Cleanup: Pull some browser keep alive functions into its own file.

chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.h

 // Copyright 2012 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 CHROME_BROWSER_METRO_VIEWER_CHROME_METRO_VIEWER_PROCESS_HOST_AURAWIN_H_
 #define CHROME_BROWSER_METRO_VIEWER_CHROME_METRO_VIEWER_PROCESS_HOST_AURAWIN_H_
 
+#include "base/memory/scoped_ptr.h"
 #include "win8/viewer/metro_viewer_process_host.h"
 
 namespace base {
 class FilePath;
 }
 
+namespace browser_lifetime {
+class ScopedKeepAlive;
+}
+
 class ChromeMetroViewerProcessHost : public win8::MetroViewerProcessHost {
  public:
   ChromeMetroViewerProcessHost();
   ~ChromeMetroViewerProcessHost() override;
 
  private:
   // win8::MetroViewerProcessHost implementation
   void OnChannelError() override;
 
   // IPC::Listener implementation
   void OnChannelConnected(int32 peer_pid) override;
   void OnSetTargetSurface(gfx::NativeViewId target_surface,
                           float device_scale) override;
   void OnOpenURL(const base::string16& url) override;
   void OnHandleSearchRequest(const base::string16& search_string) override;
   void OnWindowSizeChanged(uint32 width, uint32 height) override;
 
+  scoped_ptr<browser_lifetime::ScopedKeepAlive> keep_alive_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeMetroViewerProcessHost);
 };
 
 #endif  // CHROME_BROWSER_METRO_VIEWER_CHROME_METRO_VIEWER_PROCESS_HOST_AURAWIN_H_