Create Pinch Virtual Viewport scrollbar layers in Blink.

public/platform/WebLayer.h

 /*
  * Copyright (C) 2011 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:
  *
  * 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
@@ skipping 145 matching lines @@
 
     // The following functions suspend and resume all animations. The given time
     // is assumed to use the same time base as monotonicallyIncreasingTime().
     virtual void suspendAnimations(double monotonicTime) = 0;
     virtual void resumeAnimations(double monotonicTime) = 0;
 
     // Returns true if this layer has any active animations - useful for tests.
     virtual bool hasActiveAnimation() = 0;
 
     // Scrolling
+    // FIXME: Remove default implementation when CC-side implementation lands.

[enne (OOO), 2013/09/12 18:51:21]

Or just land the cc side first?

[wjmaclean, 2013/09/12 19:01:56]

OK, I had just thought this way it would be one less CL before I could start
cc-side development using the clip layer.

+    virtual void setScrollClipLayer(WebLayer*) { }
+
     virtual void setScrollPosition(WebPoint) = 0;
     virtual WebPoint scrollPosition() const = 0;
 
     virtual void setMaxScrollPosition(WebSize) = 0;
     virtual WebSize maxScrollPosition() const = 0;
 
     virtual void setScrollable(bool) = 0;
     virtual bool scrollable() const = 0;
 
     virtual void setHaveWheelEventHandlers(bool) = 0;
@@ skipping 29 matching lines @@
 
     // True if the layer is not part of a tree attached to a WebLayerTreeView.
     virtual bool isOrphan() const = 0;
 
     virtual void setWebLayerClient(WebLayerClient*) = 0;
 };
 
 } // namespace WebKit
 
 #endif // WebLayer_h