Introduce the abstract class WebViewBase, to decouple WebViewImpl.

third_party/WebKit/Source/web/WebFrameWidgetImpl.h

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 22 matching lines @@
 
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/heap/SelfKeepAlive.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "platform/wtf/Assertions.h"
 #include "platform/wtf/HashSet.h"
 #include "public/platform/WebCoalescedInputEvent.h"
 #include "public/platform/WebPoint.h"
 #include "public/platform/WebSize.h"
 #include "public/web/WebInputMethodController.h"
+#include "web/CompositorMutatorImpl.h"
 #include "web/PageWidgetDelegate.h"
 #include "web/WebFrameWidgetBase.h"
 #include "web/WebInputMethodControllerImpl.h"
 #include "web/WebLocalFrameImpl.h"
 #include "web/WebViewImpl.h"
 
 namespace blink {
 
 class CompositorAnimationHost;
 class Frame;
@@ skipping 191 matching lines @@
 
 DEFINE_TYPE_CASTS(WebFrameWidgetImpl,
                   WebFrameWidgetBase,
                   widget,
                   widget->ForSubframe(),
                   widget.ForSubframe());
 
 }  // namespace blink
 
 #endif