Move window.close implementation to DOMWindow

Source/core/frame/RemoteFrameClient.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 RemoteFrameClient_h
 #define RemoteFrameClient_h
 
 #include "core/frame/FrameClient.h"
 #include "core/frame/FrameTypes.h"
 #include "core/loader/FrameLoaderTypes.h"
 
 namespace blink {
 
 class Event;
 class ResourceRequest;
 
 class RemoteFrameClient : public FrameClient {
 public:
     virtual ~RemoteFrameClient() { }
 
     virtual void navigate(const ResourceRequest&, bool shouldReplaceCurrentEntry) = 0;
     virtual void reload(FrameLoadType, ClientRedirectPolicy) = 0;
+    virtual unsigned backForwardLength() = 0;
 
     // FIXME: Remove this method once we have input routing in the browser
     // process. See http://crbug.com/339659.
     virtual void forwardInputEvent(Event*) = 0;
 };
 
 } // namespace blink
 
 #endif // RemoteFrameClient_h