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

ppapi/thunk/resource_creation_api.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PPAPI_THUNK_RESOURCE_CREATION_API_H_
 #define PPAPI_THUNK_RESOURCE_CREATION_API_H_
 
 #include "ppapi/c/dev/ppb_file_chooser_dev.h"
 #include "ppapi/c/dev/ppb_graphics_3d_dev.h"
 #include "ppapi/c/dev/ppb_video_layer_dev.h"
@@ skipping 82 matching lines @@
       uint32_t key_code,
       struct PP_Var character_text) = 0;
   virtual PP_Resource CreateMouseInputEvent(
       PP_Instance instance,
       PP_InputEvent_Type type,
       PP_TimeTicks time_stamp,
       uint32_t modifiers,
       PP_InputEvent_MouseButton mouse_button,
       const PP_Point* mouse_position,
       int32_t click_count) = 0;
-  virtual PP_Resource CreateScrollbar(PP_Instance instance,
+  virtual PP_Resource CreateScrollbar(PP_Resource scrollbar_group,
                                       PP_Bool vertical) = 0;
+  virtual PP_Resource CreateScrollbarGroup(PP_Instance instance) = 0;
   virtual PP_Resource CreateSurface3D(PP_Instance instance,
                                       PP_Config3D_Dev config,
                                       const int32_t* attrib_list) = 0;
   virtual PP_Resource CreateTransport(PP_Instance instance,
                                       const char* name,
                                       const char* proto) = 0;
   virtual PP_Resource CreateURLLoader(PP_Instance instance) = 0;
   virtual PP_Resource CreateURLRequestInfo(PP_Instance instance) = 0;
   virtual PP_Resource CreateVideoCapture(PP_Instance instance) = 0;
   virtual PP_Resource CreateVideoDecoder(
@@ skipping 11 matching lines @@
       PP_Bool scroll_by_page) = 0;
 
   static const ::pp::proxy::InterfaceID interface_id =
       ::pp::proxy::INTERFACE_ID_RESOURCE_CREATION;
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif  // PPAPI_THUNK_RESOURCE_CREATION_API_H_