubject, const char* aTopic,
+                    const char16_t* aData) {
+  bool removeObserver = false;
+
+  if (!strcmp(aTopic, "browser-delayed-startup-finished")) {
+    NS_CreateServicesFromCategory("browser-delayed-startup-finished", nullptr,
+                                  "browser-delayed-startup-finished");
+  } else if (!strcmp(aTopic, "geckoview-startup-complete")) {
+    if (jni::IsAvailable()) {
+      java::GeckoThread::CheckAndSetState(
+          java::GeckoThread::State::PROFILE_READY(),
+          java::GeckoThread::State::RUNNING());
+    }
+  } else if (!strcmp(aTopic, "profile-after-change")) {
+    if (jni::IsAvailable()) {
+      java::GeckoThread::SetState(java::GeckoThread::State::PROFILE_READY());
+
+      // Gecko on Android follows the Android app model where it never
+      // stops until it is killed by the system or told explicitly to
+      // quit. Therefore, we should *not* exit Gecko when there is no
+      // window or the last window is closed. nsIAppStartup::Quit will
+      // still force Gecko to exit.
+      nsCOMPtr<nsIAppStartup> appStartup = components::AppStartup::Service();
+      if (appStartup) {
+        appStartup->EnterLastWindowClosingSurvivalArea();
+      }
+    }
+    removeObserver = true;
+
+  } else if (!strcmp(aTopic, "chrome-document-loaded")) {
+    // Set the global ready state and enable the window event dispatcher
+    // for this particular GeckoView.
+    nsCOMPtr<dom::Document> doc = do_QueryInterface(aSubject);
+    MOZ_ASSERT(doc);
+    if (const RefPtr<nsWindow> window = nsWindow::From(doc->GetWindow())) {
+      window->OnGeckoViewReady();
+    }
+  } else if (!strcmp(aTopic, "quit-application")) {
+    if (jni::IsAvailable()) {
+      const bool restarting = aData && u"restart"_ns.Equals(aData);
+      java::GeckoThread::SetState(restarting
+                                      ? java::GeckoThread::State::RESTARTING()
+                                      : java::GeckoThread::State::EXITING());
+    }
+    removeObserver = true;
+
+  } else if (!strcmp(aTopic, "quit-application-granted")) {
+    if (jni::IsAvailable()) {
+      // We are told explicitly to quit, perhaps due to
+      // nsIAppStartup::Quit being called. We should release our hold on
+      // nsIAppStartup and let it continue to quit.
+      nsCOMPtr<nsIAppStartup> appStartup = components::AppStartup::Service();
+      if (appStartup) {
+        appStartup->ExitLastWindowClosingSurvivalArea();
+      }
+    }
+    removeObserver = true;
+
+  } else if (!strcmp(aTopic, "content-document-global-created")) {
+    // Associate the PuppetWidget of the newly-created BrowserChild with a
+    // GeckoEditableChild instance.
+    MOZ_ASSERT(!XRE_IsParentProcess());
+
+    nsCOMPtr<mozIDOMWindowProxy> domWindow = do_QueryInterface(aSubject);
+    MOZ_ASSERT(domWindow);
+    nsCOMPtr<nsIWidget> domWidget = widget::WidgetUtils::DOMWindowToWidget(
+        nsPIDOMWindowOuter::From(domWindow));
+    NS_ENSURE_TRUE(domWidget, NS_OK);
+
+    widget::GeckoEditableSupport::SetOnBrowserChild(
+        domWidget->GetOwningBrowserChild());
+
+  } else if (!strcmp(aTopic, "geckoview-content-global-transferred")) {
+    // We're transferring to a new GeckoEditableParent, so notify the
+    // existing GeckoEditableChild instance associated with the docshell.
+    nsCOMPtr<nsIDocShell> docShell = do_QueryInterface(aSubject);
+    widget::GeckoEditableSupport::SetOnBrowserChild(
+        dom::BrowserChild::GetFrom(docShell));
+  } else {
+    return nsBaseAppShell::Observe(aSubject, aTopic, aData);
+  }
+
+  if (removeObserver) {
+    nsCOMPtr<nsIObserverService> obsServ =
+        mozilla::services::GetObserverService();
+    if (obsServ) {
+      obsServ->RemoveObserver(this, aTopic);
+    }
+  }
+  return NS_OK;
+}
+
+bool nsAppShell::ProcessNextNativeEvent(bool mayWait) {
+  EVLOG("nsAppShell::ProcessNextNativeEvent %d", mayWait);
+
+  AUTO_PROFILER_LABEL("nsAppShell::ProcessNextNativeEvent", OTHER);
+
+  mozilla::UniquePtr<Event> curEvent;
+
+  {
+    curEvent = mEventQueue.Pop(/* mayWait */ false);
+
+    if (!curEvent && mayWait) {
+      // This processes messages in the Android Looper. Note that we only
+      // get here if the normal Gecko event loop has been awoken
+      // (bug 750713). Looper messages effectively have the lowest
+      // priority because we only process them before we're about to
+      // wait for new events.
+      if (jni::IsAvailable() && XRE_IsParentProcess() &&
+          AndroidBridge::Bridge()->PumpMessageLoop()) {
+        return true;
+      }
+
+      AUTO_PROFILER_LABEL("nsAppShell::ProcessNextNativeEvent:Wait", IDLE);
+      mozilla::BackgroundHangMonitor().NotifyWait();
+
+      curEvent = mEventQueue.Pop(/* mayWait */ true);
+    }
+  }
+
+  if (!curEvent) return false;
+
+  mozilla::BackgroundHangMonitor().NotifyActivity();
+
+  curEvent->Run();
+  return true;
+}
+
+bool nsAppShell::SyncRunEvent(
+    Event&& event, UniquePtr<Event> (*eventFactory)(UniquePtr<Event>&&),
+    const TimeDuration timeout) {
+  // Perform the call on the Gecko thread in a separate lambda, and wait
+  // on the monitor on the current thread.
+  MOZ_ASSERT(!NS_IsMainThread());
+
+  // This is the lock to check that app shell is still alive,
+  // and to wait on for the sync call to complete.
+  mozilla::MutexAutoLock shellLock(*sAppShellLock);
+  nsAppShell* const appShell = sAppShell;
+
+  if (MOZ_UNLIKELY(!appShell)) {
+    // Post-shutdown.
+    return false;
+  }
+
+  bool finished = false;
+  auto runAndNotify = [&event, &finished] {
+    nsAppShell* const appShell = nsAppShell::Get();
+    if (MOZ_UNLIKELY(!appShell || appShell->mSyncRunQuit)) {
+      return false;
+    }
+    event.Run();
+    finished = true;
+    mozilla::MutexAutoLock shellLock(*sAppShellLock);
+    appShell->mSyncRunFinished.NotifyAll();
+    return finished;
+  };
+
+  UniquePtr<Event> runAndNotifyEvent =
+      mozilla::MakeUnique<LambdaEvent<decltype(runAndNotify)>>(
+          std::move(runAndNotify));
+
+  if (eventFactory) {
+    runAndNotifyEvent = (*eventFactory)(std::move(runAndNotifyEvent));
+  }
+
+  appShell->mEventQueue.Post(std::move(runAndNotifyEvent));
+
+  while (!finished && MOZ_LIKELY(sAppShell && !sAppShell->mSyncRunQuit)) {
+    appShell->mSyncRunFinished.Wait(timeout);
+  }
+
+  return finished;
+}
+
+already_AddRefed<nsIURI> nsAppShell::ResolveURI(const nsCString& aUriStr) {
+  nsCOMPtr<nsIIOService> ioServ = do_GetIOService();
+  nsCOMPtr<nsIURI> uri;
+
+  if (NS_SUCCEEDED(
+          ioServ->NewURI(aUriStr, nullptr, nullptr, getter_AddRefs(uri)))) {
+    return uri.forget();
+  }
+
+  nsCOMPtr<nsIURIFixup> fixup = components::URIFixup::Service();
+  nsCOMPtr<nsIURIFixupInfo> fixupInfo;
+  if (fixup &&
+      NS_SUCCEEDED(fixup->GetFixupURIInfo(aUriStr, nsIURIFixup::FIXUP_FLAG_NONE,
+                                          getter_AddRefs(fixupInfo))) &&
+      NS_SUCCEEDED(fixupInfo->GetPreferredURI(getter_AddRefs(uri)))) {
+    return uri.forget();
+  }
+  return nullptr;
+}
+
+nsresult nsAppShell::AddObserver(const nsAString& aObserverKey,
+                                 nsIObserver* aObserver) {
+  NS_ASSERTION(aObserver != nullptr,
+               "nsAppShell::AddObserver: aObserver is null!");
+  mObserversHash.InsertOrUpdate(aObserverKey, aObserver);
+  return NS_OK;
+}
+
+// Used by IPC code
+namespace mozilla {
+
+bool ProcessNextEvent() {
+  nsAppShell* const appShell = nsAppShell::Get();
+  if (!appShell) {
+    return false;
+  }
+
+  return appShell->ProcessNextNativeEvent(true) ? true : false;
+}
+
+void NotifyEvent() {
+  nsAppShell* const appShell = nsAppShell::Get();
+  if (!appShell) {
+    return;
+  }
+  appShell->NotifyNativeEvent();
+}
+
+}  // namespace mozilla
diff --git a/widget/android/nsAppShell.h b/widget/android/nsAppShell.h
new file mode 100644
index 0000000000..9b1dc5ca14
--- /dev/null
+++ b/widget/android/nsAppShell.h
@@ -0,0 +1,217 @@
+/* -*- 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 nsAppShell_h__
+#define nsAppShell_h__
+
+#include <time.h>
+
+#include <type_traits>
+#include <utility>
+
+#include "mozilla/BackgroundHangMonitor.h"
+#include "mozilla/LinkedList.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/TimeStamp.h"  // for mozilla::TimeDuration
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+#include "mozilla/jni/Natives.h"
+#include "nsBaseAppShell.h"
+#include "nsCOMPtr.h"
+#include "nsIAndroidBridge.h"
+#include "nsInterfaceHashtable.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+bool ProcessNextEvent();
+void NotifyEvent();
+}  // namespace mozilla
+
+class nsWindow;
+
+class nsAppShell : public nsBaseAppShell {
+ public:
+  struct Event : mozilla::LinkedListElement<Event> {
+    static uint64_t GetTime() {
+      timespec time;
+      if (clock_gettime(CLOCK_MONOTONIC, &time)) {
+        return 0ull;
+      }
+      return uint64_t(time.tv_sec) * 1000000000ull + time.tv_nsec;
+    }
+
+    uint64_t mPostTime{0};
+
+    bool HasSameTypeAs(const Event* other) const {
+      // Compare vtable addresses to determine same type.
+      return *reinterpret_cast<const uintptr_t*>(this) ==
+             *reinterpret_cast<const uintptr_t*>(other);
+    }
+
+    virtual ~Event() {}
+    virtual void Run() = 0;
+
+    virtual void PostTo(mozilla::LinkedList<Event>& queue) {
+      queue.insertBack(this);
+    }
+
+    virtual bool IsUIEvent() const { return false; }
+  };
+
+  template <typename T>
+  class LambdaEvent : public Event {
+   protected:
+    T lambda;
+
+   public:
+    explicit LambdaEvent(T&& l) : lambda(std::move(l)) {}
+    void Run() override { lambda(); }
+  };
+
+  class ProxyEvent : public Event {
+   protected:
+    mozilla::UniquePtr<Event> baseEvent;
+
+   public:
+    explicit ProxyEvent(mozilla::UniquePtr<Event>&& event)
+        : baseEvent(std::move(event)) {}
+
+    void PostTo(mozilla::LinkedList<Event>& queue) override {
+      baseEvent->PostTo(queue);
+    }
+
+    void Run() override { baseEvent->Run(); }
+  };
+
+  static nsAppShell* Get() {
+    MOZ_ASSERT(NS_IsMainThread());
+    return sAppShell;
+  }
+
+  nsAppShell();
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIOBSERVER
+
+  nsresult Init();
+
+  void NotifyNativeEvent();
+  bool ProcessNextNativeEvent(bool mayWait) override;
+
+  // Post a subclass of Event.
+  // e.g. PostEvent(mozilla::MakeUnique<MyEvent>());
+  template <typename T, typename D>
+  static void PostEvent(mozilla::UniquePtr<T, D>&& event) {
+    mozilla::MutexAutoLock lock(*sAppShellLock);
+    if (!sAppShell) {
+      return;
+    }
+    sAppShell->mEventQueue.Post(std::move(event));
+  }
+
+  // Post a event that will call a lambda
+  // e.g. PostEvent([=] { /* do something */ });
+  template <typename T>
+  static void PostEvent(T&& lambda) {
+    mozilla::MutexAutoLock lock(*sAppShellLock);
+    if (!sAppShell) {
+      return;
+    }
+    sAppShell->mEventQueue.Post(
+        mozilla::MakeUnique<LambdaEvent<T>>(std::move(lambda)));
+  }
+
+  // Post a event and wait for it to finish running on the Gecko thread.
+  static bool SyncRunEvent(
+      Event&& event,
+      mozilla::UniquePtr<Event> (*eventFactory)(mozilla::UniquePtr<Event>&&) =
+          nullptr,
+      const mozilla::TimeDuration timeout = mozilla::TimeDuration::Forever());
+
+  template <typename T>
+  static std::enable_if_t<!std::is_base_of<Event, T>::value, void> SyncRunEvent(
+      T&& lambda) {
+    SyncRunEvent(LambdaEvent<T>(std::forward<T>(lambda)));
+  }
+
+  static already_AddRefed<nsIURI> ResolveURI(const nsCString& aUriStr);
+
+ protected:
+  static nsAppShell* sAppShell;
+  static mozilla::StaticAutoPtr<mozilla::Mutex> sAppShellLock;
+
+  virtual ~nsAppShell();
+
+  NS_IMETHOD Exit() override;
+  nsresult AddObserver(const nsAString& aObserverKey, nsIObserver* aObserver);
+
+  class NativeCallbackEvent : public Event {
+    // Capturing the nsAppShell instance is safe because if the app
+    // shell is destroyed, this lambda will not be called either.
+    nsAppShell* const appShell;
+
+   public:
+    explicit NativeCallbackEvent(nsAppShell* as) : appShell(as) {}
+    void Run() override { appShell->NativeEventCallback(); }
+  };
+
+  void ScheduleNativeEventCallback() override {
+    mEventQueue.Post(mozilla::MakeUnique<NativeCallbackEvent>(this));
+  }
+
+  class Queue {
+   private:
+    mozilla::Monitor mMonitor MOZ_UNANNOTATED;
+    mozilla::LinkedList<Event> mQueue;
+
+   public:
+    enum { LATENCY_UI, LATENCY_OTHER, LATENCY_COUNT };
+    Queue() : mMonitor("nsAppShell.Queue") {}
+
+    void Signal() {
+      mozilla::MonitorAutoLock lock(mMonitor);
+      lock.NotifyAll();
+    }
+
+    void Post(mozilla::UniquePtr<Event>&& event) {
+      MOZ_ASSERT(event && !event->isInList());
+
+      mozilla::MonitorAutoLock lock(mMonitor);
+      event->PostTo(mQueue);
+      if (event->isInList()) {
+        event->mPostTime = Event::GetTime();
+        // Ownership of event object transfers to the queue.
+        mozilla::Unused << event.release();
+      }
+      lock.NotifyAll();
+    }
+
+    mozilla::UniquePtr<Event> Pop(bool mayWait) {
+      mozilla::MonitorAutoLock lock(mMonitor);
+
+      if (mayWait && mQueue.isEmpty()) {
+        lock.Wait();
+      }
+
+      // Ownership of event object transfers to the return value.
+      mozilla::UniquePtr<Event> event(mQueue.popFirst());
+      if (!event || !event->mPostTime) {
+        return event;
+      }
+
+      return event;
+    }
+
+  } mEventQueue;
+
+ private:
+  mozilla::CondVar mSyncRunFinished;
+  bool mSyncRunQuit;
+
+  nsInterfaceHashtable<nsStringHashKey, nsIObserver> mObserversHash;
+};
+
+#endif  // nsAppShell_h__
diff --git a/widget/android/nsClipboard.cpp b/widget/android/nsClipboard.cpp
new file mode 100644
index 0000000000..37bec159d0
--- /dev/null
+++ b/widget/android/nsClipboard.cpp
@@ -0,0 +1,182 @@
+/* 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/java/ClipboardWrappers.h"
+#include "mozilla/java/GeckoAppShellWrappers.h"
+#include "nsClipboard.h"
+#include "nsISupportsPrimitives.h"
+#include "nsCOMPtr.h"
+#include "nsComponentManagerUtils.h"
+#include "nsPrimitiveHelpers.h"
+
+using namespace mozilla;
+
+NS_IMPL_ISUPPORTS_INHERITED0(nsClipboard, ClipboardSetDataHelper)
+
+/* The Android clipboard only supports text and doesn't support mime types
+ * so we assume all clipboard data is text/plain for now. Documentation
+ * indicates that support for other data types is planned for future
+ * releases.
+ */
+
+NS_IMETHODIMP
+nsClipboard::SetNativeClipboardData(nsITransferable* aTransferable,
+                                    nsIClipboardOwner* aOwner,
+                                    int32_t aWhichClipboard) {
+  if (aWhichClipboard != kGlobalClipboard) return NS_ERROR_NOT_IMPLEMENTED;
+
+  if (!jni::IsAvailable()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsTArray<nsCString> flavors;
+  aTransferable->FlavorsTransferableCanImport(flavors);
+
+  nsAutoString html;
+  nsAutoString text;
+
+  for (auto& flavorStr : flavors) {
+    if (flavorStr.EqualsLiteral(kTextMime)) {
+      nsCOMPtr<nsISupports> item;
+      nsresult rv =
+          aTransferable->GetTransferData(kTextMime, getter_AddRefs(item));
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        continue;
+      }
+      nsCOMPtr<nsISupportsString> supportsString = do_QueryInterface(item);
+      if (supportsString) {
+        supportsString->GetData(text);
+      }
+    } else if (flavorStr.EqualsLiteral(kHTMLMime)) {
+      nsCOMPtr<nsISupports> item;
+      nsresult rv =
+          aTransferable->GetTransferData(kHTMLMime, getter_AddRefs(item));
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        continue;
+      }
+      nsCOMPtr<nsISupportsString> supportsString = do_QueryInterface(item);
+      if (supportsString) {
+        supportsString->GetData(html);
+      }
+    }
+  }
+
+  if (!html.IsEmpty() &&
+      java::Clipboard::SetHTML(java::GeckoAppShell::GetApplicationContext(),
+                               text, html)) {
+    return NS_OK;
+  }
+  if (!text.IsEmpty() &&
+      java::Clipboard::SetText(java::GeckoAppShell::GetApplicationContext(),
+                               text)) {
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsClipboard::GetData(nsITransferable* aTransferable, int32_t aWhichClipboard) {
+  if (aWhichClipboard != kGlobalClipboard) return NS_ERROR_NOT_IMPLEMENTED;
+
+  if (!jni::IsAvailable()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsTArray<nsCString> flavors;
+  aTransferable->FlavorsTransferableCanImport(flavors);
+
+  for (auto& flavorStr : flavors) {
+    if (flavorStr.EqualsLiteral(kTextMime) ||
+        flavorStr.EqualsLiteral(kHTMLMime)) {
+      auto text = java::Clipboard::GetData(
+          java::GeckoAppShell::GetApplicationContext(), flavorStr);
+      if (!text) {
+        continue;
+      }
+      nsString buffer = text->ToString();
+      if (buffer.IsEmpty()) {
+        continue;
+      }
+      nsCOMPtr<nsISupports> wrapper;
+      nsPrimitiveHelpers::CreatePrimitiveForData(flavorStr, buffer.get(),
+                                                 buffer.Length() * 2,
+                                                 getter_AddRefs(wrapper));
+      if (wrapper) {
+        aTransferable->SetTransferData(flavorStr.get(), wrapper);
+        return NS_OK;
+      }
+    }
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+RefPtr<GenericPromise> nsClipboard::AsyncGetData(nsITransferable* aTransferable,
+                                                 int32_t aWhichClipboard) {
+  nsresult rv = GetData(aTransferable, aWhichClipboard);
+  if (NS_FAILED(rv)) {
+    return GenericPromise::CreateAndReject(rv, __func__);
+  }
+
+  return GenericPromise::CreateAndResolve(true, __func__);
+}
+
+NS_IMETHODIMP
+nsClipboard::EmptyClipboard(int32_t aWhichClipboard) {
+  if (aWhichClipboard != kGlobalClipboard) return NS_ERROR_NOT_IMPLEMENTED;
+
+  if (!jni::IsAvailable()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  java::Clipboard::ClearText(java::GeckoAppShell::GetApplicationContext());
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsClipboard::HasDataMatchingFlavors(const nsTArray<nsCString>& aFlavorList,
+                                    int32_t aWhichClipboard, bool* aHasText) {
+  *aHasText = false;
+  if (aWhichClipboard != kGlobalClipboard) return NS_ERROR_NOT_IMPLEMENTED;
+
+  if (!jni::IsAvailable()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  for (auto& flavor : aFlavorList) {
+    bool hasData =
+        java::Clipboard::HasData(java::GeckoAppShell::GetApplicationContext(),
+                                 NS_ConvertASCIItoUTF16(flavor));
+    if (hasData) {
+      *aHasText = true;
+      return NS_OK;
+    }
+  }
+
+  return NS_OK;
+}
+
+RefPtr<DataFlavorsPromise> nsClipboard::AsyncHasDataMatchingFlavors(
+    const nsTArray<nsCString>& aFlavorList, int32_t aWhichClipboard) {
+  nsTArray<nsCString> results;
+  for (const auto& flavor : aFlavorList) {
+    bool hasMatchingFlavor = false;
+    nsresult rv = HasDataMatchingFlavors(AutoTArray<nsCString, 1>{flavor},
+                                         aWhichClipboard, &hasMatchingFlavor);
+    if (NS_SUCCEEDED(rv) && hasMatchingFlavor) {
+      results.AppendElement(flavor);
+    }
+  }
+
+  return DataFlavorsPromise::CreateAndResolve(std::move(results), __func__);
+}
+
+NS_IMETHODIMP
+nsClipboard::IsClipboardTypeSupported(int32_t aWhichClipboard, bool* _retval) {
+  NS_ENSURE_ARG_POINTER(_retval);
+  *_retval = kGlobalClipboard == aWhichClipboard;
+  return NS_OK;
+}
diff --git a/widget/android/nsClipboard.h b/widget/android/nsClipboard.h
new file mode 100644
index 0000000000..365a7f85f1
--- /dev/null
+++ b/widget/android/nsClipboard.h
@@ -0,0 +1,41 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; 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 NS_CLIPBOARD_H
+#define NS_CLIPBOARD_H
+
+#include "nsBaseClipboard.h"
+
+class nsClipboard final : public ClipboardSetDataHelper {
+ private:
+  ~nsClipboard() = default;
+
+ public:
+  nsClipboard() = default;
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+  // nsIClipboard
+  NS_IMETHOD GetData(nsITransferable* aTransferable,
+                     int32_t aWhichClipboard) override;
+  NS_IMETHOD EmptyClipboard(int32_t aWhichClipboard) override;
+  NS_IMETHOD HasDataMatchingFlavors(const nsTArray<nsCString>& aFlavorList,
+                                    int32_t aWhichClipboard,
+                                    bool* _retval) override;
+  NS_IMETHOD IsClipboardTypeSupported(int32_t aWhichClipboard,
+                                      bool* _retval) override;
+  RefPtr<mozilla::GenericPromise> AsyncGetData(
+      nsITransferable* aTransferable, int32_t aWhichClipboard) override;
+  RefPtr<DataFlavorsPromise> AsyncHasDataMatchingFlavors(
+      const nsTArray<nsCString>& aFlavorList, int32_t aWhichClipboard) override;
+
+ protected:
+  // Implement the native clipboard behavior.
+  NS_IMETHOD SetNativeClipboardData(nsITransferable* aTransferable,
+                                    nsIClipboardOwner* aOwner,
+                                    int32_t aWhichClipboard) override;
+};
+
+#endif
diff --git a/widget/android/nsDeviceContextAndroid.cpp b/widget/android/nsDeviceContextAndroid.cpp
new file mode 100644
index 0000000000..e6643ef9b3
--- /dev/null
+++ b/widget/android/nsDeviceContextAndroid.cpp
@@ -0,0 +1,100 @@
+/* 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 "nsDeviceContextAndroid.h"
+
+#include "mozilla/gfx/PrintTargetPDF.h"
+#include "mozilla/RefPtr.h"
+#include "nsComponentManagerUtils.h"
+#include "nsString.h"
+#include "nsIFile.h"
+#include "nsIFileStreams.h"
+#include "nsIPrintSettings.h"
+#include "nsIFileStreams.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsAnonymousTemporaryFile.h"
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+
+NS_IMPL_ISUPPORTS(nsDeviceContextSpecAndroid, nsIDeviceContextSpec)
+
+nsDeviceContextSpecAndroid::~nsDeviceContextSpecAndroid() {
+  if (mTempFile) {
+    mTempFile->Remove(false);
+  }
+}
+
+already_AddRefed<PrintTarget> nsDeviceContextSpecAndroid::MakePrintTarget() {
+  double width, height;
+  mPrintSettings->GetEffectiveSheetSize(&width, &height);
+
+  // convert twips to points
+  width /= TWIPS_PER_POINT_FLOAT;
+  height /= TWIPS_PER_POINT_FLOAT;
+
+  auto stream = [&]() -> nsCOMPtr<nsIOutputStream> {
+    if (mPrintSettings->GetOutputDestination() ==
+        nsIPrintSettings::kOutputDestinationStream) {
+      nsCOMPtr<nsIOutputStream> out;
+      mPrintSettings->GetOutputStream(getter_AddRefs(out));
+      return out;
+    }
+    if (NS_FAILED(
+            NS_OpenAnonymousTemporaryNsIFile(getter_AddRefs(mTempFile)))) {
+      return nullptr;
+    }
+    // Print to printer not supported...
+    nsCOMPtr<nsIFileOutputStream> s =
+        do_CreateInstance("@mozilla.org/network/file-output-stream;1");
+    if (NS_FAILED(s->Init(mTempFile, -1, -1, 0))) {
+      return nullptr;
+    }
+    return s;
+  }();
+
+  return PrintTargetPDF::CreateOrNull(stream, IntSize::Ceil(width, height));
+}
+
+NS_IMETHODIMP
+nsDeviceContextSpecAndroid::Init(nsIPrintSettings* aPS, bool aIsPrintPreview) {
+  mPrintSettings = aPS;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDeviceContextSpecAndroid::BeginDocument(const nsAString& aTitle,
+                                          const nsAString& aPrintToFileName,
+                                          int32_t aStartPage,
+                                          int32_t aEndPage) {
+  return NS_OK;
+}
+
+RefPtr<PrintEndDocumentPromise> nsDeviceContextSpecAndroid::EndDocument() {
+  return nsIDeviceContextSpec::EndDocumentPromiseFromResult(DoEndDocument(),
+                                                            __func__);
+}
+
+NS_IMETHODIMP
+nsDeviceContextSpecAndroid::DoEndDocument() {
+  if (mPrintSettings->GetOutputDestination() ==
+          nsIPrintSettings::kOutputDestinationFile &&
+      mTempFile) {
+    nsAutoString targetPath;
+    mPrintSettings->GetToFileName(targetPath);
+    nsCOMPtr<nsIFile> destFile;
+    MOZ_TRY(NS_NewLocalFile(targetPath, false, getter_AddRefs(destFile)));
+    nsAutoString destLeafName;
+    MOZ_TRY(destFile->GetLeafName(destLeafName));
+
+    nsCOMPtr<nsIFile> destDir;
+    MOZ_TRY(destFile->GetParent(getter_AddRefs(destDir)));
+
+    MOZ_TRY(mTempFile->MoveTo(destDir, destLeafName));
+    destFile->SetPermissions(0666);
+
+    mTempFile = nullptr;
+  }
+  return NS_OK;
+}
diff --git a/widget/android/nsDeviceContextAndroid.h b/widget/android/nsDeviceContextAndroid.h
new file mode 100644
index 0000000000..1ab3c72c1c
--- /dev/null
+++ b/widget/android/nsDeviceContextAndroid.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 nsDeviceContextAndroid_h__
+#define nsDeviceContextAndroid_h__
+
+#include "nsIDeviceContextSpec.h"
+#include "nsCOMPtr.h"
+#include "mozilla/gfx/PrintPromise.h"
+
+class nsDeviceContextSpecAndroid final : public nsIDeviceContextSpec {
+ private:
+  virtual ~nsDeviceContextSpecAndroid();
+
+ public:
+  NS_DECL_ISUPPORTS
+
+  already_AddRefed<PrintTarget> MakePrintTarget() final;
+
+  NS_IMETHOD Init(nsIPrintSettings* aPS, bool aIsPrintPreview) override;
+  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; }
+
+ private:
+  nsresult DoEndDocument();
+  nsCOMPtr<nsIFile> mTempFile;
+};
+#endif  // nsDeviceContextAndroid_h__
diff --git a/widget/android/nsIAndroidBridge.idl b/widget/android/nsIAndroidBridge.idl
new file mode 100644
index 0000000000..b30ed60d77
--- /dev/null
+++ b/widget/android/nsIAndroidBridge.idl
@@ -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 "nsISupports.idl"
+
+interface mozIDOMWindowProxy;
+
+[scriptable, uuid(e64c39b8-b8ec-477d-aef5-89d517ff9219)]
+interface nsIAndroidEventCallback : nsISupports
+{
+  [implicit_jscontext]
+  void onSuccess([optional] in jsval data);
+  [implicit_jscontext]
+  void onError([optional] in jsval data);
+};
+
+[scriptable, function, uuid(819ee2db-d3b8-46dd-a476-40f89c49133c)]
+interface nsIAndroidEventFinalizer : nsISupports
+{
+  void onFinalize();
+};
+
+[scriptable, function, uuid(73569a75-78eb-4c7f-82b9-2d4f5ccf44c3)]
+interface nsIAndroidEventListener : nsISupports
+{
+  void onEvent(in AString event,
+               [optional] in jsval data,
+               [optional] in nsIAndroidEventCallback callback);
+};
+
+[scriptable, uuid(e98bf792-4145-411e-b298-8219d9b03817)]
+interface nsIAndroidEventDispatcher : nsISupports
+{
+  [implicit_jscontext]
+  void dispatch(in jsval event,
+                [optional] in jsval data,
+                [optional] in nsIAndroidEventCallback callback,
+                [optional] in nsIAndroidEventFinalizer finalizer);
+  [implicit_jscontext]
+  void registerListener(in nsIAndroidEventListener listener,
+                        in jsval events);
+  [implicit_jscontext]
+  void unregisterListener(in nsIAndroidEventListener listener,
+                          in jsval events);
+};
+
+[scriptable, uuid(60a78a94-6117-432f-9d49-304913a931c5)]
+interface nsIAndroidView : nsIAndroidEventDispatcher
+{
+  [implicit_jscontext] readonly attribute jsval initData;
+};
+
+[scriptable, uuid(1beb70d3-70f3-4742-98cc-a3d301b26c0c)]
+interface nsIAndroidBridge : nsIAndroidEventDispatcher
+{
+  nsIAndroidEventDispatcher getDispatcherByName(in string name);
+};
diff --git a/widget/android/nsLookAndFeel.cpp b/widget/android/nsLookAndFeel.cpp
new file mode 100644
index 0000000000..84558862d7
--- /dev/null
+++ b/widget/android/nsLookAndFeel.cpp
@@ -0,0 +1,457 @@
+/* -*- 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 "nsStyleConsts.h"
+#include "nsXULAppAPI.h"
+#include "nsLookAndFeel.h"
+#include "Theme.h"
+#include "gfxFont.h"
+#include "gfxFontConstants.h"
+#include "mozilla/FontPropertyTypes.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_widget.h"
+#include "mozilla/java/GeckoAppShellWrappers.h"
+#include "mozilla/java/GeckoRuntimeWrappers.h"
+#include "mozilla/java/GeckoSystemStateListenerWrappers.h"
+#include "ThemeColors.h"
+
+using namespace mozilla;
+using namespace mozilla::widget;
+
+static const char16_t UNICODE_BULLET = 0x2022;
+
+nsLookAndFeel::nsLookAndFeel() = default;
+
+nsLookAndFeel::~nsLookAndFeel() = default;
+
+nsresult nsLookAndFeel::GetSystemColors() {
+  if (!jni::IsAvailable()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  auto arr = java::GeckoAppShell::GetSystemColors();
+  if (!arr) {
+    return NS_ERROR_FAILURE;
+  }
+
+  JNIEnv* const env = arr.Env();
+  uint32_t len = static_cast<uint32_t>(env->GetArrayLength(arr.Get()));
+  jint* elements = env->GetIntArrayElements(arr.Get(), 0);
+
+  uint32_t colorsCount = sizeof(AndroidSystemColors) / sizeof(nscolor);
+  if (len < colorsCount) colorsCount = len;
+
+  // Convert Android colors to nscolor by switching R and B in the ARGB 32 bit
+  // value
+  nscolor* colors = (nscolor*)&mSystemColors;
+
+  for (uint32_t i = 0; i < colorsCount; i++) {
+    uint32_t androidColor = static_cast<uint32_t>(elements[i]);
+    uint8_t r = (androidColor & 0x00ff0000) >> 16;
+    uint8_t b = (androidColor & 0x000000ff);
+    colors[i] = (androidColor & 0xff00ff00) | (b << 16) | r;
+  }
+
+  env->ReleaseIntArrayElements(arr.Get(), elements, 0);
+
+  return NS_OK;
+}
+
+void nsLookAndFeel::NativeInit() {
+  EnsureInitSystemColors();
+  EnsureInitShowPassword();
+  RecordTelemetry();
+}
+
+void nsLookAndFeel::RefreshImpl() {
+  mInitializedSystemColors = false;
+  mInitializedShowPassword = false;
+  nsXPLookAndFeel::RefreshImpl();
+}
+
+nsresult nsLookAndFeel::NativeGetColor(ColorID aID, ColorScheme aColorScheme,
+                                       nscolor& aColor) {
+  EnsureInitSystemColors();
+  if (!mInitializedSystemColors) {
+    // Failure to initialize colors is an error condition. Return black.
+    aColor = 0;
+    return NS_ERROR_FAILURE;
+  }
+
+  // Highlight/Highlighttext have native equivalents that we can map to (on
+  // Android) which should work fine, regardless of the color-scheme.
+  switch (aID) {
+    case ColorID::Highlight: {
+      // Matched to action_accent in java codebase. This works fine with both
+      // light and dark color scheme.
+      nscolor accent =
+          Color(ColorID::Accentcolor, aColorScheme, UseStandins::No);
+      aColor =
+          NS_RGBA(NS_GET_R(accent), NS_GET_G(accent), NS_GET_B(accent), 78);
+      return NS_OK;
+    }
+    case ColorID::Highlighttext:
+      // Selection background is transparent enough that any foreground color
+      // will do.
+      aColor = NS_SAME_AS_FOREGROUND_COLOR;
+      return NS_OK;
+    default:
+      break;
+  }
+
+  if (aColorScheme == ColorScheme::Dark) {
+    if (auto darkColor = GenericDarkColor(aID)) {
+      aColor = *darkColor;
+      return NS_OK;
+    }
+  }
+
+  // XXX we'll want to use context.obtainStyledAttributes on the java side to
+  // get all of these; see TextView.java for a good example.
+  auto UseNativeAccent = [this] {
+    return mSystemColors.colorAccent &&
+           StaticPrefs::widget_non_native_theme_use_theme_accent();
+  };
+
+  switch (aID) {
+      // These colors don't seem to be used for anything anymore in Mozilla
+      // The CSS2 colors below are used.
+    case ColorID::MozMenubartext:
+      aColor = mSystemColors.colorForeground;
+      break;
+
+    case ColorID::ThemedScrollbarThumbInactive:
+    case ColorID::ThemedScrollbarThumb:
+      // We don't need to care about the Active and Hover colors because Android
+      // scrollbars can't be hovered (they always have pointer-events: none).
+      aColor = NS_RGBA(119, 119, 119, 102);
+      break;
+
+    case ColorID::IMESelectedRawTextBackground:
+    case ColorID::IMESelectedConvertedTextBackground:
+      aColor = mSystemColors.textColorHighlight;
+      break;
+    case ColorID::IMESelectedRawTextForeground:
+    case ColorID::IMESelectedConvertedTextForeground:
+      aColor = mSystemColors.textColorPrimaryInverse;
+      break;
+    case ColorID::IMERawInputBackground:
+    case ColorID::IMEConvertedTextBackground:
+      aColor = NS_TRANSPARENT;
+      break;
+    case ColorID::IMERawInputForeground:
+    case ColorID::IMEConvertedTextForeground:
+    case ColorID::IMERawInputUnderline:
+    case ColorID::IMEConvertedTextUnderline:
+      aColor = NS_SAME_AS_FOREGROUND_COLOR;
+      break;
+    case ColorID::IMESelectedRawTextUnderline:
+    case ColorID::IMESelectedConvertedTextUnderline:
+      aColor = NS_TRANSPARENT;
+      break;
+
+      // css2  http://www.w3.org/TR/REC-CSS2/ui.html#system-colors
+    case ColorID::Activeborder:     // active window border
+    case ColorID::Appworkspace:     // MDI background color
+    case ColorID::Activecaption:    // active window caption background
+    case ColorID::Background:       // desktop background
+    case ColorID::Inactiveborder:   // inactive window border
+    case ColorID::Inactivecaption:  // inactive window caption
+    case ColorID::Scrollbar:        // scrollbar gray area
+      aColor = mSystemColors.colorBackground;
+      break;
+    case ColorID::Graytext:  // disabled text in windows, menus, etc.
+      aColor = NS_RGB(0xb1, 0xa5, 0x98);
+      break;
+    // FIXME: -moz-cellhighlight should show some kind of unfocused state.
+    case ColorID::MozCellhighlight:
+    case ColorID::Selecteditem:
+    case ColorID::Accentcolor:
+      aColor = UseNativeAccent() ? mSystemColors.colorAccent
+                                 : GetStandinForNativeColor(
+                                       ColorID::Accentcolor, aColorScheme);
+      break;
+    case ColorID::MozCellhighlighttext:
+    case ColorID::Selecteditemtext:
+    case ColorID::Accentcolortext:
+      aColor = UseNativeAccent() ? ThemeColors::ComputeCustomAccentForeground(
+                                       mSystemColors.colorAccent)
+                                 : GetStandinForNativeColor(
+                                       ColorID::Accentcolortext, aColorScheme);
+      break;
+    case ColorID::Fieldtext:
+      aColor = NS_RGB(0x1a, 0x1a, 0x1a);
+      break;
+    case ColorID::Inactivecaptiontext:
+      // text in inactive window caption
+      aColor = mSystemColors.textColorTertiary;
+      break;
+    case ColorID::Infobackground:
+      aColor = NS_RGB(0xf5, 0xf5, 0xb5);
+      break;
+    case ColorID::Infotext:
+    case ColorID::Threeddarkshadow:  // 3-D shadow outer edge color
+    case ColorID::MozButtondefault:  // default button border color
+      aColor = NS_RGB(0x00, 0x00, 0x00);
+      break;
+    case ColorID::Menu:
+      aColor = NS_RGB(0xf7, 0xf5, 0xf3);
+      break;
+
+    case ColorID::Buttonface:
+    case ColorID::MozButtondisabledface:
+    case ColorID::Threedface:
+    case ColorID::Threedlightshadow:
+    case ColorID::Buttonborder:
+    case ColorID::MozDisabledfield:
+      aColor = NS_RGB(0xec, 0xe7, 0xe2);
+      break;
+
+    case ColorID::Buttonhighlight:
+    case ColorID::Field:
+    case ColorID::Threedhighlight:
+    case ColorID::MozCombobox:
+    case ColorID::MozEventreerow:
+      aColor = NS_RGB(0xff, 0xff, 0xff);
+      break;
+
+    case ColorID::Buttonshadow:
+    case ColorID::Threedshadow:
+      aColor = NS_RGB(0xae, 0xa1, 0x94);
+      break;
+
+    case ColorID::MozDialog:
+    case ColorID::Window:
+    case ColorID::Windowframe:
+      aColor = NS_RGB(0xef, 0xeb, 0xe7);
+      break;
+    case ColorID::Buttontext:
+    case ColorID::Captiontext:
+    case ColorID::Menutext:
+    case ColorID::MozButtonhovertext:
+    case ColorID::MozDialogtext:
+    case ColorID::MozComboboxtext:
+    case ColorID::Windowtext:
+    case ColorID::MozColheadertext:
+    case ColorID::MozColheaderhovertext:
+      aColor = NS_RGB(0x10, 0x10, 0x10);
+      break;
+    case ColorID::MozDragtargetzone:
+      aColor = mSystemColors.textColorHighlight;
+      break;
+    case ColorID::MozButtonhoverface:
+    case ColorID::MozButtonactiveface:
+      aColor = NS_RGB(0xf3, 0xf0, 0xed);
+      break;
+    case ColorID::MozMenuhover:
+      aColor = NS_RGB(0xee, 0xee, 0xee);
+      break;
+    case ColorID::MozMenubarhovertext:
+    case ColorID::MozMenuhovertext:
+      aColor = NS_RGB(0x77, 0x77, 0x77);
+      break;
+    case ColorID::MozOddtreerow:
+      aColor = NS_TRANSPARENT;
+      break;
+    case ColorID::MozNativehyperlinktext:
+      aColor = NS_RGB(0, 0, 0xee);
+      break;
+    case ColorID::Marktext:
+    case ColorID::Mark:
+    case ColorID::SpellCheckerUnderline:
+      aColor = GetStandinForNativeColor(aID, aColorScheme);
+      break;
+    default:
+      /* default color is BLACK */
+      aColor = 0;
+      return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+nsresult nsLookAndFeel::NativeGetInt(IntID aID, int32_t& aResult) {
+  nsresult rv = NS_OK;
+
+  switch (aID) {
+    case IntID::ScrollButtonLeftMouseButtonAction:
+      aResult = 0;
+      break;
+
+    case IntID::ScrollButtonMiddleMouseButtonAction:
+    case IntID::ScrollButtonRightMouseButtonAction:
+      aResult = 3;
+      break;
+
+    case IntID::CaretBlinkTime:
+      aResult = 500;
+      break;
+
+    case IntID::CaretBlinkCount:
+      aResult = 10;
+      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:
+      // we want XUL popups to be able to overlap the task bar.
+      aResult = 1;
+      break;
+
+    case IntID::ScrollArrowStyle:
+      aResult = eScrollArrowStyle_Single;
+      break;
+
+    case IntID::UseOverlayScrollbars:
+      aResult = 1;
+      break;
+
+    case IntID::SpellCheckerUnderlineStyle:
+      aResult = int32_t(StyleTextDecorationStyle::Wavy);
+      break;
+
+    case IntID::ScrollbarButtonAutoRepeatBehavior:
+      aResult = 0;
+      break;
+
+    case IntID::ContextMenuOffsetVertical:
+    case IntID::ContextMenuOffsetHorizontal:
+      aResult = 2;
+      break;
+
+    case IntID::PrefersReducedMotion:
+      aResult = java::GeckoSystemStateListener::PrefersReducedMotion();
+      break;
+
+    case IntID::PrefersReducedTransparency:
+      aResult = 0;
+      break;
+
+    case IntID::InvertedColors:
+      aResult = java::GeckoSystemStateListener::IsInvertedColors();
+      break;
+
+    case IntID::PrimaryPointerCapabilities:
+      aResult = java::GeckoAppShell::GetAllPointerCapabilities();
+
+      // We cannot assume what is primary device, so we use Blink's way for web
+      // compatibility (https://crbug.com/136119#c6). If having coarse
+      // capability in any devices, return it.
+      if (aResult & static_cast<int32_t>(PointerCapabilities::Coarse)) {
+        aResult = static_cast<int32_t>(PointerCapabilities::Coarse);
+      }
+      break;
+
+    case IntID::AllPointerCapabilities:
+      aResult = java::GeckoAppShell::GetAllPointerCapabilities();
+      break;
+
+    case IntID::SystemUsesDarkTheme: {
+      java::GeckoRuntime::LocalRef runtime = java::GeckoRuntime::GetInstance();
+      aResult = runtime && runtime->UsesDarkTheme();
+      break;
+    }
+
+    case IntID::DragThresholdX:
+    case IntID::DragThresholdY:
+      // Threshold where a tap becomes a drag, in 1/240" reference pixels.
+      aResult = 25;
+      break;
+
+    case IntID::TouchDeviceSupportPresent:
+      // Touch support is always enabled on android.
+      aResult = 1;
+      break;
+
+    default:
+      aResult = 0;
+      rv = NS_ERROR_FAILURE;
+  }
+
+  return rv;
+}
+
+nsresult nsLookAndFeel::NativeGetFloat(FloatID aID, float& aResult) {
+  nsresult rv = NS_OK;
+
+  switch (aID) {
+    case FloatID::IMEUnderlineRelativeSize:
+      aResult = 1.0f;
+      break;
+    case FloatID::SpellCheckerUnderlineRelativeSize:
+      aResult = 1.0f;
+      break;
+    case FloatID::TextScaleFactor: {
+      java::GeckoRuntime::LocalRef runtime = java::GeckoRuntime::GetInstance();
+      aResult = runtime ? runtime->TextScaleFactor() : 1.0f;
+      break;
+    }
+    default:
+      aResult = -1.0;
+      rv = NS_ERROR_FAILURE;
+      break;
+  }
+  return rv;
+}
+
+bool nsLookAndFeel::NativeGetFont(FontID aID, nsString& aFontName,
+                                  gfxFontStyle& aFontStyle) {
+  aFontName.AssignLiteral("Roboto");
+  aFontStyle.style = FontSlantStyle::NORMAL;
+  aFontStyle.weight = FontWeight::NORMAL;
+  aFontStyle.stretch = FontStretch::NORMAL;
+  aFontStyle.size = 9.0 * 96.0f / 72.0f;
+  aFontStyle.systemFont = true;
+  return true;
+}
+
+bool nsLookAndFeel::GetEchoPasswordImpl() {
+  EnsureInitShowPassword();
+  return mShowPassword;
+}
+
+uint32_t nsLookAndFeel::GetPasswordMaskDelayImpl() {
+  // This value is hard-coded in Android OS's PasswordTransformationMethod.java
+  return 1500;
+}
+
+char16_t nsLookAndFeel::GetPasswordCharacterImpl() {
+  // This value is hard-coded in Android OS's PasswordTransformationMethod.java
+  return UNICODE_BULLET;
+}
+
+void nsLookAndFeel::EnsureInitSystemColors() {
+  if (!mInitializedSystemColors) {
+    mInitializedSystemColors = NS_SUCCEEDED(GetSystemColors());
+  }
+}
+
+void nsLookAndFeel::EnsureInitShowPassword() {
+  if (!mInitializedShowPassword && jni::IsAvailable()) {
+    mShowPassword = java::GeckoAppShell::GetShowPasswordSetting();
+    mInitializedShowPassword = true;
+  }
+}
diff --git a/widget/android/nsLookAndFeel.h b/widget/android/nsLookAndFeel.h
new file mode 100644
index 0000000000..128b871a08
--- /dev/null
+++ b/widget/android/nsLookAndFeel.h
@@ -0,0 +1,57 @@
+/* -*- 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
+#define __nsLookAndFeel
+
+#include "nsXPLookAndFeel.h"
+
+namespace mozilla {
+// The order and number of the members in this structure must correspond
+// to the attrsAppearance array in GeckoAppShell.getSystemColors()
+struct AndroidSystemColors {
+  nscolor textColorPrimary;
+  nscolor textColorPrimaryInverse;
+  nscolor textColorSecondary;
+  nscolor textColorSecondaryInverse;
+  nscolor textColorTertiary;
+  nscolor textColorTertiaryInverse;
+  nscolor textColorHighlight;
+  nscolor colorForeground;
+  nscolor colorBackground;
+  nscolor panelColorForeground;
+  nscolor panelColorBackground;
+  nscolor colorAccent;
+};
+}  // namespace mozilla
+
+class nsLookAndFeel final : public nsXPLookAndFeel {
+ public:
+  explicit nsLookAndFeel();
+  virtual ~nsLookAndFeel();
+
+  void NativeInit() final;
+  virtual void RefreshImpl() override;
+  nsresult NativeGetInt(IntID, int32_t& aResult) override;
+  nsresult NativeGetFloat(FloatID, float& aResult) override;
+  nsresult NativeGetColor(ColorID, ColorScheme, nscolor& aResult) override;
+  bool NativeGetFont(FontID aID, nsString& aName,
+                     gfxFontStyle& aStyle) override;
+  bool GetEchoPasswordImpl() override;
+  uint32_t GetPasswordMaskDelayImpl() override;
+  char16_t GetPasswordCharacterImpl() override;
+
+ protected:
+  bool mInitializedSystemColors = false;
+  mozilla::AndroidSystemColors mSystemColors;
+  bool mInitializedShowPassword = false;
+  bool mShowPassword = false;
+
+  nsresult GetSystemColors();
+
+  void EnsureInitSystemColors();
+  void EnsureInitShowPassword();
+};
+
+#endif
diff --git a/widget/android/nsPrintSettingsServiceAndroid.cpp b/widget/android/nsPrintSettingsServiceAndroid.cpp
new file mode 100644
index 0000000000..67f978c6e3
--- /dev/null
+++ b/widget/android/nsPrintSettingsServiceAndroid.cpp
@@ -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/. */
+#include "nsPrintSettingsServiceAndroid.h"
+
+#include "nsPrintSettingsImpl.h"
+
+class nsPrintSettingsAndroid : public nsPrintSettings {
+ public:
+  nsPrintSettingsAndroid() {
+    // The aim here is to set up the objects enough that silent printing works
+    SetOutputFormat(nsIPrintSettings::kOutputFormatPDF);
+    SetPrinterName(u"PDF printer"_ns);
+  }
+};
+
+nsresult nsPrintSettingsServiceAndroid::_CreatePrintSettings(
+    nsIPrintSettings** _retval) {
+  nsPrintSettings* printSettings = new nsPrintSettingsAndroid();
+  NS_ENSURE_TRUE(printSettings, NS_ERROR_OUT_OF_MEMORY);
+  NS_ADDREF(*_retval = printSettings);
+  (void)InitPrintSettingsFromPrefs(*_retval, false,
+                                   nsIPrintSettings::kInitSaveAll);
+  return NS_OK;
+}
+
+already_AddRefed<nsIPrintSettings> CreatePlatformPrintSettings(
+    const mozilla::PrintSettingsInitializer& aSettings) {
+  RefPtr<nsPrintSettings> settings = new nsPrintSettingsAndroid();
+  settings->InitWithInitializer(aSettings);
+  return settings.forget();
+}
diff --git a/widget/android/nsPrintSettingsServiceAndroid.h b/widget/android/nsPrintSettingsServiceAndroid.h
new file mode 100644
index 0000000000..28710feb54
--- /dev/null
+++ b/widget/android/nsPrintSettingsServiceAndroid.h
@@ -0,0 +1,18 @@
+/* -*- 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 nsPrintSettingsServiceAndroid_h
+#define nsPrintSettingsServiceAndroid_h
+
+#include "nsPrintSettingsService.h"
+#include "nsIPrintSettings.h"
+
+class nsPrintSettingsServiceAndroid final : public nsPrintSettingsService {
+ public:
+  nsPrintSettingsServiceAndroid() {}
+
+  nsresult _CreatePrintSettings(nsIPrintSettings** _retval) override;
+};
+
+#endif  // nsPrintSettingsServiceAndroid_h
diff --git a/widget/android/nsUserIdleServiceAndroid.cpp b/widget/android/nsUserIdleServiceAndroid.cpp
new file mode 100644
index 0000000000..670aebe82e
--- /dev/null
+++ b/widget/android/nsUserIdleServiceAndroid.cpp
@@ -0,0 +1,12 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:expandtab:shiftwidth=4:tabstop=4:
+ */
+/* 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 "nsUserIdleServiceAndroid.h"
+
+bool nsUserIdleServiceAndroid::PollIdleTime(uint32_t* aIdleTime) {
+  return false;
+}
diff --git a/widget/android/nsUserIdleServiceAndroid.h b/widget/android/nsUserIdleServiceAndroid.h
new file mode 100644
index 0000000000..81ab790d9d
--- /dev/null
+++ b/widget/android/nsUserIdleServiceAndroid.h
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:expandtab:shiftwidth=4:tabstop=4:
+ */
+/* 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 nsUserIdleServiceAndroid_h__
+#define nsUserIdleServiceAndroid_h__
+
+#include "nsUserIdleService.h"
+
+class nsUserIdleServiceAndroid : public nsUserIdleService {
+ public:
+  NS_INLINE_DECL_REFCOUNTING_INHERITED(nsUserIdleServiceAndroid,
+                                       nsUserIdleService)
+
+  bool PollIdleTime(uint32_t* aIdleTime) override;
+
+  static already_AddRefed<nsUserIdleServiceAndroid> GetInstance() {
+    RefPtr<nsUserIdleService> idleService = nsUserIdleService::GetInstance();
+    if (!idleService) {
+      idleService = new nsUserIdleServiceAndroid();
+    }
+
+    return idleService.forget().downcast<nsUserIdleServiceAndroid>();
+  }
+
+ protected:
+  nsUserIdleServiceAndroid() {}
+  virtual ~nsUserIdleServiceAndroid() {}
+};
+
+#endif  // nsUserIdleServiceAndroid_h__
diff --git a/widget/android/nsWidgetFactory.cpp b/widget/android/nsWidgetFactory.cpp
new file mode 100644
index 0000000000..00ebd20dd9
--- /dev/null
+++ b/widget/android/nsWidgetFactory.cpp
@@ -0,0 +1,21 @@
+/* -*- 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 "mozilla/WidgetUtils.h"
+
+#include "nsAppShell.h"
+
+#include "nsLookAndFeel.h"
+#include "nsAppShellSingleton.h"
+
+nsresult nsWidgetAndroidModuleCtor() { return nsAppShellInit(); }
+
+void nsWidgetAndroidModuleDtor() {
+  // Shutdown all XP level widget classes.
+  mozilla::widget::WidgetUtils::Shutdown();
+
+  nsLookAndFeel::Shutdown();
+  nsAppShellShutdown();
+}
diff --git a/widget/android/nsWidgetFactory.h b/widget/android/nsWidgetFactory.h
new file mode 100644
index 0000000000..934d75d8be
--- /dev/null
+++ b/widget/android/nsWidgetFactory.h
@@ -0,0 +1,21 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:expandtab:shiftwidth=4:tabstop=4:
+ */
+/* 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_android_nsWidgetFactory_h
+#define widget_android_nsWidgetFactory_h
+
+#include "nscore.h"
+#include "nsID.h"
+
+class nsISupports;
+
+nsresult nsAppShellConstructor(const nsIID& iid, void** result);
+
+nsresult nsWidgetAndroidModuleCtor();
+void nsWidgetAndroidModuleDtor();
+
+#endif  // defined widget_android_nsWidgetFactory_h
diff --git a/widget/android/nsWindow.cpp b/widget/android/nsWindow.cpp
new file mode 100644
index 0000000000..0c9fa562a4
--- /dev/null
+++ b/widget/android/nsWindow.cpp
@@ -0,0 +1,3252 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 4; indent-tabs-mode: nil; -*-
+ * vim: set sw=2 ts=4 expandtab:
+ * 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 <atomic>
+#include <android/log.h>
+#include <android/native_window.h>
+#include <android/native_window_jni.h>
+#include <math.h>
+#include <queue>
+#include <type_traits>
+#include <unistd.h>
+
+#include "AndroidGraphics.h"
+#include "AndroidBridge.h"
+#include "AndroidBridgeUtilities.h"
+#include "AndroidCompositorWidget.h"
+#include "AndroidContentController.h"
+#include "AndroidUiThread.h"
+#include "AndroidView.h"
+#include "gfxContext.h"
+#include "GeckoEditableSupport.h"
+#include "GeckoViewOutputStream.h"
+#include "GeckoViewSupport.h"
+#include "GLContext.h"
+#include "GLContextProvider.h"
+#include "JavaBuiltins.h"
+#include "JavaExceptions.h"
+#include "KeyEvent.h"
+#include "MotionEvent.h"
+#include "ScopedGLHelpers.h"
+#include "ScreenHelperAndroid.h"
+#include "TouchResampler.h"
+#include "WidgetUtils.h"
+#include "WindowRenderer.h"
+
+#include "mozilla/EventForwards.h"
+#include "nsAppShell.h"
+#include "nsContentUtils.h"
+#include "nsFocusManager.h"
+#include "nsGkAtoms.h"
+#include "nsGfxCIID.h"
+#include "nsIDocShellTreeOwner.h"
+#include "nsLayoutUtils.h"
+#include "nsNetUtil.h"
+#include "nsPrintfCString.h"
+#include "nsString.h"
+#include "nsTArray.h"
+#include "nsThreadUtils.h"
+#include "nsUserIdleService.h"
+#include "nsViewManager.h"
+#include "nsWidgetsCID.h"
+#include "nsWindow.h"
+
+#include "nsIWidgetListener.h"
+#include "nsIWindowWatcher.h"
+#include "nsIAppWindow.h"
+
+#include "mozilla/Logging.h"
+#include "mozilla/MiscEvents.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_android.h"
+#include "mozilla/StaticPrefs_ui.h"
+#include "mozilla/TouchEvents.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/WheelHandlingHelper.h"  // for WheelDeltaAdjustmentStrategy
+#include "mozilla/a11y/SessionAccessibility.h"
+#include "mozilla/dom/BrowsingContext.h"
+#include "mozilla/dom/BrowserHost.h"
+#include "mozilla/dom/CanonicalBrowsingContext.h"
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/dom/MouseEventBinding.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/DataSurfaceHelpers.h"
+#include "mozilla/gfx/Logging.h"
+#include "mozilla/gfx/Swizzle.h"
+#include "mozilla/gfx/Types.h"
+#include "mozilla/ipc/Shmem.h"
+#include "mozilla/java/EventDispatcherWrappers.h"
+#include "mozilla/java/GeckoAppShellWrappers.h"
+#include "mozilla/java/GeckoEditableChildWrappers.h"
+#include "mozilla/java/GeckoResultWrappers.h"
+#include "mozilla/java/GeckoSessionNatives.h"
+#include "mozilla/java/GeckoSystemStateListenerWrappers.h"
+#include "mozilla/java/PanZoomControllerNatives.h"
+#include "mozilla/java/SessionAccessibilityWrappers.h"
+#include "mozilla/java/SurfaceControlManagerWrappers.h"
+#include "mozilla/jni/NativesInlines.h"
+#include "mozilla/layers/APZEventState.h"
+#include "mozilla/layers/APZInputBridge.h"
+#include "mozilla/layers/APZThreadUtils.h"
+#include "mozilla/layers/CompositorBridgeChild.h"
+#include "mozilla/layers/CompositorOGL.h"
+#include "mozilla/layers/CompositorSession.h"
+#include "mozilla/layers/LayersTypes.h"
+#include "mozilla/layers/UiCompositorControllerChild.h"
+#include "mozilla/layers/IAPZCTreeManager.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/widget/AndroidVsync.h"
+#include "mozilla/widget/Screen.h"
+
+#define GVS_LOG(...) MOZ_LOG(sGVSupportLog, LogLevel::Warning, (__VA_ARGS__))
+
+using namespace mozilla;
+using namespace mozilla::dom;
+using namespace mozilla::layers;
+using namespace mozilla::widget;
+using namespace mozilla::ipc;
+
+using mozilla::dom::ContentChild;
+using mozilla::dom::ContentParent;
+using mozilla::gfx::DataSourceSurface;
+using mozilla::gfx::IntSize;
+using mozilla::gfx::Matrix;
+using mozilla::gfx::SurfaceFormat;
+using mozilla::java::GeckoSession;
+using mozilla::java::sdk::IllegalStateException;
+using GeckoPrintException = GeckoSession::GeckoPrintException;
+static mozilla::LazyLogModule sGVSupportLog("GeckoViewSupport");
+
+// All the toplevel windows that have been created; these are in
+// stacking order, so the window at gTopLevelWindows[0] is the topmost
+// one.
+static nsTArray<nsWindow*> gTopLevelWindows;
+
+static bool sFailedToCreateGLContext = false;
+
+// Multitouch swipe thresholds in inches
+static const double SWIPE_MAX_PINCH_DELTA_INCHES = 0.4;
+static const double SWIPE_MIN_DISTANCE_INCHES = 0.6;
+
+static const double kTouchResampleVsyncAdjustMs = 5.0;
+
+static const int32_t INPUT_RESULT_UNHANDLED =
+    java::PanZoomController::INPUT_RESULT_UNHANDLED;
+static const int32_t INPUT_RESULT_HANDLED =
+    java::PanZoomController::INPUT_RESULT_HANDLED;
+static const int32_t INPUT_RESULT_HANDLED_CONTENT =
+    java::PanZoomController::INPUT_RESULT_HANDLED_CONTENT;
+static const int32_t INPUT_RESULT_IGNORED =
+    java::PanZoomController::INPUT_RESULT_IGNORED;
+
+static const nsCString::size_type MAX_TOPLEVEL_DATA_URI_LEN = 2 * 1024 * 1024;
+
+// Unique ID given to each widget, to identify it for the
+// CompositorSurfaceManager.
+static std::atomic<int32_t> sWidgetId{0};
+
+namespace {
+template <class Instance, class Impl>
+std::enable_if_t<jni::detail::NativePtrPicker<Impl>::value ==
+                     jni::detail::NativePtrType::REFPTR,
+                 void>
+CallAttachNative(Instance aInstance, Impl* aImpl) {
+  Impl::AttachNative(aInstance, RefPtr<Impl>(aImpl).get());
+}
+
+template <class Instance, class Impl>
+std::enable_if_t<jni::detail::NativePtrPicker<Impl>::value ==
+                     jni::detail::NativePtrType::OWNING,
+                 void>
+CallAttachNative(Instance aInstance, Impl* aImpl) {
+  Impl::AttachNative(aInstance, UniquePtr<Impl>(aImpl));
+}
+
+template <class Lambda>
+bool DispatchToUiThread(const char* aName, Lambda&& aLambda) {
+  if (RefPtr<nsThread> uiThread = GetAndroidUiThread()) {
+    uiThread->Dispatch(NS_NewRunnableFunction(aName, std::move(aLambda)));
+    return true;
+  }
+  return false;
+}
+}  // namespace
+
+namespace mozilla {
+namespace widget {
+
+using WindowPtr = jni::NativeWeakPtr<GeckoViewSupport>;
+
+/**
+ * PanZoomController handles its native calls on the UI thread, so make
+ * it separate from GeckoViewSupport.
+ */
+class NPZCSupport final
+    : public java::PanZoomController::NativeProvider::Natives<NPZCSupport> {
+  WindowPtr mWindow;
+  java::PanZoomController::NativeProvider::WeakRef mNPZC;
+
+  // Stores the returnResult of each pending motion event between
+  // HandleMotionEvent and FinishHandlingMotionEvent.
+  std::queue<std::pair<uint64_t, java::GeckoResult::GlobalRef>>
+      mPendingMotionEventReturnResults;
+
+  RefPtr<AndroidVsync> mAndroidVsync;
+  TouchResampler mTouchResampler;
+  int mPreviousButtons = 0;
+  bool mListeningToVsync = false;
+
+  // Only true if mAndroidVsync is non-null and the resampling pref is set.
+  bool mTouchResamplingEnabled = false;
+
+  template <typename Lambda>
+  class InputEvent final : public nsAppShell::Event {
+    java::PanZoomController::NativeProvider::GlobalRef mNPZC;
+    Lambda mLambda;
+
+   public:
+    InputEvent(const NPZCSupport* aNPZCSupport, Lambda&& aLambda)
+        : mNPZC(aNPZCSupport->mNPZC), mLambda(std::move(aLambda)) {}
+
+    void Run() override {
+      MOZ_ASSERT(NS_IsMainThread());
+
+      JNIEnv* const env = jni::GetGeckoThreadEnv();
+      const auto npzcSupportWeak = GetNative(
+          java::PanZoomController::NativeProvider::LocalRef(env, mNPZC));
+      if (!npzcSupportWeak) {
+        // We already shut down.
+        env->ExceptionClear();
+        return;
+      }
+
+      auto acc = npzcSupportWeak->Access();
+      if (!acc) {
+        // We already shut down.
+        env->ExceptionClear();
+        return;
+      }
+
+      auto win = acc->mWindow.Access();
+      if (!win) {
+        // We already shut down.
+        env->ExceptionClear();
+        return;
+      }
+
+      nsWindow* const window = win->GetNsWindow();
+      if (!window) {
+        // We already shut down.
+        env->ExceptionClear();
+        return;
+      }
+
+      window->UserActivity();
+      return mLambda(window);
+    }
+
+    bool IsUIEvent() const override { return true; }
+  };
+
+  class MOZ_HEAP_CLASS Observer final : public AndroidVsync::Observer {
+   public:
+    static Observer* Create(jni::NativeWeakPtr<NPZCSupport>&& aNPZCSupport) {
+      return new Observer(std::move(aNPZCSupport));
+    }
+
+   private:
+    // Private constructor, part of a strategy to make sure
+    // we're only able to create these on the heap.
+    explicit Observer(jni::NativeWeakPtr<NPZCSupport>&& aNPZCSupport)
+        : mNPZCSupport(std::move(aNPZCSupport)) {}
+
+    void OnVsync(const TimeStamp& aTimeStamp) override {
+      auto accessor = mNPZCSupport.Access();
+
+      if (!accessor) {
+        return;
+      }
+
+      accessor->mTouchResampler.NotifyFrame(
+          aTimeStamp -
+          TimeDuration::FromMilliseconds(kTouchResampleVsyncAdjustMs));
+      accessor->ConsumeMotionEventsFromResampler();
+    }
+
+    void Dispose() override { delete this; }
+
+    jni::NativeWeakPtr<NPZCSupport> mNPZCSupport;
+  };
+
+  Observer* mObserver = nullptr;
+
+  template <typename Lambda>
+  void PostInputEvent(Lambda&& aLambda) {
+    // Use priority queue for input events.
+    nsAppShell::PostEvent(
+        MakeUnique<InputEvent<Lambda>>(this, std::move(aLambda)));
+  }
+
+ public:
+  typedef java::PanZoomController::NativeProvider::Natives<NPZCSupport> Base;
+
+  NPZCSupport(WindowPtr aWindow,
+              const java::PanZoomController::NativeProvider::LocalRef& aNPZC)
+      : mWindow(aWindow), mNPZC(aNPZC) {
+#if defined(DEBUG)
+    auto win(mWindow.Access());
+    MOZ_ASSERT(!!win);
+#endif  // defined(DEBUG)
+
+    // Use vsync for touch resampling on API level 19 and above.
+    // See gfxAndroidPlatform::CreateGlobalHardwareVsyncSource() for comparison.
+    if (jni::GetAPIVersion() >= 19) {
+      mAndroidVsync = AndroidVsync::GetInstance();
+    }
+  }
+
+  ~NPZCSupport() {
+    if (mListeningToVsync) {
+      MOZ_RELEASE_ASSERT(mAndroidVsync);
+      mAndroidVsync->UnregisterObserver(mObserver, AndroidVsync::INPUT);
+      mListeningToVsync = false;
+    }
+  }
+
+  using Base::AttachNative;
+  using Base::DisposeNative;
+
+  void OnWeakNonIntrusiveDetach(already_AddRefed<Runnable> aDisposer) {
+    RefPtr<Runnable> disposer = aDisposer;
+    // There are several considerations when shutting down NPZC. 1) The
+    // Gecko thread may destroy NPZC at any time when nsWindow closes. 2)
+    // There may be pending events on the Gecko thread when NPZC is
+    // destroyed. 3) mWindow may not be available when the pending event
+    // runs. 4) The UI thread may destroy NPZC at any time when GeckoView
+    // is destroyed. 5) The UI thread may destroy NPZC at the same time as
+    // Gecko thread trying to destroy NPZC. 6) There may be pending calls
+    // on the UI thread when NPZC is destroyed. 7) mWindow may have been
+    // cleared on the Gecko thread when the pending call happens on the UI
+    // thread.
+    //
+    // 1) happens through OnWeakNonIntrusiveDetach, which first notifies the UI
+    // thread through Destroy; Destroy then calls DisposeNative, which
+    // finally disposes the native instance back on the Gecko thread. Using
+    // Destroy to indirectly call DisposeNative here also solves 5), by
+    // making everything go through the UI thread, avoiding contention.
+    //
+    // 2) and 3) are solved by clearing mWindow, which signals to the
+    // pending event that we had shut down. In that case the event bails
+    // and does not touch mWindow.
+    //
+    // 4) happens through DisposeNative directly.
+    //
+    // 6) is solved by keeping a destroyed flag in the Java NPZC instance,
+    // and only make a pending call if the destroyed flag is not set.
+    //
+    // 7) is solved by taking a lock whenever mWindow is modified on the
+    // Gecko thread or accessed on the UI thread. That way, we don't
+    // release mWindow until the UI thread is done using it, thus avoiding
+    // the race condition.
+
+    if (RefPtr<nsThread> uiThread = GetAndroidUiThread()) {
+      auto npzc = java::PanZoomController::NativeProvider::GlobalRef(mNPZC);
+      if (!npzc) {
+        return;
+      }
+
+      uiThread->Dispatch(
+          NS_NewRunnableFunction("NPZCSupport::OnWeakNonIntrusiveDetach",
+                                 [npzc, disposer = std::move(disposer)] {
+                                   npzc->SetAttached(false);
+                                   disposer->Run();
+                                 }));
+    }
+  }
+
+  const java::PanZoomController::NativeProvider::Ref& GetJavaNPZC() const {
+    return mNPZC;
+  }
+
+ public:
+  void SetIsLongpressEnabled(bool aIsLongpressEnabled) {
+    RefPtr<IAPZCTreeManager> controller;
+
+    if (auto window = mWindow.Access()) {
+      nsWindow* gkWindow = window->GetNsWindow();
+      if (gkWindow) {
+        controller = gkWindow->mAPZC;
+      }
+    }
+
+    if (controller) {
+      controller->SetLongTapEnabled(aIsLongpressEnabled);
+    }
+  }
+
+  int32_t HandleScrollEvent(int64_t aTime, int32_t aMetaState, float aX,
+                            float aY, float aHScroll, float aVScroll) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+
+    RefPtr<IAPZCTreeManager> controller;
+
+    if (auto window = mWindow.Access()) {
+      nsWindow* gkWindow = window->GetNsWindow();
+      if (gkWindow) {
+        controller = gkWindow->mAPZC;
+      }
+    }
+
+    if (!controller) {
+      return INPUT_RESULT_UNHANDLED;
+    }
+
+    ScreenPoint origin = ScreenPoint(aX, aY);
+
+    if (StaticPrefs::ui_scrolling_negate_wheel_scroll()) {
+      aHScroll = -aHScroll;
+      aVScroll = -aVScroll;
+    }
+
+    ScrollWheelInput input(
+        nsWindow::GetEventTimeStamp(aTime), nsWindow::GetModifiers(aMetaState),
+        ScrollWheelInput::SCROLLMODE_SMOOTH,
+        ScrollWheelInput::SCROLLDELTA_PIXEL, origin, aHScroll, aVScroll, false,
+        // XXX Do we need to support auto-dir scrolling
+        // for Android widgets with a wheel device?
+        // Currently, I just leave it unimplemented. If
+        // we need to implement it, what's the extra work
+        // to do?
+        WheelDeltaAdjustmentStrategy::eNone);
+
+    APZEventResult result = controller->InputBridge()->ReceiveInputEvent(input);
+    if (result.GetStatus() == nsEventStatus_eConsumeNoDefault) {
+      return INPUT_RESULT_IGNORED;
+    }
+
+    PostInputEvent([input = std::move(input), result](nsWindow* window) {
+      WidgetWheelEvent wheelEvent = input.ToWidgetEvent(window);
+      window->ProcessUntransformedAPZEvent(&wheelEvent, result);
+    });
+
+    switch (result.GetStatus()) {
+      case nsEventStatus_eIgnore:
+        return INPUT_RESULT_UNHANDLED;
+      case nsEventStatus_eConsumeDoDefault:
+        return result.GetHandledResult()->IsHandledByRoot()
+                   ? INPUT_RESULT_HANDLED
+                   : INPUT_RESULT_HANDLED_CONTENT;
+      default:
+        MOZ_ASSERT_UNREACHABLE("Unexpected nsEventStatus");
+        return INPUT_RESULT_UNHANDLED;
+    }
+  }
+
+ private:
+  static MouseInput::ButtonType GetButtonType(int button) {
+    MouseInput::ButtonType result = MouseInput::NONE;
+
+    switch (button) {
+      case java::sdk::MotionEvent::BUTTON_PRIMARY:
+        result = MouseInput::PRIMARY_BUTTON;
+        break;
+      case java::sdk::MotionEvent::BUTTON_SECONDARY:
+        result = MouseInput::SECONDARY_BUTTON;
+        break;
+      case java::sdk::MotionEvent::BUTTON_TERTIARY:
+        result = MouseInput::MIDDLE_BUTTON;
+        break;
+      default:
+        break;
+    }
+
+    return result;
+  }
+
+  static int16_t ConvertButtons(int buttons) {
+    int16_t result = 0;
+
+    if (buttons & java::sdk::MotionEvent::BUTTON_PRIMARY) {
+      result |= MouseButtonsFlag::ePrimaryFlag;
+    }
+    if (buttons & java::sdk::MotionEvent::BUTTON_SECONDARY) {
+      result |= MouseButtonsFlag::eSecondaryFlag;
+    }
+    if (buttons & java::sdk::MotionEvent::BUTTON_TERTIARY) {
+      result |= MouseButtonsFlag::eMiddleFlag;
+    }
+    if (buttons & java::sdk::MotionEvent::BUTTON_BACK) {
+      result |= MouseButtonsFlag::e4thFlag;
+    }
+    if (buttons & java::sdk::MotionEvent::BUTTON_FORWARD) {
+      result |= MouseButtonsFlag::e5thFlag;
+    }
+
+    return result;
+  }
+
+  static int32_t ConvertAPZHandledPlace(APZHandledPlace aHandledPlace) {
+    switch (aHandledPlace) {
+      case APZHandledPlace::Unhandled:
+        return INPUT_RESULT_UNHANDLED;
+      case APZHandledPlace::HandledByRoot:
+        return INPUT_RESULT_HANDLED;
+      case APZHandledPlace::HandledByContent:
+        return INPUT_RESULT_HANDLED_CONTENT;
+      case APZHandledPlace::Invalid:
+        MOZ_ASSERT_UNREACHABLE("The handled result should NOT be Invalid");
+        return INPUT_RESULT_UNHANDLED;
+    }
+    MOZ_ASSERT_UNREACHABLE("Unknown handled result");
+    return INPUT_RESULT_UNHANDLED;
+  }
+
+  static int32_t ConvertSideBits(SideBits aSideBits) {
+    int32_t ret = java::PanZoomController::SCROLLABLE_FLAG_NONE;
+    if (aSideBits & SideBits::eTop) {
+      ret |= java::PanZoomController::SCROLLABLE_FLAG_TOP;
+    }
+    if (aSideBits & SideBits::eRight) {
+      ret |= java::PanZoomController::SCROLLABLE_FLAG_RIGHT;
+    }
+    if (aSideBits & SideBits::eBottom) {
+      ret |= java::PanZoomController::SCROLLABLE_FLAG_BOTTOM;
+    }
+    if (aSideBits & SideBits::eLeft) {
+      ret |= java::PanZoomController::SCROLLABLE_FLAG_LEFT;
+    }
+    return ret;
+  }
+
+  static int32_t ConvertScrollDirections(
+      layers::ScrollDirections aScrollDirections) {
+    int32_t ret = java::PanZoomController::OVERSCROLL_FLAG_NONE;
+    if (aScrollDirections.contains(layers::HorizontalScrollDirection)) {
+      ret |= java::PanZoomController::OVERSCROLL_FLAG_HORIZONTAL;
+    }
+    if (aScrollDirections.contains(layers::VerticalScrollDirection)) {
+      ret |= java::PanZoomController::OVERSCROLL_FLAG_VERTICAL;
+    }
+    return ret;
+  }
+
+  static java::PanZoomController::InputResultDetail::LocalRef
+  ConvertAPZHandledResult(const APZHandledResult& aHandledResult) {
+    return java::PanZoomController::InputResultDetail::New(
+        ConvertAPZHandledPlace(aHandledResult.mPlace),
+        ConvertSideBits(aHandledResult.mScrollableDirections),
+        ConvertScrollDirections(aHandledResult.mOverscrollDirections));
+  }
+
+ public:
+  int32_t HandleMouseEvent(int32_t aAction, int64_t aTime, int32_t aMetaState,
+                           float aX, float aY, int buttons) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+
+    RefPtr<IAPZCTreeManager> controller;
+
+    if (auto window = mWindow.Access()) {
+      nsWindow* gkWindow = window->GetNsWindow();
+      if (gkWindow) {
+        controller = gkWindow->mAPZC;
+      }
+    }
+
+    if (!controller) {
+      return INPUT_RESULT_UNHANDLED;
+    }
+
+    MouseInput::MouseType mouseType = MouseInput::MOUSE_NONE;
+    MouseInput::ButtonType buttonType = MouseInput::NONE;
+    switch (aAction) {
+      case java::sdk::MotionEvent::ACTION_DOWN:
+        mouseType = MouseInput::MOUSE_DOWN;
+        buttonType = GetButtonType(buttons ^ mPreviousButtons);
+        mPreviousButtons = buttons;
+        break;
+      case java::sdk::MotionEvent::ACTION_UP:
+        mouseType = MouseInput::MOUSE_UP;
+        buttonType = GetButtonType(buttons ^ mPreviousButtons);
+        mPreviousButtons = buttons;
+        break;
+      case java::sdk::MotionEvent::ACTION_MOVE:
+        mouseType = MouseInput::MOUSE_MOVE;
+        break;
+      case java::sdk::MotionEvent::ACTION_HOVER_MOVE:
+        mouseType = MouseInput::MOUSE_MOVE;
+        break;
+      case java::sdk::MotionEvent::ACTION_HOVER_ENTER:
+        mouseType = MouseInput::MOUSE_WIDGET_ENTER;
+        break;
+      case java::sdk::MotionEvent::ACTION_HOVER_EXIT:
+        mouseType = MouseInput::MOUSE_WIDGET_EXIT;
+        break;
+      default:
+        break;
+    }
+
+    if (mouseType == MouseInput::MOUSE_NONE) {
+      return INPUT_RESULT_UNHANDLED;
+    }
+
+    ScreenPoint origin = ScreenPoint(aX, aY);
+
+    MouseInput input(
+        mouseType, buttonType, MouseEvent_Binding::MOZ_SOURCE_MOUSE,
+        ConvertButtons(buttons), origin, nsWindow::GetEventTimeStamp(aTime),
+        nsWindow::GetModifiers(aMetaState));
+
+    APZEventResult result = controller->InputBridge()->ReceiveInputEvent(input);
+    if (result.GetStatus() == nsEventStatus_eConsumeNoDefault) {
+      return INPUT_RESULT_IGNORED;
+    }
+
+    PostInputEvent([input = std::move(input), result](nsWindow* window) {
+      WidgetMouseEvent mouseEvent = input.ToWidgetEvent(window);
+      window->ProcessUntransformedAPZEvent(&mouseEvent, result);
+    });
+
+    switch (result.GetStatus()) {
+      case nsEventStatus_eIgnore:
+        return INPUT_RESULT_UNHANDLED;
+      case nsEventStatus_eConsumeDoDefault:
+        return result.GetHandledResult()->IsHandledByRoot()
+                   ? INPUT_RESULT_HANDLED
+                   : INPUT_RESULT_HANDLED_CONTENT;
+      default:
+        MOZ_ASSERT_UNREACHABLE("Unexpected nsEventStatus");
+        return INPUT_RESULT_UNHANDLED;
+    }
+  }
+
+  // Convert MotionEvent touch radius and orientation into the format required
+  // by w3c touchevents.
+  // toolMajor and toolMinor span a rectangle that's oriented as per
+  // aOrientation, centered around the touch point.
+  static std::pair<float, ScreenSize> ConvertOrientationAndRadius(
+      float aOrientation, float aToolMajor, float aToolMinor) {
+    float angle = aOrientation * 180.0f / M_PI;
+    // w3c touchevents spec does not allow orientations == 90
+    // this shifts it to -90, which will be shifted to zero below
+    if (angle >= 90.0) {
+      angle -= 180.0f;
+    }
+
+    // w3c touchevent radii are given with an orientation between 0 and
+    // 90. The radii are found by removing the orientation and
+    // measuring the x and y radii of the resulting ellipse. For
+    // Android orientations >= 0 and < 90, use the y radius as the
+    // major radius, and x as the minor radius. However, for an
+    // orientation < 0, we have to shift the orientation by adding 90,
+    // and reverse which radius is major and minor.
+    ScreenSize radius;
+    if (angle < 0.0f) {
+      angle += 90.0f;
+      radius =
+          ScreenSize(int32_t(aToolMajor / 2.0f), int32_t(aToolMinor / 2.0f));
+    } else {
+      radius =
+          ScreenSize(int32_t(aToolMinor / 2.0f), int32_t(aToolMajor / 2.0f));
+    }
+
+    return std::make_pair(angle, radius);
+  }
+
+  void HandleMotionEvent(
+      const java::PanZoomController::NativeProvider::LocalRef& aInstance,
+      jni::Object::Param aEventData, float aScreenX, float aScreenY,
+      jni::Object::Param aResult) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+
+    auto returnResult = java::GeckoResult::Ref::From(aResult);
+    auto eventData =
+        java::PanZoomController::MotionEventData::Ref::From(aEventData);
+    nsTArray<int32_t> pointerId(eventData->PointerId()->GetElements());
+    size_t pointerCount = pointerId.Length();
+    MultiTouchInput::MultiTouchType type;
+    size_t startIndex = 0;
+    size_t endIndex = pointerCount;
+
+    switch (eventData->Action()) {
+      case java::sdk::MotionEvent::ACTION_DOWN:
+      case java::sdk::MotionEvent::ACTION_POINTER_DOWN:
+        type = MultiTouchInput::MULTITOUCH_START;
+        break;
+      case java::sdk::MotionEvent::ACTION_MOVE:
+        type = MultiTouchInput::MULTITOUCH_MOVE;
+        break;
+      case java::sdk::MotionEvent::ACTION_UP:
+      case java::sdk::MotionEvent::ACTION_POINTER_UP:
+        // for pointer-up events we only want the data from
+        // the one pointer that went up
+        type = MultiTouchInput::MULTITOUCH_END;
+        startIndex = eventData->ActionIndex();
+        endIndex = startIndex + 1;
+        break;
+      case java::sdk::MotionEvent::ACTION_OUTSIDE:
+      case java::sdk::MotionEvent::ACTION_CANCEL:
+        type = MultiTouchInput::MULTITOUCH_CANCEL;
+        break;
+      default:
+        if (returnResult) {
+          returnResult->Complete(
+              java::sdk::Integer::ValueOf(INPUT_RESULT_UNHANDLED));
+        }
+        return;
+    }
+
+    MultiTouchInput input(type, eventData->Time(),
+                          nsWindow::GetEventTimeStamp(eventData->Time()), 0);
+    input.modifiers = nsWindow::GetModifiers(eventData->MetaState());
+    input.mTouches.SetCapacity(endIndex - startIndex);
+    input.mScreenOffset =
+        ExternalIntPoint(int32_t(floorf(aScreenX)), int32_t(floorf(aScreenY)));
+
+    size_t historySize = eventData->HistorySize();
+    nsTArray<int64_t> historicalTime(
+        eventData->HistoricalTime()->GetElements());
+    MOZ_RELEASE_ASSERT(historicalTime.Length() == historySize);
+
+    // Each of these is |historySize| sets of |pointerCount| values.
+    size_t historicalDataCount = historySize * pointerCount;
+    nsTArray<float> historicalX(eventData->HistoricalX()->GetElements());
+    nsTArray<float> historicalY(eventData->HistoricalY()->GetElements());
+    nsTArray<float> historicalOrientation(
+        eventData->HistoricalOrientation()->GetElements());
+    nsTArray<float> historicalPressure(
+        eventData->HistoricalPressure()->GetElements());
+    nsTArray<float> historicalToolMajor(
+        eventData->HistoricalToolMajor()->GetElements());
+    nsTArray<float> historicalToolMinor(
+        eventData->HistoricalToolMinor()->GetElements());
+
+    MOZ_RELEASE_ASSERT(historicalX.Length() == historicalDataCount);
+    MOZ_RELEASE_ASSERT(historicalY.Length() == historicalDataCount);
+    MOZ_RELEASE_ASSERT(historicalOrientation.Length() == historicalDataCount);
+    MOZ_RELEASE_ASSERT(historicalPressure.Length() == historicalDataCount);
+    MOZ_RELEASE_ASSERT(historicalToolMajor.Length() == historicalDataCount);
+    MOZ_RELEASE_ASSERT(historicalToolMinor.Length() == historicalDataCount);
+
+    // Each of these is |pointerCount| values.
+    nsTArray<float> x(eventData->X()->GetElements());
+    nsTArray<float> y(eventData->Y()->GetElements());
+    nsTArray<float> orientation(eventData->Orientation()->GetElements());
+    nsTArray<float> pressure(eventData->Pressure()->GetElements());
+    nsTArray<float> toolMajor(eventData->ToolMajor()->GetElements());
+    nsTArray<float> toolMinor(eventData->ToolMinor()->GetElements());
+
+    MOZ_ASSERT(x.Length() == pointerCount);
+    MOZ_ASSERT(y.Length() == pointerCount);
+    MOZ_ASSERT(orientation.Length() == pointerCount);
+    MOZ_ASSERT(pressure.Length() == pointerCount);
+    MOZ_ASSERT(toolMajor.Length() == pointerCount);
+    MOZ_ASSERT(toolMinor.Length() == pointerCount);
+
+    for (size_t i = startIndex; i < endIndex; i++) {
+      auto [orien, radius] = ConvertOrientationAndRadius(
+          orientation[i], toolMajor[i], toolMinor[i]);
+
+      ScreenIntPoint point(int32_t(floorf(x[i])), int32_t(floorf(y[i])));
+      SingleTouchData singleTouchData(pointerId[i], point, radius, orien,
+                                      pressure[i]);
+
+      for (size_t historyIndex = 0; historyIndex < historySize;
+           historyIndex++) {
+        size_t historicalI = historyIndex * pointerCount + i;
+        auto [historicalAngle, historicalRadius] = ConvertOrientationAndRadius(
+            historicalOrientation[historicalI],
+            historicalToolMajor[historicalI], historicalToolMinor[historicalI]);
+        ScreenIntPoint historicalPoint(
+            int32_t(floorf(historicalX[historicalI])),
+            int32_t(floorf(historicalY[historicalI])));
+        singleTouchData.mHistoricalData.AppendElement(
+            SingleTouchData::HistoricalTouchData{
+                nsWindow::GetEventTimeStamp(historicalTime[historyIndex]),
+                historicalPoint,
+                {},  // mLocalScreenPoint will be computed later by APZ
+                historicalRadius,
+                historicalAngle,
+                historicalPressure[historicalI]});
+      }
+
+      input.mTouches.AppendElement(singleTouchData);
+    }
+
+    if (mAndroidVsync &&
+        eventData->Action() == java::sdk::MotionEvent::ACTION_DOWN) {
+      // Query pref value at the beginning of a touch gesture so that we don't
+      // leave events stuck in the resampler after a pref flip.
+      mTouchResamplingEnabled = StaticPrefs::android_touch_resampling_enabled();
+    }
+
+    if (!mTouchResamplingEnabled) {
+      FinishHandlingMotionEvent(std::move(input),
+                                java::GeckoResult::LocalRef(returnResult));
+      return;
+    }
+
+    uint64_t eventId = mTouchResampler.ProcessEvent(std::move(input));
+    mPendingMotionEventReturnResults.push(
+        {eventId, java::GeckoResult::GlobalRef(returnResult)});
+
+    RegisterOrUnregisterForVsync(mTouchResampler.InTouchingState());
+    ConsumeMotionEventsFromResampler();
+  }
+
+  void RegisterOrUnregisterForVsync(bool aNeedVsync) {
+    MOZ_RELEASE_ASSERT(mAndroidVsync);
+    if (aNeedVsync && !mListeningToVsync) {
+      MOZ_ASSERT(!mObserver);
+      auto win = mWindow.Access();
+      if (!win) {
+        return;
+      }
+      RefPtr<nsWindow> gkWindow = win->GetNsWindow();
+      if (!gkWindow) {
+        return;
+      }
+      MutexAutoLock lock(gkWindow->GetDestroyMutex());
+      if (gkWindow->Destroyed()) {
+        return;
+      }
+      jni::NativeWeakPtr<NPZCSupport> weakPtrToThis =
+          gkWindow->GetNPZCSupportWeakPtr();
+      mObserver = Observer::Create(std::move(weakPtrToThis));
+      mAndroidVsync->RegisterObserver(mObserver, AndroidVsync::INPUT);
+    } else if (!aNeedVsync && mListeningToVsync) {
+      mAndroidVsync->UnregisterObserver(mObserver, AndroidVsync::INPUT);
+      mObserver = nullptr;
+    }
+    mListeningToVsync = aNeedVsync;
+  }
+
+  void ConsumeMotionEventsFromResampler() {
+    auto outgoing = mTouchResampler.ConsumeOutgoingEvents();
+    while (!outgoing.empty()) {
+      auto outgoingEvent = std::move(outgoing.front());
+      outgoing.pop();
+      java::GeckoResult::GlobalRef returnResult;
+      if (outgoingEvent.mEventId) {
+        // Look up the GeckoResult for this event.
+        // The outgoing events from the resampler are in the same order as the
+        // original events, and no event IDs are skipped.
+        MOZ_RELEASE_ASSERT(!mPendingMotionEventReturnResults.empty());
+        auto pair = mPendingMotionEventReturnResults.front();
+        mPendingMotionEventReturnResults.pop();
+        MOZ_RELEASE_ASSERT(pair.first == *outgoingEvent.mEventId);
+        returnResult = pair.second;
+      }
+      FinishHandlingMotionEvent(std::move(outgoingEvent.mEvent),
+                                java::GeckoResult::LocalRef(returnResult));
+    }
+  }
+
+  void FinishHandlingMotionEvent(MultiTouchInput&& aInput,
+                                 java::GeckoResult::LocalRef&& aReturnResult) {
+    RefPtr<IAPZCTreeManager> controller;
+
+    if (auto window = mWindow.Access()) {
+      nsWindow* gkWindow = window->GetNsWindow();
+      if (gkWindow) {
+        controller = gkWindow->mAPZC;
+      }
+    }
+
+    if (!controller) {
+      if (aReturnResult) {
+        aReturnResult->Complete(java::PanZoomController::InputResultDetail::New(
+            INPUT_RESULT_UNHANDLED,
+            java::PanZoomController::SCROLLABLE_FLAG_NONE,
+            java::PanZoomController::OVERSCROLL_FLAG_NONE));
+      }
+      return;
+    }
+
+    APZInputBridge::InputBlockCallback callback;
+    if (aReturnResult) {
+      callback = [aReturnResult = java::GeckoResult::GlobalRef(aReturnResult)](
+                     uint64_t aInputBlockId,
+                     const APZHandledResult& aHandledResult) {
+        aReturnResult->Complete(ConvertAPZHandledResult(aHandledResult));
+      };
+    }
+    APZEventResult result = controller->InputBridge()->ReceiveInputEvent(
+        aInput, std::move(callback));
+
+    if (result.GetStatus() == nsEventStatus_eConsumeNoDefault) {
+      if (aReturnResult) {
+        if (result.GetHandledResult() != Nothing()) {
+          aReturnResult->Complete(
+              ConvertAPZHandledResult(result.GetHandledResult().value()));
+        } else {
+          MOZ_ASSERT_UNREACHABLE(
+              "nsEventStatus_eConsumeNoDefault should involve a valid "
+              "APZHandledResult");
+          aReturnResult->Complete(
+              java::PanZoomController::InputResultDetail::New(
+                  INPUT_RESULT_IGNORED,
+                  java::PanZoomController::SCROLLABLE_FLAG_NONE,
+                  java::PanZoomController::OVERSCROLL_FLAG_NONE));
+        }
+      }
+      return;
+    }
+
+    // Dispatch APZ input event on Gecko thread.
+    PostInputEvent([input = std::move(aInput), result](nsWindow* window) {
+      WidgetTouchEvent touchEvent = input.ToWidgetEvent(window);
+      window->ProcessUntransformedAPZEvent(&touchEvent, result);
+      window->DispatchHitTest(touchEvent);
+    });
+
+    if (aReturnResult && result.GetHandledResult() != Nothing()) {
+      MOZ_ASSERT(result.GetStatus() == nsEventStatus_eConsumeDoDefault ||
+                 result.GetStatus() == nsEventStatus_eIgnore);
+      aReturnResult->Complete(
+          ConvertAPZHandledResult(result.GetHandledResult().value()));
+    }
+  }
+};
+
+NS_IMPL_ISUPPORTS(AndroidView, nsIAndroidEventDispatcher, nsIAndroidView)
+
+nsresult AndroidView::GetInitData(JSContext* aCx,
+                                  JS::MutableHandle<JS::Value> aOut) {
+  if (!mInitData) {
+    aOut.setNull();
+    return NS_OK;
+  }
+
+  return widget::EventDispatcher::UnboxBundle(aCx, mInitData, aOut);
+}
+
+/**
+ * Compositor has some unique requirements for its native calls, so make it
+ * separate from GeckoViewSupport.
+ */
+class LayerViewSupport final
+    : public GeckoSession::Compositor::Natives<LayerViewSupport> {
+  WindowPtr mWindow;
+  GeckoSession::Compositor::WeakRef mCompositor;
+  Atomic<bool, ReleaseAcquire> mCompositorPaused;
+  java::sdk::Surface::GlobalRef mSurface;
+  java::sdk::SurfaceControl::GlobalRef mSurfaceControl;
+  int32_t mX;
+  int32_t mY;
+  int32_t mWidth;
+  int32_t mHeight;
+  // Used to communicate with the gecko compositor from the UI thread.
+  // Set in NotifyCompositorCreated and cleared in
+  // NotifyCompositorSessionLost.
+  RefPtr<UiCompositorControllerChild> mUiCompositorControllerChild;
+  // Whether we have requested a new Surface from the GeckoSession.
+  bool mRequestedNewSurface = false;
+
+  Maybe<uint32_t> mDefaultClearColor;
+
+  struct CaptureRequest {
+    explicit CaptureRequest() : mResult(nullptr) {}
+    explicit CaptureRequest(java::GeckoResult::GlobalRef aResult,
+                            java::sdk::Bitmap::GlobalRef aBitmap,
+                            const ScreenRect& aSource,
+                            const IntSize& aOutputSize)
+        : mResult(aResult),
+          mBitmap(aBitmap),
+          mSource(aSource),
+          mOutputSize(aOutputSize) {}
+
+    // where to send the pixels
+    java::GeckoResult::GlobalRef mResult;
+
+    // where to store the pixels
+    java::sdk::Bitmap::GlobalRef mBitmap;
+
+    ScreenRect mSource;
+
+    IntSize mOutputSize;
+  };
+  std::queue<CaptureRequest> mCapturePixelsResults;
+
+  // In order to use Event::HasSameTypeAs in PostTo(), we cannot make
+  // LayerViewEvent a template because each template instantiation is
+  // a different type. So implement LayerViewEvent as a ProxyEvent.
+  class LayerViewEvent final : public nsAppShell::ProxyEvent {
+    using Event = nsAppShell::Event;
+
+   public:
+    static UniquePtr<Event> MakeEvent(UniquePtr<Event>&& event) {
+      return MakeUnique<LayerViewEvent>(std::move(event));
+    }
+
+    explicit LayerViewEvent(UniquePtr<Event>&& event)
+        : nsAppShell::ProxyEvent(std::move(event)) {}
+
+    void PostTo(LinkedList<Event>& queue) override {
+      // Give priority to compositor events, but keep in order with
+      // existing compositor events.
+      nsAppShell::Event* event = queue.getFirst();
+      while (event && event->HasSameTypeAs(this)) {
+        event = event->getNext();
+      }
+      if (event) {
+        event->setPrevious(this);
+      } else {
+        queue.insertBack(this);
+      }
+    }
+  };
+
+ public:
+  typedef GeckoSession::Compositor::Natives<LayerViewSupport> Base;
+
+  LayerViewSupport(WindowPtr aWindow,
+                   const GeckoSession::Compositor::LocalRef& aInstance)
+      : mWindow(aWindow), mCompositor(aInstance), mCompositorPaused(true) {
+#if defined(DEBUG)
+    auto win(mWindow.Access());
+    MOZ_ASSERT(!!win);
+#endif  // defined(DEBUG)
+  }
+
+  ~LayerViewSupport() {}
+
+  using Base::AttachNative;
+  using Base::DisposeNative;
+
+  void OnWeakNonIntrusiveDetach(already_AddRefed<Runnable> aDisposer) {
+    RefPtr<Runnable> disposer = aDisposer;
+    if (RefPtr<nsThread> uiThread = GetAndroidUiThread()) {
+      GeckoSession::Compositor::GlobalRef compositor(mCompositor);
+      if (!compositor) {
+        return;
+      }
+
+      uiThread->Dispatch(NS_NewRunnableFunction(
+          "LayerViewSupport::OnWeakNonIntrusiveDetach",
+          [compositor, disposer = std::move(disposer),
+           results = &mCapturePixelsResults, window = mWindow]() mutable {
+            if (auto accWindow = window.Access()) {
+              while (!results->empty()) {
+                auto aResult =
+                    java::GeckoResult::LocalRef(results->front().mResult);
+                if (aResult) {
+                  aResult->CompleteExceptionally(
+                      java::sdk::IllegalStateException::New(
+                          "The compositor has detached from the session")
+                          .Cast<jni::Throwable>());
+                }
+                results->pop();
+              }
+            }
+
+            compositor->OnCompositorDetached();
+            disposer->Run();
+          }));
+    }
+  }
+
+  const GeckoSession::Compositor::Ref& GetJavaCompositor() const {
+    return mCompositor;
+  }
+
+  bool CompositorPaused() const { return mCompositorPaused; }
+
+  /// Called from the main thread whenever the compositor has been
+  /// (re)initialized.
+  void NotifyCompositorCreated(
+      RefPtr<UiCompositorControllerChild> aUiCompositorControllerChild) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+    mUiCompositorControllerChild = aUiCompositorControllerChild;
+
+    if (mDefaultClearColor) {
+      mUiCompositorControllerChild->SetDefaultClearColor(*mDefaultClearColor);
+    }
+
+    if (!mCompositorPaused) {
+      // If we are using SurfaceControl but mSurface is null, that means the
+      // previous surface was destroyed along with the the previous
+      // compositor, and we need to create a new one.
+      if (mSurfaceControl && !mSurface) {
+        mSurface = java::SurfaceControlManager::GetInstance()->GetChildSurface(
+            mSurfaceControl, mWidth, mHeight);
+      }
+
+      if (auto window{mWindow.Access()}) {
+        nsWindow* gkWindow = window->GetNsWindow();
+        if (gkWindow) {
+          mUiCompositorControllerChild->OnCompositorSurfaceChanged(
+              gkWindow->mWidgetId, mSurface);
+        }
+      }
+
+      bool resumed = mUiCompositorControllerChild->ResumeAndResize(
+          mX, mY, mWidth, mHeight);
+      if (!resumed) {
+        gfxCriticalNote
+            << "Failed to resume compositor from NotifyCompositorCreated";
+        RequestNewSurface();
+      }
+    }
+  }
+
+  /// Called from the main thread whenever the compositor has been destroyed.
+  void NotifyCompositorSessionLost() {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+    mUiCompositorControllerChild = nullptr;
+
+    if (mSurfaceControl) {
+      // If we are using SurfaceControl then we must set the Surface to null
+      // here to ensure we create a new one when the new compositor is
+      // created.
+      mSurface = nullptr;
+    }
+
+    if (auto window = mWindow.Access()) {
+      while (!mCapturePixelsResults.empty()) {
+        auto result =
+            java::GeckoResult::LocalRef(mCapturePixelsResults.front().mResult);
+        if (result) {
+          result->CompleteExceptionally(
+              java::sdk::IllegalStateException::New(
+                  "Compositor session lost during screen pixels request")
+                  .Cast<jni::Throwable>());
+        }
+        mCapturePixelsResults.pop();
+      }
+    }
+  }
+
+  java::sdk::Surface::Param GetSurface() { return mSurface; }
+
+ private:
+  already_AddRefed<DataSourceSurface> FlipScreenPixels(
+      Shmem& aMem, const ScreenIntSize& aInSize, const ScreenRect& aInRegion,
+      const IntSize& aOutSize) {
+    RefPtr<gfx::DataSourceSurface> image =
+        gfx::Factory::CreateWrappingDataSourceSurface(
+            aMem.get<uint8_t>(),
+            StrideForFormatAndWidth(SurfaceFormat::B8G8R8A8, aInSize.width),
+            IntSize(aInSize.width, aInSize.height), SurfaceFormat::B8G8R8A8);
+    RefPtr<gfx::DrawTarget> drawTarget =
+        gfxPlatform::GetPlatform()->CreateOffscreenContentDrawTarget(
+            aOutSize, SurfaceFormat::B8G8R8A8);
+    if (!drawTarget) {
+      return nullptr;
+    }
+
+    drawTarget->SetTransform(Matrix::Scaling(1.0, -1.0) *
+                             Matrix::Translation(0, aOutSize.height));
+
+    gfx::Rect srcRect(aInRegion.x,
+                      (aInSize.height - aInRegion.height) - aInRegion.y,
+                      aInRegion.width, aInRegion.height);
+    gfx::Rect destRect(0, 0, aOutSize.width, aOutSize.height);
+    drawTarget->DrawSurface(image, destRect, srcRect);
+
+    RefPtr<gfx::SourceSurface> snapshot = drawTarget->Snapshot();
+    RefPtr<gfx::DataSourceSurface> data = snapshot->GetDataSurface();
+    return data.forget();
+  }
+
+  /**
+   * Compositor methods
+   */
+ public:
+  void AttachNPZC(jni::Object::Param aNPZC) {
+    MOZ_ASSERT(NS_IsMainThread());
+    MOZ_ASSERT(aNPZC);
+
+    auto locked(mWindow.Access());
+    if (!locked) {
+      return;  // Already shut down.
+    }
+
+    nsWindow* gkWindow = locked->GetNsWindow();
+
+    // We can have this situation if we get two GeckoViewSupport::Transfer()
+    // called before the first AttachNPZC() gets here. Just detach the current
+    // instance since that's what happens in GeckoViewSupport::Transfer() as
+    // well.
+    gkWindow->mNPZCSupport.Detach();
+
+    auto npzc = java::PanZoomController::NativeProvider::LocalRef(
+        jni::GetGeckoThreadEnv(),
+        java::PanZoomController::NativeProvider::Ref::From(aNPZC));
+    gkWindow->mNPZCSupport =
+        jni::NativeWeakPtrHolder<NPZCSupport>::Attach(npzc, mWindow, npzc);
+
+    DispatchToUiThread(
+        "LayerViewSupport::AttachNPZC",
+        [npzc = java::PanZoomController::NativeProvider::GlobalRef(npzc)] {
+          npzc->SetAttached(true);
+        });
+  }
+
+  void OnBoundsChanged(int32_t aLeft, int32_t aTop, int32_t aWidth,
+                       int32_t aHeight) {
+    MOZ_ASSERT(NS_IsMainThread());
+    auto acc = mWindow.Access();
+    if (!acc) {
+      return;  // Already shut down.
+    }
+
+    nsWindow* gkWindow = acc->GetNsWindow();
+    if (!gkWindow) {
+      return;
+    }
+
+    gkWindow->Resize(aLeft, aTop, aWidth, aHeight, /* repaint */ false);
+  }
+
+  void NotifyMemoryPressure() {
+    MOZ_ASSERT(NS_IsMainThread());
+    auto acc = mWindow.Access();
+    if (!acc) {
+      return;  // Already shut down.
+    }
+
+    nsWindow* gkWindow = acc->GetNsWindow();
+    if (!gkWindow || !gkWindow->mCompositorBridgeChild) {
+      return;
+    }
+
+    gkWindow->mCompositorBridgeChild->SendNotifyMemoryPressure();
+  }
+
+  void SetDynamicToolbarMaxHeight(int32_t aHeight) {
+    MOZ_ASSERT(NS_IsMainThread());
+    auto acc = mWindow.Access();
+    if (!acc) {
+      return;  // Already shut down.
+    }
+
+    nsWindow* gkWindow = acc->GetNsWindow();
+    if (!gkWindow) {
+      return;
+    }
+
+    gkWindow->UpdateDynamicToolbarMaxHeight(ScreenIntCoord(aHeight));
+  }
+
+  void SyncPauseCompositor() {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+
+    mCompositorPaused = true;
+
+    if (mUiCompositorControllerChild) {
+      mUiCompositorControllerChild->Pause();
+
+      mSurface = nullptr;
+      mSurfaceControl = nullptr;
+      if (auto window = mWindow.Access()) {
+        nsWindow* gkWindow = window->GetNsWindow();
+        if (gkWindow) {
+          mUiCompositorControllerChild->OnCompositorSurfaceChanged(
+              gkWindow->mWidgetId, nullptr);
+        }
+      }
+    }
+
+    if (auto lock{mWindow.Access()}) {
+      while (!mCapturePixelsResults.empty()) {
+        auto result =
+            java::GeckoResult::LocalRef(mCapturePixelsResults.front().mResult);
+        if (result) {
+          result->CompleteExceptionally(
+              java::sdk::IllegalStateException::New(
+                  "The compositor has detached from the session")
+                  .Cast<jni::Throwable>());
+        }
+        mCapturePixelsResults.pop();
+      }
+    }
+  }
+
+  void SyncResumeCompositor() {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+
+    if (mUiCompositorControllerChild) {
+      mCompositorPaused = false;
+      bool resumed = mUiCompositorControllerChild->Resume();
+      if (!resumed) {
+        gfxCriticalNote
+            << "Failed to resume compositor from SyncResumeCompositor";
+        RequestNewSurface();
+      }
+    }
+  }
+
+  void SyncResumeResizeCompositor(
+      const GeckoSession::Compositor::LocalRef& aObj, int32_t aX, int32_t aY,
+      int32_t aWidth, int32_t aHeight, jni::Object::Param aSurface,
+      jni::Object::Param aSurfaceControl) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+
+    mX = aX;
+    mY = aY;
+    mWidth = aWidth;
+    mHeight = aHeight;
+    mSurfaceControl =
+        java::sdk::SurfaceControl::GlobalRef::From(aSurfaceControl);
+    if (mSurfaceControl) {
+      // When using SurfaceControl, we create a child Surface to render in to
+      // rather than rendering directly in to the Surface provided by the
+      // application. This allows us to work around a bug on some versions of
+      // Android when recovering from a GPU process crash.
+      mSurface = java::SurfaceControlManager::GetInstance()->GetChildSurface(
+          mSurfaceControl, mWidth, mHeight);
+    } else {
+      mSurface = java::sdk::Surface::GlobalRef::From(aSurface);
+    }
+
+    if (mUiCompositorControllerChild) {
+      if (auto window = mWindow.Access()) {
+        nsWindow* gkWindow = window->GetNsWindow();
+        if (gkWindow) {
+          // Send new Surface to GPU process, if one exists.
+          mUiCompositorControllerChild->OnCompositorSurfaceChanged(
+              gkWindow->mWidgetId, mSurface);
+        }
+      }
+
+      bool resumed = mUiCompositorControllerChild->ResumeAndResize(
+          aX, aY, aWidth, aHeight);
+      if (!resumed) {
+        gfxCriticalNote
+            << "Failed to resume compositor from SyncResumeResizeCompositor";
+        // Only request a new Surface if this SyncResumeAndResize call is not
+        // response to a previous request, otherwise we will get stuck in an
+        // infinite loop.
+        if (!mRequestedNewSurface) {
+          RequestNewSurface();
+        }
+        return;
+      }
+    }
+
+    mRequestedNewSurface = false;
+
+    mCompositorPaused = false;
+
+    class OnResumedEvent : public nsAppShell::Event {
+      GeckoSession::Compositor::GlobalRef mCompositor;
+
+     public:
+      explicit OnResumedEvent(GeckoSession::Compositor::GlobalRef&& aCompositor)
+          : mCompositor(std::move(aCompositor)) {}
+
+      void Run() override {
+        MOZ_ASSERT(NS_IsMainThread());
+
+        JNIEnv* const env = jni::GetGeckoThreadEnv();
+        const auto lvsHolder =
+            GetNative(GeckoSession::Compositor::LocalRef(env, mCompositor));
+
+        if (!lvsHolder) {
+          env->ExceptionClear();
+          return;  // Already shut down.
+        }
+
+        auto lvs(lvsHolder->Access());
+        if (!lvs) {
+          env->ExceptionClear();
+          return;  // Already shut down.
+        }
+
+        auto win = lvs->mWindow.Access();
+        if (!win) {
+          env->ExceptionClear();
+          return;  // Already shut down.
+        }
+
+        // When we get here, the compositor has already been told to
+        // resume. This means it's now safe for layer updates to occur.
+        // Since we might have prevented one or more draw events from
+        // occurring while the compositor was paused, we need to
+        // schedule a draw event now.
+        if (!lvs->mCompositorPaused) {
+          nsWindow* const gkWindow = win->GetNsWindow();
+          if (gkWindow) {
+            gkWindow->RedrawAll();
+          }
+        }
+      }
+    };
+
+    // Use priority queue for timing-sensitive event.
+    nsAppShell::PostEvent(
+        MakeUnique<LayerViewEvent>(MakeUnique<OnResumedEvent>(aObj)));
+  }
+
+  void RequestNewSurface() {
+    if (const auto& compositor = GetJavaCompositor()) {
+      mRequestedNewSurface = true;
+      if (mSurfaceControl) {
+        java::SurfaceControlManager::GetInstance()->RemoveSurface(
+            mSurfaceControl);
+      }
+      compositor->RequestNewSurface();
+    }
+  }
+
+  mozilla::jni::Object::LocalRef GetMagnifiableSurface() {
+    return mozilla::jni::Object::LocalRef::From(GetSurface());
+  }
+
+  void SyncInvalidateAndScheduleComposite() {
+    if (!mUiCompositorControllerChild) {
+      return;
+    }
+
+    if (AndroidBridge::IsJavaUiThread()) {
+      mUiCompositorControllerChild->InvalidateAndRender();
+      return;
+    }
+
+    if (RefPtr<nsThread> uiThread = GetAndroidUiThread()) {
+      uiThread->Dispatch(NewRunnableMethod<>(
+                             "LayerViewSupport::InvalidateAndRender",
+                             mUiCompositorControllerChild,
+                             &UiCompositorControllerChild::InvalidateAndRender),
+                         nsIThread::DISPATCH_NORMAL);
+    }
+  }
+
+  void SetMaxToolbarHeight(int32_t aHeight) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+
+    if (mUiCompositorControllerChild) {
+      mUiCompositorControllerChild->SetMaxToolbarHeight(aHeight);
+    }
+  }
+
+  void SetFixedBottomOffset(int32_t aOffset) {
+    if (auto acc{mWindow.Access()}) {
+      nsWindow* gkWindow = acc->GetNsWindow();
+      if (gkWindow) {
+        gkWindow->UpdateDynamicToolbarOffset(ScreenIntCoord(aOffset));
+      }
+    }
+
+    if (RefPtr<nsThread> uiThread = GetAndroidUiThread()) {
+      uiThread->Dispatch(NS_NewRunnableFunction(
+          "LayerViewSupport::SetFixedBottomOffset", [this, offset = aOffset] {
+            if (mUiCompositorControllerChild) {
+              mUiCompositorControllerChild->SetFixedBottomOffset(offset);
+            }
+          }));
+    }
+  }
+
+  void SendToolbarAnimatorMessage(int32_t aMessage) {
+    if (!mUiCompositorControllerChild) {
+      return;
+    }
+
+    if (AndroidBridge::IsJavaUiThread()) {
+      mUiCompositorControllerChild->ToolbarAnimatorMessageFromUI(aMessage);
+      return;
+    }
+
+    if (RefPtr<nsThread> uiThread = GetAndroidUiThread()) {
+      uiThread->Dispatch(
+          NewRunnableMethod<int32_t>(
+              "LayerViewSupport::ToolbarAnimatorMessageFromUI",
+              mUiCompositorControllerChild,
+              &UiCompositorControllerChild::ToolbarAnimatorMessageFromUI,
+              aMessage),
+          nsIThread::DISPATCH_NORMAL);
+    }
+  }
+
+  void RecvToolbarAnimatorMessage(int32_t aMessage) {
+    auto compositor = GeckoSession::Compositor::LocalRef(mCompositor);
+    if (compositor) {
+      compositor->RecvToolbarAnimatorMessage(aMessage);
+    }
+  }
+
+  void SetDefaultClearColor(int32_t aColor) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+    mDefaultClearColor = Some((uint32_t)aColor);
+    if (mUiCompositorControllerChild) {
+      mUiCompositorControllerChild->SetDefaultClearColor((uint32_t)aColor);
+    }
+  }
+
+  void RequestScreenPixels(jni::Object::Param aResult,
+                           jni::Object::Param aTarget, int32_t aXOffset,
+                           int32_t aYOffset, int32_t aSrcWidth,
+                           int32_t aSrcHeight, int32_t aOutWidth,
+                           int32_t aOutHeight) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+    auto result = java::GeckoResult::LocalRef(aResult);
+
+    if (!mUiCompositorControllerChild) {
+      if (result) {
+        if (auto window = mWindow.Access()) {
+          result->CompleteExceptionally(
+              java::sdk::IllegalStateException::New(
+                  "Compositor session lost prior to screen pixels request")
+                  .Cast<jni::Throwable>());
+        }
+      }
+      return;
+    }
+
+    int size = 0;
+    if (auto window = mWindow.Access()) {
+      mCapturePixelsResults.push(CaptureRequest(
+          java::GeckoResult::GlobalRef(result),
+          java::sdk::Bitmap::GlobalRef(java::sdk::Bitmap::LocalRef(aTarget)),
+          ScreenRect(aXOffset, aYOffset, aSrcWidth, aSrcHeight),
+          IntSize(aOutWidth, aOutHeight)));
+      size = mCapturePixelsResults.size();
+    }
+
+    if (size == 1) {
+      mUiCompositorControllerChild->RequestScreenPixels();
+    }
+  }
+
+  void RecvScreenPixels(Shmem&& aMem, const ScreenIntSize& aSize,
+                        bool aNeedsYFlip) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+    CaptureRequest request;
+    java::GeckoResult::LocalRef result = nullptr;
+    java::sdk::Bitmap::LocalRef bitmap = nullptr;
+    if (auto window = mWindow.Access()) {
+      // The result might have been already rejected if the compositor was
+      // detached from the session
+      if (!mCapturePixelsResults.empty()) {
+        request = mCapturePixelsResults.front();
+        result = java::GeckoResult::LocalRef(request.mResult);
+        bitmap = java::sdk::Bitmap::LocalRef(request.mBitmap);
+        mCapturePixelsResults.pop();
+      }
+    }
+
+    if (result) {
+      if (bitmap) {
+        RefPtr<DataSourceSurface> surf;
+        if (aNeedsYFlip) {
+          surf = FlipScreenPixels(aMem, aSize, request.mSource,
+                                  request.mOutputSize);
+        } else {
+          surf = gfx::Factory::CreateWrappingDataSourceSurface(
+              aMem.get<uint8_t>(),
+              StrideForFormatAndWidth(SurfaceFormat::B8G8R8A8, aSize.width),
+              IntSize(aSize.width, aSize.height), SurfaceFormat::B8G8R8A8);
+        }
+        if (surf) {
+          DataSourceSurface::ScopedMap smap(surf, DataSourceSurface::READ);
+          auto pixels = mozilla::jni::ByteBuffer::New(
+              reinterpret_cast<int8_t*>(smap.GetData()),
+              smap.GetStride() * request.mOutputSize.height);
+          bitmap->CopyPixelsFromBuffer(pixels);
+          result->Complete(bitmap);
+        } else {
+          result->CompleteExceptionally(
+              java::sdk::IllegalStateException::New(
+                  "Failed to create flipped snapshot surface (probably out "
+                  "of memory)")
+                  .Cast<jni::Throwable>());
+        }
+      } else {
+        result->CompleteExceptionally(java::sdk::IllegalArgumentException::New(
+                                          "No target bitmap argument provided")
+                                          .Cast<jni::Throwable>());
+      }
+    }
+
+    // Pixels have been copied, so Dealloc Shmem
+    if (mUiCompositorControllerChild) {
+      mUiCompositorControllerChild->DeallocPixelBuffer(aMem);
+
+      if (auto window = mWindow.Access()) {
+        if (!mCapturePixelsResults.empty()) {
+          mUiCompositorControllerChild->RequestScreenPixels();
+        }
+      }
+    }
+  }
+
+  void EnableLayerUpdateNotifications(bool aEnable) {
+    MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+    if (mUiCompositorControllerChild) {
+      mUiCompositorControllerChild->EnableLayerUpdateNotifications(aEnable);
+    }
+  }
+
+  void OnSafeAreaInsetsChanged(int32_t aTop, int32_t aRight, int32_t aBottom,
+                               int32_t aLeft) {
+    MOZ_ASSERT(NS_IsMainThread());
+    auto win(mWindow.Access());
+    if (!win) {
+      return;  // Already shut down.
+    }
+
+    nsWindow* gkWindow = win->GetNsWindow();
+    if (!gkWindow) {
+      return;
+    }
+
+    ScreenIntMargin safeAreaInsets(aTop, aRight, aBottom, aLeft);
+    gkWindow->UpdateSafeAreaInsets(safeAreaInsets);
+  }
+};
+
+GeckoViewSupport::~GeckoViewSupport() {
+  if (mWindow) {
+    mWindow->DetachNatives();
+  }
+}
+
+/* static */
+void GeckoViewSupport::Open(
+    const jni::Class::LocalRef& aCls, GeckoSession::Window::Param aWindow,
+    jni::Object::Param aQueue, jni::Object::Param aCompositor,
+    jni::Object::Param aDispatcher, jni::Object::Param aSessionAccessibility,
+    jni::Object::Param aInitData, jni::String::Param aId,
+    jni::String::Param aChromeURI, bool aPrivateMode) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  AUTO_PROFILER_LABEL("mozilla::widget::GeckoViewSupport::Open", OTHER);
+
+  // We'll need gfxPlatform to be initialized to create a compositor later.
+  // Might as well do that now so that the GPU process launch can get a head
+  // start.
+  gfxPlatform::GetPlatform();
+
+  nsCOMPtr<nsIWindowWatcher> ww = do_GetService(NS_WINDOWWATCHER_CONTRACTID);
+  MOZ_RELEASE_ASSERT(ww);
+
+  nsAutoCString url;
+  if (aChromeURI) {
+    url = aChromeURI->ToCString();
+  } else {
+    nsresult rv = Preferences::GetCString("toolkit.defaultChromeURI", url);
+    if (NS_FAILED(rv)) {
+      url = "chrome://geckoview/content/geckoview.xhtml"_ns;
+    }
+  }
+
+  // Prepare an nsIAndroidView to pass as argument to the window.
+  RefPtr<AndroidView> androidView = new AndroidView();
+  androidView->mEventDispatcher->Attach(
+      java::EventDispatcher::Ref::From(aDispatcher), nullptr);
+  androidView->mInitData = java::GeckoBundle::Ref::From(aInitData);
+
+  nsAutoCString chromeFlags("chrome,dialog=0,remote,resizable,scrollbars");
+  if (aPrivateMode) {
+    chromeFlags += ",private";
+  }
+  nsCOMPtr<mozIDOMWindowProxy> domWindow;
+  ww->OpenWindow(nullptr, url, nsDependentCString(aId->ToCString().get()),
+                 chromeFlags, androidView, getter_AddRefs(domWindow));
+  MOZ_RELEASE_ASSERT(domWindow);
+
+  nsCOMPtr<nsPIDOMWindowOuter> pdomWindow = nsPIDOMWindowOuter::From(domWindow);
+  const RefPtr<nsWindow> window = nsWindow::From(pdomWindow);
+  MOZ_ASSERT(window);
+
+  // Attach a new GeckoView support object to the new window.
+  GeckoSession::Window::LocalRef sessionWindow(aCls.Env(), aWindow);
+  auto weakGeckoViewSupport =
+      jni::NativeWeakPtrHolder<GeckoViewSupport>::Attach(
+          sessionWindow, window, sessionWindow, pdomWindow);
+
+  window->mGeckoViewSupport = weakGeckoViewSupport;
+  window->mAndroidView = androidView;
+
+  // Attach other session support objects.
+  {  // Scope for gvsAccess
+    auto gvsAccess = weakGeckoViewSupport.Access();
+    MOZ_ASSERT(gvsAccess);
+
+    gvsAccess->Transfer(sessionWindow, aQueue, aCompositor, aDispatcher,
+                        aSessionAccessibility, aInitData);
+  }
+
+  if (window->mWidgetListener) {
+    nsCOMPtr<nsIAppWindow> appWindow(window->mWidgetListener->GetAppWindow());
+    if (appWindow) {
+      // Our window is not intrinsically sized, so tell AppWindow to
+      // not set a size for us.
+      appWindow->SetIntrinsicallySized(false);
+    }
+  }
+}
+
+void GeckoViewSupport::Close() {
+  if (mWindow) {
+    if (mWindow->mAndroidView) {
+      mWindow->mAndroidView->mEventDispatcher->Detach();
+    }
+    mWindow = nullptr;
+  }
+
+  if (!mDOMWindow) {
+    return;
+  }
+
+  mDOMWindow->ForceClose();
+  mDOMWindow = nullptr;
+  mGeckoViewWindow = nullptr;
+}
+
+void GeckoViewSupport::Transfer(const GeckoSession::Window::LocalRef& inst,
+                                jni::Object::Param aQueue,
+                                jni::Object::Param aCompositor,
+                                jni::Object::Param aDispatcher,
+                                jni::Object::Param aSessionAccessibility,
+                                jni::Object::Param aInitData) {
+  mWindow->mNPZCSupport.Detach();
+
+  auto compositor = GeckoSession::Compositor::LocalRef(
+      inst.Env(), GeckoSession::Compositor::Ref::From(aCompositor));
+
+  bool attachLvs;
+  {  // Scope for lvsAccess
+    auto lvsAccess{mWindow->mLayerViewSupport.Access()};
+    // If we do not yet have mLayerViewSupport, or if the compositor has
+    // changed, then we must attach a new one.
+    attachLvs = !lvsAccess || lvsAccess->GetJavaCompositor() != compositor;
+  }
+
+  if (attachLvs) {
+    mWindow->mLayerViewSupport =
+        jni::NativeWeakPtrHolder<LayerViewSupport>::Attach(
+            compositor, mWindow->mGeckoViewSupport, compositor);
+
+    if (RefPtr<UiCompositorControllerChild> uiCompositorController =
+            mWindow->GetUiCompositorControllerChild()) {
+      DispatchToUiThread(
+          "LayerViewSupport::NotifyCompositorCreated",
+          [lvs = mWindow->mLayerViewSupport, uiCompositorController] {
+            if (auto lvsAccess{lvs.Access()}) {
+              lvsAccess->NotifyCompositorCreated(uiCompositorController);
+            }
+          });
+    }
+  }
+
+  MOZ_ASSERT(mWindow->mAndroidView);
+  mWindow->mAndroidView->mEventDispatcher->Attach(
+      java::EventDispatcher::Ref::From(aDispatcher), mDOMWindow);
+
+  RefPtr<jni::DetachPromise> promise = mWindow->mSessionAccessibility.Detach();
+  if (aSessionAccessibility) {
+    // SessionAccessibility's JNI object isn't released immediately, it uses
+    // recycled object, we have to wait for released object completely.
+    auto sa = java::SessionAccessibility::NativeProvider::LocalRef(
+        aSessionAccessibility);
+    promise->Then(
+        GetMainThreadSerialEventTarget(),
+        "GeckoViewSupprt::Transfer::SessionAccessibility",
+        [inst = GeckoSession::Window::GlobalRef(inst),
+         sa = java::SessionAccessibility::NativeProvider::GlobalRef(sa),
+         window = mWindow, gvs = mWindow->mGeckoViewSupport](
+            const mozilla::jni::DetachPromise::ResolveOrRejectValue& aValue) {
+          MOZ_ASSERT(aValue.IsResolve());
+          if (window->Destroyed()) {
+            return;
+          }
+
+          MOZ_ASSERT(!window->mSessionAccessibility.IsAttached());
+          if (auto gvsAccess{gvs.Access()}) {
+            gvsAccess->AttachAccessibility(inst, sa);
+          }
+        });
+  }
+
+  if (mIsReady) {
+    // We're in a transfer; update init-data and notify JS code.
+    mWindow->mAndroidView->mInitData = java::GeckoBundle::Ref::From(aInitData);
+    OnReady(aQueue);
+    mWindow->mAndroidView->mEventDispatcher->Dispatch(
+        u"GeckoView:UpdateInitData");
+  }
+
+  DispatchToUiThread("GeckoViewSupport::Transfer",
+                     [compositor = GeckoSession::Compositor::GlobalRef(
+                          compositor)] { compositor->OnCompositorAttached(); });
+}
+
+void GeckoViewSupport::AttachEditable(
+    const GeckoSession::Window::LocalRef& inst,
+    jni::Object::Param aEditableParent) {
+  if (auto win{mWindow->mEditableSupport.Access()}) {
+    win->TransferParent(aEditableParent);
+  } else {
+    auto editableChild = java::GeckoEditableChild::New(aEditableParent,
+                                                       /* default */ true);
+    mWindow->mEditableSupport =
+        jni::NativeWeakPtrHolder<GeckoEditableSupport>::Attach(
+            editableChild, mWindow->mGeckoViewSupport, editableChild);
+  }
+
+  mWindow->mEditableParent = aEditableParent;
+}
+
+void GeckoViewSupport::AttachAccessibility(
+    const GeckoSession::Window::LocalRef& inst,
+    jni::Object::Param aSessionAccessibility) {
+  java::SessionAccessibility::NativeProvider::LocalRef sessionAccessibility(
+      inst.Env());
+  sessionAccessibility = java::SessionAccessibility::NativeProvider::Ref::From(
+      aSessionAccessibility);
+
+  mWindow->mSessionAccessibility =
+      jni::NativeWeakPtrHolder<a11y::SessionAccessibility>::Attach(
+          sessionAccessibility, mWindow->mGeckoViewSupport,
+          sessionAccessibility);
+}
+
+auto GeckoViewSupport::OnLoadRequest(mozilla::jni::String::Param aUri,
+                                     int32_t aWindowType, int32_t aFlags,
+                                     mozilla::jni::String::Param aTriggeringUri,
+                                     bool aHasUserGesture,
+                                     bool aIsTopLevel) const
+    -> java::GeckoResult::LocalRef {
+  GeckoSession::Window::LocalRef window(mGeckoViewWindow);
+  if (!window) {
+    return nullptr;
+  }
+  return window->OnLoadRequest(aUri, aWindowType, aFlags, aTriggeringUri,
+                               aHasUserGesture, aIsTopLevel);
+}
+
+void GeckoViewSupport::OnShowDynamicToolbar() const {
+  GeckoSession::Window::LocalRef window(mGeckoViewWindow);
+  if (!window) {
+    return;
+  }
+
+  window->OnShowDynamicToolbar();
+}
+
+void GeckoViewSupport::OnReady(jni::Object::Param aQueue) {
+  GeckoSession::Window::LocalRef window(mGeckoViewWindow);
+  if (!window) {
+    return;
+  }
+  window->OnReady(aQueue);
+  mIsReady = true;
+}
+
+void GeckoViewSupport::PassExternalResponse(
+    java::WebResponse::Param aResponse) {
+  GeckoSession::Window::LocalRef window(mGeckoViewWindow);
+  if (!window) {
+    return;
+  }
+
+  auto response = java::WebResponse::GlobalRef(aResponse);
+
+  DispatchToUiThread("GeckoViewSupport::PassExternalResponse",
+                     [window = java::GeckoSession::Window::GlobalRef(window),
+                      response] { window->PassExternalWebResponse(response); });
+}
+
+RefPtr<CanonicalBrowsingContext>
+GeckoViewSupport::GetContentCanonicalBrowsingContext() {
+  nsCOMPtr<nsIDocShellTreeOwner> treeOwner = mDOMWindow->GetTreeOwner();
+  if (!treeOwner) {
+    return nullptr;
+  }
+  RefPtr<BrowsingContext> bc;
+  nsresult rv = treeOwner->GetPrimaryContentBrowsingContext(getter_AddRefs(bc));
+  if (NS_WARN_IF(NS_FAILED(rv)) || !bc) {
+    return nullptr;
+  }
+  return bc->Canonical();
+}
+
+void GeckoViewSupport::CreatePdf(
+    jni::LocalRef<mozilla::java::GeckoResult> aGeckoResult,
+    RefPtr<dom::CanonicalBrowsingContext> aCbc) {
+  MOZ_ASSERT(NS_IsMainThread());
+  const auto pdfErrorMsg = "Could not save this page as PDF.";
+  auto stream = java::GeckoInputStream::New(nullptr);
+  RefPtr<GeckoViewOutputStream> streamListener =
+      new GeckoViewOutputStream(stream);
+
+  nsCOMPtr<nsIPrintSettingsService> printSettingsService =
+      do_GetService("@mozilla.org/gfx/printsettings-service;1");
+  if (!printSettingsService) {
+    aGeckoResult->CompleteExceptionally(
+        GeckoPrintException::New(
+            GeckoPrintException::ERROR_PRINT_SETTINGS_SERVICE_NOT_AVAILABLE)
+            .Cast<jni::Throwable>());
+    GVS_LOG("Could not create print settings service.");
+    return;
+  }
+
+  nsCOMPtr<nsIPrintSettings> printSettings;
+  nsresult rv = printSettingsService->CreateNewPrintSettings(
+      getter_AddRefs(printSettings));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    aGeckoResult->CompleteExceptionally(
+        GeckoPrintException::New(
+            GeckoPrintException::ERROR_UNABLE_TO_CREATE_PRINT_SETTINGS)
+            .Cast<jni::Throwable>());
+    GVS_LOG("Could not create print settings.");
+    return;
+  }
+
+  printSettings->SetPrinterName(u"Mozilla Save to PDF"_ns);
+  printSettings->SetOutputDestination(
+      nsIPrintSettings::kOutputDestinationStream);
+  printSettings->SetOutputFormat(nsIPrintSettings::kOutputFormatPDF);
+  printSettings->SetOutputStream(streamListener);
+  printSettings->SetPrintSilent(true);
+
+  RefPtr<CanonicalBrowsingContext::PrintPromise> print =
+      aCbc->Print(printSettings);
+
+  aGeckoResult->Complete(stream);
+  print->Then(
+      mozilla::GetCurrentSerialEventTarget(), __func__,
+      [result = java::GeckoResult::GlobalRef(aGeckoResult), stream,
+       pdfErrorMsg](
+          const CanonicalBrowsingContext::PrintPromise::ResolveOrRejectValue&
+              aValue) {
+        if (aValue.IsReject()) {
+          GVS_LOG("Could not print. %s", pdfErrorMsg);
+          stream->WriteError();
+        }
+      });
+}
+
+void GeckoViewSupport::PrintToPdf(
+    const java::GeckoSession::Window::LocalRef& inst,
+    jni::Object::Param aResult) {
+  auto geckoResult = java::GeckoResult::Ref::From(aResult);
+  RefPtr<CanonicalBrowsingContext> cbc = GetContentCanonicalBrowsingContext();
+  if (!cbc) {
+    geckoResult->CompleteExceptionally(
+        GeckoPrintException::New(
+            GeckoPrintException::
+                ERROR_UNABLE_TO_RETRIEVE_CANONICAL_BROWSING_CONTEXT)
+            .Cast<jni::Throwable>());
+    GVS_LOG("Could not retrieve content canonical browsing context.");
+    return;
+  }
+  CreatePdf(geckoResult, cbc);
+}
+
+void GeckoViewSupport::PrintToPdf(
+    const java::GeckoSession::Window::LocalRef& inst,
+    jni::Object::Param aResult, int64_t aBcId) {
+  auto geckoResult = java::GeckoResult::Ref::From(aResult);
+
+  RefPtr<CanonicalBrowsingContext> cbc = CanonicalBrowsingContext::Get(aBcId);
+  if (!cbc) {
+    geckoResult->CompleteExceptionally(
+        GeckoPrintException::New(
+            GeckoPrintException::
+                ERROR_UNABLE_TO_RETRIEVE_CANONICAL_BROWSING_CONTEXT)
+            .Cast<jni::Throwable>());
+    GVS_LOG("Could not retrieve content canonical browsing context by ID.");
+    return;
+  }
+  CreatePdf(geckoResult, cbc);
+}
+}  // namespace widget
+}  // namespace mozilla
+
+void nsWindow::InitNatives() {
+  jni::InitConversionStatics();
+  mozilla::widget::GeckoViewSupport::Base::Init();
+  mozilla::widget::LayerViewSupport::Init();
+  mozilla::widget::NPZCSupport::Init();
+
+  mozilla::widget::GeckoEditableSupport::Init();
+  a11y::SessionAccessibility::Init();
+}
+
+void nsWindow::DetachNatives() {
+  MOZ_ASSERT(NS_IsMainThread());
+  mEditableSupport.Detach();
+  mNPZCSupport.Detach();
+  mLayerViewSupport.Detach();
+  mSessionAccessibility.Detach();
+}
+
+/* static */
+already_AddRefed<nsWindow> nsWindow::From(nsPIDOMWindowOuter* aDOMWindow) {
+  nsCOMPtr<nsIWidget> widget = WidgetUtils::DOMWindowToWidget(aDOMWindow);
+  return From(widget);
+}
+
+/* static */
+already_AddRefed<nsWindow> nsWindow::From(nsIWidget* aWidget) {
+  // `widget` may be one of several different types in the parent
+  // process, including the Android nsWindow, PuppetWidget, etc. To
+  // ensure that the cast to the Android nsWindow is valid, we check that the
+  // widget is a top-level window and that its NS_NATIVE_WIDGET value is
+  // non-null, which is not the case for non-native widgets like
+  // PuppetWidget.
+  if (aWidget && aWidget->GetWindowType() == WindowType::TopLevel &&
+      aWidget->GetNativeData(NS_NATIVE_WIDGET) == aWidget) {
+    RefPtr<nsWindow> window = static_cast<nsWindow*>(aWidget);
+    return window.forget();
+  }
+  return nullptr;
+}
+
+nsWindow* nsWindow::TopWindow() {
+  if (!gTopLevelWindows.IsEmpty()) return gTopLevelWindows[0];
+  return nullptr;
+}
+
+void nsWindow::LogWindow(nsWindow* win, int index, int indent) {
+#if defined(DEBUG) || defined(FORCE_ALOG)
+  char spaces[] = "                    ";
+  spaces[indent < 20 ? indent : 20] = 0;
+  ALOG("%s [% 2d] 0x%p [parent 0x%p] [% 3d,% 3dx% 3d,% 3d] vis %d type %d",
+       spaces, index, win, win->mParent, win->mBounds.x, win->mBounds.y,
+       win->mBounds.width, win->mBounds.height, win->mIsVisible,
+       int(win->mWindowType));
+#endif
+}
+
+void nsWindow::DumpWindows() { DumpWindows(gTopLevelWindows); }
+
+void nsWindow::DumpWindows(const nsTArray<nsWindow*>& wins, int indent) {
+  for (uint32_t i = 0; i < wins.Length(); ++i) {
+    nsWindow* w = wins[i];
+    LogWindow(w, i, indent);
+    DumpWindows(w->mChildren, indent + 1);
+  }
+}
+
+nsWindow::nsWindow()
+    : mWidgetId(++sWidgetId),
+      mIsVisible(false),
+      mParent(nullptr),
+      mDynamicToolbarMaxHeight(0),
+      mSizeMode(nsSizeMode_Normal),
+      mIsFullScreen(false),
+      mCompositorWidgetDelegate(nullptr),
+      mDestroyMutex("nsWindow::mDestroyMutex") {}
+
+nsWindow::~nsWindow() {
+  gTopLevelWindows.RemoveElement(this);
+  ALOG("nsWindow %p destructor", (void*)this);
+  // The mCompositorSession should have been cleaned up in nsWindow::Destroy()
+  // DestroyLayerManager() will call DestroyCompositor() which will crash if
+  // called from nsBaseWidget destructor. See Bug 1392705
+  MOZ_ASSERT(!mCompositorSession);
+}
+
+bool nsWindow::IsTopLevel() {
+  return mWindowType == WindowType::TopLevel ||
+         mWindowType == WindowType::Dialog ||
+         mWindowType == WindowType::Invisible;
+}
+
+nsresult nsWindow::Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
+                          const LayoutDeviceIntRect& aRect,
+                          InitData* aInitData) {
+  ALOG("nsWindow[%p]::Create %p [%d %d %d %d]", (void*)this, (void*)aParent,
+       aRect.x, aRect.y, aRect.width, aRect.height);
+
+  nsWindow* parent = (nsWindow*)aParent;
+  if (aNativeParent) {
+    if (parent) {
+      ALOG(
+          "Ignoring native parent on Android window [%p], "
+          "since parent was specified (%p %p)",
+          (void*)this, (void*)aNativeParent, (void*)aParent);
+    } else {
+      parent = (nsWindow*)aNativeParent;
+    }
+  }
+
+  // A default size of 1x1 confuses MobileViewportManager, so
+  // use 0x0 instead. This is also a little more fitting since
+  // we don't yet have a surface yet (and therefore a valid size)
+  // and 0x0 is usually recognized as invalid.
+  LayoutDeviceIntRect rect = aRect;
+  if (aRect.width == 1 && aRect.height == 1) {
+    rect.width = 0;
+    rect.height = 0;
+  }
+
+  mBounds = rect;
+  SetSizeConstraints(SizeConstraints());
+
+  BaseCreate(nullptr, aInitData);
+
+  NS_ASSERTION(IsTopLevel() || parent,
+               "non-top-level window doesn't have a parent!");
+
+  if (IsTopLevel()) {
+    gTopLevelWindows.AppendElement(this);
+
+  } else if (parent) {
+    parent->mChildren.AppendElement(this);
+    mParent = parent;
+  }
+
+#ifdef DEBUG_ANDROID_WIDGET
+  DumpWindows();
+#endif
+
+  return NS_OK;
+}
+
+void nsWindow::Destroy() {
+  MutexAutoLock lock(mDestroyMutex);
+
+  nsBaseWidget::mOnDestroyCalled = true;
+
+  // Disassociate our native object from GeckoView.
+  mGeckoViewSupport.Detach();
+
+  // Stuff below may release the last ref to this
+  nsCOMPtr<nsIWidget> kungFuDeathGrip(this);
+
+  while (mChildren.Length()) {
+    // why do we still have children?
+    ALOG("### Warning: Destroying window %p and reparenting child %p to null!",
+         (void*)this, (void*)mChildren[0]);
+    mChildren[0]->SetParent(nullptr);
+  }
+
+  // Ensure the compositor has been shutdown before this nsWindow is potentially
+  // deleted
+  nsBaseWidget::DestroyCompositor();
+
+  nsBaseWidget::Destroy();
+
+  if (IsTopLevel()) gTopLevelWindows.RemoveElement(this);
+
+  SetParent(nullptr);
+
+  nsBaseWidget::OnDestroy();
+
+#ifdef DEBUG_ANDROID_WIDGET
+  DumpWindows();
+#endif
+}
+
+mozilla::widget::EventDispatcher* nsWindow::GetEventDispatcher() const {
+  if (mAndroidView) {
+    return mAndroidView->mEventDispatcher;
+  }
+  return nullptr;
+}
+
+void nsWindow::RedrawAll() {
+  if (mAttachedWidgetListener) {
+    mAttachedWidgetListener->RequestRepaint();
+  } else if (mWidgetListener) {
+    mWidgetListener->RequestRepaint();
+  }
+}
+
+RefPtr<UiCompositorControllerChild> nsWindow::GetUiCompositorControllerChild() {
+  return mCompositorSession
+             ? mCompositorSession->GetUiCompositorControllerChild()
+             : nullptr;
+}
+
+mozilla::layers::LayersId nsWindow::GetRootLayerId() const {
+  return mCompositorSession ? mCompositorSession->RootLayerTreeId()
+                            : mozilla::layers::LayersId{0};
+}
+
+void nsWindow::OnGeckoViewReady() {
+  auto acc(mGeckoViewSupport.Access());
+  if (!acc) {
+    return;
+  }
+
+  acc->OnReady();
+}
+
+void nsWindow::SetParent(nsIWidget* aNewParent) {
+  if ((nsIWidget*)mParent == aNewParent) return;
+
+  // If we had a parent before, remove ourselves from its list of
+  // children.
+  if (mParent) mParent->mChildren.RemoveElement(this);
+
+  mParent = (nsWindow*)aNewParent;
+
+  if (mParent) mParent->mChildren.AppendElement(this);
+
+  // if we are now in the toplevel window's hierarchy, schedule a redraw
+  if (FindTopLevel() == nsWindow::TopWindow()) RedrawAll();
+}
+
+nsIWidget* nsWindow::GetParent() { return mParent; }
+
+RefPtr<MozPromise<bool, bool, false>> nsWindow::OnLoadRequest(
+    nsIURI* aUri, int32_t aWindowType, int32_t aFlags,
+    nsIPrincipal* aTriggeringPrincipal, bool aHasUserGesture,
+    bool aIsTopLevel) {
+  auto geckoViewSupport(mGeckoViewSupport.Access());
+  if (!geckoViewSupport) {
+    return MozPromise<bool, bool, false>::CreateAndResolve(false, __func__);
+  }
+
+  nsAutoCString spec, triggeringSpec;
+  if (aUri) {
+    aUri->GetDisplaySpec(spec);
+    if (aIsTopLevel && mozilla::net::SchemeIsData(aUri) &&
+        spec.Length() > MAX_TOPLEVEL_DATA_URI_LEN) {
+      return MozPromise<bool, bool, false>::CreateAndResolve(false, __func__);
+    }
+  }
+
+  bool isNullPrincipal = false;
+  if (aTriggeringPrincipal) {
+    aTriggeringPrincipal->GetIsNullPrincipal(&isNullPrincipal);
+
+    if (!isNullPrincipal) {
+      nsCOMPtr<nsIURI> triggeringUri;
+      BasePrincipal::Cast(aTriggeringPrincipal)
+          ->GetURI(getter_AddRefs(triggeringUri));
+      if (triggeringUri) {
+        triggeringUri->GetDisplaySpec(triggeringSpec);
+      }
+    }
+  }
+
+  auto geckoResult = geckoViewSupport->OnLoadRequest(
+      spec.get(), aWindowType, aFlags,
+      isNullPrincipal ? nullptr : triggeringSpec.get(), aHasUserGesture,
+      aIsTopLevel);
+  return geckoResult
+             ? MozPromise<bool, bool, false>::FromGeckoResult(geckoResult)
+             : nullptr;
+}
+
+void nsWindow::OnUpdateSessionStore(mozilla::jni::Object::Param aBundle) {
+  auto geckoViewSupport(mGeckoViewSupport.Access());
+  if (!geckoViewSupport) {
+    return;
+  }
+
+  geckoViewSupport->OnUpdateSessionStore(aBundle);
+}
+
+float nsWindow::GetDPI() {
+  float dpi = 160.0f;
+
+  nsCOMPtr<nsIScreen> screen = GetWidgetScreen();
+  if (screen) {
+    screen->GetDpi(&dpi);
+  }
+
+  return dpi;
+}
+
+double nsWindow::GetDefaultScaleInternal() {
+  double scale = 1.0f;
+
+  nsCOMPtr<nsIScreen> screen = GetWidgetScreen();
+  if (screen) {
+    screen->GetContentsScaleFactor(&scale);
+  }
+
+  return scale;
+}
+
+void nsWindow::Show(bool aState) {
+  ALOG("nsWindow[%p]::Show %d", (void*)this, aState);
+
+  if (mWindowType == WindowType::Invisible) {
+    ALOG("trying to show invisible window! ignoring..");
+    return;
+  }
+
+  if (aState == mIsVisible) return;
+
+  mIsVisible = aState;
+
+  if (IsTopLevel()) {
+    // XXX should we bring this to the front when it's shown,
+    // if it's a toplevel widget?
+
+    // XXX we should synthesize a eMouseExitFromWidget (for old top
+    // window)/eMouseEnterIntoWidget (for new top window) since we need
+    // to pretend that the top window always has focus.  Not sure
+    // if Show() is the right place to do this, though.
+
+    if (aState) {
+      // It just became visible, so bring it to the front.
+      BringToFront();
+
+    } else if (nsWindow::TopWindow() == this) {
+      // find the next visible window to show
+      unsigned int i;
+      for (i = 1; i < gTopLevelWindows.Length(); i++) {
+        nsWindow* win = gTopLevelWindows[i];
+        if (!win->mIsVisible) continue;
+
+        win->BringToFront();
+        break;
+      }
+    }
+  } else if (FindTopLevel() == nsWindow::TopWindow()) {
+    RedrawAll();
+  }
+
+#ifdef DEBUG_ANDROID_WIDGET
+  DumpWindows();
+#endif
+}
+
+bool nsWindow::IsVisible() const { return mIsVisible; }
+
+void nsWindow::ConstrainPosition(DesktopIntPoint& aPoint) {
+  ALOG("nsWindow[%p]::ConstrainPosition [%d %d]", (void*)this, aPoint.x.value,
+       aPoint.y.value);
+
+  // Constrain toplevel windows; children we don't care about
+  if (IsTopLevel()) {
+    aPoint = DesktopIntPoint();
+  }
+}
+
+void nsWindow::Move(double aX, double aY) {
+  if (IsTopLevel()) return;
+
+  Resize(aX, aY, mBounds.width, mBounds.height, true);
+}
+
+void nsWindow::Resize(double aWidth, double aHeight, bool aRepaint) {
+  Resize(mBounds.x, mBounds.y, aWidth, aHeight, aRepaint);
+}
+
+void nsWindow::Resize(double aX, double aY, double aWidth, double aHeight,
+                      bool aRepaint) {
+  ALOG("nsWindow[%p]::Resize [%f %f %f %f] (repaint %d)", (void*)this, aX, aY,
+       aWidth, aHeight, aRepaint);
+
+  LayoutDeviceIntRect oldBounds = mBounds;
+
+  mBounds.x = NSToIntRound(aX);
+  mBounds.y = NSToIntRound(aY);
+  mBounds.width = NSToIntRound(aWidth);
+  mBounds.height = NSToIntRound(aHeight);
+
+  ConstrainSize(&mBounds.width, &mBounds.height);
+
+  bool needPositionDispatch = mBounds.TopLeft() != oldBounds.TopLeft();
+  bool needSizeDispatch = mBounds.Size() != oldBounds.Size();
+
+  if (needSizeDispatch) {
+    OnSizeChanged(mBounds.Size().ToUnknownSize());
+  }
+
+  if (needPositionDispatch) {
+    NotifyWindowMoved(mBounds.x, mBounds.y);
+  }
+
+  // Should we skip honoring aRepaint here?
+  if (aRepaint && FindTopLevel() == nsWindow::TopWindow()) RedrawAll();
+}
+
+void nsWindow::SetZIndex(int32_t aZIndex) {
+  ALOG("nsWindow[%p]::SetZIndex %d ignored", (void*)this, aZIndex);
+}
+
+void nsWindow::SetSizeMode(nsSizeMode aMode) {
+  if (aMode == mSizeMode) {
+    return;
+  }
+
+  mSizeMode = aMode;
+
+  switch (aMode) {
+    case nsSizeMode_Minimized:
+      java::GeckoAppShell::MoveTaskToBack();
+      break;
+    case nsSizeMode_Fullscreen:
+      MakeFullScreen(true);
+      break;
+    default:
+      break;
+  }
+}
+
+void nsWindow::Enable(bool aState) {
+  ALOG("nsWindow[%p]::Enable %d ignored", (void*)this, aState);
+}
+
+bool nsWindow::IsEnabled() const { return true; }
+
+void nsWindow::Invalidate(const LayoutDeviceIntRect& aRect) {}
+
+nsWindow* nsWindow::FindTopLevel() {
+  nsWindow* toplevel = this;
+  while (toplevel) {
+    if (toplevel->IsTopLevel()) return toplevel;
+
+    toplevel = toplevel->mParent;
+  }
+
+  ALOG(
+      "nsWindow::FindTopLevel(): couldn't find a toplevel or dialog window in "
+      "this [%p] widget's hierarchy!",
+      (void*)this);
+  return this;
+}
+
+void nsWindow::SetFocus(Raise, mozilla::dom::CallerType aCallerType) {
+  FindTopLevel()->BringToFront();
+}
+
+void nsWindow::BringToFront() {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  // If the window to be raised is the same as the currently raised one,
+  // do nothing. We need to check the focus manager as well, as the first
+  // window that is created will be first in the window list but won't yet
+  // be focused.
+  nsFocusManager* fm = nsFocusManager::GetFocusManager();
+  if (fm && fm->GetActiveWindow() && FindTopLevel() == nsWindow::TopWindow()) {
+    return;
+  }
+
+  if (!IsTopLevel()) {
+    FindTopLevel()->BringToFront();
+    return;
+  }
+
+  RefPtr<nsWindow> kungFuDeathGrip(this);
+
+  nsWindow* oldTop = nullptr;
+  if (!gTopLevelWindows.IsEmpty()) {
+    oldTop = gTopLevelWindows[0];
+  }
+
+  gTopLevelWindows.RemoveElement(this);
+  gTopLevelWindows.InsertElementAt(0, this);
+
+  if (oldTop) {
+    nsIWidgetListener* listener = oldTop->GetWidgetListener();
+    if (listener) {
+      listener->WindowDeactivated();
+    }
+  }
+
+  if (mWidgetListener) {
+    mWidgetListener->WindowActivated();
+  }
+
+  RedrawAll();
+}
+
+LayoutDeviceIntRect nsWindow::GetScreenBounds() {
+  return LayoutDeviceIntRect(WidgetToScreenOffset(), mBounds.Size());
+}
+
+LayoutDeviceIntPoint nsWindow::WidgetToScreenOffset() {
+  LayoutDeviceIntPoint p(0, 0);
+
+  for (nsWindow* w = this; !!w; w = w->mParent) {
+    p.x += w->mBounds.x;
+    p.y += w->mBounds.y;
+
+    if (w->IsTopLevel()) {
+      break;
+    }
+  }
+  return p;
+}
+
+nsresult nsWindow::DispatchEvent(WidgetGUIEvent* aEvent,
+                                 nsEventStatus& aStatus) {
+  aStatus = DispatchEvent(aEvent);
+  return NS_OK;
+}
+
+nsEventStatus nsWindow::DispatchEvent(WidgetGUIEvent* aEvent) {
+  if (mAttachedWidgetListener) {
+    return mAttachedWidgetListener->HandleEvent(aEvent, mUseAttachedEvents);
+  } else if (mWidgetListener) {
+    return mWidgetListener->HandleEvent(aEvent, mUseAttachedEvents);
+  }
+  return nsEventStatus_eIgnore;
+}
+
+nsresult nsWindow::MakeFullScreen(bool aFullScreen) {
+  if (!mAndroidView) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  mIsFullScreen = aFullScreen;
+  mAndroidView->mEventDispatcher->Dispatch(
+      aFullScreen ? u"GeckoView:FullScreenEnter" : u"GeckoView:FullScreenExit");
+
+  nsIWidgetListener* listener = GetWidgetListener();
+  if (listener) {
+    mSizeMode = mIsFullScreen ? nsSizeMode_Fullscreen : nsSizeMode_Normal;
+    listener->SizeModeChanged(mSizeMode);
+  }
+  return NS_OK;
+}
+
+mozilla::WindowRenderer* nsWindow::GetWindowRenderer() {
+  if (!mWindowRenderer) {
+    CreateLayerManager();
+  }
+
+  return mWindowRenderer;
+}
+
+void nsWindow::CreateLayerManager() {
+  if (mWindowRenderer) {
+    return;
+  }
+
+  nsWindow* topLevelWindow = FindTopLevel();
+  if (!topLevelWindow || topLevelWindow->mWindowType == WindowType::Invisible) {
+    // don't create a layer manager for an invisible top-level window
+    return;
+  }
+
+  // Ensure that gfxPlatform is initialized first.
+  gfxPlatform::GetPlatform();
+
+  if (ShouldUseOffMainThreadCompositing()) {
+    LayoutDeviceIntRect rect = GetBounds();
+    CreateCompositor(rect.Width(), rect.Height());
+    if (mWindowRenderer) {
+      if (mLayerViewSupport.IsAttached()) {
+        DispatchToUiThread(
+            "LayerViewSupport::NotifyCompositorCreated",
+            [lvs = mLayerViewSupport,
+             uiCompositorController = GetUiCompositorControllerChild()] {
+              if (auto lvsAccess{lvs.Access()}) {
+                lvsAccess->NotifyCompositorCreated(uiCompositorController);
+              }
+            });
+      }
+
+      return;
+    }
+
+    // If we get here, then off main thread compositing failed to initialize.
+    sFailedToCreateGLContext = true;
+  }
+
+  if (!ComputeShouldAccelerate() || sFailedToCreateGLContext) {
+    printf_stderr(" -- creating basic, not accelerated\n");
+    mWindowRenderer = CreateFallbackRenderer();
+  }
+}
+
+void nsWindow::NotifyCompositorSessionLost(
+    mozilla::layers::CompositorSession* aSession) {
+  nsBaseWidget::NotifyCompositorSessionLost(aSession);
+
+  DispatchToUiThread("nsWindow::NotifyCompositorSessionLost",
+                     [lvs = mLayerViewSupport] {
+                       if (auto lvsAccess{lvs.Access()}) {
+                         lvsAccess->NotifyCompositorSessionLost();
+                       }
+                     });
+
+  RedrawAll();
+}
+
+void nsWindow::ShowDynamicToolbar() {
+  auto acc(mGeckoViewSupport.Access());
+  if (!acc) {
+    return;
+  }
+
+  acc->OnShowDynamicToolbar();
+}
+
+void GeckoViewSupport::OnUpdateSessionStore(
+    mozilla::jni::Object::Param aBundle) {
+  GeckoSession::Window::LocalRef window(mGeckoViewWindow);
+  if (!window) {
+    return;
+  }
+
+  window->OnUpdateSessionStore(aBundle);
+}
+
+void nsWindow::OnSizeChanged(const gfx::IntSize& aSize) {
+  ALOG("nsWindow: %p OnSizeChanged [%d %d]", (void*)this, aSize.width,
+       aSize.height);
+
+  if (mWidgetListener) {
+    mWidgetListener->WindowResized(this, aSize.width, aSize.height);
+  }
+
+  if (mAttachedWidgetListener) {
+    mAttachedWidgetListener->WindowResized(this, aSize.width, aSize.height);
+  }
+
+  if (mCompositorWidgetDelegate) {
+    mCompositorWidgetDelegate->NotifyClientSizeChanged(
+        LayoutDeviceIntSize::FromUnknownSize(aSize));
+  }
+}
+
+void nsWindow::InitEvent(WidgetGUIEvent& event, LayoutDeviceIntPoint* aPoint) {
+  if (aPoint) {
+    event.mRefPoint = *aPoint;
+  } else {
+    event.mRefPoint = LayoutDeviceIntPoint(0, 0);
+  }
+}
+
+void nsWindow::UpdateOverscrollVelocity(const float aX, const float aY) {
+  if (::mozilla::jni::NativeWeakPtr<LayerViewSupport>::Accessor lvs{
+          mLayerViewSupport.Access()}) {
+    const auto& compositor = lvs->GetJavaCompositor();
+    if (AndroidBridge::IsJavaUiThread()) {
+      compositor->UpdateOverscrollVelocity(aX, aY);
+      return;
+    }
+
+    DispatchToUiThread(
+        "nsWindow::UpdateOverscrollVelocity",
+        [compositor = GeckoSession::Compositor::GlobalRef(compositor), aX, aY] {
+          compositor->UpdateOverscrollVelocity(aX, aY);
+        });
+  }
+}
+
+void nsWindow::UpdateOverscrollOffset(const float aX, const float aY) {
+  if (::mozilla::jni::NativeWeakPtr<LayerViewSupport>::Accessor lvs{
+          mLayerViewSupport.Access()}) {
+    const auto& compositor = lvs->GetJavaCompositor();
+    if (AndroidBridge::IsJavaUiThread()) {
+      compositor->UpdateOverscrollOffset(aX, aY);
+      return;
+    }
+
+    DispatchToUiThread(
+        "nsWindow::UpdateOverscrollOffset",
+        [compositor = GeckoSession::Compositor::GlobalRef(compositor), aX, aY] {
+          compositor->UpdateOverscrollOffset(aX, aY);
+        });
+  }
+}
+
+void* nsWindow::GetNativeData(uint32_t aDataType) {
+  switch (aDataType) {
+    // used by GLContextProviderEGL, nullptr is EGL_DEFAULT_DISPLAY
+    case NS_NATIVE_WIDGET:
+      return (void*)this;
+
+    case NS_RAW_NATIVE_IME_CONTEXT: {
+      void* pseudoIMEContext = GetPseudoIMEContext();
+      if (pseudoIMEContext) {
+        return pseudoIMEContext;
+      }
+      // We assume that there is only one context per process on Android
+      return NS_ONLY_ONE_NATIVE_IME_CONTEXT;
+    }
+
+    case NS_JAVA_SURFACE:
+      if (::mozilla::jni::NativeWeakPtr<LayerViewSupport>::Accessor lvs{
+              mLayerViewSupport.Access()}) {
+        return lvs->GetSurface().Get();
+      }
+      return nullptr;
+  }
+
+  return nullptr;
+}
+
+void nsWindow::DispatchHitTest(const WidgetTouchEvent& aEvent) {
+  if (aEvent.mMessage == eTouchStart && aEvent.mTouches.Length() == 1) {
+    // Since touch events don't get retargeted by PositionedEventTargeting.cpp
+    // code, we dispatch a dummy mouse event that *does* get retargeted.
+    // Front-end code can use this to activate the highlight element in case
+    // this touchstart is the start of a tap.
+    WidgetMouseEvent hittest(true, eMouseHitTest, this,
+                             WidgetMouseEvent::eReal);
+    hittest.mRefPoint = aEvent.mTouches[0]->mRefPoint;
+    hittest.mInputSource = MouseEvent_Binding::MOZ_SOURCE_TOUCH;
+    nsEventStatus status;
+    DispatchEvent(&hittest, status);
+  }
+}
+
+void nsWindow::PassExternalResponse(java::WebResponse::Param aResponse) {
+  auto acc(mGeckoViewSupport.Access());
+  if (!acc) {
+    return;
+  }
+
+  acc->PassExternalResponse(aResponse);
+}
+
+mozilla::Modifiers nsWindow::GetModifiers(int32_t metaState) {
+  using mozilla::java::sdk::KeyEvent;
+  return (metaState & KeyEvent::META_ALT_MASK ? MODIFIER_ALT : 0) |
+         (metaState & KeyEvent::META_SHIFT_MASK ? MODIFIER_SHIFT : 0) |
+         (metaState & KeyEvent::META_CTRL_MASK ? MODIFIER_CONTROL : 0) |
+         (metaState & KeyEvent::META_META_MASK ? MODIFIER_META : 0) |
+         (metaState & KeyEvent::META_FUNCTION_ON ? MODIFIER_FN : 0) |
+         (metaState & KeyEvent::META_CAPS_LOCK_ON ? MODIFIER_CAPSLOCK : 0) |
+         (metaState & KeyEvent::META_NUM_LOCK_ON ? MODIFIER_NUMLOCK : 0) |
+         (metaState & KeyEvent::META_SCROLL_LOCK_ON ? MODIFIER_SCROLLLOCK : 0);
+}
+
+TimeStamp nsWindow::GetEventTimeStamp(int64_t aEventTime) {
+  // Android's event time is SystemClock.uptimeMillis that is counted in ms
+  // since OS was booted.
+  // (https://developer.android.com/reference/android/os/SystemClock.html)
+  // and this SystemClock.uptimeMillis uses SYSTEM_TIME_MONOTONIC.
+  // Our posix implemententaion of TimeStamp::Now uses SYSTEM_TIME_MONOTONIC
+  //  too. Due to same implementation, we can use this via FromSystemTime.
+  int64_t tick =
+      BaseTimeDurationPlatformUtils::TicksFromMilliseconds(aEventTime);
+  return TimeStamp::FromSystemTime(tick);
+}
+
+void nsWindow::UserActivity() {
+  if (!mIdleService) {
+    mIdleService = do_GetService("@mozilla.org/widget/useridleservice;1");
+  }
+
+  if (mIdleService) {
+    mIdleService->ResetIdleTimeOut(0);
+  }
+
+  if (FindTopLevel() != nsWindow::TopWindow()) {
+    BringToFront();
+  }
+}
+
+RefPtr<mozilla::a11y::SessionAccessibility>
+nsWindow::GetSessionAccessibility() {
+  auto acc(mSessionAccessibility.Access());
+  if (!acc) {
+    return nullptr;
+  }
+
+  return acc.AsRefPtr();
+}
+
+TextEventDispatcherListener* nsWindow::GetNativeTextEventDispatcherListener() {
+  nsWindow* top = FindTopLevel();
+  MOZ_ASSERT(top);
+
+  auto acc(top->mEditableSupport.Access());
+  if (!acc) {
+    // Non-GeckoView windows don't support IME operations.
+    return nullptr;
+  }
+
+  nsCOMPtr<TextEventDispatcherListener> ptr;
+  if (NS_FAILED(acc->QueryInterface(NS_GET_IID(TextEventDispatcherListener),
+                                    getter_AddRefs(ptr)))) {
+    return nullptr;
+  }
+
+  return ptr.get();
+}
+
+void nsWindow::SetInputContext(const InputContext& aContext,
+                               const InputContextAction& aAction) {
+  nsWindow* top = FindTopLevel();
+  MOZ_ASSERT(top);
+
+  auto acc(top->mEditableSupport.Access());
+  if (!acc) {
+    // Non-GeckoView windows don't support IME operations.
+    return;
+  }
+
+  // We are using an IME event later to notify Java, and the IME event
+  // will be processed by the top window. Therefore, to ensure the
+  // IME event uses the correct mInputContext, we need to let the top
+  // window process SetInputContext
+  acc->SetInputContext(aContext, aAction);
+}
+
+InputContext nsWindow::GetInputContext() {
+  nsWindow* top = FindTopLevel();
+  MOZ_ASSERT(top);
+
+  auto acc(top->mEditableSupport.Access());
+  if (!acc) {
+    // Non-GeckoView windows don't support IME operations.
+    return InputContext();
+  }
+
+  // We let the top window process SetInputContext,
+  // so we should let it process GetInputContext as well.
+  return acc->GetInputContext();
+}
+
+nsresult nsWindow::SynthesizeNativeTouchPoint(uint32_t aPointerId,
+                                              TouchPointerState aPointerState,
+                                              LayoutDeviceIntPoint aPoint,
+                                              double aPointerPressure,
+                                              uint32_t aPointerOrientation,
+                                              nsIObserver* aObserver) {
+  mozilla::widget::AutoObserverNotifier notifier(aObserver, "touchpoint");
+
+  int eventType;
+  switch (aPointerState) {
+    case TOUCH_CONTACT:
+      // This could be a ACTION_DOWN or ACTION_MOVE depending on the
+      // existing state; it is mapped to the right thing in Java.
+      eventType = java::sdk::MotionEvent::ACTION_POINTER_DOWN;
+      break;
+    case TOUCH_REMOVE:
+      // This could be turned into a ACTION_UP in Java
+      eventType = java::sdk::MotionEvent::ACTION_POINTER_UP;
+      break;
+    case TOUCH_CANCEL:
+      eventType = java::sdk::MotionEvent::ACTION_CANCEL;
+      break;
+    case TOUCH_HOVER:  // not supported for now
+    default:
+      return NS_ERROR_UNEXPECTED;
+  }
+
+  MOZ_ASSERT(mNPZCSupport.IsAttached());
+  auto npzcSup(mNPZCSupport.Access());
+  MOZ_ASSERT(!!npzcSup);
+
+  const auto& npzc = npzcSup->GetJavaNPZC();
+  const auto& bounds = FindTopLevel()->mBounds;
+  aPoint.x -= bounds.x;
+  aPoint.y -= bounds.y;
+
+  DispatchToUiThread(
+      "nsWindow::SynthesizeNativeTouchPoint",
+      [npzc = java::PanZoomController::NativeProvider::GlobalRef(npzc),
+       aPointerId, eventType, aPoint, aPointerPressure, aPointerOrientation] {
+        npzc->SynthesizeNativeTouchPoint(aPointerId, eventType, aPoint.x,
+                                         aPoint.y, aPointerPressure,
+                                         aPointerOrientation);
+      });
+  return NS_OK;
+}
+
+nsresult nsWindow::SynthesizeNativeMouseEvent(
+    LayoutDeviceIntPoint aPoint, NativeMouseMessage aNativeMessage,
+    MouseButton aButton, nsIWidget::Modifiers aModifierFlags,
+    nsIObserver* aObserver) {
+  mozilla::widget::AutoObserverNotifier notifier(aObserver, "mouseevent");
+
+  MOZ_ASSERT(mNPZCSupport.IsAttached());
+  auto npzcSup(mNPZCSupport.Access());
+  MOZ_ASSERT(!!npzcSup);
+
+  const auto& npzc = npzcSup->GetJavaNPZC();
+  const auto& bounds = FindTopLevel()->mBounds;
+  aPoint.x -= bounds.x;
+  aPoint.y -= bounds.y;
+
+  int32_t nativeMessage;
+  switch (aNativeMessage) {
+    case NativeMouseMessage::ButtonDown:
+      nativeMessage = java::sdk::MotionEvent::ACTION_POINTER_DOWN;
+      break;
+    case NativeMouseMessage::ButtonUp:
+      nativeMessage = java::sdk::MotionEvent::ACTION_POINTER_UP;
+      break;
+    case NativeMouseMessage::Move:
+      nativeMessage = java::sdk::MotionEvent::ACTION_HOVER_MOVE;
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Non supported mouse event on Android");
+      return NS_ERROR_INVALID_ARG;
+  }
+  int32_t button = 0;
+  if (aNativeMessage != NativeMouseMessage::ButtonUp) {
+    switch (aButton) {
+      case MouseButton::ePrimary:
+        button = java::sdk::MotionEvent::BUTTON_PRIMARY;
+        break;
+      case MouseButton::eMiddle:
+        button = java::sdk::MotionEvent::BUTTON_TERTIARY;
+        break;
+      case MouseButton::eSecondary:
+        button = java::sdk::MotionEvent::BUTTON_SECONDARY;
+        break;
+      case MouseButton::eX1:
+        button = java::sdk::MotionEvent::BUTTON_BACK;
+        break;
+      case MouseButton::eX2:
+        button = java::sdk::MotionEvent::BUTTON_FORWARD;
+        break;
+      default:
+        if (aNativeMessage == NativeMouseMessage::ButtonDown) {
+          MOZ_ASSERT_UNREACHABLE("Non supported mouse button type on Android");
+          return NS_ERROR_INVALID_ARG;
+        }
+        break;
+    }
+  }
+
+  // TODO (bug 1693237): Handle aModifierFlags.
+  DispatchToUiThread(
+      "nsWindow::SynthesizeNativeMouseEvent",
+      [npzc = java::PanZoomController::NativeProvider::GlobalRef(npzc),
+       nativeMessage, aPoint, button] {
+        npzc->SynthesizeNativeMouseEvent(nativeMessage, aPoint.x, aPoint.y,
+                                         button);
+      });
+  return NS_OK;
+}
+
+nsresult nsWindow::SynthesizeNativeMouseMove(LayoutDeviceIntPoint aPoint,
+                                             nsIObserver* aObserver) {
+  return SynthesizeNativeMouseEvent(
+      aPoint, NativeMouseMessage::Move, MouseButton::eNotPressed,
+      nsIWidget::Modifiers::NO_MODIFIERS, aObserver);
+}
+
+void nsWindow::SetCompositorWidgetDelegate(CompositorWidgetDelegate* delegate) {
+  if (delegate) {
+    mCompositorWidgetDelegate = delegate->AsPlatformSpecificDelegate();
+    MOZ_ASSERT(mCompositorWidgetDelegate,
+               "nsWindow::SetCompositorWidgetDelegate called with a "
+               "non-PlatformCompositorWidgetDelegate");
+  } else {
+    mCompositorWidgetDelegate = nullptr;
+  }
+}
+
+void nsWindow::GetCompositorWidgetInitData(
+    mozilla::widget::CompositorWidgetInitData* aInitData) {
+  *aInitData = mozilla::widget::AndroidCompositorWidgetInitData(
+      mWidgetId, GetClientSize());
+}
+
+bool nsWindow::WidgetPaintsBackground() {
+  return StaticPrefs::android_widget_paints_background();
+}
+
+bool nsWindow::NeedsPaint() {
+  auto lvs(mLayerViewSupport.Access());
+  if (!lvs || lvs->CompositorPaused() || !GetWindowRenderer()) {
+    return false;
+  }
+
+  return nsIWidget::NeedsPaint();
+}
+
+void nsWindow::ConfigureAPZControllerThread() {
+  nsCOMPtr<nsISerialEventTarget> thread = mozilla::GetAndroidUiThread();
+  APZThreadUtils::SetControllerThread(thread);
+}
+
+already_AddRefed<GeckoContentController>
+nsWindow::CreateRootContentController() {
+  RefPtr<GeckoContentController> controller =
+      new AndroidContentController(this, mAPZEventState, mAPZC);
+  return controller.forget();
+}
+
+uint32_t nsWindow::GetMaxTouchPoints() const {
+  return java::GeckoAppShell::GetMaxTouchPoints();
+}
+
+void nsWindow::UpdateZoomConstraints(
+    const uint32_t& aPresShellId, const ScrollableLayerGuid::ViewID& aViewId,
+    const mozilla::Maybe<ZoomConstraints>& aConstraints) {
+  nsBaseWidget::UpdateZoomConstraints(aPresShellId, aViewId, aConstraints);
+}
+
+CompositorBridgeChild* nsWindow::GetCompositorBridgeChild() const {
+  return mCompositorSession ? mCompositorSession->GetCompositorBridgeChild()
+                            : nullptr;
+}
+
+void nsWindow::SetContentDocumentDisplayed(bool aDisplayed) {
+  mContentDocumentDisplayed = aDisplayed;
+}
+
+bool nsWindow::IsContentDocumentDisplayed() {
+  return mContentDocumentDisplayed;
+}
+
+void nsWindow::RecvToolbarAnimatorMessageFromCompositor(int32_t aMessage) {
+  MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+  if (::mozilla::jni::NativeWeakPtr<LayerViewSupport>::Accessor lvs{
+          mLayerViewSupport.Access()}) {
+    lvs->RecvToolbarAnimatorMessage(aMessage);
+  }
+}
+
+void nsWindow::UpdateRootFrameMetrics(const ScreenPoint& aScrollOffset,
+                                      const CSSToScreenScale& aZoom) {
+  MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+  if (::mozilla::jni::NativeWeakPtr<LayerViewSupport>::Accessor lvs{
+          mLayerViewSupport.Access()}) {
+    const auto& compositor = lvs->GetJavaCompositor();
+    mContentDocumentDisplayed = true;
+    compositor->UpdateRootFrameMetrics(aScrollOffset.x, aScrollOffset.y,
+                                       aZoom.scale);
+  }
+}
+
+void nsWindow::RecvScreenPixels(Shmem&& aMem, const ScreenIntSize& aSize,
+                                bool aNeedsYFlip) {
+  MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
+  if (::mozilla::jni::NativeWeakPtr<LayerViewSupport>::Accessor lvs{
+          mLayerViewSupport.Access()}) {
+    lvs->RecvScreenPixels(std::move(aMem), aSize, aNeedsYFlip);
+  }
+}
+
+void nsWindow::UpdateDynamicToolbarMaxHeight(ScreenIntCoord aHeight) {
+  if (mDynamicToolbarMaxHeight == aHeight) {
+    return;
+  }
+
+  mDynamicToolbarMaxHeight = aHeight;
+
+  if (mWidgetListener) {
+    mWidgetListener->DynamicToolbarMaxHeightChanged(aHeight);
+  }
+
+  if (mAttachedWidgetListener) {
+    mAttachedWidgetListener->DynamicToolbarMaxHeightChanged(aHeight);
+  }
+}
+
+void nsWindow::UpdateDynamicToolbarOffset(ScreenIntCoord aOffset) {
+  if (mWidgetListener) {
+    mWidgetListener->DynamicToolbarOffsetChanged(aOffset);
+  }
+
+  if (mAttachedWidgetListener) {
+    mAttachedWidgetListener->DynamicToolbarOffsetChanged(aOffset);
+  }
+}
+
+ScreenIntMargin nsWindow::GetSafeAreaInsets() const { return mSafeAreaInsets; }
+
+void nsWindow::UpdateSafeAreaInsets(const ScreenIntMargin& aSafeAreaInsets) {
+  mSafeAreaInsets = aSafeAreaInsets;
+
+  if (mWidgetListener) {
+    mWidgetListener->SafeAreaInsetsChanged(aSafeAreaInsets);
+  }
+
+  if (mAttachedWidgetListener) {
+    mAttachedWidgetListener->SafeAreaInsetsChanged(aSafeAreaInsets);
+  }
+}
+
+jni::NativeWeakPtr<NPZCSupport> nsWindow::GetNPZCSupportWeakPtr() {
+  return mNPZCSupport;
+}
+
+already_AddRefed<nsIWidget> nsIWidget::CreateTopLevelWindow() {
+  nsCOMPtr<nsIWidget> window = new nsWindow();
+  return window.forget();
+}
+
+already_AddRefed<nsIWidget> nsIWidget::CreateChildWindow() {
+  nsCOMPtr<nsIWidget> window = new nsWindow();
+  return window.forget();
+}
+
+static already_AddRefed<DataSourceSurface> GetCursorImage(
+    const nsIWidget::Cursor& aCursor, mozilla::CSSToLayoutDeviceScale aScale) {
+  if (!aCursor.IsCustom()) {
+    return nullptr;
+  }
+
+  RefPtr<DataSourceSurface> destDataSurface;
+
+  nsIntSize size = nsIWidget::CustomCursorSize(aCursor);
+  // prevent DoS attacks
+  if (size.width > 128 || size.height > 128) {
+    return nullptr;
+  }
+
+  RefPtr<gfx::SourceSurface> surface = aCursor.mContainer->GetFrameAtSize(
+      size * aScale.scale, imgIContainer::FRAME_CURRENT,
+      imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
+  if (NS_WARN_IF(!surface)) {
+    return nullptr;
+  }
+
+  RefPtr<DataSourceSurface> srcDataSurface = surface->GetDataSurface();
+  if (NS_WARN_IF(!srcDataSurface)) {
+    return nullptr;
+  }
+
+  DataSourceSurface::ScopedMap sourceMap(srcDataSurface,
+                                         DataSourceSurface::READ);
+
+  destDataSurface = gfx::Factory::CreateDataSourceSurfaceWithStride(
+      srcDataSurface->GetSize(), SurfaceFormat::R8G8B8A8,
+      sourceMap.GetStride());
+  if (NS_WARN_IF(!destDataSurface)) {
+    return nullptr;
+  }
+
+  DataSourceSurface::ScopedMap destMap(destDataSurface,
+                                       DataSourceSurface::READ_WRITE);
+
+  SwizzleData(sourceMap.GetData(), sourceMap.GetStride(), surface->GetFormat(),
+              destMap.GetData(), destMap.GetStride(), SurfaceFormat::R8G8B8A8,
+              destDataSurface->GetSize());
+
+  return destDataSurface.forget();
+}
+
+static int32_t GetCursorType(nsCursor aCursor) {
+  // When our minimal requirement of SDK version is 25+,
+  // we should replace with JNI auto-generator.
+  switch (aCursor) {
+    case eCursor_standard:
+      // android.view.PointerIcon.TYPE_ARROW
+      return 0x3e8;
+    case eCursor_wait:
+      // android.view.PointerIcon.TYPE_WAIT
+      return 0x3ec;
+    case eCursor_select:
+      // android.view.PointerIcon.TYPE_TEXT;
+      return 0x3f0;
+    case eCursor_hyperlink:
+      // android.view.PointerIcon.TYPE_HAND
+      return 0x3ea;
+    case eCursor_n_resize:
+    case eCursor_s_resize:
+    case eCursor_ns_resize:
+    case eCursor_row_resize:
+      // android.view.PointerIcon.TYPE_VERTICAL_DOUBLE_ARROW
+      return 0x3f7;
+    case eCursor_w_resize:
+    case eCursor_e_resize:
+    case eCursor_ew_resize:
+    case eCursor_col_resize:
+      // android.view.PointerIcon.TYPE_HORIZONTAL_DOUBLE_ARROW
+      return 0x3f6;
+    case eCursor_nw_resize:
+    case eCursor_se_resize:
+    case eCursor_nwse_resize:
+      // android.view.PointerIcon.TYPE_TOP_LEFT_DIAGONAL_DOUBLE_ARROW
+      return 0x3f9;
+    case eCursor_ne_resize:
+    case eCursor_sw_resize:
+    case eCursor_nesw_resize:
+      // android.view.PointerIcon.TYPE_TOP_RIGHT_DIAGONAL_DOUBLE_ARROW
+      return 0x3f8;
+    case eCursor_crosshair:
+      // android.view.PointerIcon.TYPE_CROSSHAIR
+      return 0x3ef;
+    case eCursor_move:
+      // android.view.PointerIcon.TYPE_ARROW
+      return 0x3e8;
+    case eCursor_help:
+      // android.view.PointerIcon.TYPE_HELP
+      return 0x3eb;
+    case eCursor_copy:
+      // android.view.PointerIcon.TYPE_COPY
+      return 0x3f3;
+    case eCursor_alias:
+      // android.view.PointerIcon.TYPE_ALIAS
+      return 0x3f2;
+    case eCursor_context_menu:
+      // android.view.PointerIcon.TYPE_CONTEXT_MENU
+      return 0x3e9;
+    case eCursor_cell:
+      // android.view.PointerIcon.TYPE_CELL
+      return 0x3ee;
+    case eCursor_grab:
+      // android.view.PointerIcon.TYPE_GRAB
+      return 0x3fc;
+    case eCursor_grabbing:
+      // android.view.PointerIcon.TYPE_GRABBING
+      return 0x3fd;
+    case eCursor_spinning:
+      // android.view.PointerIcon.TYPE_WAIT
+      return 0x3ec;
+    case eCursor_zoom_in:
+      // android.view.PointerIcon.TYPE_ZOOM_IN
+      return 0x3fa;
+    case eCursor_zoom_out:
+      // android.view.PointerIcon.TYPE_ZOOM_OUT
+      return 0x3fb;
+    case eCursor_not_allowed:
+      // android.view.PointerIcon.TYPE_NO_DROP:
+      return 0x3f4;
+    case eCursor_no_drop:
+      // android.view.PointerIcon.TYPE_NO_DROP:
+      return 0x3f4;
+    case eCursor_vertical_text:
+      // android.view.PointerIcon.TYPE_VERTICAL_TEXT
+      return 0x3f1;
+    case eCursor_all_scroll:
+      // android.view.PointerIcon.TYPE_ALL_SCROLL
+      return 0x3f5;
+    case eCursor_none:
+      // android.view.PointerIcon.TYPE_NULL
+      return 0;
+    default:
+      NS_WARNING_ASSERTION(aCursor, "Invalid cursor type");
+      // android.view.PointerIcon.TYPE_ARROW
+      return 0x3e8;
+  }
+}
+
+void nsWindow::SetCursor(const Cursor& aCursor) {
+  if (mozilla::jni::GetAPIVersion() < 24) {
+    return;
+  }
+
+  // Only change cursor if it's actually been changed
+  if (!mUpdateCursor && mCursor == aCursor) {
+    return;
+  }
+
+  mUpdateCursor = false;
+  mCursor = aCursor;
+
+  int32_t type = 0;
+  RefPtr<DataSourceSurface> destDataSurface =
+      GetCursorImage(aCursor, GetDefaultScale());
+  if (!destDataSurface) {
+    type = GetCursorType(aCursor.mDefaultCursor);
+  }
+
+  if (mozilla::jni::NativeWeakPtr<LayerViewSupport>::Accessor lvs{
+          mLayerViewSupport.Access()}) {
+    const auto& compositor = lvs->GetJavaCompositor();
+
+    DispatchToUiThread(
+        "nsWindow::SetCursor",
+        [compositor = GeckoSession::Compositor::GlobalRef(compositor), type,
+         destDataSurface = std::move(destDataSurface),
+         hotspotX = aCursor.mHotspotX, hotspotY = aCursor.mHotspotY] {
+          java::sdk::Bitmap::LocalRef bitmap;
+          if (destDataSurface) {
+            DataSourceSurface::ScopedMap destMap(destDataSurface,
+                                                 DataSourceSurface::READ);
+            auto pixels = mozilla::jni::ByteBuffer::New(
+                reinterpret_cast<int8_t*>(destMap.GetData()),
+                destMap.GetStride() * destDataSurface->GetSize().height);
+            bitmap = java::sdk::Bitmap::CreateBitmap(
+                destDataSurface->GetSize().width,
+                destDataSurface->GetSize().height,
+                java::sdk::Bitmap::Config::ARGB_8888());
+            bitmap->CopyPixelsFromBuffer(pixels);
+          }
+          compositor->SetPointerIcon(type, bitmap, hotspotX, hotspotY);
+        });
+  }
+}
diff --git a/widget/android/nsWindow.h b/widget/android/nsWindow.h
new file mode 100644
index 0000000000..7c6f8ba9bb
--- /dev/null
+++ b/widget/android/nsWindow.h
@@ -0,0 +1,292 @@
+/* -*- Mode: c++; c-basic-offset: 2; tab-width: 20; indent-tabs-mode: nil; -*-
+ * vim: set sw=2 ts=4 expandtab:
+ * 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 NSWINDOW_H_
+#define NSWINDOW_H_
+
+#include "nsBaseWidget.h"
+#include "gfxPoint.h"
+#include "nsIUserIdleServiceInternal.h"
+#include "nsTArray.h"
+#include "EventDispatcher.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/java/GeckoSessionNatives.h"
+#include "mozilla/java/WebResponseWrappers.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/TextRange.h"
+#include "mozilla/UniquePtr.h"
+
+struct ANPEvent;
+
+namespace mozilla {
+class WidgetTouchEvent;
+
+namespace layers {
+class CompositorBridgeChild;
+class LayerManager;
+class APZCTreeManager;
+class UiCompositorControllerChild;
+}  // namespace layers
+
+namespace widget {
+class AndroidView;
+class GeckoEditableSupport;
+class GeckoViewSupport;
+class LayerViewSupport;
+class NPZCSupport;
+class PlatformCompositorWidgetDelegate;
+}  // namespace widget
+
+namespace ipc {
+class Shmem;
+}  // namespace ipc
+
+namespace a11y {
+class SessionAccessibility;
+}  // namespace a11y
+}  // namespace mozilla
+
+class nsWindow final : public nsBaseWidget {
+ private:
+  virtual ~nsWindow();
+
+ public:
+  using nsBaseWidget::GetWindowRenderer;
+
+  nsWindow();
+
+  NS_INLINE_DECL_REFCOUNTING_INHERITED(nsWindow, nsBaseWidget)
+
+  static void InitNatives();
+  void OnGeckoViewReady();
+  RefPtr<mozilla::MozPromise<bool, bool, false>> OnLoadRequest(
+      nsIURI* aUri, int32_t aWindowType, int32_t aFlags,
+      nsIPrincipal* aTriggeringPrincipal, bool aHasUserGesture,
+      bool aIsTopLevel);
+
+  void OnUpdateSessionStore(mozilla::jni::Object::Param aBundle);
+
+ private:
+  // Unique ID given to each widget, used to map Surfaces to widgets
+  // in the CompositorSurfaceManager.
+  int32_t mWidgetId;
+
+ private:
+  RefPtr<mozilla::widget::AndroidView> mAndroidView;
+
+  // Object that implements native LayerView calls.
+  // Owned by the Java Compositor instance.
+  mozilla::jni::NativeWeakPtr<mozilla::widget::LayerViewSupport>
+      mLayerViewSupport;
+
+  // Object that implements native NativePanZoomController calls.
+  // Owned by the Java NativePanZoomController instance.
+  mozilla::jni::NativeWeakPtr<mozilla::widget::NPZCSupport> mNPZCSupport;
+
+  // Object that implements native GeckoEditable calls.
+  // Strong referenced by the Java instance.
+  mozilla::jni::NativeWeakPtr<mozilla::widget::GeckoEditableSupport>
+      mEditableSupport;
+  mozilla::jni::Object::GlobalRef mEditableParent;
+
+  // Object that implements native SessionAccessibility calls.
+  // Strong referenced by the Java instance.
+  mozilla::jni::NativeWeakPtr<mozilla::a11y::SessionAccessibility>
+      mSessionAccessibility;
+
+  // Object that implements native GeckoView calls and associated states.
+  // nullptr for nsWindows that were not opened from GeckoView.
+  mozilla::jni::NativeWeakPtr<mozilla::widget::GeckoViewSupport>
+      mGeckoViewSupport;
+
+  mozilla::Atomic<bool, mozilla::ReleaseAcquire> mContentDocumentDisplayed;
+
+ public:
+  static already_AddRefed<nsWindow> From(nsPIDOMWindowOuter* aDOMWindow);
+  static already_AddRefed<nsWindow> From(nsIWidget* aWidget);
+
+  static nsWindow* TopWindow();
+
+  static mozilla::Modifiers GetModifiers(int32_t aMetaState);
+  static mozilla::TimeStamp GetEventTimeStamp(int64_t aEventTime);
+
+  void InitEvent(mozilla::WidgetGUIEvent& event,
+                 LayoutDeviceIntPoint* aPoint = 0);
+
+  void UpdateOverscrollVelocity(const float aX, const float aY);
+  void UpdateOverscrollOffset(const float aX, const float aY);
+
+  mozilla::widget::EventDispatcher* GetEventDispatcher() const;
+
+  void PassExternalResponse(mozilla::java::WebResponse::Param aResponse);
+
+  void ShowDynamicToolbar();
+
+  void DetachNatives();
+
+  mozilla::Mutex& GetDestroyMutex() { return mDestroyMutex; }
+
+  //
+  // nsIWidget
+  //
+
+  using nsBaseWidget::Create;  // for Create signature not overridden here
+  [[nodiscard]] virtual nsresult Create(nsIWidget* aParent,
+                                        nsNativeWidget aNativeParent,
+                                        const LayoutDeviceIntRect& aRect,
+                                        InitData* aInitData) override;
+  virtual void Destroy() override;
+  virtual void SetParent(nsIWidget* aNewParent) override;
+  virtual nsIWidget* GetParent(void) override;
+  virtual float GetDPI() override;
+  virtual double GetDefaultScaleInternal() override;
+  virtual void Show(bool aState) override;
+  virtual bool IsVisible() const override;
+  virtual void ConstrainPosition(DesktopIntPoint&) 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;
+  void SetZIndex(int32_t aZIndex) override;
+  virtual nsSizeMode SizeMode() override { return mSizeMode; }
+  virtual void SetSizeMode(nsSizeMode aMode) override;
+  virtual void Enable(bool aState) override;
+  virtual bool IsEnabled() const override;
+  virtual void Invalidate(const LayoutDeviceIntRect& aRect) override;
+  virtual void SetFocus(Raise, mozilla::dom::CallerType aCallerType) override;
+  virtual LayoutDeviceIntRect GetScreenBounds() override;
+  virtual LayoutDeviceIntPoint WidgetToScreenOffset() override;
+  virtual nsresult DispatchEvent(mozilla::WidgetGUIEvent* aEvent,
+                                 nsEventStatus& aStatus) override;
+  nsEventStatus DispatchEvent(mozilla::WidgetGUIEvent* aEvent);
+  virtual nsresult MakeFullScreen(bool aFullScreen) override;
+  void SetCursor(const Cursor& aDefaultCursor) override;
+  void* GetNativeData(uint32_t aDataType) override;
+  virtual nsresult SetTitle(const nsAString& aTitle) override { return NS_OK; }
+  [[nodiscard]] virtual nsresult GetAttention(int32_t aCycleCount) override {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  TextEventDispatcherListener* GetNativeTextEventDispatcherListener() override;
+  virtual void SetInputContext(const InputContext& aContext,
+                               const InputContextAction& aAction) override;
+  virtual InputContext GetInputContext() override;
+
+  WindowRenderer* GetWindowRenderer() override;
+
+  void NotifyCompositorSessionLost(
+      mozilla::layers::CompositorSession* aSession) override;
+
+  virtual bool NeedsPaint() override;
+
+  virtual bool WidgetPaintsBackground() override;
+
+  virtual uint32_t GetMaxTouchPoints() const override;
+
+  void UpdateZoomConstraints(
+      const uint32_t& aPresShellId, const ScrollableLayerGuid::ViewID& aViewId,
+      const mozilla::Maybe<ZoomConstraints>& aConstraints) override;
+
+  nsresult SynthesizeNativeTouchPoint(uint32_t aPointerId,
+                                      TouchPointerState aPointerState,
+                                      LayoutDeviceIntPoint aPoint,
+                                      double aPointerPressure,
+                                      uint32_t aPointerOrientation,
+                                      nsIObserver* aObserver) override;
+  nsresult SynthesizeNativeMouseEvent(LayoutDeviceIntPoint aPoint,
+                                      NativeMouseMessage aNativeMessage,
+                                      mozilla::MouseButton aButton,
+                                      nsIWidget::Modifiers aModifierFlags,
+                                      nsIObserver* aObserver) override;
+  nsresult SynthesizeNativeMouseMove(LayoutDeviceIntPoint aPoint,
+                                     nsIObserver* aObserver) override;
+
+  void SetCompositorWidgetDelegate(CompositorWidgetDelegate* delegate) override;
+
+  virtual void GetCompositorWidgetInitData(
+      mozilla::widget::CompositorWidgetInitData* aInitData) override;
+
+  mozilla::layers::CompositorBridgeChild* GetCompositorBridgeChild() const;
+
+  void SetContentDocumentDisplayed(bool aDisplayed);
+  bool IsContentDocumentDisplayed();
+
+  // Call this function when the users activity is the direct cause of an
+  // event (like a keypress or mouse click).
+  void UserActivity();
+
+  mozilla::jni::Object::Ref& GetEditableParent() { return mEditableParent; }
+
+  RefPtr<mozilla::a11y::SessionAccessibility> GetSessionAccessibility();
+
+  void RecvToolbarAnimatorMessageFromCompositor(int32_t aMessage) override;
+  void UpdateRootFrameMetrics(const ScreenPoint& aScrollOffset,
+                              const CSSToScreenScale& aZoom) override;
+  void RecvScreenPixels(mozilla::ipc::Shmem&& aMem, const ScreenIntSize& aSize,
+                        bool aNeedsYFlip) override;
+  void UpdateDynamicToolbarMaxHeight(mozilla::ScreenIntCoord aHeight) override;
+  mozilla::ScreenIntCoord GetDynamicToolbarMaxHeight() const override {
+    return mDynamicToolbarMaxHeight;
+  }
+
+  void UpdateDynamicToolbarOffset(mozilla::ScreenIntCoord aOffset);
+
+  virtual mozilla::ScreenIntMargin GetSafeAreaInsets() const override;
+  void UpdateSafeAreaInsets(const mozilla::ScreenIntMargin& aSafeAreaInsets);
+
+  mozilla::jni::NativeWeakPtr<mozilla::widget::NPZCSupport>
+  GetNPZCSupportWeakPtr();
+
+ protected:
+  void BringToFront();
+  nsWindow* FindTopLevel();
+  bool IsTopLevel();
+
+  void ConfigureAPZControllerThread() override;
+  void DispatchHitTest(const mozilla::WidgetTouchEvent& aEvent);
+
+  already_AddRefed<GeckoContentController> CreateRootContentController()
+      override;
+
+  bool mIsVisible;
+  nsTArray<nsWindow*> mChildren;
+  nsWindow* mParent;
+
+  nsCOMPtr<nsIUserIdleServiceInternal> mIdleService;
+  mozilla::ScreenIntCoord mDynamicToolbarMaxHeight;
+  mozilla::ScreenIntMargin mSafeAreaInsets;
+
+  nsSizeMode mSizeMode;
+  bool mIsFullScreen;
+
+  bool UseExternalCompositingSurface() const override { return true; }
+
+  static void DumpWindows();
+  static void DumpWindows(const nsTArray<nsWindow*>& wins, int indent = 0);
+  static void LogWindow(nsWindow* win, int index, int indent);
+
+ private:
+  void CreateLayerManager();
+  void RedrawAll();
+
+  void OnSizeChanged(const mozilla::gfx::IntSize& aSize);
+
+  mozilla::layers::LayersId GetRootLayerId() const;
+  RefPtr<mozilla::layers::UiCompositorControllerChild>
+  GetUiCompositorControllerChild();
+
+  mozilla::widget::PlatformCompositorWidgetDelegate* mCompositorWidgetDelegate;
+
+  mozilla::Mutex mDestroyMutex;
+
+  friend class mozilla::widget::GeckoViewSupport;
+  friend class mozilla::widget::LayerViewSupport;
+  friend class mozilla::widget::NPZCSupport;
+};
+
+#endif /* NSWINDOW_H_ */