Refactor overlay fullscreen video handling into a single callback

third_party/WebKit/Source/web/FullscreenController.h

Index: third_party/WebKit/Source/web/FullscreenController.h
diff --git a/third_party/WebKit/Source/web/FullscreenController.h b/third_party/WebKit/Source/web/FullscreenController.h
index 9b45481f41c191b11c5237b0130d1eb9bcb08d59..3250456888119ef5a3bfb6bdcb77d4bd6de01a26 100644
--- a/third_party/WebKit/Source/web/FullscreenController.h
+++ b/third_party/WebKit/Source/web/FullscreenController.h
@@ -47,11 +47,20 @@ class FullscreenController final
  public:
   static FullscreenController* create(WebViewImpl*);
 
+  // Called by Fullscreen (via ChromeClient) to request entering or exiting
+  // fullscreen.
+  void enterFullscreenForElement(Element*);
+  void exitFullscreen(LocalFrame*);
+
+  // Called by content::RenderWidget (via WebWidget) to notify that we've
+  // entered or exited fullscreen. This can be because we requested it, or it
+  // can be initiated by the browser directly.
   void didEnterFullscreen();
   void didExitFullscreen();
 
-  void enterFullscreenForElement(Element*);
-  void exitFullscreen(LocalFrame*);
+  // Called by Fullscreen (via ChromeClient) to notify that the fullscreen
+  // element has changed.
+  void fullscreenElementChanged(Element*, Element*);
 
   bool isFullscreen() { return m_fullscreenFrame; }