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

chrome/browser/metro_viewer/metro_viewer_process_host_win.h

Index: chrome/browser/metro_viewer/metro_viewer_process_host_win.h
diff --git a/chrome/browser/metro_viewer/metro_viewer_process_host_win.h b/chrome/browser/metro_viewer/metro_viewer_process_host_win.h
index 1527d52da5eb7124ec257d4e8d8fd2a108f72a4f..765877ba0f33004b8b7ed2fe4bdfa95334f3223e 100644
--- a/chrome/browser/metro_viewer/metro_viewer_process_host_win.h
+++ b/chrome/browser/metro_viewer/metro_viewer_process_host_win.h
@@ -8,6 +8,7 @@
 #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"
@@ -24,6 +25,10 @@ class MetroViewerProcessHost : public IPC::Listener,
   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;