Have browser process shutdown metro viewer on Metro -> Metro restart.

ui/aura/remote_root_window_host_win.cc

 // Copyright (c) 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.
 
 #include "ui/aura/remote_root_window_host_win.h"
 
 #include <windows.h>
 
 #include <algorithm>
 
@@ skipping 124 matching lines @@
                                                                 on_failure);
 }
 
 void HandleActivateDesktop(const base::FilePath& shortcut,
                            bool ash_exit) {
   DCHECK(aura::RemoteWindowTreeHostWin::Instance());
   aura::RemoteWindowTreeHostWin::Instance()->HandleActivateDesktop(shortcut,
                                                                    ash_exit);
 }
 
+void HandleMetroExit() {
+  DCHECK(aura::RemoteWindowTreeHostWin::Instance());
+  aura::RemoteWindowTreeHostWin::Instance()->HandleMetroExit();
+}
+
 RemoteWindowTreeHostWin* g_instance = NULL;
 
 RemoteWindowTreeHostWin* RemoteWindowTreeHostWin::Instance() {
   if (g_instance)
     return g_instance;
   return Create(gfx::Rect());
 }
 
 RemoteWindowTreeHostWin* RemoteWindowTreeHostWin::Create(
     const gfx::Rect& bounds) {
@@ skipping 87 matching lines @@
 }
 
 void RemoteWindowTreeHostWin::HandleActivateDesktop(
     const base::FilePath& shortcut,
     bool ash_exit) {
   if (!host_)
     return;
   host_->Send(new MetroViewerHostMsg_ActivateDesktop(shortcut, ash_exit));
 }
 
+void RemoteWindowTreeHostWin::HandleMetroExit() {
+  if (!host_)
+    return;
+  host_->Send(new MetroViewerHostMsg_MetroExit());
+}
+
 void RemoteWindowTreeHostWin::HandleOpenFile(
     const base::string16& title,
     const base::FilePath& default_path,
     const base::string16& filter,
     const OpenFileCompletion& on_success,
     const FileSelectionCanceled& on_failure) {
   if (!host_)
     return;
 
   // Can only have one of these operations in flight.
@@ skipping 464 matching lines @@
 }
 
 void RemoteWindowTreeHostWin::SetEventFlags(uint32 flags) {
   if (flags == event_flags_)
     return;
   event_flags_ = flags;
   SetVirtualKeyStates(event_flags_);
 }
 
 }  // namespace aura