In WinAura, also kill the Metro viewer process in AttemptExit().

chrome/browser/metro_viewer/metro_viewer_process_host_win.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_METRO_VIEWER_PROCESS_HOST_WIN_H_
 #define CHROME_BROWSER_METRO_VIEWER_METRO_VIEWER_PROCESS_HOST_WIN_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
+#include "base/process_util.h"
 #include "base/threading/non_thread_safe.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_sender.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace IPC {
 class ChannelProxy;
 }
 
 class MetroViewerProcessHost : public IPC::Listener,
                                public IPC::Sender,
                                public base::NonThreadSafe {
  public:
   explicit MetroViewerProcessHost(const std::string& ipc_channel_name);
   virtual ~MetroViewerProcessHost();
 
+  // Returns the process id of the viewer process if one is connected to this
+  // host, returns base::kNullProcessId otherwise.
+  base::ProcessId GetViewerProcessId();
+
  private:
   // IPC::Sender implementation:
   virtual bool Send(IPC::Message* msg) OVERRIDE;
 
   // IPC::Listener implementation:
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   virtual void OnChannelError() OVERRIDE;
 
   void OnSetTargetSurface(gfx::NativeViewId target_surface);
 
   scoped_ptr<IPC::ChannelProxy> channel_;
 
   DISALLOW_COPY_AND_ASSIGN(MetroViewerProcessHost);
 };
 
 #endif  // CHROME_BROWSER_METRO_VIEWER_METRO_VIEWER_PROCESS_HOST_WIN_H_