Pepper and WebKit API change to support a plugin knowing if a scrollbar is an overlay one.

webkit/plugins/ppapi/ppb_scrollbar_impl.h

Index: webkit/plugins/ppapi/ppb_scrollbar_impl.h
===================================================================
--- webkit/plugins/ppapi/ppb_scrollbar_impl.h	(revision 95011)
+++ webkit/plugins/ppapi/ppb_scrollbar_impl.h	(working copy)
@@ -33,8 +33,14 @@
   // version of this API.
   static const PPB_Scrollbar_0_3_Dev* Get0_3Interface();
 
+  // Returns a pointer to the interface implementing PPB_Scrollbar_0_4 that is
+  // exposed to the plugin. New code should use the thunk system for the new
+  // version of this API.
+  static const PPB_Scrollbar_0_4_Dev* Get0_4Interface();
+
   // PPB_Scrollbar_API implementation.
   virtual uint32_t GetThickness() OVERRIDE;
+  virtual bool IsOverlay() OVERRIDE;
   virtual uint32_t GetValue() OVERRIDE;
   virtual void SetValue(uint32_t value) OVERRIDE;
   virtual void SetDocumentSize(uint32_t size) OVERRIDE;
@@ -51,6 +57,7 @@
 
   // WebKit::WebScrollbarClient implementation.
   virtual void valueChanged(WebKit::WebScrollbar* scrollbar) OVERRIDE;
+  virtual void overlayChanged(WebKit::WebScrollbar* scrollbar) OVERRIDE;
   virtual void invalidateScrollbarRect(WebKit::WebScrollbar* scrollbar,
                                        const WebKit::WebRect& rect) OVERRIDE;
   virtual void getTickmarks(