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

ppapi/tests/test_scrollbar.h

 // Copyright (c) 2010 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 PAPPI_TESTS_TEST_SCROLLBAR_H_
 #define PAPPI_TESTS_TEST_SCROLLBAR_H_
 
 #include "ppapi/cpp/dev/scrollbar_dev.h"
 #include "ppapi/cpp/dev/widget_client_dev.h"
 #include "ppapi/cpp/dev/widget_dev.h"
 #include "ppapi/tests/test_case.h"
 
 class TestScrollbar : public TestCase,
                       public pp::WidgetClient_Dev {
  public:
   TestScrollbar(TestingInstance* instance);
 
   // TestCase implementation.
   virtual bool Init();
   virtual void RunTest();
 
  private:
   std::string TestHandleEvent();
 
   virtual void InvalidateWidget(pp::Widget_Dev widget,
                                 const pp::Rect& dirty_rect);
   virtual void ScrollbarValueChanged(pp::Scrollbar_Dev scrollbar,
                                      uint32_t value);
+  virtual void ScrollbarOverlayChanged(pp::Scrollbar_Dev scrollbar,
+                                       bool type);
 
   pp::Scrollbar_Dev scrollbar_;
   bool scrollbar_value_changed_;
 };
 
 #endif  // PAPPI_TESTS_TEST_SCROLLBAR_H_