Switch ContentSettingsObserver to be a RenderFrameObserver instead of a RenderViewObserver

content/browser/frame_host/render_frame_host_delegate.cc

 // Copyright 2013 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.
 
 #include "content/browser/frame_host/render_frame_host_delegate.h"
 
+#include <stddef.h>
+
 namespace content {
 
 bool RenderFrameHostDelegate::OnMessageReceived(
     RenderFrameHost* render_view_host,
     const IPC::Message& message) {
   return false;
 }
 
+WebContents* RenderFrameHostDelegate::GetAsWebContents() {
+  return NULL;
+}
+
 }  // namespace content