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 96213)
+++ webkit/plugins/ppapi/ppb_scrollbar_impl.h	(working copy)
@@ -22,7 +22,9 @@
                            public ::ppapi::thunk::PPB_Scrollbar_API,
                            public WebKit::WebScrollbarClient {
  public:
-  PPB_Scrollbar_Impl(PluginInstance* instance, bool vertical);
+  static PP_Resource Create(PluginInstance* instance,
+                            bool vertical);
+
   virtual ~PPB_Scrollbar_Impl();
 
   // ResourceObjectBase override.
@@ -33,8 +35,14 @@
   // 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;
@@ -42,6 +50,9 @@
   virtual void ScrollBy(PP_ScrollBy_Dev unit, int32_t multiplier) OVERRIDE;
 
  private:
+  PPB_Scrollbar_Impl(PluginInstance* instance);
+  void Init(bool vertical);
+
   // PPB_Widget private implementation.
   virtual PP_Bool PaintInternal(const gfx::Rect& rect,
                                 PPB_ImageData_Impl* image) OVERRIDE;
@@ -51,6 +62,8 @@
 
   // WebKit::WebScrollbarClient implementation.
   virtual void valueChanged(WebKit::WebScrollbar* scrollbar) OVERRIDE;
+  // TODO(jam): add OVERRIDE once WebKit is rolled
+  virtual void overlayChanged(WebKit::WebScrollbar* scrollbar);
   virtual void invalidateScrollbarRect(WebKit::WebScrollbar* scrollbar,
                                        const WebKit::WebRect& rect) OVERRIDE;
   virtual void getTickmarks(