Re-add snap-back behavior (Chrome side)

content/renderer/renderer_webkitplatformsupport_impl.h

Index: content/renderer/renderer_webkitplatformsupport_impl.h
===================================================================
--- content/renderer/renderer_webkitplatformsupport_impl.h	(revision 254242)
+++ content/renderer/renderer_webkitplatformsupport_impl.h	(working copy)
@@ -93,6 +93,7 @@
                              blink::WebPluginListBuilder* builder);
   virtual blink::WebPublicSuffixList* publicSuffixList();
   virtual void screenColorProfile(blink::WebVector<char>* to_profile);
+  virtual blink::WebScrollbarBehavior* scrollbarBehavior();
   virtual blink::WebIDBFactory* idbFactory();
   virtual blink::WebFileSystem* fileSystem();
   virtual bool canAccelerate2dCanvas();
@@ -231,6 +232,8 @@
 
   scoped_ptr<ScreenOrientationDispatcher> screen_orientation_dispatcher_;
 
+  scoped_ptr<blink::WebScrollbarBehavior> web_scrollbar_behavior_;
+
   DISALLOW_COPY_AND_ASSIGN(RendererWebKitPlatformSupportImpl);
 };