Expose Frame::detach() to the Blink API layer.

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:
+    // Notify the embedder that it should remove this frame from the frame tree
+    // and release any resources associated with it.
+    virtual void frameDetached() { }
+
     // Notifies the embedder that a postMessage was issued to a remote frame.
     virtual void postMessageEvent(
         WebLocalFrame* sourceFrame,
         WebRemoteFrame* targetFrame,
         WebSecurityOrigin targetOrigin,
         WebDOMMessageEvent) = 0;
 };
 
 } // namespace blink
 
 #endif // WebRemoteFrameClient_h