Let PagePopupChromeClient schedule frames before attachRootGraphicsLayer.

third_party/WebKit/Source/web/WebPagePopupImpl.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 87 matching lines @@
 
   bool isViewportPointInWindow(int x, int y);
 
   // PagePopup function
   AXObject* rootAXObject() override;
   void setWindowRect(const IntRect&) override;
 
   explicit WebPagePopupImpl(WebWidgetClient*);
   bool initializePage();
   void destroyPage();
+  void initializeLayerTreeView();
   void setRootGraphicsLayer(GraphicsLayer*);
-  void setIsAcceleratedCompositingActive(bool enter);
 
   WebRect windowRectInScreen() const;
 
   WebWidgetClient* m_widgetClient;
   WebViewImpl* m_webView;
   Persistent<Page> m_page;
   Persistent<PagePopupChromeClient> m_chromeClient;
   PagePopupClient* m_popupClient;
   bool m_closing;
 
@@ skipping 11 matching lines @@
                   WebWidget,
                   widget,
                   widget->isPagePopup(),
                   widget.isPagePopup());
 // WebPagePopupImpl is the only implementation of PagePopup, so no
 // further checking required.
 DEFINE_TYPE_CASTS(WebPagePopupImpl, PagePopup, popup, true, true);
 
 }  // namespace blink
 #endif  // WebPagePopupImpl_h