Made double-tap zoom work in pinch virtual viewport mode. (Blink-side)

Source/core/page/scrolling/ScrollingCoordinator.h

 /*
  * Copyright (C) 2011 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 100 matching lines @@
     void updateTouchEventTargetRectsIfNeeded();
 
     // For testing purposes only. This ScrollingCoordinator is reused between layout test, and must be reset
     // for the results to be valid.
     void reset();
 
 protected:
     explicit ScrollingCoordinator(Page*);
 
     bool isForMainFrame(ScrollableArea*) const;
+    bool isForViewport(ScrollableArea*) const;
 
     Page* m_page;
 
     // Dirty flags used to idenfity what really needs to be computed after compositing is updated.
     bool m_scrollGestureRegionIsDirty;
     bool m_touchEventTargetRectsAreDirty;
     bool m_shouldScrollOnMainThreadDirty;
 
 private:
     bool shouldUpdateAfterCompositingChange() const { return m_scrollGestureRegionIsDirty || m_touchEventTargetRectsAreDirty || frameViewIsDirty(); }
@@ skipping 18 matching lines @@
     HashSet<const RenderLayer*> m_layersWithTouchRects;
     bool m_wasFrameScrollable;
 
     // This is retained for testing.
     MainThreadScrollingReasons m_lastMainThreadScrollingReasons;
 };
 
 } // namespace blink
 
 #endif // ScrollingCoordinator_h