Move the logic to retrieve the WebPluginContainer to LocalFrame and Node.

third_party/WebKit/Source/web/WebPluginContainerImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2014 Opera Software ASA. 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.
@@ skipping 154 matching lines @@
   bool ExecuteEditCommand(const WebString& name) override;
   bool ExecuteEditCommand(const WebString& name,
                           const WebString& value) override;
 
   // Resource load events for the plugin's source data:
   void DidReceiveResponse(const ResourceResponse&) override;
   void DidReceiveData(const char* data, int data_length) override;
   void DidFinishLoading() override;
   void DidFailLoading(const ResourceError&) override;
 
+  WebPluginContainerBase* GetWebPluginContainerBase() const override {
+    return const_cast<WebPluginContainerImpl*>(this);
+  }
+
   DECLARE_VIRTUAL_TRACE();
   void Dispose() override;
 
  private:
   // Sets |windowRect| to the content rect of the plugin in screen space.
   // Sets |clippedAbsoluteRect| to the visible rect for the plugin, clipped to
   // the visible screen of the root frame, in local space of the plugin.
   // Sets |unclippedAbsoluteRect| to the visible rect for the plugin (but
   // without also clipping to the screen), in local space of the plugin.
   void ComputeClipRectsForPlugin(
@@ skipping 49 matching lines @@
 // WebPluginContainerImpl is the only subclass of WebPluginContainer.
 DEFINE_TYPE_CASTS(WebPluginContainerImpl,
                   WebPluginContainer,
                   container,
                   true,
                   true);
 
 }  // namespace blink
 
 #endif