Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 3498 insertions, 0 deletions

diff --git a/xpfe/appshell/AppWindow.cpp b/xpfe/appshell/AppWindow.cpp
new file mode 100644
index 0000000000..a5dab3b157
--- /dev/null
+++ b/xpfe/appshell/AppWindow.cpp
@@ -0,0 +1,3498 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 ci et: */
+/* 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 "ErrorList.h"
+#include "mozilla/MathAlgorithms.h"
+
+// Local includes
+#include "AppWindow.h"
+#include <algorithm>
+
+// Helper classes
+#include "nsPrintfCString.h"
+#include "nsString.h"
+#include "nsWidgetsCID.h"
+#include "nsThreadUtils.h"
+#include "nsNetCID.h"
+#include "nsQueryObject.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/Sprintf.h"
+
+// Interfaces needed to be included
+#include "nsGlobalWindowOuter.h"
+#include "nsIAppShell.h"
+#include "nsIAppShellService.h"
+#include "nsIContentViewer.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/CanonicalBrowsingContext.h"
+#include "nsPIDOMWindow.h"
+#include "nsScreen.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIIOService.h"
+#include "nsIObserverService.h"
+#include "nsIOpenWindowInfo.h"
+#include "nsIWindowMediator.h"
+#include "nsIScreenManager.h"
+#include "nsIScreen.h"
+#include "nsIWindowWatcher.h"
+#include "nsIURI.h"
+#include "nsAppShellCID.h"
+#include "nsReadableUtils.h"
+#include "nsStyleConsts.h"
+#include "nsPresContext.h"
+#include "nsContentUtils.h"
+#include "nsGlobalWindow.h"
+#include "nsXULTooltipListener.h"
+#include "nsXULPopupManager.h"
+#include "nsFocusManager.h"
+#include "nsContentList.h"
+#include "nsIDOMWindowUtils.h"
+#include "nsServiceManagerUtils.h"
+
+#include "prenv.h"
+#include "mozilla/AppShutdown.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/Services.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/dom/BarProps.h"
+#include "mozilla/dom/DOMRect.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/BrowserHost.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/LoadURIOptionsBinding.h"
+#include "mozilla/intl/LocaleService.h"
+#include "mozilla/EventDispatcher.h"
+
+#ifdef XP_WIN
+#  include "mozilla/PreXULSkeletonUI.h"
+#  include "nsIWindowsUIUtils.h"
+#endif
+
+#include "mozilla/dom/DocumentL10n.h"
+
+#ifdef XP_MACOSX
+#  include "mozilla/widget/NativeMenuSupport.h"
+#  define USE_NATIVE_MENUS
+#endif
+
+#define SIZEMODE_NORMAL u"normal"_ns
+#define SIZEMODE_MAXIMIZED u"maximized"_ns
+#define SIZEMODE_MINIMIZED u"minimized"_ns
+#define SIZEMODE_FULLSCREEN u"fullscreen"_ns
+
+#define SIZE_PERSISTENCE_TIMEOUT 500  // msec
+
+//*****************************************************************************
+//***    AppWindow: Object Management
+//*****************************************************************************
+
+namespace mozilla {
+
+using dom::AutoNoJSAPI;
+using dom::BrowserHost;
+using dom::BrowsingContext;
+using dom::Document;
+using dom::DocumentL10n;
+using dom::Element;
+using dom::EventTarget;
+using dom::LoadURIOptions;
+using dom::Promise;
+
+AppWindow::AppWindow(uint32_t aChromeFlags)
+    : mChromeTreeOwner(nullptr),
+      mContentTreeOwner(nullptr),
+      mPrimaryContentTreeOwner(nullptr),
+      mModalStatus(NS_OK),
+      mFullscreenChangeState(FullscreenChangeState::NotChanging),
+      mContinueModalLoop(false),
+      mDebuting(false),
+      mChromeLoaded(false),
+      mSizingShellFromXUL(false),
+      mShowAfterLoad(false),
+      mIntrinsicallySized(false),
+      mCenterAfterLoad(false),
+      mIsHiddenWindow(false),
+      mLockedUntilChromeLoad(false),
+      mIgnoreXULSize(false),
+      mIgnoreXULPosition(false),
+      mChromeFlagsFrozen(false),
+      mIgnoreXULSizeMode(false),
+      mDestroying(false),
+      mRegistered(false),
+      mDominantClientSize(false),
+      mChromeFlags(aChromeFlags),
+      mWidgetListenerDelegate(this) {}
+
+AppWindow::~AppWindow() {
+  if (mSPTimer) {
+    mSPTimer->Cancel();
+    mSPTimer = nullptr;
+  }
+  Destroy();
+}
+
+//*****************************************************************************
+// AppWindow::nsISupports
+//*****************************************************************************
+
+NS_IMPL_ADDREF(AppWindow)
+NS_IMPL_RELEASE(AppWindow)
+
+NS_INTERFACE_MAP_BEGIN(AppWindow)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIAppWindow)
+  NS_INTERFACE_MAP_ENTRY(nsIAppWindow)
+  NS_INTERFACE_MAP_ENTRY(nsIBaseWindow)
+  NS_INTERFACE_MAP_ENTRY(nsIInterfaceRequestor)
+  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
+  NS_INTERFACE_MAP_ENTRY(nsIWebProgressListener)
+  NS_INTERFACE_MAP_ENTRY_CONCRETE(AppWindow)
+NS_INTERFACE_MAP_END
+
+nsresult AppWindow::Initialize(nsIAppWindow* aParent, nsIAppWindow* aOpener,
+                               int32_t aInitialWidth, int32_t aInitialHeight,
+                               bool aIsHiddenWindow,
+                               widget::InitData& widgetInitData) {
+  nsresult rv;
+  nsCOMPtr<nsIWidget> parentWidget;
+
+  mIsHiddenWindow = aIsHiddenWindow;
+
+  DesktopIntPoint initialPos;
+  nsCOMPtr<nsIBaseWindow> base(do_QueryInterface(aOpener));
+  if (base) {
+    LayoutDeviceIntRect rect = base->GetPositionAndSize();
+    mOpenerScreenRect =
+        DesktopIntRect::Round(rect / base->DevicePixelsPerDesktopPixel());
+    if (!mOpenerScreenRect.IsEmpty()) {
+      initialPos = mOpenerScreenRect.TopLeft();
+      ConstrainToOpenerScreen(&initialPos.x.value, &initialPos.y.value);
+    }
+  }
+
+  // XXX: need to get the default window size from prefs...
+  // Doesn't come from prefs... will come from CSS/XUL/RDF
+  DesktopIntRect deskRect(initialPos,
+                          DesktopIntSize(aInitialWidth, aInitialHeight));
+
+  // Create top level window
+  if (gfxPlatform::IsHeadless()) {
+    mWindow = nsIWidget::CreateHeadlessWidget();
+  } else {
+    mWindow = nsIWidget::CreateTopLevelWindow();
+  }
+  if (!mWindow) {
+    return NS_ERROR_FAILURE;
+  }
+
+  /* This next bit is troublesome. We carry two different versions of a pointer
+     to our parent window. One is the parent window's widget, which is passed
+     to our own widget. The other is a weak reference we keep here to our
+     parent AppWindow. The former is useful to the widget, and we can't
+     trust its treatment of the parent reference because they're platform-
+     specific. The latter is useful to this class.
+       A better implementation would be one in which the parent keeps strong
+     references to its children and closes them before it allows itself
+     to be closed. This would mimic the behaviour of OSes that support
+     top-level child windows in OSes that do not. Later.
+  */
+  nsCOMPtr<nsIBaseWindow> parentAsWin(do_QueryInterface(aParent));
+  if (parentAsWin) {
+    parentAsWin->GetMainWidget(getter_AddRefs(parentWidget));
+    mParentWindow = do_GetWeakReference(aParent);
+  }
+
+  mWindow->SetWidgetListener(&mWidgetListenerDelegate);
+  rv = mWindow->Create((nsIWidget*)parentWidget,  // Parent nsIWidget
+                       nullptr,                   // Native parent widget
+                       deskRect,                  // Widget dimensions
+                       &widgetInitData);          // Widget initialization data
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  LayoutDeviceIntRect r = mWindow->GetClientBounds();
+  // Match the default background color of content. Important on windows
+  // since we no longer use content child widgets.
+  mWindow->SetBackgroundColor(NS_RGB(255, 255, 255));
+
+  // All Chrome BCs exist within the same BrowsingContextGroup, so we don't need
+  // to pass in the opener window here. The opener is set later, if needed, by
+  // nsWindowWatcher.
+  RefPtr<BrowsingContext> browsingContext =
+      BrowsingContext::CreateIndependent(BrowsingContext::Type::Chrome);
+
+  // Create web shell
+  mDocShell = nsDocShell::Create(browsingContext);
+  NS_ENSURE_TRUE(mDocShell, NS_ERROR_FAILURE);
+
+  // Make sure to set the item type on the docshell _before_ calling
+  // InitWindow() so it knows what type it is.
+  NS_ENSURE_SUCCESS(EnsureChromeTreeOwner(), NS_ERROR_FAILURE);
+
+  mDocShell->SetTreeOwner(mChromeTreeOwner);
+
+  r.MoveTo(0, 0);
+  NS_ENSURE_SUCCESS(mDocShell->InitWindow(nullptr, mWindow, r.X(), r.Y(),
+                                          r.Width(), r.Height()),
+                    NS_ERROR_FAILURE);
+
+  // Attach a WebProgress listener.during initialization...
+  mDocShell->AddProgressListener(this, nsIWebProgress::NOTIFY_STATE_NETWORK);
+
+  mWindow->MaybeDispatchInitialFocusEvent();
+
+  return rv;
+}
+
+//*****************************************************************************
+// AppWindow::nsIIntefaceRequestor
+//*****************************************************************************
+
+NS_IMETHODIMP AppWindow::GetInterface(const nsIID& aIID, void** aSink) {
+  nsresult rv;
+
+  NS_ENSURE_ARG_POINTER(aSink);
+
+  if (aIID.Equals(NS_GET_IID(nsIPrompt))) {
+    rv = EnsurePrompter();
+    if (NS_FAILED(rv)) return rv;
+    return mPrompter->QueryInterface(aIID, aSink);
+  }
+  if (aIID.Equals(NS_GET_IID(nsIAuthPrompt))) {
+    rv = EnsureAuthPrompter();
+    if (NS_FAILED(rv)) return rv;
+    return mAuthPrompter->QueryInterface(aIID, aSink);
+  }
+  if (aIID.Equals(NS_GET_IID(mozIDOMWindowProxy))) {
+    return GetWindowDOMWindow(reinterpret_cast<mozIDOMWindowProxy**>(aSink));
+  }
+  if (aIID.Equals(NS_GET_IID(nsIDOMWindow))) {
+    nsCOMPtr<mozIDOMWindowProxy> window = nullptr;
+    rv = GetWindowDOMWindow(getter_AddRefs(window));
+    nsCOMPtr<nsIDOMWindow> domWindow = do_QueryInterface(window);
+    domWindow.forget(aSink);
+    return rv;
+  }
+  if (aIID.Equals(NS_GET_IID(nsIWebBrowserChrome)) &&
+      NS_SUCCEEDED(EnsureContentTreeOwner()) &&
+      NS_SUCCEEDED(mContentTreeOwner->QueryInterface(aIID, aSink))) {
+    return NS_OK;
+  }
+
+  return QueryInterface(aIID, aSink);
+}
+
+//*****************************************************************************
+// AppWindow::nsIAppWindow
+//*****************************************************************************
+
+NS_IMETHODIMP AppWindow::GetDocShell(nsIDocShell** aDocShell) {
+  NS_ENSURE_ARG_POINTER(aDocShell);
+
+  *aDocShell = mDocShell;
+  NS_IF_ADDREF(*aDocShell);
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetZLevel(uint32_t* outLevel) {
+  nsCOMPtr<nsIWindowMediator> mediator(
+      do_GetService(NS_WINDOWMEDIATOR_CONTRACTID));
+  if (mediator)
+    mediator->GetZLevel(this, outLevel);
+  else
+    *outLevel = normalZ;
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::SetZLevel(uint32_t aLevel) {
+  nsCOMPtr<nsIWindowMediator> mediator(
+      do_GetService(NS_WINDOWMEDIATOR_CONTRACTID));
+  if (!mediator) return NS_ERROR_FAILURE;
+
+  uint32_t zLevel;
+  mediator->GetZLevel(this, &zLevel);
+  if (zLevel == aLevel) return NS_OK;
+
+  /* refuse to raise a maximized window above the normal browser level,
+     for fear it could hide newly opened browser windows */
+  if (aLevel > nsIAppWindow::normalZ && mWindow) {
+    nsSizeMode sizeMode = mWindow->SizeMode();
+    if (sizeMode == nsSizeMode_Maximized || sizeMode == nsSizeMode_Fullscreen) {
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  // do it
+  mediator->SetZLevel(this, aLevel);
+  PersistentAttributesDirty(PersistentAttribute::Misc, Sync);
+
+  nsCOMPtr<nsIContentViewer> cv;
+  mDocShell->GetContentViewer(getter_AddRefs(cv));
+  if (cv) {
+    RefPtr<dom::Document> doc = cv->GetDocument();
+    if (doc) {
+      ErrorResult rv;
+      RefPtr<dom::Event> event =
+          doc->CreateEvent(u"Events"_ns, dom::CallerType::System, rv);
+      if (event) {
+        event->InitEvent(u"windowZLevel"_ns, true, false);
+
+        event->SetTrusted(true);
+
+        doc->DispatchEvent(*event);
+      }
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetChromeFlags(uint32_t* aChromeFlags) {
+  NS_ENSURE_ARG_POINTER(aChromeFlags);
+  *aChromeFlags = mChromeFlags;
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::SetChromeFlags(uint32_t aChromeFlags) {
+  NS_ASSERTION(!mChromeFlagsFrozen,
+               "SetChromeFlags() after AssumeChromeFlagsAreFrozen()!");
+
+  mChromeFlags = aChromeFlags;
+  if (mChromeLoaded) {
+    ApplyChromeFlags();
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::AssumeChromeFlagsAreFrozen() {
+  mChromeFlagsFrozen = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::SetIntrinsicallySized(bool aIntrinsicallySized) {
+  mIntrinsicallySized = aIntrinsicallySized;
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetIntrinsicallySized(bool* aIntrinsicallySized) {
+  NS_ENSURE_ARG_POINTER(aIntrinsicallySized);
+
+  *aIntrinsicallySized = mIntrinsicallySized;
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetPrimaryContentShell(
+    nsIDocShellTreeItem** aDocShellTreeItem) {
+  NS_ENSURE_ARG_POINTER(aDocShellTreeItem);
+  NS_IF_ADDREF(*aDocShellTreeItem = mPrimaryContentShell);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::RemoteTabAdded(nsIRemoteTab* aTab, bool aPrimary) {
+  if (aPrimary) {
+    mPrimaryBrowserParent = aTab;
+    mPrimaryContentShell = nullptr;
+  } else if (mPrimaryBrowserParent == aTab) {
+    mPrimaryBrowserParent = nullptr;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::RemoteTabRemoved(nsIRemoteTab* aTab) {
+  if (aTab == mPrimaryBrowserParent) {
+    mPrimaryBrowserParent = nullptr;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::GetPrimaryRemoteTab(nsIRemoteTab** aTab) {
+  nsCOMPtr<nsIRemoteTab> tab = mPrimaryBrowserParent;
+  tab.forget(aTab);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::GetPrimaryContentBrowsingContext(
+    mozilla::dom::BrowsingContext** aBc) {
+  if (mPrimaryBrowserParent) {
+    return mPrimaryBrowserParent->GetBrowsingContext(aBc);
+  }
+  if (mPrimaryContentShell) {
+    return mPrimaryContentShell->GetBrowsingContextXPCOM(aBc);
+  }
+  *aBc = nullptr;
+  return NS_OK;
+}
+
+static LayoutDeviceIntSize GetOuterToInnerSizeDifference(nsIWidget* aWindow) {
+  if (!aWindow) {
+    return LayoutDeviceIntSize();
+  }
+  return aWindow->ClientToWindowSizeDifference();
+}
+
+static CSSIntSize GetOuterToInnerSizeDifferenceInCSSPixels(
+    nsIWidget* aWindow, CSSToLayoutDeviceScale aScale) {
+  LayoutDeviceIntSize devPixelSize = GetOuterToInnerSizeDifference(aWindow);
+  return RoundedToInt(devPixelSize / aScale);
+}
+
+NS_IMETHODIMP
+AppWindow::GetOuterToInnerHeightDifferenceInCSSPixels(uint32_t* aResult) {
+  *aResult = GetOuterToInnerSizeDifferenceInCSSPixels(
+                 mWindow, UnscaledDevicePixelsPerCSSPixel())
+                 .height;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::GetOuterToInnerWidthDifferenceInCSSPixels(uint32_t* aResult) {
+  *aResult = GetOuterToInnerSizeDifferenceInCSSPixels(
+                 mWindow, UnscaledDevicePixelsPerCSSPixel())
+                 .width;
+  return NS_OK;
+}
+
+nsTArray<RefPtr<mozilla::LiveResizeListener>>
+AppWindow::GetLiveResizeListeners() {
+  nsTArray<RefPtr<mozilla::LiveResizeListener>> listeners;
+  if (mPrimaryBrowserParent) {
+    BrowserHost* host = BrowserHost::GetFrom(mPrimaryBrowserParent.get());
+    RefPtr<mozilla::LiveResizeListener> actor = host->GetActor();
+    if (actor) {
+      listeners.AppendElement(actor);
+    }
+  }
+  return listeners;
+}
+
+NS_IMETHODIMP AppWindow::AddChildWindow(nsIAppWindow* aChild) {
+  // we're not really keeping track of this right now
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::RemoveChildWindow(nsIAppWindow* aChild) {
+  // we're not really keeping track of this right now
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::ShowModal() {
+  AUTO_PROFILER_LABEL("AppWindow::ShowModal", OTHER);
+
+  if (AppShutdown::IsInOrBeyond(ShutdownPhase::AppShutdownConfirmed)) {
+    MOZ_ASSERT_UNREACHABLE(
+        "Trying to show modal window after shutdown started.");
+    return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
+  }
+
+  // Store locally so it doesn't die on us
+  nsCOMPtr<nsIWidget> window = mWindow;
+  nsCOMPtr<nsIAppWindow> tempRef = this;
+
+  window->SetModal(true);
+  mContinueModalLoop = true;
+  EnableParent(false);
+
+  {
+    AutoNoJSAPI nojsapi;
+    SpinEventLoopUntil("AppWindow::ShowModal"_ns, [&]() {
+      if (MOZ_UNLIKELY(
+              AppShutdown::IsInOrBeyond(ShutdownPhase::AppShutdownConfirmed))) {
+        // TODO: Bug 1699041 would apply also here: Should we return an error
+        // if we are bailing out from a pre-existing modal dialog for shutdown?
+        ExitModalLoop(NS_OK);
+      }
+      return !mContinueModalLoop;
+    });
+  }
+
+  mContinueModalLoop = false;
+  window->SetModal(false);
+  /*   Note there's no EnableParent(true) here to match the false one
+     above. That's done in ExitModalLoop. It's important that the parent
+     be re-enabled before this window is made invisible; to do otherwise
+     causes bizarre z-ordering problems. At this point, the window is
+     already invisible.
+       No known current implementation of Enable would have a problem with
+     re-enabling the parent twice, so we could do it again here without
+     breaking any current implementation. But that's unnecessary if the
+     modal loop is always exited using ExitModalLoop (the other way would be
+     to change the protected member variable directly.)
+  */
+
+  return mModalStatus;
+}
+
+//*****************************************************************************
+// AppWindow::nsIBaseWindow
+//*****************************************************************************
+
+NS_IMETHODIMP AppWindow::InitWindow(nativeWindow aParentNativeWindow,
+                                    nsIWidget* parentWidget, int32_t x,
+                                    int32_t y, int32_t cx, int32_t cy) {
+  // XXX First Check In
+  NS_ASSERTION(false, "Not Yet Implemented");
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::Destroy() {
+  nsCOMPtr<nsIAppWindow> kungFuDeathGrip(this);
+
+  if (mDocShell) {
+    mDocShell->RemoveProgressListener(this);
+  }
+
+  if (mSPTimer) {
+    mSPTimer->Cancel();
+    SavePersistentAttributes();
+    mSPTimer = nullptr;
+  }
+
+  if (!mWindow) return NS_OK;
+
+  // Ensure we don't reenter this code
+  if (mDestroying) return NS_OK;
+
+  mozilla::AutoRestore<bool> guard(mDestroying);
+  mDestroying = true;
+
+  nsCOMPtr<nsIAppShellService> appShell(
+      do_GetService(NS_APPSHELLSERVICE_CONTRACTID));
+  NS_ASSERTION(appShell, "Couldn't get appShell... xpcom shutdown?");
+  if (appShell)
+    appShell->UnregisterTopLevelWindow(static_cast<nsIAppWindow*>(this));
+
+  nsCOMPtr<nsIAppWindow> parentWindow(do_QueryReferent(mParentWindow));
+  if (parentWindow) parentWindow->RemoveChildWindow(this);
+
+  // Remove modality (if any) and hide while destroying. More than
+  // a convenience, the hide prevents user interaction with the partially
+  // destroyed window. This is especially necessary when the eldest window
+  // in a stack of modal windows is destroyed first. It happens.
+  ExitModalLoop(NS_OK);
+  // XXX: Skip unmapping the window on Linux due to GLX hangs on the compositor
+  // thread with NVIDIA driver 310.32. We don't need to worry about user
+  // interactions with destroyed windows on X11 either.
+#ifndef MOZ_WIDGET_GTK
+  if (mWindow) mWindow->Show(false);
+#endif
+
+#if defined(XP_WIN)
+  // We need to explicitly set the focus on Windows, but
+  // only if the parent is visible.
+  nsCOMPtr<nsIBaseWindow> parent(do_QueryReferent(mParentWindow));
+  if (parent) {
+    nsCOMPtr<nsIWidget> parentWidget;
+    parent->GetMainWidget(getter_AddRefs(parentWidget));
+
+    if (parentWidget && parentWidget->IsVisible()) {
+      bool isParentHiddenWindow = false;
+
+      if (appShell) {
+        bool hasHiddenWindow = false;
+        appShell->GetHasHiddenWindow(&hasHiddenWindow);
+        if (hasHiddenWindow) {
+          nsCOMPtr<nsIBaseWindow> baseHiddenWindow;
+          nsCOMPtr<nsIAppWindow> hiddenWindow;
+          appShell->GetHiddenWindow(getter_AddRefs(hiddenWindow));
+          if (hiddenWindow) {
+            baseHiddenWindow = do_GetInterface(hiddenWindow);
+            isParentHiddenWindow = (baseHiddenWindow == parent);
+          }
+        }
+      }
+
+      // somebody screwed up somewhere. hiddenwindow shouldn't be anybody's
+      // parent. still, when it happens, skip activating it.
+      if (!isParentHiddenWindow) {
+        parentWidget->PlaceBehind(eZPlacementTop, 0, true);
+      }
+    }
+  }
+#endif
+
+  RemoveTooltipSupport();
+
+  mDOMWindow = nullptr;
+  if (mDocShell) {
+    RefPtr<BrowsingContext> bc(mDocShell->GetBrowsingContext());
+    mDocShell->Destroy();
+    bc->Detach();
+    mDocShell = nullptr;  // this can cause reentrancy of this function
+  }
+
+  mPrimaryContentShell = nullptr;
+
+  if (mContentTreeOwner) {
+    mContentTreeOwner->AppWindow(nullptr);
+    NS_RELEASE(mContentTreeOwner);
+  }
+  if (mPrimaryContentTreeOwner) {
+    mPrimaryContentTreeOwner->AppWindow(nullptr);
+    NS_RELEASE(mPrimaryContentTreeOwner);
+  }
+  if (mChromeTreeOwner) {
+    mChromeTreeOwner->AppWindow(nullptr);
+    NS_RELEASE(mChromeTreeOwner);
+  }
+  if (mWindow) {
+    mWindow->SetWidgetListener(nullptr);  // nsWebShellWindow hackery
+    mWindow->Destroy();
+    mWindow = nullptr;
+  }
+
+  if (!mIsHiddenWindow && mRegistered) {
+    /* Inform appstartup we've destroyed this window and it could
+       quit now if it wanted. This must happen at least after mDocShell
+       is destroyed, because onunload handlers fire then, and those being
+       script, anything could happen. A new window could open, even.
+       See bug 130719. */
+    nsCOMPtr<nsIObserverService> obssvc = services::GetObserverService();
+    NS_ASSERTION(obssvc, "Couldn't get observer service?");
+
+    if (obssvc)
+      obssvc->NotifyObservers(nullptr, "xul-window-destroyed", nullptr);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetDevicePixelsPerDesktopPixel(double* aScale) {
+  *aScale = mWindow ? mWindow->GetDesktopToDeviceScale().scale : 1.0;
+  return NS_OK;
+}
+
+double AppWindow::GetWidgetCSSToDeviceScale() {
+  return mWindow ? mWindow->GetDefaultScale().scale : 1.0;
+}
+
+NS_IMETHODIMP AppWindow::SetPositionDesktopPix(int32_t aX, int32_t aY) {
+  return MoveResize(Some(DesktopIntPoint(aX, aY)), Nothing(), false);
+}
+
+// The parameters here are device pixels; do the best we can to convert to
+// desktop px, using the window's current scale factor (if available).
+NS_IMETHODIMP AppWindow::SetPosition(int32_t aX, int32_t aY) {
+  // Don't reset the window's size mode here - platforms that don't want to move
+  // maximized windows should reset it in their respective Move implementation.
+  return MoveResize(Some(LayoutDeviceIntPoint(aX, aY)), Nothing(), false);
+}
+
+NS_IMETHODIMP AppWindow::GetPosition(int32_t* aX, int32_t* aY) {
+  return GetPositionAndSize(aX, aY, nullptr, nullptr);
+}
+
+NS_IMETHODIMP AppWindow::SetSize(int32_t aCX, int32_t aCY, bool aRepaint) {
+  /* any attempt to set the window's size or position overrides the window's
+     zoom state. this is important when these two states are competing while
+     the window is being opened. but it should probably just always be so. */
+  return MoveResize(Nothing(), Some(LayoutDeviceIntSize(aCX, aCY)), aRepaint);
+}
+
+NS_IMETHODIMP AppWindow::GetSize(int32_t* aCX, int32_t* aCY) {
+  return GetPositionAndSize(nullptr, nullptr, aCX, aCY);
+}
+
+NS_IMETHODIMP AppWindow::SetPositionAndSize(int32_t aX, int32_t aY, int32_t aCX,
+                                            int32_t aCY, uint32_t aFlags) {
+  /* any attempt to set the window's size or position overrides the window's
+     zoom state. this is important when these two states are competing while
+     the window is being opened. but it should probably just always be so. */
+  return MoveResize(Some(LayoutDeviceIntPoint(aX, aY)),
+                    Some(LayoutDeviceIntSize(aCX, aCY)),
+                    !!(aFlags & nsIBaseWindow::eRepaint));
+}
+
+NS_IMETHODIMP AppWindow::GetPositionAndSize(int32_t* x, int32_t* y, int32_t* cx,
+                                            int32_t* cy) {
+  if (!mWindow) return NS_ERROR_FAILURE;
+
+  LayoutDeviceIntRect rect = mWindow->GetScreenBounds();
+
+  if (x) *x = rect.X();
+  if (y) *y = rect.Y();
+  if (cx) *cx = rect.Width();
+  if (cy) *cy = rect.Height();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::SetDimensions(DimensionRequest&& aRequest) {
+  if (aRequest.mDimensionKind == DimensionKind::Inner) {
+    // For the chrome the inner size is the root shell size, and for the
+    // content it's the primary content size. We lack an indicator here that
+    // would allow us to distinguish between the two.
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  MOZ_TRY(aRequest.SupplementFrom(this));
+  return aRequest.ApplyOuterTo(this);
+}
+
+NS_IMETHODIMP
+AppWindow::GetDimensions(DimensionKind aDimensionKind, int32_t* aX, int32_t* aY,
+                         int32_t* aCX, int32_t* aCY) {
+  if (aDimensionKind == DimensionKind::Inner) {
+    // For the chrome the inner size is the root shell size, and for the
+    // content it's the primary content size. We lack an indicator here that
+    // would allow us to distinguish between the two.
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+  return GetPositionAndSize(aX, aY, aCX, aCY);
+}
+
+nsresult AppWindow::MoveResize(const Maybe<LayoutDeviceIntPoint>& aPosition,
+                               const Maybe<LayoutDeviceIntSize>& aSize,
+                               bool aRepaint) {
+  DesktopToLayoutDeviceScale scale = mWindow->GetDesktopToDeviceScale();
+
+  return MoveResize(aPosition ? Some(*aPosition / scale) : Nothing(),
+                    aSize ? Some(*aSize / scale) : Nothing(), aRepaint);
+}
+
+nsresult AppWindow::MoveResize(const Maybe<DesktopPoint>& aPosition,
+                               const Maybe<DesktopSize>& aSize, bool aRepaint) {
+  NS_ENSURE_STATE(mWindow);
+  PersistentAttributes dirtyAttributes;
+
+  if (!aPosition && !aSize) {
+    MOZ_ASSERT_UNREACHABLE("Doing nothing?");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (aSize) {
+    mWindow->SetSizeMode(nsSizeMode_Normal);
+    mIntrinsicallySized = false;
+    mDominantClientSize = false;
+  }
+
+  if (aPosition && aSize) {
+    mWindow->Resize(aPosition->x, aPosition->y, aSize->width, aSize->height,
+                    aRepaint);
+    dirtyAttributes = {PersistentAttribute::Size,
+                       PersistentAttribute::Position};
+  } else if (aSize) {
+    mWindow->Resize(aSize->width, aSize->height, aRepaint);
+    dirtyAttributes = {PersistentAttribute::Size};
+  } else if (aPosition) {
+    mWindow->Move(aPosition->x, aPosition->y);
+    dirtyAttributes = {PersistentAttribute::Position};
+  }
+
+  if (mSizingShellFromXUL) {
+    // If we're invoked for sizing from XUL, we want to neither ignore anything
+    // nor persist anything, since it's already the value in XUL.
+    return NS_OK;
+  }
+  if (!mChromeLoaded) {
+    // If we're called before the chrome is loaded someone obviously wants this
+    // window at this size & in the normal size mode (since it is the only mode
+    // in which setting dimensions makes sense). We don't persist this one-time
+    // position/size.
+    if (aPosition) {
+      mIgnoreXULPosition = true;
+    }
+    if (aSize) {
+      mIgnoreXULSize = true;
+      mIgnoreXULSizeMode = true;
+    }
+    return NS_OK;
+  }
+
+  PersistentAttributesDirty(dirtyAttributes, Sync);
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::Center(nsIAppWindow* aRelative, bool aScreen,
+                                bool aAlert) {
+  DesktopIntRect rect;
+  bool screenCoordinates = false, windowCoordinates = false;
+  nsresult result;
+
+  if (!mChromeLoaded) {
+    // note we lose the parameters. at time of writing, this isn't a problem.
+    mCenterAfterLoad = true;
+    return NS_OK;
+  }
+
+  if (!aScreen && !aRelative) return NS_ERROR_INVALID_ARG;
+
+  nsCOMPtr<nsIScreenManager> screenmgr =
+      do_GetService("@mozilla.org/gfx/screenmanager;1", &result);
+  if (NS_FAILED(result)) {
+    return result;
+  }
+
+  nsCOMPtr<nsIScreen> screen;
+
+  if (aRelative) {
+    nsCOMPtr<nsIBaseWindow> base(do_QueryInterface(aRelative));
+    if (base) {
+      rect = RoundedToInt(base->GetPositionAndSize() /
+                          base->DevicePixelsPerDesktopPixel());
+      // if centering on screen, convert that to the corresponding screen
+      if (aScreen) {
+        screen = screenmgr->ScreenForRect(rect);
+      } else {
+        windowCoordinates = true;
+      }
+    }
+  }
+  if (!aRelative) {
+    if (!mOpenerScreenRect.IsEmpty()) {
+      screen = screenmgr->ScreenForRect(mOpenerScreenRect);
+    } else {
+      screenmgr->GetPrimaryScreen(getter_AddRefs(screen));
+    }
+  }
+
+  if (aScreen && screen) {
+    rect = screen->GetAvailRectDisplayPix();
+    screenCoordinates = true;
+  }
+
+  if (!screenCoordinates && !windowCoordinates) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NS_ASSERTION(mWindow, "what, no window?");
+  const LayoutDeviceIntSize ourDevSize = GetSize();
+  const DesktopIntSize ourSize =
+      RoundedToInt(ourDevSize / DevicePixelsPerDesktopPixel());
+  auto newPos =
+      rect.TopLeft() +
+      DesktopIntPoint((rect.width - ourSize.width) / 2,
+                      (rect.height - ourSize.height) / (aAlert ? 3 : 2));
+  if (windowCoordinates) {
+    mWindow->ConstrainPosition(newPos);
+  }
+
+  SetPositionDesktopPix(newPos.x, newPos.y);
+
+  // If moving the window caused it to change size, re-do the centering.
+  if (GetSize() != ourDevSize) {
+    return Center(aRelative, aScreen, aAlert);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::Repaint(bool aForce) {
+  // XXX First Check In
+  NS_ASSERTION(false, "Not Yet Implemented");
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetParentWidget(nsIWidget** aParentWidget) {
+  NS_ENSURE_ARG_POINTER(aParentWidget);
+  NS_ENSURE_STATE(mWindow);
+
+  NS_IF_ADDREF(*aParentWidget = mWindow->GetParent());
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::SetParentWidget(nsIWidget* aParentWidget) {
+  // XXX First Check In
+  NS_ASSERTION(false, "Not Yet Implemented");
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetParentNativeWindow(
+    nativeWindow* aParentNativeWindow) {
+  NS_ENSURE_ARG_POINTER(aParentNativeWindow);
+
+  nsCOMPtr<nsIWidget> parentWidget;
+  NS_ENSURE_SUCCESS(GetParentWidget(getter_AddRefs(parentWidget)),
+                    NS_ERROR_FAILURE);
+
+  if (parentWidget) {
+    *aParentNativeWindow = parentWidget->GetNativeData(NS_NATIVE_WIDGET);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::SetParentNativeWindow(
+    nativeWindow aParentNativeWindow) {
+  // XXX First Check In
+  NS_ASSERTION(false, "Not Yet Implemented");
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetNativeHandle(nsAString& aNativeHandle) {
+  nsCOMPtr<nsIWidget> mainWidget;
+  NS_ENSURE_SUCCESS(GetMainWidget(getter_AddRefs(mainWidget)),
+                    NS_ERROR_FAILURE);
+
+  if (mainWidget) {
+    nativeWindow nativeWindowPtr = mainWidget->GetNativeData(NS_NATIVE_WINDOW);
+    /* the nativeWindow pointer is converted to and exposed as a string. This
+       is a more reliable way not to lose information (as opposed to JS
+       |Number| for instance) */
+    aNativeHandle =
+        NS_ConvertASCIItoUTF16(nsPrintfCString("0x%p", nativeWindowPtr));
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetVisibility(bool* aVisibility) {
+  NS_ENSURE_ARG_POINTER(aVisibility);
+
+  // Always claim to be visible for now. See bug
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=306245.
+
+  *aVisibility = true;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::SetVisibility(bool aVisibility) {
+  if (!mChromeLoaded) {
+    mShowAfterLoad = aVisibility;
+    return NS_OK;
+  }
+
+  if (mDebuting) {
+    return NS_OK;
+  }
+
+  NS_ENSURE_STATE(mDocShell);
+
+  mDebuting = true;  // (Show / Focus is recursive)
+
+  // XXXTAB Do we really need to show docshell and the window?  Isn't
+  // the window good enough?
+  mDocShell->SetVisibility(aVisibility);
+  // Store locally so it doesn't die on us. 'Show' can result in the window
+  // being closed with AppWindow::Destroy being called. That would set
+  // mWindow to null and posibly destroy the nsIWidget while its Show method
+  // is on the stack. We need to keep it alive until Show finishes.
+  nsCOMPtr<nsIWidget> window = mWindow;
+  window->Show(aVisibility);
+
+  nsCOMPtr<nsIWindowMediator> windowMediator(
+      do_GetService(NS_WINDOWMEDIATOR_CONTRACTID));
+  if (windowMediator)
+    windowMediator->UpdateWindowTimeStamp(static_cast<nsIAppWindow*>(this));
+
+  // notify observers so that we can hide the splash screen if possible
+  nsCOMPtr<nsIObserverService> obssvc = services::GetObserverService();
+  NS_ASSERTION(obssvc, "Couldn't get observer service.");
+  if (obssvc) {
+    obssvc->NotifyObservers(static_cast<nsIAppWindow*>(this),
+                            "xul-window-visible", nullptr);
+  }
+
+  mDebuting = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetEnabled(bool* aEnabled) {
+  NS_ENSURE_ARG_POINTER(aEnabled);
+
+  if (mWindow) {
+    *aEnabled = mWindow->IsEnabled();
+    return NS_OK;
+  }
+
+  *aEnabled = true;  // better guess than most
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP AppWindow::SetEnabled(bool aEnable) {
+  if (mWindow) {
+    mWindow->Enable(aEnable);
+    return NS_OK;
+  }
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP AppWindow::GetMainWidget(nsIWidget** aMainWidget) {
+  NS_ENSURE_ARG_POINTER(aMainWidget);
+  NS_IF_ADDREF(*aMainWidget = mWindow);
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetTitle(nsAString& aTitle) {
+  aTitle = mTitle;
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::SetTitle(const nsAString& aTitle) {
+  NS_ENSURE_STATE(mWindow);
+  mTitle.Assign(aTitle);
+  mTitle.StripCRLF();
+  NS_ENSURE_SUCCESS(mWindow->SetTitle(mTitle), NS_ERROR_FAILURE);
+  return NS_OK;
+}
+
+//*****************************************************************************
+// AppWindow: Helpers
+//*****************************************************************************
+
+NS_IMETHODIMP AppWindow::EnsureChromeTreeOwner() {
+  if (mChromeTreeOwner) return NS_OK;
+
+  mChromeTreeOwner = new nsChromeTreeOwner();
+  NS_ADDREF(mChromeTreeOwner);
+  mChromeTreeOwner->AppWindow(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::EnsureContentTreeOwner() {
+  if (mContentTreeOwner) return NS_OK;
+
+  mContentTreeOwner = new nsContentTreeOwner(false);
+  NS_ADDREF(mContentTreeOwner);
+  mContentTreeOwner->AppWindow(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::EnsurePrimaryContentTreeOwner() {
+  if (mPrimaryContentTreeOwner) return NS_OK;
+
+  mPrimaryContentTreeOwner = new nsContentTreeOwner(true);
+  NS_ADDREF(mPrimaryContentTreeOwner);
+  mPrimaryContentTreeOwner->AppWindow(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::EnsurePrompter() {
+  if (mPrompter) return NS_OK;
+
+  nsCOMPtr<mozIDOMWindowProxy> ourWindow;
+  nsresult rv = GetWindowDOMWindow(getter_AddRefs(ourWindow));
+  if (NS_SUCCEEDED(rv)) {
+    nsCOMPtr<nsIWindowWatcher> wwatch =
+        do_GetService(NS_WINDOWWATCHER_CONTRACTID);
+    if (wwatch) wwatch->GetNewPrompter(ourWindow, getter_AddRefs(mPrompter));
+  }
+  return mPrompter ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP AppWindow::EnsureAuthPrompter() {
+  if (mAuthPrompter) return NS_OK;
+
+  nsCOMPtr<mozIDOMWindowProxy> ourWindow;
+  nsresult rv = GetWindowDOMWindow(getter_AddRefs(ourWindow));
+  if (NS_SUCCEEDED(rv)) {
+    nsCOMPtr<nsIWindowWatcher> wwatch(
+        do_GetService(NS_WINDOWWATCHER_CONTRACTID));
+    if (wwatch)
+      wwatch->GetNewAuthPrompter(ourWindow, getter_AddRefs(mAuthPrompter));
+  }
+  return mAuthPrompter ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP AppWindow::GetAvailScreenSize(int32_t* aAvailWidth,
+                                            int32_t* aAvailHeight) {
+  nsCOMPtr<mozIDOMWindowProxy> domWindow;
+  GetWindowDOMWindow(getter_AddRefs(domWindow));
+  NS_ENSURE_STATE(domWindow);
+
+  auto* window = nsGlobalWindowOuter::Cast(domWindow);
+
+  RefPtr<nsScreen> screen = window->GetScreen();
+  NS_ENSURE_STATE(screen);
+
+  ErrorResult rv;
+  *aAvailWidth = screen->GetAvailWidth(rv);
+  if (NS_WARN_IF(rv.Failed())) {
+    return rv.StealNSResult();
+  }
+
+  *aAvailHeight = screen->GetAvailHeight(rv);
+  if (NS_WARN_IF(rv.Failed())) {
+    return rv.StealNSResult();
+  }
+
+  return NS_OK;
+}
+
+// Rounds window size to 1000x1000, or, if there isn't enough available
+// screen space, to a multiple of 200x100.
+NS_IMETHODIMP AppWindow::ForceRoundedDimensions() {
+  if (mIsHiddenWindow) {
+    return NS_OK;
+  }
+
+  CSSToLayoutDeviceScale scale = UnscaledDevicePixelsPerCSSPixel();
+
+  CSSIntSize availSizeCSS;
+  GetAvailScreenSize(&availSizeCSS.width, &availSizeCSS.height);
+
+  // To get correct chrome size, we have to resize the window to a proper
+  // size first. So, here, we size it to its available size.
+  SetSpecifiedSize(availSizeCSS.width, availSizeCSS.height);
+
+  // Get the current window size for calculating chrome UI size.
+  CSSIntSize windowSizeCSS = RoundedToInt(GetSize() / scale);
+
+  // Get the content size for calculating chrome UI size.
+  LayoutDeviceIntSize contentSizeDev;
+  GetPrimaryContentSize(&contentSizeDev.width, &contentSizeDev.height);
+  CSSIntSize contentSizeCSS = RoundedToInt(contentSizeDev / scale);
+
+  // Calculate the chrome UI size.
+  CSSIntSize chromeSizeCSS = windowSizeCSS - contentSizeCSS;
+
+  CSSIntSize targetSizeCSS;
+  // Here, we use the available screen dimensions as the input dimensions to
+  // force the window to be rounded as the maximum available content size.
+  nsContentUtils::CalcRoundedWindowSizeForResistingFingerprinting(
+      chromeSizeCSS.width, chromeSizeCSS.height, availSizeCSS.width,
+      availSizeCSS.height, availSizeCSS.width, availSizeCSS.height,
+      false,  // aSetOuterWidth
+      false,  // aSetOuterHeight
+      &targetSizeCSS.width, &targetSizeCSS.height);
+
+  LayoutDeviceIntSize targetSizeDev = RoundedToInt(targetSizeCSS * scale);
+
+  SetPrimaryContentSize(targetSizeDev.width, targetSizeDev.height);
+
+  return NS_OK;
+}
+
+void AppWindow::OnChromeLoaded() {
+  nsresult rv = EnsureContentTreeOwner();
+
+  if (NS_SUCCEEDED(rv)) {
+    mChromeLoaded = true;
+    ApplyChromeFlags();
+    SyncAttributesToWidget();
+    if (mWindow) {
+      SizeShell();
+      if (mShowAfterLoad) {
+        SetVisibility(true);
+      }
+      AddTooltipSupport();
+    }
+    // At this point the window may have been closed already during Show() or
+    // SyncAttributesToWidget(), so AppWindow::Destroy may already have been
+    // called. Take care!
+  }
+  mPersistentAttributesMask += AllPersistentAttributes();
+}
+
+bool AppWindow::NeedsTooltipListener() {
+  nsCOMPtr<dom::Element> docShellElement = GetWindowDOMElement();
+  if (!docShellElement || docShellElement->IsXULElement()) {
+    // Tooltips in XUL are handled by each element.
+    return false;
+  }
+  // All other non-XUL document types need a tooltip listener.
+  return true;
+}
+
+void AppWindow::AddTooltipSupport() {
+  if (!NeedsTooltipListener()) {
+    return;
+  }
+  nsXULTooltipListener* listener = nsXULTooltipListener::GetInstance();
+  if (!listener) {
+    return;
+  }
+
+  nsCOMPtr<dom::Element> docShellElement = GetWindowDOMElement();
+  MOZ_ASSERT(docShellElement);
+  listener->AddTooltipSupport(docShellElement);
+}
+
+void AppWindow::RemoveTooltipSupport() {
+  if (!NeedsTooltipListener()) {
+    return;
+  }
+  nsXULTooltipListener* listener = nsXULTooltipListener::GetInstance();
+  if (!listener) {
+    return;
+  }
+
+  nsCOMPtr<dom::Element> docShellElement = GetWindowDOMElement();
+  MOZ_ASSERT(docShellElement);
+  listener->RemoveTooltipSupport(docShellElement);
+}
+
+static Maybe<int32_t> ReadIntAttribute(const Element& aElement,
+                                       nsAtom* aPrimary,
+                                       nsAtom* aSecondary = nullptr) {
+  nsAutoString attrString;
+  if (!aElement.GetAttr(aPrimary, attrString)) {
+    if (aSecondary) {
+      return ReadIntAttribute(aElement, aSecondary);
+    }
+    return Nothing();
+  }
+
+  nsresult res = NS_OK;
+  int32_t ret = attrString.ToInteger(&res);
+  return NS_SUCCEEDED(res) ? Some(ret) : Nothing();
+}
+
+// If aSpecWidth and/or aSpecHeight are > 0, we will use these CSS px sizes
+// to fit to the screen when staggering windows; if they're negative,
+// we use the window's current size instead.
+bool AppWindow::LoadPositionFromXUL(int32_t aSpecWidth, int32_t aSpecHeight) {
+  bool gotPosition = false;
+
+  // if we're the hidden window, don't try to validate our size/position. We're
+  // special.
+  if (mIsHiddenWindow) {
+    return false;
+  }
+
+  RefPtr<dom::Element> root = GetWindowDOMElement();
+  NS_ENSURE_TRUE(root, false);
+
+  const LayoutDeviceIntRect devRect = GetPositionAndSize();
+
+  // Convert to global display pixels for consistent window management across
+  // screens with diverse resolutions
+  const DesktopIntPoint curPoint =
+      RoundedToInt(devRect.TopLeft() / DevicePixelsPerDesktopPixel());
+
+  // For size, use specified value if > 0, else current value
+  CSSIntSize cssSize(aSpecWidth, aSpecHeight);
+  {
+    CSSIntSize currentSize =
+        RoundedToInt(devRect.Size() / UnscaledDevicePixelsPerCSSPixel());
+    if (aSpecHeight <= 0) {
+      cssSize.height = currentSize.height;
+    }
+    if (aSpecWidth <= 0) {
+      cssSize.width = currentSize.width;
+    }
+  }
+
+  // Obtain the position information from the <xul:window> element.
+  DesktopIntPoint specPoint = curPoint;
+
+  // Also read lowercase screenx/y because the front-end sometimes sets these
+  // via setAttribute on HTML documents like about:blank, and stuff gets
+  // lowercased.
+  //
+  // TODO(emilio): We should probably rename screenX/Y to screen-x/y to
+  // prevent this impedance mismatch.
+  if (auto attr =
+          ReadIntAttribute(*root, nsGkAtoms::screenX, nsGkAtoms::screenx)) {
+    specPoint.x = *attr;
+    gotPosition = true;
+  }
+
+  if (auto attr =
+          ReadIntAttribute(*root, nsGkAtoms::screenY, nsGkAtoms::screeny)) {
+    specPoint.y = *attr;
+    gotPosition = true;
+  }
+
+  if (gotPosition) {
+    // Our position will be relative to our parent, if any
+    nsCOMPtr<nsIBaseWindow> parent(do_QueryReferent(mParentWindow));
+    if (parent) {
+      const DesktopIntPoint parentPos = RoundedToInt(
+          parent->GetPosition() / parent->DevicePixelsPerDesktopPixel());
+      specPoint += parentPos;
+    } else {
+      StaggerPosition(specPoint.x.value, specPoint.y.value, cssSize.width,
+                      cssSize.height);
+    }
+  }
+  mWindow->ConstrainPosition(specPoint);
+  if (specPoint != curPoint) {
+    SetPositionDesktopPix(specPoint.x, specPoint.y);
+  }
+
+  return gotPosition;
+}
+
+static Maybe<int32_t> ReadSize(const Element& aElement, nsAtom* aAttr,
+                               nsAtom* aMinAttr, nsAtom* aMaxAttr) {
+  Maybe<int32_t> attr = ReadIntAttribute(aElement, aAttr);
+  if (!attr) {
+    return Nothing();
+  }
+
+  int32_t min =
+      std::max(100, ReadIntAttribute(aElement, aMinAttr).valueOr(100));
+  int32_t max = ReadIntAttribute(aElement, aMaxAttr)
+                    .valueOr(std::numeric_limits<int32_t>::max());
+
+  return Some(std::min(max, std::max(*attr, min)));
+}
+
+bool AppWindow::LoadSizeFromXUL(int32_t& aSpecWidth, int32_t& aSpecHeight) {
+  bool gotSize = false;
+
+  // if we're the hidden window, don't try to validate our size/position. We're
+  // special.
+  if (mIsHiddenWindow) {
+    return false;
+  }
+
+  nsCOMPtr<dom::Element> windowElement = GetWindowDOMElement();
+  NS_ENSURE_TRUE(windowElement, false);
+
+  // Obtain the sizing information from the <xul:window> element.
+  aSpecWidth = 100;
+  aSpecHeight = 100;
+
+  if (auto width = ReadSize(*windowElement, nsGkAtoms::width,
+                            nsGkAtoms::minwidth, nsGkAtoms::maxwidth)) {
+    aSpecWidth = *width;
+    gotSize = true;
+  }
+
+  if (auto height = ReadSize(*windowElement, nsGkAtoms::height,
+                             nsGkAtoms::minheight, nsGkAtoms::maxheight)) {
+    aSpecHeight = *height;
+    gotSize = true;
+  }
+
+  return gotSize;
+}
+
+void AppWindow::SetSpecifiedSize(int32_t aSpecWidth, int32_t aSpecHeight) {
+  // These are in CSS pixels of the main window.
+  // TODO(emilio): In my testing we usually have a pres context around, can we
+  // just use it? That'd simplify the coordinate calculations.
+  {
+    int32_t screenWidth;
+    int32_t screenHeight;
+
+    if (NS_SUCCEEDED(GetAvailScreenSize(&screenWidth, &screenHeight))) {
+      if (aSpecWidth > screenWidth) {
+        aSpecWidth = screenWidth;
+      }
+      if (aSpecHeight > screenHeight) {
+        aSpecHeight = screenHeight;
+      }
+    }
+  }
+
+  NS_ASSERTION(mWindow, "we expected to have a window already");
+
+  mIntrinsicallySized = false;
+
+  // Convert specified values to device pixels, and resize
+  auto newSize = RoundedToInt(CSSIntSize(aSpecWidth, aSpecHeight) *
+                              UnscaledDevicePixelsPerCSSPixel());
+
+  // Note: Because of the asynchronous resizing on Linux we have to call
+  // SetSize even when the size doesn't appear to change. A previous call that
+  // has yet to complete can still change the size. We want the latest call to
+  // define the final size.
+  SetSize(newSize.width, newSize.height, false);
+}
+
+/* Miscellaneous persistent attributes are attributes named in the
+   |persist| attribute, other than size and position. Those are special
+   because it's important to load those before one of the misc
+   attributes (sizemode) and they require extra processing. */
+bool AppWindow::UpdateWindowStateFromMiscXULAttributes() {
+  bool gotState = false;
+
+  /* There are no misc attributes of interest to the hidden window.
+     It's especially important not to try to validate that window's
+     size or position, because some platforms (Mac OS X) need to
+     make it visible and offscreen. */
+  if (mIsHiddenWindow) return false;
+
+  nsCOMPtr<dom::Element> windowElement = GetWindowDOMElement();
+  NS_ENSURE_TRUE(windowElement, false);
+
+  nsAutoString stateString;
+  nsSizeMode sizeMode = nsSizeMode_Normal;
+
+  // If we are told to ignore the size mode attribute, force
+  // normal sizemode.
+  if (mIgnoreXULSizeMode) {
+    windowElement->SetAttr(nsGkAtoms::sizemode, SIZEMODE_NORMAL,
+                           IgnoreErrors());
+  } else {
+    // Otherwise, read sizemode from DOM and, if the window is resizable,
+    // set it later.
+    windowElement->GetAttr(nsGkAtoms::sizemode, stateString);
+    if ((stateString.Equals(SIZEMODE_MAXIMIZED) ||
+         stateString.Equals(SIZEMODE_FULLSCREEN))) {
+      /* Honor request to maximize only if the window is sizable.
+         An unsizable, unmaximizable, yet maximized window confuses
+         Windows OS and is something of a travesty, anyway. */
+      if (mChromeFlags & nsIWebBrowserChrome::CHROME_WINDOW_RESIZE) {
+        mIntrinsicallySized = false;
+
+        if (stateString.Equals(SIZEMODE_MAXIMIZED))
+          sizeMode = nsSizeMode_Maximized;
+        else
+          sizeMode = nsSizeMode_Fullscreen;
+      }
+    }
+  }
+
+  if (sizeMode == nsSizeMode_Fullscreen) {
+    nsCOMPtr<mozIDOMWindowProxy> ourWindow;
+    GetWindowDOMWindow(getter_AddRefs(ourWindow));
+    auto* piWindow = nsPIDOMWindowOuter::From(ourWindow);
+    piWindow->SetFullScreen(true);
+  } else {
+    // For maximized windows, ignore the XUL size and position attributes,
+    // as setting them would set the window back to normal sizemode.
+    if (sizeMode == nsSizeMode_Maximized) {
+      mIgnoreXULSize = true;
+      mIgnoreXULPosition = true;
+    }
+    mWindow->SetSizeMode(sizeMode);
+  }
+  gotState = true;
+
+  // zlevel
+  windowElement->GetAttr(nsGkAtoms::zlevel, stateString);
+  if (!stateString.IsEmpty()) {
+    nsresult errorCode;
+    int32_t zLevel = stateString.ToInteger(&errorCode);
+    if (NS_SUCCEEDED(errorCode) && zLevel >= lowestZ && zLevel <= highestZ)
+      SetZLevel(zLevel);
+  }
+
+  return gotState;
+}
+
+/* Stagger windows of the same type so they don't appear on top of each other.
+   This code does have a scary double loop -- it'll keep passing through
+   the entire list of open windows until it finds a non-collision. Doesn't
+   seem to be a problem, but it deserves watching.
+   The aRequested{X,Y} parameters here are in desktop pixels;
+   the aSpec{Width,Height} parameters are CSS pixel dimensions.
+*/
+void AppWindow::StaggerPosition(int32_t& aRequestedX, int32_t& aRequestedY,
+                                int32_t aSpecWidth, int32_t aSpecHeight) {
+  // These "constants" will be converted from CSS to desktop pixels
+  // for the appropriate screen, assuming we find a screen to use...
+  // hence they're not actually declared const here.
+  int32_t kOffset = 22;
+  uint32_t kSlop = 4;
+
+  bool keepTrying;
+  int bouncedX = 0,  // bounced off vertical edge of screen
+      bouncedY = 0;  // bounced off horizontal edge
+
+  // look for any other windows of this type
+  nsCOMPtr<nsIWindowMediator> wm(do_GetService(NS_WINDOWMEDIATOR_CONTRACTID));
+  if (!wm) return;
+
+  nsCOMPtr<dom::Element> windowElement = GetWindowDOMElement();
+  if (!windowElement) return;
+
+  nsCOMPtr<nsIAppWindow> ourAppWindow(this);
+
+  nsAutoString windowType;
+  windowElement->GetAttr(nsGkAtoms::windowtype, windowType);
+
+  DesktopIntRect screenRect;
+  bool gotScreen = false;
+
+  {  // fetch screen coordinates
+    nsCOMPtr<nsIScreenManager> screenMgr(
+        do_GetService("@mozilla.org/gfx/screenmanager;1"));
+    if (screenMgr) {
+      nsCOMPtr<nsIScreen> ourScreen;
+      // The coordinates here are already display pixels
+      // XXX aSpecWidth and aSpecHeight are CSS pixels!
+      screenMgr->ScreenForRect(aRequestedX, aRequestedY, aSpecWidth,
+                               aSpecHeight, getter_AddRefs(ourScreen));
+      if (ourScreen) {
+        screenRect = ourScreen->GetAvailRectDisplayPix();
+
+        // Get the screen's scaling factors and convert staggering constants
+        // from CSS px to desktop pixel units
+        auto scale = ourScreen->GetCSSToDesktopScale();
+        kOffset = (CSSCoord(kOffset) * scale).Rounded();
+        kSlop = (CSSCoord(kSlop) * scale).Rounded();
+        // Convert dimensions from CSS to desktop pixels
+        aSpecWidth = (CSSCoord(aSpecWidth) * scale).Rounded();
+        aSpecHeight = (CSSCoord(aSpecHeight) * scale).Rounded();
+        gotScreen = true;
+      }
+    }
+  }
+
+  // One full pass through all windows of this type, repeat until no collisions.
+  do {
+    keepTrying = false;
+    nsCOMPtr<nsISimpleEnumerator> windowList;
+    wm->GetAppWindowEnumerator(windowType.get(), getter_AddRefs(windowList));
+
+    if (!windowList) break;
+
+    // One full pass through all windows of this type, offset and stop on
+    // collision.
+    do {
+      bool more;
+      windowList->HasMoreElements(&more);
+      if (!more) break;
+
+      nsCOMPtr<nsISupports> supportsWindow;
+      windowList->GetNext(getter_AddRefs(supportsWindow));
+
+      nsCOMPtr<nsIAppWindow> listAppWindow(do_QueryInterface(supportsWindow));
+      if (listAppWindow != ourAppWindow) {
+        int32_t listX, listY;
+        nsCOMPtr<nsIBaseWindow> listBaseWindow(
+            do_QueryInterface(supportsWindow));
+        listBaseWindow->GetPosition(&listX, &listY);
+        double scale;
+        if (NS_SUCCEEDED(
+                listBaseWindow->GetDevicePixelsPerDesktopPixel(&scale))) {
+          listX = NSToIntRound(listX / scale);
+          listY = NSToIntRound(listY / scale);
+        }
+
+        if (Abs(listX - aRequestedX) <= kSlop &&
+            Abs(listY - aRequestedY) <= kSlop) {
+          // collision! offset and start over
+          if (bouncedX & 0x1)
+            aRequestedX -= kOffset;
+          else
+            aRequestedX += kOffset;
+          aRequestedY += kOffset;
+
+          if (gotScreen) {
+            // if we're moving to the right and we need to bounce...
+            if (!(bouncedX & 0x1) &&
+                ((aRequestedX + aSpecWidth) > screenRect.XMost())) {
+              aRequestedX = screenRect.XMost() - aSpecWidth;
+              ++bouncedX;
+            }
+
+            // if we're moving to the left and we need to bounce...
+            if ((bouncedX & 0x1) && aRequestedX < screenRect.X()) {
+              aRequestedX = screenRect.X();
+              ++bouncedX;
+            }
+
+            // if we hit the bottom then bounce to the top
+            if (aRequestedY + aSpecHeight > screenRect.YMost()) {
+              aRequestedY = screenRect.Y();
+              ++bouncedY;
+            }
+          }
+
+          /* loop around again,
+             but it's time to give up once we've covered the screen.
+             there's a potential infinite loop with lots of windows. */
+          keepTrying = bouncedX < 2 || bouncedY == 0;
+          break;
+        }
+      }
+    } while (true);
+  } while (keepTrying);
+}
+
+void AppWindow::SyncAttributesToWidget() {
+  nsCOMPtr<dom::Element> windowElement = GetWindowDOMElement();
+  if (!windowElement) return;
+
+  MOZ_DIAGNOSTIC_ASSERT(mWindow, "No widget on SyncAttributesToWidget?");
+
+  nsAutoString attr;
+
+  // Some attributes can change the client size (e.g. chromemargin on Windows
+  // and MacOS). But we might want to keep it.
+  const LayoutDeviceIntSize oldClientSize = mWindow->GetClientSize();
+  // We have to check now whether we want to restore the client size, as any
+  // change in size will reset its state.
+  bool maintainClientSize = mDominantClientSize;
+
+  // "hidechrome" attribute
+  if (windowElement->AttrValueIs(kNameSpaceID_None, nsGkAtoms::hidechrome,
+                                 nsGkAtoms::_true, eCaseMatters)) {
+    mWindow->HideWindowChrome(true);
+  }
+
+  NS_ENSURE_TRUE_VOID(mWindow);
+
+  // "chromemargin" attribute
+  nsIntMargin margins;
+  windowElement->GetAttribute(u"chromemargin"_ns, attr);
+  if (nsContentUtils::ParseIntMarginValue(attr, margins)) {
+    mWindow->SetNonClientMargins(
+        LayoutDeviceIntMargin::FromUnknownMargin(margins));
+  }
+
+  NS_ENSURE_TRUE_VOID(mWindow);
+
+  // "windowtype", "windowclass", "windowname" attributes
+  nsAutoString windowClassAttr, windowNameAttr;
+  windowElement->GetAttr(nsGkAtoms::windowtype, attr);
+  windowElement->GetAttribute(u"windowclass"_ns, windowClassAttr);
+  windowElement->GetAttribute(u"windowname"_ns, windowNameAttr);
+  mWindow->SetWindowClass(attr, windowClassAttr, windowNameAttr);
+
+  NS_ENSURE_TRUE_VOID(mWindow);
+
+  // "icon" attribute
+  windowElement->GetAttribute(u"icon"_ns, attr);
+  if (!attr.IsEmpty()) {
+    mWindow->SetIcon(attr);
+
+    NS_ENSURE_TRUE_VOID(mWindow);
+  }
+
+  // "drawtitle" attribute
+  windowElement->GetAttribute(u"drawtitle"_ns, attr);
+  mWindow->SetDrawsTitle(attr.LowerCaseEqualsLiteral("true"));
+
+  NS_ENSURE_TRUE_VOID(mWindow);
+
+  // "toggletoolbar" attribute
+  windowElement->GetAttribute(u"toggletoolbar"_ns, attr);
+  mWindow->SetShowsToolbarButton(attr.LowerCaseEqualsLiteral("true"));
+
+  NS_ENSURE_TRUE_VOID(mWindow);
+
+  // "macnativefullscreen" attribute
+  windowElement->GetAttribute(u"macnativefullscreen"_ns, attr);
+  mWindow->SetSupportsNativeFullscreen(attr.LowerCaseEqualsLiteral("true"));
+
+  NS_ENSURE_TRUE_VOID(mWindow);
+
+  // "macanimationtype" attribute
+  windowElement->GetAttribute(u"macanimationtype"_ns, attr);
+  if (attr.EqualsLiteral("document")) {
+    mWindow->SetWindowAnimationType(nsIWidget::eDocumentWindowAnimation);
+  }
+
+  // Check if the client size did change and if we want to restore it.
+  if (maintainClientSize && mWindow->SizeMode() == nsSizeMode_Normal &&
+      oldClientSize != mWindow->GetClientSize()) {
+    mWindow->ResizeClient(oldClientSize / mWindow->GetDesktopToDeviceScale(),
+                          true);
+    mDominantClientSize = true;
+  }
+}
+
+enum class ConversionDirection {
+  InnerToOuter,
+  OuterToInner,
+};
+
+static void ConvertWindowSize(nsIAppWindow* aWin, const nsAtom* aAttr,
+                              ConversionDirection aDirection,
+                              nsAString& aInOutString) {
+  MOZ_ASSERT(aWin);
+  MOZ_ASSERT(aAttr == nsGkAtoms::width || aAttr == nsGkAtoms::height);
+
+  nsresult rv;
+  int32_t size = aInOutString.ToInteger(&rv);
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  int32_t sizeDiff = aAttr == nsGkAtoms::width
+                         ? aWin->GetOuterToInnerWidthDifferenceInCSSPixels()
+                         : aWin->GetOuterToInnerHeightDifferenceInCSSPixels();
+
+  if (!sizeDiff) {
+    return;
+  }
+
+  int32_t multiplier = aDirection == ConversionDirection::InnerToOuter ? 1 : -1;
+
+  CopyASCIItoUTF16(nsPrintfCString("%d", size + multiplier * sizeDiff),
+                   aInOutString);
+}
+
+nsresult AppWindow::GetPersistentValue(const nsAtom* aAttr, nsAString& aValue) {
+  nsCOMPtr<dom::Element> docShellElement = GetWindowDOMElement();
+  if (!docShellElement) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsAutoString windowElementId;
+  docShellElement->GetId(windowElementId);
+  // Elements must have an ID to be persisted.
+  if (windowElementId.IsEmpty()) {
+    return NS_OK;
+  }
+
+  RefPtr<dom::Document> ownerDoc = docShellElement->OwnerDoc();
+  nsIURI* docURI = ownerDoc->GetDocumentURI();
+  if (!docURI) {
+    return NS_ERROR_FAILURE;
+  }
+  nsAutoCString utf8uri;
+  nsresult rv = docURI->GetSpec(utf8uri);
+  NS_ENSURE_SUCCESS(rv, rv);
+  NS_ConvertUTF8toUTF16 uri(utf8uri);
+
+  if (!mLocalStore) {
+    mLocalStore = do_GetService("@mozilla.org/xul/xulstore;1");
+    if (NS_WARN_IF(!mLocalStore)) {
+      return NS_ERROR_NOT_INITIALIZED;
+    }
+  }
+
+  rv = mLocalStore->GetValue(uri, windowElementId, nsDependentAtomString(aAttr),
+                             aValue);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (aAttr == nsGkAtoms::width || aAttr == nsGkAtoms::height) {
+    // Convert attributes from outer size to inner size for top-level
+    // windows, see bug 1444525 & co.
+    ConvertWindowSize(this, aAttr, ConversionDirection::OuterToInner, aValue);
+  }
+
+  return NS_OK;
+}
+
+nsresult AppWindow::GetDocXulStoreKeys(nsString& aUriSpec,
+                                       nsString& aWindowElementId) {
+  nsCOMPtr<dom::Element> docShellElement = GetWindowDOMElement();
+  if (!docShellElement) {
+    return NS_ERROR_FAILURE;
+  }
+
+  docShellElement->GetId(aWindowElementId);
+  // Match the behavior of XULPersist and only persist values if the element
+  // has an ID.
+  if (aWindowElementId.IsEmpty()) {
+    return NS_OK;
+  }
+
+  RefPtr<dom::Document> ownerDoc = docShellElement->OwnerDoc();
+  nsIURI* docURI = ownerDoc->GetDocumentURI();
+  if (!docURI) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsAutoCString utf8uri;
+  nsresult rv = docURI->GetSpec(utf8uri);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  aUriSpec = NS_ConvertUTF8toUTF16(utf8uri);
+
+  return NS_OK;
+}
+
+nsresult AppWindow::MaybeSaveEarlyWindowPersistentValues(
+    const LayoutDeviceIntRect& aRect) {
+#ifdef XP_WIN
+  nsAutoString uri;
+  nsAutoString windowElementId;
+  nsresult rv = GetDocXulStoreKeys(uri, windowElementId);
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (!windowElementId.EqualsLiteral("main-window") ||
+      !uri.EqualsLiteral("chrome://browser/content/browser.xhtml")) {
+    return NS_OK;
+  }
+
+  SkeletonUISettings settings;
+
+  settings.screenX = aRect.X();
+  settings.screenY = aRect.Y();
+  settings.width = aRect.Width();
+  settings.height = aRect.Height();
+
+  settings.maximized = mWindow->SizeMode() == nsSizeMode_Maximized;
+  settings.cssToDevPixelScaling = UnscaledDevicePixelsPerCSSPixel().scale;
+
+  nsCOMPtr<dom::Element> windowElement = GetWindowDOMElement();
+  Document* doc = windowElement->GetComposedDoc();
+  Element* urlbarEl = doc->GetElementById(u"urlbar"_ns);
+
+  nsCOMPtr<nsPIDOMWindowOuter> window = mDocShell->GetWindow();
+  nsCOMPtr<nsIDOMWindowUtils> utils =
+      nsGlobalWindowOuter::Cast(window)->WindowUtils();
+  RefPtr<dom::DOMRect> urlbarRect;
+  rv = utils->GetBoundsWithoutFlushing(urlbarEl, getter_AddRefs(urlbarRect));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  double urlbarX = urlbarRect->X();
+  double urlbarWidth = urlbarRect->Width();
+
+  // Hard-coding the following values and this behavior in general is rather
+  // fragile, and can easily get out of sync with the actual front-end values.
+  // This is not intended as a long-term solution, but only as the relatively
+  // straightforward implementation of an experimental feature. If we want to
+  // ship the skeleton UI to all users, we should strongly consider a more
+  // robust solution than this. The vertical position of the urlbar will be
+  // fixed.
+  nsAutoString attributeValue;
+  urlbarEl->GetAttribute(u"breakout-extend"_ns, attributeValue);
+  // Scale down the urlbar if it is focused
+  if (attributeValue.EqualsLiteral("true")) {
+    // defined in browser.inc.css as 2px
+    int urlbarBreakoutExtend = 2;
+    // defined in urlbar-searchbar.inc.css as 5px
+    int urlbarMarginInline = 5;
+
+    // breakout-extend measurements are defined in urlbar-searchbar.inc.css
+    urlbarX += (double)(urlbarBreakoutExtend + urlbarMarginInline);
+    urlbarWidth -= (double)(2 * (urlbarBreakoutExtend + urlbarMarginInline));
+  }
+  CSSPixelSpan urlbar;
+  urlbar.start = urlbarX;
+  urlbar.end = urlbar.start + urlbarWidth;
+  settings.urlbarSpan = urlbar;
+
+  Element* navbar = doc->GetElementById(u"nav-bar"_ns);
+
+  Element* searchbarEl = doc->GetElementById(u"searchbar"_ns);
+  CSSPixelSpan searchbar;
+  if (navbar->Contains(searchbarEl)) {
+    RefPtr<dom::DOMRect> searchbarRect;
+    rv = utils->GetBoundsWithoutFlushing(searchbarEl,
+                                         getter_AddRefs(searchbarRect));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    searchbar.start = searchbarRect->X();
+    searchbar.end = searchbar.start + searchbarRect->Width();
+  } else {
+    // There is no searchbar in the UI
+    searchbar.start = 0;
+    searchbar.end = 0;
+  }
+  settings.searchbarSpan = searchbar;
+
+  nsAutoString bookmarksVisibility;
+  Preferences::GetString("browser.toolbars.bookmarks.visibility",
+                         bookmarksVisibility);
+  settings.bookmarksToolbarShown =
+      bookmarksVisibility.EqualsLiteral("always") ||
+      bookmarksVisibility.EqualsLiteral("newtab");
+
+  Element* menubar = doc->GetElementById(u"toolbar-menubar"_ns);
+  menubar->GetAttribute(u"autohide"_ns, attributeValue);
+  settings.menubarShown = attributeValue.EqualsLiteral("false");
+
+  ErrorResult err;
+  nsCOMPtr<nsIHTMLCollection> toolbarSprings = navbar->GetElementsByTagNameNS(
+      u"http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"_ns,
+      u"toolbarspring"_ns, err);
+  if (err.Failed()) {
+    return NS_ERROR_FAILURE;
+  }
+  mozilla::Vector<CSSPixelSpan> springs;
+  for (size_t i = 0; i < toolbarSprings->Length(); i++) {
+    RefPtr<Element> springEl = toolbarSprings->Item(i);
+    RefPtr<dom::DOMRect> springRect;
+    rv = utils->GetBoundsWithoutFlushing(springEl, getter_AddRefs(springRect));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    CSSPixelSpan spring;
+    spring.start = springRect->X();
+    spring.end = spring.start + springRect->Width();
+    if (!settings.springs.append(spring)) {
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  settings.rtlEnabled = intl::LocaleService::GetInstance()->IsAppLocaleRTL();
+
+  bool isInTabletMode = false;
+  bool autoTouchModePref =
+      Preferences::GetBool("browser.touchmode.auto", false);
+  if (autoTouchModePref) {
+    nsCOMPtr<nsIWindowsUIUtils> uiUtils(
+        do_GetService("@mozilla.org/windows-ui-utils;1"));
+    if (!NS_WARN_IF(!uiUtils)) {
+      uiUtils->GetInTabletMode(&isInTabletMode);
+    }
+  }
+
+  if (isInTabletMode) {
+    settings.uiDensity = SkeletonUIDensity::Touch;
+  } else {
+    int uiDensityPref = Preferences::GetInt("browser.uidensity", 0);
+    switch (uiDensityPref) {
+      case 0: {
+        settings.uiDensity = SkeletonUIDensity::Default;
+        break;
+      }
+      case 1: {
+        settings.uiDensity = SkeletonUIDensity::Compact;
+        break;
+      }
+      case 2: {
+        settings.uiDensity = SkeletonUIDensity::Touch;
+        break;
+      }
+    }
+  }
+
+  Unused << PersistPreXULSkeletonUIValues(settings);
+#endif
+
+  return NS_OK;
+}
+
+nsresult AppWindow::SetPersistentValue(const nsAtom* aAttr,
+                                       const nsAString& aValue) {
+  nsAutoString uri;
+  nsAutoString windowElementId;
+  nsresult rv = GetDocXulStoreKeys(uri, windowElementId);
+
+  if (NS_FAILED(rv) || windowElementId.IsEmpty()) {
+    return rv;
+  }
+
+  nsAutoString maybeConvertedValue(aValue);
+  if (aAttr == nsGkAtoms::width || aAttr == nsGkAtoms::height) {
+    // Make sure we store the <window> attributes as outer window size, see
+    // bug 1444525 & co.
+    ConvertWindowSize(this, aAttr, ConversionDirection::InnerToOuter,
+                      maybeConvertedValue);
+  }
+
+  if (!mLocalStore) {
+    mLocalStore = do_GetService("@mozilla.org/xul/xulstore;1");
+    if (NS_WARN_IF(!mLocalStore)) {
+      return NS_ERROR_NOT_INITIALIZED;
+    }
+  }
+
+  return mLocalStore->SetValue(
+      uri, windowElementId, nsDependentAtomString(aAttr), maybeConvertedValue);
+}
+
+void AppWindow::MaybeSavePersistentPositionAndSize(
+    PersistentAttributes aAttributes, Element& aRootElement,
+    const nsAString& aPersistString, bool aShouldPersist) {
+  if ((aAttributes & PersistentAttributes{PersistentAttribute::Position,
+                                          PersistentAttribute::Size})
+          .isEmpty()) {
+    return;
+  }
+
+  // get our size, position and mode to persist
+  LayoutDeviceIntRect rect;
+  if (NS_FAILED(mWindow->GetRestoredBounds(rect))) {
+    return;
+  }
+
+  // we use CSS pixels for size, but desktop pixels for position
+  CSSToLayoutDeviceScale sizeScale = UnscaledDevicePixelsPerCSSPixel();
+  DesktopToLayoutDeviceScale posScale = DevicePixelsPerDesktopPixel();
+
+  // make our position relative to our parent, if any
+  nsCOMPtr<nsIBaseWindow> parent(do_QueryReferent(mParentWindow));
+  if (parent) {
+    int32_t parentX, parentY;
+    if (NS_SUCCEEDED(parent->GetPosition(&parentX, &parentY))) {
+      rect.MoveBy(-parentX, -parentY);
+    }
+  }
+
+  nsAutoString sizeString;
+  // (only for size elements which are persisted)
+  if (aAttributes.contains(PersistentAttribute::Position)) {
+    if (aPersistString.Find(u"screenX") >= 0) {
+      sizeString.Truncate();
+      sizeString.AppendInt(NSToIntRound(rect.X() / posScale.scale));
+      aRootElement.SetAttr(nsGkAtoms::screenX, sizeString, IgnoreErrors());
+      if (aShouldPersist) {
+        Unused << SetPersistentValue(nsGkAtoms::screenX, sizeString);
+      }
+    }
+    if (aPersistString.Find(u"screenY") >= 0) {
+      sizeString.Truncate();
+      sizeString.AppendInt(NSToIntRound(rect.Y() / posScale.scale));
+      aRootElement.SetAttr(nsGkAtoms::screenY, sizeString, IgnoreErrors());
+      if (aShouldPersist) {
+        Unused << SetPersistentValue(nsGkAtoms::screenY, sizeString);
+      }
+    }
+  }
+
+  if (aAttributes.contains(PersistentAttribute::Size)) {
+    LayoutDeviceIntRect innerRect =
+        rect - GetOuterToInnerSizeDifference(mWindow);
+    if (aPersistString.Find(u"width") >= 0) {
+      sizeString.Truncate();
+      sizeString.AppendInt(NSToIntRound(innerRect.Width() / sizeScale.scale));
+      aRootElement.SetAttr(nsGkAtoms::width, sizeString, IgnoreErrors());
+      if (aShouldPersist) {
+        Unused << SetPersistentValue(nsGkAtoms::width, sizeString);
+      }
+    }
+    if (aPersistString.Find(u"height") >= 0) {
+      sizeString.Truncate();
+      sizeString.AppendInt(NSToIntRound(innerRect.Height() / sizeScale.scale));
+      aRootElement.SetAttr(nsGkAtoms::height, sizeString, IgnoreErrors());
+      if (aShouldPersist) {
+        Unused << SetPersistentValue(nsGkAtoms::height, sizeString);
+      }
+    }
+  }
+
+  Unused << MaybeSaveEarlyWindowPersistentValues(rect);
+}
+
+void AppWindow::MaybeSavePersistentMiscAttributes(
+    PersistentAttributes aAttributes, Element& aRootElement,
+    const nsAString& aPersistString, bool aShouldPersist) {
+  if (!aAttributes.contains(PersistentAttribute::Misc)) {
+    return;
+  }
+
+  nsSizeMode sizeMode = mWindow->SizeMode();
+  nsAutoString sizeString;
+  if (sizeMode != nsSizeMode_Minimized) {
+    if (sizeMode == nsSizeMode_Maximized) {
+      sizeString.Assign(SIZEMODE_MAXIMIZED);
+    } else if (sizeMode == nsSizeMode_Fullscreen) {
+      sizeString.Assign(SIZEMODE_FULLSCREEN);
+    } else {
+      sizeString.Assign(SIZEMODE_NORMAL);
+    }
+    aRootElement.SetAttr(nsGkAtoms::sizemode, sizeString, IgnoreErrors());
+    if (aShouldPersist && aPersistString.Find(u"sizemode") >= 0) {
+      Unused << SetPersistentValue(nsGkAtoms::sizemode, sizeString);
+    }
+  }
+  aRootElement.SetAttribute(u"gtktiledwindow"_ns,
+                            mWindow->IsTiled() ? u"true"_ns : u"false"_ns,
+                            IgnoreErrors());
+  if (aPersistString.Find(u"zlevel") >= 0) {
+    uint32_t zLevel;
+    nsCOMPtr<nsIWindowMediator> mediator(
+        do_GetService(NS_WINDOWMEDIATOR_CONTRACTID));
+    if (mediator) {
+      mediator->GetZLevel(this, &zLevel);
+      sizeString.Truncate();
+      sizeString.AppendInt(zLevel);
+      aRootElement.SetAttr(nsGkAtoms::zlevel, sizeString, IgnoreErrors());
+      if (aShouldPersist) {
+        Unused << SetPersistentValue(nsGkAtoms::zlevel, sizeString);
+      }
+    }
+  }
+}
+
+void AppWindow::SavePersistentAttributes(
+    const PersistentAttributes aAttributes) {
+  // can happen when the persistence timer fires at an inopportune time
+  // during window shutdown
+  if (!mDocShell) {
+    return;
+  }
+
+  nsCOMPtr<dom::Element> docShellElement = GetWindowDOMElement();
+  if (!docShellElement) {
+    return;
+  }
+
+  nsAutoString persistString;
+  docShellElement->GetAttr(nsGkAtoms::persist, persistString);
+  if (persistString.IsEmpty()) {  // quick check which sometimes helps
+    mPersistentAttributesDirty.clear();
+    return;
+  }
+
+  bool shouldPersist = mWindow->SizeMode() != nsSizeMode_Fullscreen;
+  MaybeSavePersistentPositionAndSize(aAttributes, *docShellElement,
+                                     persistString, shouldPersist);
+  MaybeSavePersistentMiscAttributes(aAttributes, *docShellElement,
+                                    persistString, shouldPersist);
+  mPersistentAttributesDirty -= aAttributes;
+}
+
+NS_IMETHODIMP AppWindow::GetWindowDOMWindow(mozIDOMWindowProxy** aDOMWindow) {
+  NS_ENSURE_STATE(mDocShell);
+
+  if (!mDOMWindow) mDOMWindow = mDocShell->GetWindow();
+  NS_ENSURE_TRUE(mDOMWindow, NS_ERROR_FAILURE);
+
+  *aDOMWindow = mDOMWindow;
+  NS_ADDREF(*aDOMWindow);
+  return NS_OK;
+}
+
+dom::Element* AppWindow::GetWindowDOMElement() const {
+  NS_ENSURE_TRUE(mDocShell, nullptr);
+
+  nsCOMPtr<nsIContentViewer> cv;
+  mDocShell->GetContentViewer(getter_AddRefs(cv));
+  NS_ENSURE_TRUE(cv, nullptr);
+
+  const dom::Document* document = cv->GetDocument();
+  NS_ENSURE_TRUE(document, nullptr);
+
+  return document->GetRootElement();
+}
+
+nsresult AppWindow::ContentShellAdded(nsIDocShellTreeItem* aContentShell,
+                                      bool aPrimary) {
+  // Set the default content tree owner
+  if (aPrimary) {
+    NS_ENSURE_SUCCESS(EnsurePrimaryContentTreeOwner(), NS_ERROR_FAILURE);
+    aContentShell->SetTreeOwner(mPrimaryContentTreeOwner);
+    mPrimaryContentShell = aContentShell;
+    mPrimaryBrowserParent = nullptr;
+  } else {
+    NS_ENSURE_SUCCESS(EnsureContentTreeOwner(), NS_ERROR_FAILURE);
+    aContentShell->SetTreeOwner(mContentTreeOwner);
+    if (mPrimaryContentShell == aContentShell) mPrimaryContentShell = nullptr;
+  }
+
+  return NS_OK;
+}
+
+nsresult AppWindow::ContentShellRemoved(nsIDocShellTreeItem* aContentShell) {
+  if (mPrimaryContentShell == aContentShell) {
+    mPrimaryContentShell = nullptr;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::GetPrimaryContentSize(int32_t* aWidth, int32_t* aHeight) {
+  if (mPrimaryBrowserParent) {
+    return GetPrimaryRemoteTabSize(aWidth, aHeight);
+  }
+  if (mPrimaryContentShell) {
+    return GetPrimaryContentShellSize(aWidth, aHeight);
+  }
+  return NS_ERROR_UNEXPECTED;
+}
+
+nsresult AppWindow::GetPrimaryRemoteTabSize(int32_t* aWidth, int32_t* aHeight) {
+  BrowserHost* host = BrowserHost::GetFrom(mPrimaryBrowserParent.get());
+  // Need strong ref, since Client* can run script.
+  RefPtr<dom::Element> element = host->GetOwnerElement();
+  NS_ENSURE_STATE(element);
+
+  CSSIntSize size(element->ClientWidth(), element->ClientHeight());
+  LayoutDeviceIntSize sizeDev =
+      RoundedToInt(size * UnscaledDevicePixelsPerCSSPixel());
+  if (aWidth) {
+    *aWidth = sizeDev.width;
+  }
+  if (aHeight) {
+    *aHeight = sizeDev.height;
+  }
+  return NS_OK;
+}
+
+nsresult AppWindow::GetPrimaryContentShellSize(int32_t* aWidth,
+                                               int32_t* aHeight) {
+  NS_ENSURE_STATE(mPrimaryContentShell);
+
+  nsCOMPtr<nsIBaseWindow> shellWindow(do_QueryInterface(mPrimaryContentShell));
+  NS_ENSURE_STATE(shellWindow);
+
+  LayoutDeviceIntSize sizeDev = shellWindow->GetSize();
+  if (aWidth) {
+    *aWidth = sizeDev.width;
+  }
+  if (aHeight) {
+    *aHeight = sizeDev.height;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::SetPrimaryContentSize(int32_t aWidth, int32_t aHeight) {
+  if (mPrimaryBrowserParent) {
+    return SetPrimaryRemoteTabSize(aWidth, aHeight);
+  }
+  if (mPrimaryContentShell) {
+    return SizeShellTo(mPrimaryContentShell, aWidth, aHeight);
+  }
+  return NS_ERROR_UNEXPECTED;
+}
+
+nsresult AppWindow::SetPrimaryRemoteTabSize(int32_t aWidth, int32_t aHeight) {
+  int32_t shellWidth, shellHeight;
+  GetPrimaryRemoteTabSize(&shellWidth, &shellHeight);
+  SizeShellToWithLimit(aWidth, aHeight, shellWidth, shellHeight);
+  return NS_OK;
+}
+
+nsresult AppWindow::GetRootShellSize(int32_t* aWidth, int32_t* aHeight) {
+  NS_ENSURE_TRUE(mDocShell, NS_ERROR_FAILURE);
+  return mDocShell->GetSize(aWidth, aHeight);
+}
+
+nsresult AppWindow::SetRootShellSize(int32_t aWidth, int32_t aHeight) {
+  return SizeShellTo(mDocShell, aWidth, aHeight);
+}
+
+NS_IMETHODIMP AppWindow::SizeShellTo(nsIDocShellTreeItem* aShellItem,
+                                     int32_t aCX, int32_t aCY) {
+  MOZ_ASSERT(aShellItem == mDocShell || aShellItem == mPrimaryContentShell);
+  if (aShellItem == mDocShell) {
+    auto newSize =
+        LayoutDeviceIntSize(aCX, aCY) + GetOuterToInnerSizeDifference(mWindow);
+    SetSize(newSize.width, newSize.height, /* aRepaint = */ true);
+    mDominantClientSize = true;
+    return NS_OK;
+  }
+
+  // XXXTAB This is wrong, we should actually reflow based on the passed in
+  // shell.  For now we are hacking and doing delta sizing.  This is bad
+  // because it assumes all size we add will go to the shell which probably
+  // won't happen.
+  nsCOMPtr<nsIBaseWindow> shellAsWin(do_QueryInterface(aShellItem));
+  NS_ENSURE_TRUE(shellAsWin, NS_ERROR_FAILURE);
+
+  int32_t width = 0;
+  int32_t height = 0;
+  shellAsWin->GetSize(&width, &height);
+
+  SizeShellToWithLimit(aCX, aCY, width, height);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::ExitModalLoop(nsresult aStatus) {
+  if (mContinueModalLoop) EnableParent(true);
+  mContinueModalLoop = false;
+  mModalStatus = aStatus;
+  return NS_OK;
+}
+
+// top-level function to create a new window
+NS_IMETHODIMP AppWindow::CreateNewWindow(int32_t aChromeFlags,
+                                         nsIOpenWindowInfo* aOpenWindowInfo,
+                                         nsIAppWindow** _retval) {
+  NS_ENSURE_ARG_POINTER(_retval);
+
+  if (aChromeFlags & nsIWebBrowserChrome::CHROME_OPENAS_CHROME) {
+    MOZ_RELEASE_ASSERT(
+        !aOpenWindowInfo,
+        "Unexpected nsOpenWindowInfo when creating a new chrome window");
+    return CreateNewChromeWindow(aChromeFlags, _retval);
+  }
+
+  return CreateNewContentWindow(aChromeFlags, aOpenWindowInfo, _retval);
+}
+
+NS_IMETHODIMP AppWindow::CreateNewChromeWindow(int32_t aChromeFlags,
+                                               nsIAppWindow** _retval) {
+  nsCOMPtr<nsIAppShellService> appShell(
+      do_GetService(NS_APPSHELLSERVICE_CONTRACTID));
+  NS_ENSURE_TRUE(appShell, NS_ERROR_FAILURE);
+
+  // Just do a normal create of a window and return.
+  nsCOMPtr<nsIAppWindow> newWindow;
+  appShell->CreateTopLevelWindow(
+      this, nullptr, aChromeFlags, nsIAppShellService::SIZE_TO_CONTENT,
+      nsIAppShellService::SIZE_TO_CONTENT, getter_AddRefs(newWindow));
+
+  NS_ENSURE_TRUE(newWindow, NS_ERROR_FAILURE);
+
+  newWindow.forget(_retval);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::CreateNewContentWindow(
+    int32_t aChromeFlags, nsIOpenWindowInfo* aOpenWindowInfo,
+    nsIAppWindow** _retval) {
+  nsCOMPtr<nsIAppShellService> appShell(
+      do_GetService(NS_APPSHELLSERVICE_CONTRACTID));
+  NS_ENSURE_TRUE(appShell, NS_ERROR_FAILURE);
+
+  // We need to create a new top level window and then enter a nested
+  // loop. Eventually the new window will be told that it has loaded,
+  // at which time we know it is safe to spin out of the nested loop
+  // and allow the opening code to proceed.
+
+  nsCOMPtr<nsIURI> uri;
+  nsAutoCString urlStr;
+  urlStr.AssignLiteral(BROWSER_CHROME_URL_QUOTED);
+
+  nsCOMPtr<nsIIOService> service(do_GetService(NS_IOSERVICE_CONTRACTID));
+  if (service) {
+    service->NewURI(urlStr, nullptr, nullptr, getter_AddRefs(uri));
+  }
+  NS_ENSURE_TRUE(uri, NS_ERROR_FAILURE);
+
+  // We need to create a chrome window to contain the content window we're about
+  // to pass back. The subject principal needs to be system while we're creating
+  // it to make things work right, so force a system caller. See bug 799348
+  // comment 13 for a description of what happens when we don't.
+  nsCOMPtr<nsIAppWindow> newWindow;
+  {
+    AutoNoJSAPI nojsapi;
+    appShell->CreateTopLevelWindow(this, uri, aChromeFlags, 615, 480,
+                                   getter_AddRefs(newWindow));
+    NS_ENSURE_TRUE(newWindow, NS_ERROR_FAILURE);
+  }
+
+  AppWindow* appWin =
+      static_cast<AppWindow*>(static_cast<nsIAppWindow*>(newWindow));
+
+  // Specify which flags should be used by browser.xhtml to create the initial
+  // content browser window.
+  appWin->mInitialOpenWindowInfo = aOpenWindowInfo;
+
+  // Specify that we want the window to remain locked until the chrome has
+  // loaded.
+  appWin->LockUntilChromeLoad();
+
+  {
+    AutoNoJSAPI nojsapi;
+    SpinEventLoopUntil("AppWindow::CreateNewContentWindow"_ns,
+                       [&]() { return !appWin->IsLocked(); });
+  }
+
+  NS_ENSURE_STATE(appWin->mPrimaryContentShell ||
+                  appWin->mPrimaryBrowserParent);
+  MOZ_ASSERT_IF(appWin->mPrimaryContentShell,
+                !aOpenWindowInfo->GetNextRemoteBrowser());
+
+  newWindow.forget(_retval);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::GetHasPrimaryContent(bool* aResult) {
+  *aResult = mPrimaryBrowserParent || mPrimaryContentShell;
+  return NS_OK;
+}
+
+void AppWindow::EnableParent(bool aEnable) {
+  nsCOMPtr<nsIBaseWindow> parentWindow;
+  nsCOMPtr<nsIWidget> parentWidget;
+
+  parentWindow = do_QueryReferent(mParentWindow);
+  if (parentWindow) parentWindow->GetMainWidget(getter_AddRefs(parentWidget));
+  if (parentWidget) parentWidget->Enable(aEnable);
+}
+
+// Constrain the window to its proper z-level
+bool AppWindow::ConstrainToZLevel(bool aImmediate, nsWindowZ* aPlacement,
+                                  nsIWidget* aReqBelow,
+                                  nsIWidget** aActualBelow) {
+#if 0
+  /* Do we have a parent window? This means our z-order is already constrained,
+     since we're a dependent window. Our window list isn't hierarchical,
+     so we can't properly calculate placement for such a window.
+     Should we just abort? */
+  nsCOMPtr<nsIBaseWindow> parentWindow = do_QueryReferent(mParentWindow);
+  if (parentWindow)
+    return false;
+#endif
+
+  nsCOMPtr<nsIWindowMediator> mediator(
+      do_GetService(NS_WINDOWMEDIATOR_CONTRACTID));
+  if (!mediator) return false;
+
+  bool altered;
+  uint32_t position, newPosition, zLevel;
+  nsIAppWindow* us = this;
+
+  altered = false;
+  mediator->GetZLevel(this, &zLevel);
+
+  // translate from WidgetGUIEvent to nsIWindowMediator constants
+  position = nsIWindowMediator::zLevelTop;
+  if (*aPlacement == nsWindowZBottom || zLevel == nsIAppWindow::lowestZ)
+    position = nsIWindowMediator::zLevelBottom;
+  else if (*aPlacement == nsWindowZRelative)
+    position = nsIWindowMediator::zLevelBelow;
+
+  if (NS_SUCCEEDED(mediator->CalculateZPosition(
+          us, position, aReqBelow, &newPosition, aActualBelow, &altered))) {
+    /* If we were asked to move to the top but constrained to remain
+       below one of our other windows, first move all windows in that
+       window's layer and above to the top. This allows the user to
+       click a window which can't be topmost and still bring mozilla
+       to the foreground. */
+    if (altered &&
+        (position == nsIWindowMediator::zLevelTop ||
+         (position == nsIWindowMediator::zLevelBelow && aReqBelow == 0)))
+      PlaceWindowLayersBehind(zLevel + 1, nsIAppWindow::highestZ, 0);
+
+    if (*aPlacement != nsWindowZBottom &&
+        position == nsIWindowMediator::zLevelBottom)
+      altered = true;
+    if (altered || aImmediate) {
+      if (newPosition == nsIWindowMediator::zLevelTop)
+        *aPlacement = nsWindowZTop;
+      else if (newPosition == nsIWindowMediator::zLevelBottom)
+        *aPlacement = nsWindowZBottom;
+      else
+        *aPlacement = nsWindowZRelative;
+
+      if (aImmediate) {
+        nsCOMPtr<nsIBaseWindow> ourBase = do_QueryObject(this);
+        if (ourBase) {
+          nsCOMPtr<nsIWidget> ourWidget;
+          ourBase->GetMainWidget(getter_AddRefs(ourWidget));
+          ourWidget->PlaceBehind(*aPlacement == nsWindowZBottom
+                                     ? eZPlacementBottom
+                                     : eZPlacementBelow,
+                                 *aActualBelow, false);
+        }
+      }
+    }
+
+    /* CalculateZPosition can tell us to be below nothing, because it tries
+       not to change something it doesn't recognize. A request to verify
+       being below an unrecognized window, then, is treated as a request
+       to come to the top (below null) */
+    nsCOMPtr<nsIAppWindow> windowAbove;
+    if (newPosition == nsIWindowMediator::zLevelBelow && *aActualBelow) {
+      windowAbove = (*aActualBelow)->GetWidgetListener()->GetAppWindow();
+    }
+
+    mediator->SetZPosition(us, newPosition, windowAbove);
+  }
+
+  return altered;
+}
+
+/* Re-z-position all windows in the layers from aLowLevel to aHighLevel,
+   inclusive, to be behind aBehind. aBehind of null means on top.
+   Note this method actually does nothing to our relative window positions.
+   (And therefore there's no need to inform WindowMediator we're moving
+   things, because we aren't.) This method is useful for, say, moving
+   a range of layers of our own windows relative to windows belonging to
+   external applications.
+*/
+void AppWindow::PlaceWindowLayersBehind(uint32_t aLowLevel, uint32_t aHighLevel,
+                                        nsIAppWindow* aBehind) {
+  // step through windows in z-order from top to bottommost window
+
+  nsCOMPtr<nsIWindowMediator> mediator(
+      do_GetService(NS_WINDOWMEDIATOR_CONTRACTID));
+  if (!mediator) return;
+
+  nsCOMPtr<nsISimpleEnumerator> windowEnumerator;
+  mediator->GetZOrderAppWindowEnumerator(0, true,
+                                         getter_AddRefs(windowEnumerator));
+  if (!windowEnumerator) return;
+
+  // each window will be moved behind previousHighWidget, itself
+  // a moving target. initialize it.
+  nsCOMPtr<nsIWidget> previousHighWidget;
+  if (aBehind) {
+    nsCOMPtr<nsIBaseWindow> highBase(do_QueryInterface(aBehind));
+    if (highBase) highBase->GetMainWidget(getter_AddRefs(previousHighWidget));
+  }
+
+  // get next lower window
+  bool more;
+  while (NS_SUCCEEDED(windowEnumerator->HasMoreElements(&more)) && more) {
+    uint32_t nextZ;  // z-level of nextWindow
+    nsCOMPtr<nsISupports> nextWindow;
+    windowEnumerator->GetNext(getter_AddRefs(nextWindow));
+    nsCOMPtr<nsIAppWindow> nextAppWindow(do_QueryInterface(nextWindow));
+    nextAppWindow->GetZLevel(&nextZ);
+    if (nextZ < aLowLevel)
+      break;  // we've processed all windows through aLowLevel
+
+    // move it just below its next higher window
+    nsCOMPtr<nsIBaseWindow> nextBase(do_QueryInterface(nextAppWindow));
+    if (nextBase) {
+      nsCOMPtr<nsIWidget> nextWidget;
+      nextBase->GetMainWidget(getter_AddRefs(nextWidget));
+      if (nextZ <= aHighLevel)
+        nextWidget->PlaceBehind(eZPlacementBelow, previousHighWidget, false);
+      previousHighWidget = nextWidget;
+    }
+  }
+}
+
+void AppWindow::SetContentScrollbarVisibility(bool aVisible) {
+  nsCOMPtr<nsPIDOMWindowOuter> contentWin(
+      do_GetInterface(mPrimaryContentShell));
+  if (!contentWin) {
+    return;
+  }
+
+  nsContentUtils::SetScrollbarsVisibility(contentWin->GetDocShell(), aVisible);
+}
+
+void AppWindow::ApplyChromeFlags() {
+  nsCOMPtr<dom::Element> window = GetWindowDOMElement();
+  if (!window) {
+    return;
+  }
+
+  if (mChromeLoaded) {
+    // The two calls in this block don't need to happen early because they
+    // don't cause a global restyle on the document.  Not only that, but the
+    // scrollbar stuff needs a content area to toggle the scrollbars on anyway.
+    // So just don't do these until mChromeLoaded is true.
+
+    // Scrollbars have their own special treatment.
+    SetContentScrollbarVisibility(mChromeFlags &
+                                  nsIWebBrowserChrome::CHROME_SCROLLBARS);
+  }
+
+  /* the other flags are handled together. we have style rules
+     in navigator.css that trigger visibility based on
+     the 'chromehidden' attribute of the <window> tag. */
+  nsAutoString newvalue;
+
+  if (!(mChromeFlags & nsIWebBrowserChrome::CHROME_MENUBAR))
+    newvalue.AppendLiteral("menubar ");
+
+  if (!(mChromeFlags & nsIWebBrowserChrome::CHROME_TOOLBAR))
+    newvalue.AppendLiteral("toolbar ");
+
+  if (!(mChromeFlags & nsIWebBrowserChrome::CHROME_LOCATIONBAR))
+    newvalue.AppendLiteral("location ");
+
+  if (!(mChromeFlags & nsIWebBrowserChrome::CHROME_PERSONAL_TOOLBAR))
+    newvalue.AppendLiteral("directories ");
+
+  if (!(mChromeFlags & nsIWebBrowserChrome::CHROME_STATUSBAR))
+    newvalue.AppendLiteral("status ");
+
+  if (!(mChromeFlags & nsIWebBrowserChrome::CHROME_EXTRA))
+    newvalue.AppendLiteral("extrachrome ");
+
+  // Note that if we're not actually changing the value this will be a no-op,
+  // so no need to compare to the old value.
+  IgnoredErrorResult rv;
+  window->SetAttribute(u"chromehidden"_ns, newvalue, rv);
+}
+
+NS_IMETHODIMP
+AppWindow::BeforeStartLayout() {
+  ApplyChromeFlags();
+  // Ordering here is important, loading width/height values in
+  // LoadPersistentWindowState() depends on the chromemargin attribute (since
+  // we need to translate outer to inner sizes).
+  SyncAttributesToWidget();
+  LoadPersistentWindowState();
+  if (mWindow) {
+    SizeShell();
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::LockAspectRatio(bool aShouldLock) {
+  mWindow->LockAspectRatio(aShouldLock);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::NeedFastSnaphot() {
+  MOZ_ASSERT(mWindow);
+  if (!mWindow) {
+    return NS_ERROR_FAILURE;
+  }
+  mWindow->SetNeedFastSnaphot();
+  return NS_OK;
+}
+
+void AppWindow::LoadPersistentWindowState() {
+  nsCOMPtr<dom::Element> docShellElement = GetWindowDOMElement();
+  if (!docShellElement) {
+    return;
+  }
+
+  // Check if the window wants to persist anything.
+  nsAutoString persist;
+  docShellElement->GetAttr(nsGkAtoms::persist, persist);
+  if (persist.IsEmpty()) {
+    return;
+  }
+
+  auto loadValue = [&](nsAtom* aAttr) {
+    nsDependentAtomString attrString(aAttr);
+    if (persist.Find(attrString) >= 0) {
+      nsAutoString value;
+      nsresult rv = GetPersistentValue(aAttr, value);
+      NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Failed to get persistent state.");
+      if (NS_SUCCEEDED(rv) && !value.IsEmpty()) {
+        docShellElement->SetAttr(aAttr, value, IgnoreErrors());
+      }
+    }
+  };
+
+  loadValue(nsGkAtoms::screenX);
+  loadValue(nsGkAtoms::screenY);
+  loadValue(nsGkAtoms::width);
+  loadValue(nsGkAtoms::height);
+  loadValue(nsGkAtoms::sizemode);
+}
+
+void AppWindow::IntrinsicallySizeShell(const CSSIntSize& aWindowDiff,
+                                       int32_t& aSpecWidth,
+                                       int32_t& aSpecHeight) {
+  nsCOMPtr<nsIContentViewer> cv;
+  mDocShell->GetContentViewer(getter_AddRefs(cv));
+  if (!cv) {
+    return;
+  }
+  RefPtr<nsDocShell> docShell = mDocShell;
+
+  CSSIntCoord maxWidth = 0;
+  CSSIntCoord maxHeight = 0;
+  CSSIntCoord prefWidth = 0;
+  if (RefPtr element = GetWindowDOMElement()) {
+    nsAutoString prefWidthAttr;
+    if (element->GetAttr(nsGkAtoms::prefwidth, prefWidthAttr)) {
+      // TODO: Make this more generic perhaps?
+      if (prefWidthAttr.EqualsLiteral("min-width")) {
+        if (auto* f = element->GetPrimaryFrame(FlushType::Frames)) {
+          const auto& coord = f->StylePosition()->mMinWidth;
+          if (coord.ConvertsToLength()) {
+            prefWidth = CSSPixel::FromAppUnitsRounded(coord.ToLength());
+          }
+        }
+      }
+    }
+  }
+
+  Maybe<CSSIntSize> size = cv->GetContentSize(maxWidth, maxHeight, prefWidth);
+  if (!size) {
+    return;
+  }
+  nsPresContext* pc = cv->GetPresContext();
+  MOZ_ASSERT(pc, "Should have pres context");
+
+  int32_t width = pc->CSSPixelsToDevPixels(size->width);
+  int32_t height = pc->CSSPixelsToDevPixels(size->height);
+  SizeShellTo(docShell, width, height);
+
+  // Update specified size for the final LoadPositionFromXUL call.
+  aSpecWidth = size->width + aWindowDiff.width;
+  aSpecHeight = size->height + aWindowDiff.height;
+}
+
+void AppWindow::SizeShell() {
+  AutoRestore<bool> sizingShellFromXUL(mSizingShellFromXUL);
+  mSizingShellFromXUL = true;
+
+  int32_t specWidth = -1, specHeight = -1;
+  bool gotSize = false;
+
+  nsAutoString windowType;
+  if (nsCOMPtr<dom::Element> windowElement = GetWindowDOMElement()) {
+    windowElement->GetAttr(nsGkAtoms::windowtype, windowType);
+  }
+
+  const CSSIntSize windowDiff = GetOuterToInnerSizeDifferenceInCSSPixels(
+      mWindow, UnscaledDevicePixelsPerCSSPixel());
+
+  // If we're using fingerprint resistance, we're going to resize the window
+  // once we have primary content.
+  if (nsContentUtils::ShouldResistFingerprinting(
+          "if RFP is enabled we want to round the dimensions of the new"
+          "new pop up window regardless of their origin") &&
+      windowType.EqualsLiteral("navigator:browser")) {
+    // Once we've got primary content, force dimensions.
+    if (mPrimaryContentShell || mPrimaryBrowserParent) {
+      ForceRoundedDimensions();
+    }
+    // Always avoid setting size/sizemode on this window.
+    mIgnoreXULSize = true;
+    mIgnoreXULSizeMode = true;
+  } else if (!mIgnoreXULSize) {
+    gotSize = LoadSizeFromXUL(specWidth, specHeight);
+    specWidth += windowDiff.width;
+    specHeight += windowDiff.height;
+  }
+
+  bool positionSet = !mIgnoreXULPosition;
+  nsCOMPtr<nsIAppWindow> parentWindow(do_QueryReferent(mParentWindow));
+#if defined(XP_UNIX) && !defined(XP_MACOSX)
+  // don't override WM placement on unix for independent, top-level windows
+  // (however, we think the benefits of intelligent dependent window placement
+  // trump that override.)
+  if (!parentWindow) positionSet = false;
+#endif
+  if (positionSet) {
+    // We have to do this before sizing the window, because sizing depends
+    // on the resolution of the screen we're on. But positioning needs to
+    // know the size so that it can constrain to screen bounds.... as an
+    // initial guess here, we'll use the specified size (if any).
+    positionSet = LoadPositionFromXUL(specWidth, specHeight);
+  }
+
+  if (gotSize) {
+    SetSpecifiedSize(specWidth, specHeight);
+  }
+
+  // If LoadSizeFromXUL set the size, mIntrinsicallySized will be false.
+  if (mIntrinsicallySized) {
+    IntrinsicallySizeShell(windowDiff, specWidth, specHeight);
+  }
+
+  // Now that we have set the window's final size, we can re-do its
+  // positioning so that it is properly constrained to the screen.
+  if (positionSet) {
+    LoadPositionFromXUL(specWidth, specHeight);
+  }
+
+  UpdateWindowStateFromMiscXULAttributes();
+
+  if (mChromeLoaded && mCenterAfterLoad && !positionSet &&
+      mWindow->SizeMode() == nsSizeMode_Normal) {
+    Center(parentWindow, parentWindow ? false : true, false);
+  }
+}
+
+NS_IMETHODIMP AppWindow::GetXULBrowserWindow(
+    nsIXULBrowserWindow** aXULBrowserWindow) {
+  NS_IF_ADDREF(*aXULBrowserWindow = mXULBrowserWindow);
+  return NS_OK;
+}
+
+NS_IMETHODIMP AppWindow::SetXULBrowserWindow(
+    nsIXULBrowserWindow* aXULBrowserWindow) {
+  mXULBrowserWindow = aXULBrowserWindow;
+  return NS_OK;
+}
+
+// Given the dimensions of some content area held within this XUL window, and
+// assuming that that content area will change its dimensions in linear
+// proportion to the dimensions of this XUL window, changes the size of the XUL
+// window so that the content area reaches a particular size.
+void AppWindow::SizeShellToWithLimit(int32_t aDesiredWidth,
+                                     int32_t aDesiredHeight,
+                                     int32_t shellItemWidth,
+                                     int32_t shellItemHeight) {
+  int32_t widthDelta = aDesiredWidth - shellItemWidth;
+  int32_t heightDelta = aDesiredHeight - shellItemHeight;
+
+  int32_t winWidth = 0;
+  int32_t winHeight = 0;
+
+  GetSize(&winWidth, &winHeight);
+  // There's no point in trying to make the window smaller than the
+  // desired content area size --- that's not likely to work. This whole
+  // function assumes that the outer docshell is adding some constant
+  // "border" chrome to the content area.
+  winWidth = std::max(winWidth + widthDelta, aDesiredWidth);
+  winHeight = std::max(winHeight + heightDelta, aDesiredHeight);
+
+  // Note: Because of the asynchronous resizing on Linux we have to call
+  // SetSize even when the size doesn't appear to change. A previous call that
+  // has yet to complete can still change the size. We want the latest call to
+  // define the final size.
+  SetSize(winWidth, winHeight, true);
+  mDominantClientSize = true;
+}
+
+nsresult AppWindow::GetTabCount(uint32_t* aResult) {
+  if (mXULBrowserWindow) {
+    return mXULBrowserWindow->GetTabCount(aResult);
+  }
+
+  *aResult = 0;
+  return NS_OK;
+}
+
+nsresult AppWindow::GetInitialOpenWindowInfo(
+    nsIOpenWindowInfo** aOpenWindowInfo) {
+  NS_ENSURE_ARG_POINTER(aOpenWindowInfo);
+  *aOpenWindowInfo = do_AddRef(mInitialOpenWindowInfo).take();
+  return NS_OK;
+}
+
+PresShell* AppWindow::GetPresShell() {
+  if (!mDocShell) {
+    return nullptr;
+  }
+  return mDocShell->GetPresShell();
+}
+
+bool AppWindow::WindowMoved(nsIWidget* aWidget, int32_t x, int32_t y) {
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm) {
+    nsCOMPtr<nsPIDOMWindowOuter> window =
+        mDocShell ? mDocShell->GetWindow() : nullptr;
+    pm->AdjustPopupsOnWindowChange(window);
+  }
+
+  // Notify all tabs that the widget moved.
+  if (mDocShell && mDocShell->GetWindow()) {
+    nsCOMPtr<EventTarget> eventTarget =
+        mDocShell->GetWindow()->GetTopWindowRoot();
+    nsContentUtils::DispatchChromeEvent(
+        mDocShell->GetDocument(), eventTarget, u"MozUpdateWindowPos"_ns,
+        CanBubble::eNo, Cancelable::eNo, nullptr);
+  }
+
+  // Persist position, but not immediately, in case this OS is firing
+  // repeated move events as the user drags the window
+  PersistentAttributesDirty(PersistentAttribute::Position, Async);
+  return false;
+}
+
+bool AppWindow::WindowResized(nsIWidget* aWidget, int32_t aWidth,
+                              int32_t aHeight) {
+  mDominantClientSize = false;
+  if (mDocShell) {
+    mDocShell->SetPositionAndSize(0, 0, aWidth, aHeight, 0);
+  }
+  // Persist size, but not immediately, in case this OS is firing
+  // repeated size events as the user drags the sizing handle
+  if (!IsLocked()) {
+    PersistentAttributesDirty(AllPersistentAttributes(), Async);
+  }
+  // Check if we need to continue a fullscreen change.
+  switch (mFullscreenChangeState) {
+    case FullscreenChangeState::WillChange:
+      mFullscreenChangeState = FullscreenChangeState::WidgetResized;
+      break;
+    case FullscreenChangeState::WidgetEnteredFullscreen:
+      FinishFullscreenChange(true);
+      break;
+    case FullscreenChangeState::WidgetExitedFullscreen:
+      FinishFullscreenChange(false);
+      break;
+    case FullscreenChangeState::WidgetResized:
+    case FullscreenChangeState::NotChanging:
+      break;
+  }
+  return true;
+}
+
+bool AppWindow::RequestWindowClose(nsIWidget* aWidget) {
+  // Maintain a reference to this as it is about to get destroyed.
+  nsCOMPtr<nsIAppWindow> appWindow(this);
+
+  nsCOMPtr<nsPIDOMWindowOuter> window(mDocShell ? mDocShell->GetWindow()
+                                                : nullptr);
+  nsCOMPtr<EventTarget> eventTarget = do_QueryInterface(window);
+
+  RefPtr<PresShell> presShell = mDocShell->GetPresShell();
+  if (!presShell) {
+    mozilla::DebugOnly<bool> dying;
+    MOZ_ASSERT(NS_SUCCEEDED(mDocShell->IsBeingDestroyed(&dying)) && dying,
+               "No presShell, but window is not being destroyed");
+  } else if (eventTarget) {
+    RefPtr<nsPresContext> presContext = presShell->GetPresContext();
+
+    nsEventStatus status = nsEventStatus_eIgnore;
+    WidgetMouseEvent event(true, eClose, nullptr, WidgetMouseEvent::eReal);
+    if (NS_SUCCEEDED(EventDispatcher::Dispatch(eventTarget, presContext, &event,
+                                               nullptr, &status)) &&
+        status == nsEventStatus_eConsumeNoDefault)
+      return false;
+  }
+
+  Destroy();
+  return false;
+}
+
+void AppWindow::SizeModeChanged(nsSizeMode aSizeMode) {
+  const bool wasWidgetInFullscreen = mIsWidgetInFullscreen;
+  // Fullscreen and minimized states are usually compatible, and the widget
+  // typically returns to fullscreen after restoration. By not updating the
+  // widget's fullscreen state while it is minimized, we can avoid unnecessary
+  // fullscreen exits, such as those encountered in bug 1823284.
+  if (aSizeMode != nsSizeMode_Minimized) {
+    mIsWidgetInFullscreen = aSizeMode == nsSizeMode_Fullscreen;
+  }
+
+  const bool fullscreenChanged = wasWidgetInFullscreen != mIsWidgetInFullscreen;
+  if (fullscreenChanged) {
+    FullscreenWillChange(mIsWidgetInFullscreen);
+  }
+
+  // An alwaysRaised (or higher) window will hide any newly opened normal
+  // browser windows, so here we just drop a raised window to the normal
+  // zlevel if it's maximized. We make no provision for automatically
+  // re-raising it when restored.
+  if (aSizeMode == nsSizeMode_Maximized || aSizeMode == nsSizeMode_Fullscreen) {
+    uint32_t zLevel;
+    GetZLevel(&zLevel);
+    if (zLevel > nsIAppWindow::normalZ) {
+      SetZLevel(nsIAppWindow::normalZ);
+    }
+  }
+
+  RecomputeBrowsingContextVisibility();
+
+  PersistentAttributesDirty(PersistentAttribute::Misc, Sync);
+  nsCOMPtr<nsPIDOMWindowOuter> ourWindow =
+      mDocShell ? mDocShell->GetWindow() : nullptr;
+  if (ourWindow) {
+    // Always fire a user-defined sizemodechange event on the window
+    ourWindow->DispatchCustomEvent(u"sizemodechange"_ns);
+  }
+
+  if (PresShell* presShell = GetPresShell()) {
+    presShell->GetPresContext()->SizeModeChanged(aSizeMode);
+  }
+
+  if (fullscreenChanged) {
+    FullscreenChanged(mIsWidgetInFullscreen);
+  }
+
+  // Note the current implementation of SetSizeMode just stores
+  // the new state; it doesn't actually resize. So here we store
+  // the state and pass the event on to the OS. The day is coming
+  // when we'll handle the event here, and the return result will
+  // then need to be different.
+}
+
+void AppWindow::UIResolutionChanged() {
+  nsCOMPtr<nsPIDOMWindowOuter> ourWindow =
+      mDocShell ? mDocShell->GetWindow() : nullptr;
+  if (ourWindow) {
+    ourWindow->DispatchCustomEvent(u"resolutionchange"_ns,
+                                   ChromeOnlyDispatch::eYes);
+  }
+}
+
+void AppWindow::FullscreenWillChange(bool aInFullscreen) {
+  if (mDocShell) {
+    if (nsCOMPtr<nsPIDOMWindowOuter> ourWindow = mDocShell->GetWindow()) {
+      ourWindow->FullscreenWillChange(aInFullscreen);
+    }
+  }
+  MOZ_ASSERT(mFullscreenChangeState == FullscreenChangeState::NotChanging);
+
+  int32_t winWidth = 0;
+  int32_t winHeight = 0;
+  GetSize(&winWidth, &winHeight);
+
+  int32_t screenWidth = 0;
+  int32_t screenHeight = 0;
+  GetAvailScreenSize(&screenWidth, &screenHeight);
+
+  // Check if the window is already at the expected dimensions. If it is, set
+  // the fullscreen change state to WidgetResized to avoid waiting for a resize
+  // event. On macOS, a fullscreen window could be slightly higher than
+  // available screen size because of the OS menu bar isn't yet hidden.
+  mFullscreenChangeState =
+      (aInFullscreen == (winWidth == screenWidth && winHeight >= screenHeight))
+          ? FullscreenChangeState::WidgetResized
+          : FullscreenChangeState::WillChange;
+}
+
+void AppWindow::FullscreenChanged(bool aInFullscreen) {
+  if (mFullscreenChangeState == FullscreenChangeState::WidgetResized) {
+    FinishFullscreenChange(aInFullscreen);
+  } else {
+    NS_WARNING_ASSERTION(
+        mFullscreenChangeState == FullscreenChangeState::WillChange,
+        "Unexpected fullscreen change state");
+    FullscreenChangeState newState =
+        aInFullscreen ? FullscreenChangeState::WidgetEnteredFullscreen
+                      : FullscreenChangeState::WidgetExitedFullscreen;
+    mFullscreenChangeState = newState;
+    nsCOMPtr<nsIAppWindow> kungFuDeathGrip(this);
+    // Wait for resize for a small amount of time.
+    // 80ms is actually picked arbitrarily. But it shouldn't be too large
+    // in case the widget resize is not going to happen at all, which can
+    // be the case for some Linux window managers and possibly Android.
+    NS_DelayedDispatchToCurrentThread(
+        NS_NewRunnableFunction(
+            "AppWindow::FullscreenChanged",
+            [this, kungFuDeathGrip, newState, aInFullscreen]() {
+              if (mFullscreenChangeState == newState) {
+                FinishFullscreenChange(aInFullscreen);
+              }
+            }),
+        80);
+  }
+}
+
+void AppWindow::FinishFullscreenChange(bool aInFullscreen) {
+  mFullscreenChangeState = FullscreenChangeState::NotChanging;
+  if (mDocShell) {
+    if (nsCOMPtr<nsPIDOMWindowOuter> ourWindow = mDocShell->GetWindow()) {
+      ourWindow->FinishFullscreenChange(aInFullscreen);
+    }
+  }
+}
+
+void AppWindow::MacFullscreenMenubarOverlapChanged(
+    mozilla::DesktopCoord aOverlapAmount) {
+  if (mDocShell) {
+    if (nsCOMPtr<nsPIDOMWindowOuter> ourWindow = mDocShell->GetWindow()) {
+      ourWindow->MacFullscreenMenubarOverlapChanged(aOverlapAmount);
+    }
+  }
+}
+
+void AppWindow::RecomputeBrowsingContextVisibility() {
+  if (!mDocShell) {
+    return;
+  }
+  RefPtr bc = mDocShell->GetBrowsingContext();
+  if (!bc) {
+    return;
+  }
+  bc->Canonical()->RecomputeAppWindowVisibility();
+}
+
+void AppWindow::OcclusionStateChanged(bool aIsFullyOccluded) {
+  if (!mDocShell) {
+    return;
+  }
+  RecomputeBrowsingContextVisibility();
+  if (RefPtr win = mDocShell->GetWindow()) {
+    // And always fire a user-defined occlusionstatechange event on the window
+    win->DispatchCustomEvent(u"occlusionstatechange"_ns,
+                             ChromeOnlyDispatch::eYes);
+  }
+}
+
+void AppWindow::OSToolbarButtonPressed() {
+  // Keep a reference as setting the chrome flags can fire events.
+  nsCOMPtr<nsIAppWindow> appWindow(this);
+
+  // rjc: don't use "nsIWebBrowserChrome::CHROME_EXTRA"
+  //      due to components with multiple sidebar components
+  //      (such as Mail/News, Addressbook, etc)... and frankly,
+  //      Mac IE, OmniWeb, and other Mac OS X apps all work this way
+  uint32_t chromeMask = (nsIWebBrowserChrome::CHROME_TOOLBAR |
+                         nsIWebBrowserChrome::CHROME_LOCATIONBAR |
+                         nsIWebBrowserChrome::CHROME_PERSONAL_TOOLBAR);
+
+  nsCOMPtr<nsIWebBrowserChrome> wbc(do_GetInterface(appWindow));
+  if (!wbc) return;
+
+  uint32_t chromeFlags, newChromeFlags = 0;
+  wbc->GetChromeFlags(&chromeFlags);
+  newChromeFlags = chromeFlags & chromeMask;
+  if (!newChromeFlags)
+    chromeFlags |= chromeMask;
+  else
+    chromeFlags &= (~newChromeFlags);
+  wbc->SetChromeFlags(chromeFlags);
+}
+
+bool AppWindow::ZLevelChanged(bool aImmediate, nsWindowZ* aPlacement,
+                              nsIWidget* aRequestBelow,
+                              nsIWidget** aActualBelow) {
+  if (aActualBelow) *aActualBelow = nullptr;
+
+  return ConstrainToZLevel(aImmediate, aPlacement, aRequestBelow, aActualBelow);
+}
+
+void AppWindow::WindowActivated() {
+  nsCOMPtr<nsIAppWindow> appWindow(this);
+
+  // focusing the window could cause it to close, so keep a reference to it
+  if (mDocShell) {
+    if (nsCOMPtr<nsPIDOMWindowOuter> window = mDocShell->GetWindow()) {
+      if (RefPtr<nsFocusManager> fm = nsFocusManager::GetFocusManager()) {
+        fm->WindowRaised(window, nsFocusManager::GenerateFocusActionId());
+      }
+    }
+  }
+
+  if (mChromeLoaded) {
+    PersistentAttributesDirty(AllPersistentAttributes(), Sync);
+  }
+}
+
+void AppWindow::WindowDeactivated() {
+  if (mDocShell) {
+    if (nsCOMPtr<nsPIDOMWindowOuter> window = mDocShell->GetWindow()) {
+      if (RefPtr<nsFocusManager> fm = nsFocusManager::GetFocusManager()) {
+        if (!fm->IsTestMode()) {
+          fm->WindowLowered(window, nsFocusManager::GenerateFocusActionId());
+        }
+      }
+    }
+  }
+}
+
+#ifdef USE_NATIVE_MENUS
+
+struct LoadNativeMenusListener {
+  LoadNativeMenusListener(Document* aDoc, nsIWidget* aParentWindow)
+      : mDocument(aDoc), mParentWindow(aParentWindow) {}
+
+  RefPtr<Document> mDocument;
+  nsCOMPtr<nsIWidget> mParentWindow;
+};
+
+static bool sHiddenWindowLoadedNativeMenus = false;
+static nsTArray<LoadNativeMenusListener> sLoadNativeMenusListeners;
+
+static void BeginLoadNativeMenus(Document* aDoc, nsIWidget* aParentWindow);
+
+static void LoadNativeMenus(Document* aDoc, nsIWidget* aParentWindow) {
+  MOZ_ASSERT(!gfxPlatform::IsHeadless());
+
+  // Find the menubar tag (if there is more than one, we ignore all but
+  // the first).
+  nsCOMPtr<nsINodeList> menubarElements = aDoc->GetElementsByTagNameNS(
+      nsLiteralString(
+          u"http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"),
+      u"menubar"_ns);
+
+  nsCOMPtr<nsINode> menubarNode;
+  if (menubarElements) {
+    menubarNode = menubarElements->Item(0);
+  }
+
+  using widget::NativeMenuSupport;
+  if (menubarNode) {
+    nsCOMPtr<Element> menubarContent(do_QueryInterface(menubarNode));
+    NativeMenuSupport::CreateNativeMenuBar(aParentWindow, menubarContent);
+  } else {
+    NativeMenuSupport::CreateNativeMenuBar(aParentWindow, nullptr);
+  }
+
+  if (!sHiddenWindowLoadedNativeMenus) {
+    sHiddenWindowLoadedNativeMenus = true;
+    for (auto& listener : sLoadNativeMenusListeners) {
+      BeginLoadNativeMenus(listener.mDocument, listener.mParentWindow);
+    }
+    sLoadNativeMenusListeners.Clear();
+  }
+}
+
+class L10nReadyPromiseHandler final : public dom::PromiseNativeHandler {
+ public:
+  NS_DECL_ISUPPORTS
+
+  L10nReadyPromiseHandler(Document* aDoc, nsIWidget* aParentWindow)
+      : mDocument(aDoc), mWindow(aParentWindow) {}
+
+  void ResolvedCallback(JSContext* aCx, JS::Handle<JS::Value> aValue,
+                        ErrorResult& aRv) override {
+    LoadNativeMenus(mDocument, mWindow);
+  }
+
+  void RejectedCallback(JSContext* aCx, JS::Handle<JS::Value> aValue,
+                        ErrorResult& aRv) override {
+    // Again, this shouldn't happen, but fallback to loading the menus as is.
+    NS_WARNING(
+        "L10nReadyPromiseHandler rejected - loading fallback native "
+        "menu.");
+    LoadNativeMenus(mDocument, mWindow);
+  }
+
+ private:
+  ~L10nReadyPromiseHandler() = default;
+
+  RefPtr<Document> mDocument;
+  nsCOMPtr<nsIWidget> mWindow;
+};
+
+NS_IMPL_ISUPPORTS0(L10nReadyPromiseHandler)
+
+static void BeginLoadNativeMenus(Document* aDoc, nsIWidget* aParentWindow) {
+  RefPtr<DocumentL10n> l10n = aDoc->GetL10n();
+  if (l10n) {
+    // Wait for l10n to be ready so the menus are localized.
+    RefPtr<Promise> promise = l10n->Ready();
+    MOZ_ASSERT(promise);
+    RefPtr<L10nReadyPromiseHandler> handler =
+        new L10nReadyPromiseHandler(aDoc, aParentWindow);
+    promise->AppendNativeHandler(handler);
+  } else {
+    // Something went wrong loading the doc and l10n wasn't created. This
+    // shouldn't really happen, but if it does fallback to trying to load
+    // the menus as is.
+    LoadNativeMenus(aDoc, aParentWindow);
+  }
+}
+
+#endif
+
+class AppWindowTimerCallback final : public nsITimerCallback, public nsINamed {
+ public:
+  explicit AppWindowTimerCallback(AppWindow* aWindow) : mWindow(aWindow) {}
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  NS_IMETHOD Notify(nsITimer* aTimer) override {
+    // Although this object participates in a refcount cycle (this -> mWindow
+    // -> mSPTimer -> this), mSPTimer is a one-shot timer and releases this
+    // after it fires.  So we don't need to release mWindow here.
+
+    mWindow->FirePersistenceTimer();
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetName(nsACString& aName) override {
+    aName.AssignLiteral("AppWindowTimerCallback");
+    return NS_OK;
+  }
+
+ private:
+  ~AppWindowTimerCallback() {}
+
+  RefPtr<AppWindow> mWindow;
+};
+
+NS_IMPL_ISUPPORTS(AppWindowTimerCallback, nsITimerCallback, nsINamed)
+
+void AppWindow::PersistentAttributesDirty(PersistentAttributes aAttributes,
+                                          PersistentAttributeUpdate aUpdate) {
+  aAttributes = aAttributes & mPersistentAttributesMask;
+  if (aAttributes.isEmpty()) {
+    return;
+  }
+
+  mPersistentAttributesDirty += aAttributes;
+  if (aUpdate == Sync) {
+    // Only apply the attributes we've been requested to apply sync, not other
+    // potentially dirty attributes that have been requested asynchronously.
+    SavePersistentAttributes(aAttributes);
+    return;
+  }
+  if (!mSPTimer) {
+    mSPTimer = NS_NewTimer();
+    if (!mSPTimer) {
+      NS_WARNING("Couldn't create timer instance?");
+      return;
+    }
+  }
+
+  RefPtr<AppWindowTimerCallback> callback = new AppWindowTimerCallback(this);
+  mSPTimer->InitWithCallback(callback, SIZE_PERSISTENCE_TIMEOUT,
+                             nsITimer::TYPE_ONE_SHOT);
+}
+
+void AppWindow::FirePersistenceTimer() { SavePersistentAttributes(); }
+
+//----------------------------------------
+// nsIWebProgessListener implementation
+//----------------------------------------
+NS_IMETHODIMP
+AppWindow::OnProgressChange(nsIWebProgress* aProgress, nsIRequest* aRequest,
+                            int32_t aCurSelfProgress, int32_t aMaxSelfProgress,
+                            int32_t aCurTotalProgress,
+                            int32_t aMaxTotalProgress) {
+  MOZ_ASSERT_UNREACHABLE("notification excluded in AddProgressListener(...)");
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::OnStateChange(nsIWebProgress* aProgress, nsIRequest* aRequest,
+                         uint32_t aStateFlags, nsresult aStatus) {
+  // If the notification is not about a document finishing, then just
+  // ignore it...
+  if (!(aStateFlags & nsIWebProgressListener::STATE_STOP) ||
+      !(aStateFlags & nsIWebProgressListener::STATE_IS_NETWORK)) {
+    return NS_OK;
+  }
+
+  if (mChromeLoaded) return NS_OK;
+
+  // If this document notification is for a frame then ignore it...
+  nsCOMPtr<mozIDOMWindowProxy> eventWin;
+  aProgress->GetDOMWindow(getter_AddRefs(eventWin));
+  auto* eventPWin = nsPIDOMWindowOuter::From(eventWin);
+  if (eventPWin) {
+    nsPIDOMWindowOuter* rootPWin = eventPWin->GetPrivateRoot();
+    if (eventPWin != rootPWin) return NS_OK;
+  }
+
+  mChromeLoaded = true;
+  mLockedUntilChromeLoad = false;
+
+#ifdef USE_NATIVE_MENUS
+  ///////////////////////////////
+  // Find the Menubar DOM  and Load the menus, hooking them up to the loaded
+  // commands
+  ///////////////////////////////
+  if (!gfxPlatform::IsHeadless()) {
+    nsCOMPtr<nsIContentViewer> cv;
+    mDocShell->GetContentViewer(getter_AddRefs(cv));
+    if (cv) {
+      RefPtr<Document> menubarDoc = cv->GetDocument();
+      if (menubarDoc) {
+        if (mIsHiddenWindow || sHiddenWindowLoadedNativeMenus) {
+          BeginLoadNativeMenus(menubarDoc, mWindow);
+        } else {
+          sLoadNativeMenusListeners.EmplaceBack(menubarDoc, mWindow);
+        }
+      }
+    }
+  }
+#endif  // USE_NATIVE_MENUS
+
+  OnChromeLoaded();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::OnLocationChange(nsIWebProgress* aProgress, nsIRequest* aRequest,
+                            nsIURI* aURI, uint32_t aFlags) {
+  MOZ_ASSERT_UNREACHABLE("notification excluded in AddProgressListener(...)");
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::OnStatusChange(nsIWebProgress* aWebProgress, nsIRequest* aRequest,
+                          nsresult aStatus, const char16_t* aMessage) {
+  MOZ_ASSERT_UNREACHABLE("notification excluded in AddProgressListener(...)");
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::OnSecurityChange(nsIWebProgress* aWebProgress, nsIRequest* aRequest,
+                            uint32_t aState) {
+  MOZ_ASSERT_UNREACHABLE("notification excluded in AddProgressListener(...)");
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AppWindow::OnContentBlockingEvent(nsIWebProgress* aWebProgress,
+                                  nsIRequest* aRequest, uint32_t aEvent) {
+  MOZ_ASSERT_UNREACHABLE("notification excluded in AddProgressListener(...)");
+  return NS_OK;
+}
+
+/**
+ * ExecuteCloseHandler - Run the close handler, if any.
+ * @return true iff we found a close handler to run.
+ */
+bool AppWindow::ExecuteCloseHandler() {
+  /* If the event handler closes this window -- a likely scenario --
+     things get deleted out of order without this death grip.
+     (The problem may be the death grip in nsWindow::windowProc,
+     which forces this window's widget to remain alive longer
+     than it otherwise would.) */
+  nsCOMPtr<nsIAppWindow> kungFuDeathGrip(this);
+
+  nsCOMPtr<EventTarget> eventTarget;
+  if (mDocShell) {
+    eventTarget = do_QueryInterface(mDocShell->GetWindow());
+  }
+
+  if (eventTarget) {
+    nsCOMPtr<nsIContentViewer> contentViewer;
+    mDocShell->GetContentViewer(getter_AddRefs(contentViewer));
+    if (contentViewer) {
+      RefPtr<nsPresContext> presContext = contentViewer->GetPresContext();
+
+      nsEventStatus status = nsEventStatus_eIgnore;
+      WidgetMouseEvent event(true, eClose, nullptr, WidgetMouseEvent::eReal);
+
+      nsresult rv = EventDispatcher::Dispatch(eventTarget, presContext, &event,
+                                              nullptr, &status);
+      if (NS_SUCCEEDED(rv) && status == nsEventStatus_eConsumeNoDefault)
+        return true;
+      // else fall through and return false
+    }
+  }
+
+  return false;
+}  // ExecuteCloseHandler
+
+void AppWindow::ConstrainToOpenerScreen(int32_t* aX, int32_t* aY) {
+  if (mOpenerScreenRect.IsEmpty()) {
+    *aX = *aY = 0;
+    return;
+  }
+
+  int32_t left, top, width, height;
+  // Constrain initial positions to the same screen as opener
+  nsCOMPtr<nsIScreenManager> screenmgr =
+      do_GetService("@mozilla.org/gfx/screenmanager;1");
+  if (screenmgr) {
+    nsCOMPtr<nsIScreen> screen = screenmgr->ScreenForRect(mOpenerScreenRect);
+    if (screen) {
+      screen->GetAvailRectDisplayPix(&left, &top, &width, &height);
+      if (*aX < left || *aX > left + width) {
+        *aX = left;
+      }
+      if (*aY < top || *aY > top + height) {
+        *aY = top;
+      }
+    }
+  }
+}
+
+nsIAppWindow* AppWindow::WidgetListenerDelegate::GetAppWindow() {
+  return mAppWindow->GetAppWindow();
+}
+
+PresShell* AppWindow::WidgetListenerDelegate::GetPresShell() {
+  return mAppWindow->GetPresShell();
+}
+
+bool AppWindow::WidgetListenerDelegate::WindowMoved(nsIWidget* aWidget,
+                                                    int32_t aX, int32_t aY,
+                                                    ByMoveToRect) {
+  RefPtr<AppWindow> holder = mAppWindow;
+  return holder->WindowMoved(aWidget, aX, aY);
+}
+
+bool AppWindow::WidgetListenerDelegate::WindowResized(nsIWidget* aWidget,
+                                                      int32_t aWidth,
+                                                      int32_t aHeight) {
+  RefPtr<AppWindow> holder = mAppWindow;
+  return holder->WindowResized(aWidget, aWidth, aHeight);
+}
+
+bool AppWindow::WidgetListenerDelegate::RequestWindowClose(nsIWidget* aWidget) {
+  RefPtr<AppWindow> holder = mAppWindow;
+  return holder->RequestWindowClose(aWidget);
+}
+
+void AppWindow::WidgetListenerDelegate::SizeModeChanged(nsSizeMode aSizeMode) {
+  RefPtr<AppWindow> holder = mAppWindow;
+  holder->SizeModeChanged(aSizeMode);
+}
+
+void AppWindow::WidgetListenerDelegate::UIResolutionChanged() {
+  RefPtr<AppWindow> holder = mAppWindow;
+  holder->UIResolutionChanged();
+}
+
+void AppWindow::WidgetListenerDelegate::MacFullscreenMenubarOverlapChanged(
+    DesktopCoord aOverlapAmount) {
+  RefPtr<AppWindow> holder = mAppWindow;
+  return holder->MacFullscreenMenubarOverlapChanged(aOverlapAmount);
+}
+
+void AppWindow::WidgetListenerDelegate::OcclusionStateChanged(
+    bool aIsFullyOccluded) {
+  RefPtr<AppWindow> holder = mAppWindow;
+  holder->OcclusionStateChanged(aIsFullyOccluded);
+}
+
+void AppWindow::WidgetListenerDelegate::OSToolbarButtonPressed() {
+  RefPtr<AppWindow> holder = mAppWindow;
+  holder->OSToolbarButtonPressed();
+}
+
+bool AppWindow::WidgetListenerDelegate::ZLevelChanged(
+    bool aImmediate, nsWindowZ* aPlacement, nsIWidget* aRequestBelow,
+    nsIWidget** aActualBelow) {
+  RefPtr<AppWindow> holder = mAppWindow;
+  return holder->ZLevelChanged(aImmediate, aPlacement, aRequestBelow,
+                               aActualBelow);
+}
+
+void AppWindow::WidgetListenerDelegate::WindowActivated() {
+  RefPtr<AppWindow> holder = mAppWindow;
+  holder->WindowActivated();
+}
+
+void AppWindow::WidgetListenerDelegate::WindowDeactivated() {
+  RefPtr<AppWindow> holder = mAppWindow;
+  holder->WindowDeactivated();
+}
+
+}  // namespace mozilla