Fix scroll restoration when exiting fullscreen mode.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 88f58a782fd7544ae316343b06dc0b6dd50546c2..6602aed312d0e1dde99dd5ac03ccc0fa9ab37e55 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1656,11 +1656,13 @@ void WebContentsImpl::EnterFullscreenMode(const GURL& origin) {
     delegate_->EnterFullscreenModeForTab(this, origin);
 
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
-                    DidToggleFullscreenModeForTab(IsFullscreenForCurrentTab(
-                        GetRenderViewHost()->GetWidget())));
+                    DidToggleFullscreenModeForTab(
+                        IsFullscreenForCurrentTab(
+                            GetRenderViewHost()->GetWidget()),
+                        false));
 }
 
-void WebContentsImpl::ExitFullscreenMode() {
+void WebContentsImpl::ExitFullscreenMode(bool will_cause_resize) {
   // This method is being called to leave renderer-initiated fullscreen mode.
   // Make sure any existing fullscreen widget is shut down first.
   RenderWidgetHostView* const widget_view = GetFullscreenRenderWidgetHostView();
@@ -1684,14 +1686,18 @@ void WebContentsImpl::ExitFullscreenMode() {
   // and then the contents entering "tab fullscreen". Exiting the contents
   // "tab fullscreen" then won't have the side effect of the view resizing,
   // hence the explicit call here is required.

[Avi (use Gerrit), 2016/01/05 16:17:57]

Does this comment need a change? It talks about always sending a resize message,
while the block of code below is now guarded by an if().

[bokan, 2016/01/05 17:15:47]

I've made it clearer that this is only for the case where the view size doesn't
change.

-  if (RenderWidgetHostView* rwh_view = GetRenderWidgetHostView()) {
-    if (RenderWidgetHost* render_widget_host = rwh_view->GetRenderWidgetHost())
-      render_widget_host->WasResized();
+  if (!will_cause_resize) {
+    if (RenderWidgetHostView* rwhv = GetRenderWidgetHostView()) {
+        if (RenderWidgetHost* render_widget_host = rwhv->GetRenderWidgetHost())
+          render_widget_host->WasResized();
+    }
   }
 
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
-                    DidToggleFullscreenModeForTab(IsFullscreenForCurrentTab(
-                        GetRenderViewHost()->GetWidget())));
+                    DidToggleFullscreenModeForTab(
+                        IsFullscreenForCurrentTab(
+                            GetRenderViewHost()->GetWidget()),
+                        will_cause_resize));
 }
 
 bool WebContentsImpl::IsFullscreenForCurrentTab(
@@ -2860,10 +2866,10 @@ void WebContentsImpl::HasManifest(const HasManifestCallback& callback) {
   manifest_manager_host_->HasManifest(GetMainFrame(), callback);
 }
 
-void WebContentsImpl::ExitFullscreen() {
+void WebContentsImpl::ExitFullscreen(bool will_cause_resize) {
   // Clean up related state and initiate the fullscreen exit.
   GetRenderViewHost()->GetWidget()->RejectMouseLockOrUnlockIfNecessary();
-  ExitFullscreenMode();
+  ExitFullscreenMode(will_cause_resize);
 }
 
 void WebContentsImpl::ResumeLoadingCreatedWebContents() {
@@ -3046,7 +3052,7 @@ void WebContentsImpl::DidNavigateMainFramePreCommit(
     return;
   }
   if (IsFullscreenForCurrentTab(GetRenderViewHost()->GetWidget()))
-    ExitFullscreen();
+    ExitFullscreen(false);
   DCHECK(!IsFullscreenForCurrentTab(GetRenderViewHost()->GetWidget()));
 }
 
@@ -3918,7 +3924,7 @@ void WebContentsImpl::RenderViewTerminated(RenderViewHost* rvh,
   // Ensure fullscreen mode is exited in the |delegate_| since a crashed
   // renderer may not have made a clean exit.
   if (IsFullscreenForCurrentTab(GetRenderViewHost()->GetWidget()))
-    ExitFullscreenMode();
+    ExitFullscreenMode(false);
 
   // Cancel any visible dialogs so they are not left dangling over the sad tab.
   CancelActiveAndPendingDialogs();