Bug 1177155 part 1 - Defer resize reflow and freeze refresh driver during window fullscreen change. r=smaug

dom/base/nsGlobalWindow.cpp

@@ -6383,7 +6383,8 @@ FullscreenTransitionTask::Run()
       mWindow->mFullScreen = mFullscreen;
     }
     // Toggle the fullscreen state on the widget
-    mWidget->MakeFullScreen(mFullscreen, mScreen);
+    mWindow->SetWidgetFullscreen(nsPIDOMWindow::eForFullscreenAPI,
+                                 mFullscreen, mWidget, mScreen);
     // Set observer for the next content paint.
     nsCOMPtr<nsIObserver> observer = new Observer(this);
     nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
@@ -6462,13 +6463,7 @@ MakeWidgetFullscreen(nsGlobalWindow* aWindow, gfx::VRHMDInfo* aHMD,
   }
   nsCOMPtr<nsIScreen> screen = aHMD ? aHMD->GetScreen() : nullptr;
   if (!performTransition) {
-    if (aReason == nsPIDOMWindow::eForFullscreenMode) {
-      // If we enter fullscreen for fullscreen mode, we want
-      // the native system behavior.
-      widget->MakeFullScreenWithNativeTransition(aFullscreen, screen);
-    } else {
-      widget->MakeFullScreen(aFullscreen, screen);
-    }
+    aWindow->SetWidgetFullscreen(aReason, aFullscreen, widget, screen);
   } else {
     nsCOMPtr<nsIRunnable> task =
       new FullscreenTransitionTask(duration, aWindow, aFullscreen,
@@ -6572,6 +6567,27 @@ nsGlobalWindow::SetFullscreenInternal(FullscreenReason aReason,
   return NS_OK;
 }
 
+void
+nsGlobalWindow::SetWidgetFullscreen(FullscreenReason aReason, bool aIsFullscreen,
+                                    nsIWidget* aWidget, nsIScreen* aScreen)
+{
+  MOZ_ASSERT(IsOuterWindow());
+  MOZ_ASSERT(this == GetTop(), "Only topmost window should call this");
+  MOZ_ASSERT(!GetFrameElementInternal(), "Content window should not call this");
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+
+  if (nsCOMPtr<nsIPresShell> presShell = mDocShell->GetPresShell()) {
+    presShell->SetIsInFullscreenChange(true);
+  }
+  if (aReason == nsPIDOMWindow::eForFullscreenMode) {
+    // If we enter fullscreen for fullscreen mode, we want
+    // the native system behavior.
+    aWidget->MakeFullScreenWithNativeTransition(aIsFullscreen, aScreen);
+  } else {
+    aWidget->MakeFullScreen(aIsFullscreen, aScreen);
+  }
+}
+
 /* virtual */ void
 nsGlobalWindow::FinishFullscreenChange(bool aIsFullscreen)
 {
@@ -6604,6 +6620,11 @@ nsGlobalWindow::FinishFullscreenChange(bool aIsFullscreen)
   // respond visually if we are kicked into full screen mode
   DispatchCustomEvent(NS_LITERAL_STRING("fullscreen"));
 
+  if (nsCOMPtr<nsIPresShell> presShell = mDocShell->GetPresShell()) {
+    MOZ_ASSERT(presShell->IsInFullscreenChange());
+    presShell->SetIsInFullscreenChange(false);
+  }
+
   if (!mWakeLock && mFullScreen) {
     nsRefPtr<power::PowerManagerService> pmService =
       power::PowerManagerService::GetInstance();

dom/base/nsGlobalWindow.h

@@ -498,6 +498,8 @@ public:
     FullscreenReason aReason, bool aIsFullscreen,
     mozilla::gfx::VRHMDInfo *aHMD = nullptr) override final;
   virtual void FinishFullscreenChange(bool aIsFullscreen) override final;
+  void SetWidgetFullscreen(FullscreenReason aReason, bool aIsFullscreen,
+                           nsIWidget* aWidget, nsIScreen* aScreen);
   bool FullScreen() const;
 
   // Inner windows only.

layout/base/nsIPresShell.h

@@ -1589,6 +1589,9 @@ public:
   nsresult HasRuleProcessorUsedByMultipleStyleSets(uint32_t aSheetType,
                                                    bool* aRetVal);
 
+  bool IsInFullscreenChange() const { return mIsInFullscreenChange; }
+  void SetIsInFullscreenChange(bool aValue);
+
   /**
    * Refresh observer management.
    */
@@ -1770,6 +1773,11 @@ protected:
   bool                      mIsZombie : 1;
   bool                      mIsReflowing : 1;
 
+  // Indicates that the whole document is performing fullscreen change,
+  // in which case, we need to defer dispatching resize event and freeze
+  // the refresh driver to avoid unnecessary reflow.
+  bool                      mIsInFullscreenChange : 1;
+
   // For all documents we initially lock down painting.
   bool                      mPaintingSuppressed : 1;
 

layout/base/nsPresShell.cpp

@@ -10956,3 +10956,21 @@ nsIPresShell::HasRuleProcessorUsedByMultipleStyleSets(uint32_t aSheetType,
   *aRetVal = mStyleSet->HasRuleProcessorUsedByMultipleStyleSets(type);
   return NS_OK;
 }
+
+void
+nsIPresShell::SetIsInFullscreenChange(bool aValue)
+{
+  if (mIsInFullscreenChange == aValue) {
+    NS_WARNING(aValue ? "Pres shell has been in fullscreen change?" :
+               "Pres shell is not in fullscreen change?");
+    return;
+  }
+  mIsInFullscreenChange = aValue;
+  if (nsRefreshDriver* rd = mPresContext->RefreshDriver()) {
+    if (aValue) {
+      rd->Freeze();
+    } else {
+      rd->Thaw();
+    }
+  }
+}

view/nsViewManager.cpp

@@ -197,7 +197,8 @@ void
 nsViewManager::SetWindowDimensions(nscoord aWidth, nscoord aHeight)
 {
   if (mRootView) {
-    if (mRootView->IsEffectivelyVisible() && mPresShell && mPresShell->IsVisible()) {
+    if (mRootView->IsEffectivelyVisible() && mPresShell &&
+        mPresShell->IsVisible() && !mPresShell->IsInFullscreenChange()) {
       if (mDelayedResize != nsSize(NSCOORD_NONE, NSCOORD_NONE) &&
           mDelayedResize != nsSize(aWidth, aHeight)) {
         // We have a delayed resize; that now obsolete size may already have