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

ui/aura/remote_root_window_host_win.h

 // 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.
 
 #ifndef UI_AURA_REMOTE_ROOT_WINDOW_HOST_WIN_H_
 #define UI_AURA_REMOTE_ROOT_WINDOW_HOST_WIN_H_
 
 #include <vector>
 
 #include "base/callback.h"
@@ skipping 68 matching lines @@
                                 const SaveFileCompletion& on_success,
                                 const FileSelectionCanceled& on_failure);
 
 // Handles the select folder for Metro Chrome Ash. The on_success
 // callback passed in is invoked when we receive the folder name from the
 // metro viewer. The on failure callback is invoked on failure.
 AURA_EXPORT void HandleSelectFolder(const base::string16& title,
                                     const SelectFolderCompletion& on_success,
                                     const FileSelectionCanceled& on_failure);
 
-// Handles the activate desktop command for Metro Chrome Ash. The on_success
-// callback passed in is invoked when activation is completed.
-// The |ash_exit| parameter indicates whether the Ash process would be shutdown
-// after activating the desktop.
+// Handles the activate desktop command for Metro Chrome Ash.   The |ash_exit|
+// parameter indicates whether the Ash process would be shutdown after
+// activating the desktop.
 AURA_EXPORT void HandleActivateDesktop(
     const base::FilePath& shortcut,
     bool ash_exit);
 
+// Handles the metro exit command.  Causes the metro viewer to close itself
+// gracefully.
+AURA_EXPORT void HandleMetroExit();

[sky, 2014/01/09 16:40:05]

Why do we need this instead of having callers do
aura::RemoteRootWindowHostWin::Instance()->HandleMetroExit(); ? I suppose this
question applies to all the Hande functions here. Also, why do these have
'Handle' in them? ExitMetro() would be a lot clearer name for this.

[zturner, 2014/01/10 19:00:26]

I believe it's because on component builds we have aura.dll, which hosts
RemoteRootWindowHostWin, so we need to call an exported function.

As for the Handle, I'm not sure.  I left it for consistency, but I can change it
if you feel strongly.  These are basically one-to-one mappings which translate
into "Send an IPC to the Metro Viewer that does X"

+
 // RootWindowHost implementaton that receives events from a different
 // process. In the case of Windows this is the Windows 8 (aka Metro)
 // frontend process, which forwards input events to this class.
 class AURA_EXPORT RemoteRootWindowHostWin
     : public RootWindowHost,
       public ui::internal::RemoteInputMethodDelegateWin {
  public:
   // Returns the only RemoteRootWindowHostWin, if this is the first time
   // this function is called, it will call Create() wiht empty bounds.
   static RemoteRootWindowHostWin* Instance();
   static RemoteRootWindowHostWin* Create(const gfx::Rect& bounds);
 
   // Called when the remote process has established its IPC connection.
   // The |host| can be used when we need to send a message to it and
   // |remote_window| is the actual window owned by the viewer process.
   void Connected(IPC::Sender* host, HWND remote_window);
   // Called when the remote process has closed its IPC connection.
   void Disconnected();
 
   // Called when we have a message from the remote process.
   bool OnMessageReceived(const IPC::Message& message);
 
   void HandleOpenURLOnDesktop(const base::FilePath& shortcut,
                               const base::string16& url);
 
   // The |ash_exit| parameter indicates whether the Ash process would be
   // shutdown after activating the desktop.
-  void HandleActivateDesktop(
-      const base::FilePath& shortcut,
-      bool ash_exit);
+  void HandleActivateDesktop(const base::FilePath& shortcut, bool ash_exit);
+
+  void HandleMetroExit();
 
   void HandleOpenFile(const base::string16& title,
                       const base::FilePath& default_path,
                       const base::string16& filter,
                       const OpenFileCompletion& on_success,
                       const FileSelectionCanceled& on_failure);
 
   void HandleOpenMultipleFiles(const base::string16& title,
                                const base::FilePath& default_path,
                                const base::string16& filter,
@@ skipping 146 matching lines @@
 
   // Current size of this root window.
   gfx::Size window_size_;
 
   DISALLOW_COPY_AND_ASSIGN(RemoteRootWindowHostWin);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_REMOTE_ROOT_WINDOW_HOST_WIN_H_