Add UMA stats for pinch-zoom behavior on Android

third_party/WebKit/Source/core/frame/VisualViewport.h

 /*
  * Copyright (C) 2013 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 177 matching lines @@
     bool shouldPlaceVerticalScrollbarOnLeft() const override { return false; }
     void invalidateScrollbarRect(Scrollbar*, const IntRect&) override;
     void invalidateScrollCornerRect(const IntRect&) override { }
     void setScrollOffset(const IntPoint&, ScrollType) override;
     void setScrollOffset(const DoublePoint&, ScrollType) override;
     GraphicsLayer* layerForContainer() const override;
     GraphicsLayer* layerForScrolling() const override;
     GraphicsLayer* layerForHorizontalScrollbar() const override;
     GraphicsLayer* layerForVerticalScrollbar() const override;
 
+    // Used for gathering data on user pinch-zoom statistics.
+    void userDidChangeScale();
+    void sendUMAMetrics();
+    void startTrackingPinchStats();
+
 private:
     explicit VisualViewport(FrameHost&);
 
     bool visualViewportSuppliesScrollbars() const;
 
     // GraphicsLayerClient implementation.
     void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect& inClip) override;
     String debugName(const GraphicsLayer*) override;
 
     void setupScrollbar(WebScrollbar::Orientation);
@@ skipping 16 matching lines @@
     OwnPtr<GraphicsLayer> m_overlayScrollbarHorizontal;
     OwnPtr<GraphicsLayer> m_overlayScrollbarVertical;
     OwnPtr<WebScrollbarLayer> m_webOverlayScrollbarHorizontal;
     OwnPtr<WebScrollbarLayer> m_webOverlayScrollbarVertical;
 
     // Offset of the visual viewport from the main frame's origin, in CSS pixels.
     FloatPoint m_offset;
     float m_scale;
     IntSize m_size;
     float m_topControlsAdjustment;
+    float m_maxPageScale;
+    bool m_trackPinchZoomStatsForPage;
 };
 
 } // namespace blink
 
 #endif // VisualViewport_h