Made Blink aware of top controls offset (Blink-side)

public/web/WebWidget.h

 /*
  * Copyright (C) 2009 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 125 matching lines @@
     // Called to inform the WebWidget of an input event. Returns true if
     // the event has been processed, false otherwise.
     virtual bool handleInputEvent(const WebInputEvent&) { return false; }
 
     // Called to inform the WebWidget of the mouse cursor's visibility.
     virtual void setCursorVisibilityState(bool isVisible) { }
 
     // Check whether the given point hits any registered touch event handlers.
     virtual bool hasTouchEventHandlersAt(const WebPoint&) { return true; }
 
-    // Applies a scroll delta to the root layer, which is bundled with a page
-    // scale factor that may apply a CSS transform on the whole document (used
-    // for mobile-device pinch zooming). This is triggered by events sent to the
-    // compositor thread.
-    virtual void applyScrollAndScale(const WebSize& scrollDelta, float scaleFactor) { }
+    // FIXME(bokan): Remove once Chromium-side patch lands
+    virtual void applyScrollAndScale(const WebSize& scrollDelta, float scaleFactor)
+    {
+        applyViewportDeltas(scrollDelta, scaleFactor, 0);
+    }
+
+    // Applies viewport related properties during a commit from the compositor
+    // thread.
+    virtual void applyViewportDeltas(
+        const WebSize& scrollDelta,
+        float scaleFactor,
+        float topControlsDelta) { }
 
     // Called to inform the WebWidget that mouse capture was lost.
     virtual void mouseCaptureLost() { }
 
     // Called to inform the WebWidget that it has gained or lost keyboard focus.
     virtual void setFocus(bool) { }
 
     // Called to inform the WebWidget of a new composition text.
     // If selectionStart and selectionEnd has the same value, then it indicates
     // the input caret position. If the text is empty, then the existing
@@ skipping 93 matching lines @@
     // content.
     virtual WebColor backgroundColor() const { return 0xFFFFFFFF; /* SK_ColorWHITE */ }
 
 protected:
     ~WebWidget() { }
 };
 
 } // namespace blink
 
 #endif