Made top controls work with virtual viewport pinch-to-zoom. (Blink)

Source/core/frame/PinchViewport.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 69 matching lines @@
         return m_innerViewportContainerLayer.get();
     }
 
     // Sets the location of the inner viewport relative to the outer viewport. The
     // coordinates are in partial CSS pixels.
     void setLocation(const FloatPoint&);
     void move(const FloatPoint&);
     FloatPoint location() const { return m_offset; }
 
     // Sets the size of the inner viewport when unscaled in CSS pixels.
-    // This will be clamped to the size of the outer viewport (the main frame).
     void setSize(const IntSize&);
     IntSize size() const { return m_size; }
 
     // Resets the viewport to initial state.
     void reset();
 
     // Let the viewport know that the main frame changed size (either through screen
     // rotation on Android or window resize elsewhere).
     void mainFrameDidChangeSize();
 
@@ skipping 14 matching lines @@
 
     // Scroll the main frame and pinch viewport so that the given rect in the
     // top-level document is centered in the viewport. This method will avoid
     // scrolling the pinch viewport unless necessary.
     void scrollIntoView(const FloatRect&);
 
     // Clamp the given point, in document coordinates, to the maximum/minimum
     // scroll extents of the viewport within the document.
     IntPoint clampDocumentOffsetAtScale(const IntPoint& offset, float scale);
 
+    // FIXME: This is kind of a hack. Ideally, we would just resize the
+    // viewports to account for top controls. However, FrameView includes much
+    // more than just scrolling so we can't simply resize it without incurring
+    // all sorts of side-effects. Until we can seperate out the scrollability
+    // aspect from FrameView, we use this method to let PinchViewport make the
+    // necessary adjustments so that we don't incorrectly clamp scroll offsets
+    // coming from the compositor. crbug.com/422328
+    void setTopControlsAdjustment(float);
 private:
     explicit PinchViewport(FrameHost&);
 
     // ScrollableArea implementation
     virtual bool isActive() const override { return false; }
     virtual int scrollSize(ScrollbarOrientation) const override;
     virtual bool isScrollCornerVisible() const override { return false; }
     virtual IntRect scrollCornerRect() const override { return IntRect(); }
     virtual IntPoint scrollPosition() const override { return flooredIntPoint(m_offset); }
     virtual IntPoint minimumScrollPosition() const override;
@@ skipping 37 matching lines @@
     OwnPtr<GraphicsLayer> m_innerViewportScrollLayer;
     OwnPtr<GraphicsLayer> m_overlayScrollbarHorizontal;
     OwnPtr<GraphicsLayer> m_overlayScrollbarVertical;
     OwnPtr<blink::WebScrollbarLayer> m_webOverlayScrollbarHorizontal;
     OwnPtr<blink::WebScrollbarLayer> m_webOverlayScrollbarVertical;
 
     // Offset of the pinch viewport from the main frame's origin, in CSS pixels.
     FloatPoint m_offset;
     float m_scale;
     IntSize m_size;
+    float m_topControlsAdjustment;
 };
 
 } // namespace blink
 
 #endif // PinchViewport_h