Send initializeChildFrame from RenderFrameProxy instead of WebLocalFrame

public/web/WebRemoteFrameClient.h

 // Copyright 2014 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 WebRemoteFrameClient_h
 #define WebRemoteFrameClient_h
 
 #include "public/web/WebDOMMessageEvent.h"
 #include "public/web/WebSecurityOrigin.h"
 
 namespace blink {
 class WebLocalFrame;
 class WebRemoteFrame;
 
 class WebRemoteFrameClient {
 public:
     // Notifies the embedder that a postMessage was issued to a remote frame.
     virtual void postMessageEvent(
         WebLocalFrame* sourceFrame,
         WebRemoteFrame* targetFrame,
         WebSecurityOrigin targetOrigin,
-        WebDOMMessageEvent) = 0;
+        WebDOMMessageEvent) { }
+
+    // Send initial drawing parameters to a child frame that is being rendered
+    // out of process.
+    virtual void initializeChildFrame(
+        const WebRect& frameRect,
+        float scaleFactor) { }
 };
 
 } // namespace blink
 
 #endif // WebRemoteFrameClient_h