Add relaunch into ASH and desktop support for Chrome on Windows 7.

chrome/browser/lifetime/application_lifetime.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 CHROME_BROWSER_LIFETIME_APPLICATION_LIFETIME_H_
 #define CHROME_BROWSER_LIFETIME_APPLICATION_LIFETIME_H_
 
 #include "base/compiler_specific.h"
 
 class Browser;
@@ skipping 23 matching lines @@
 enum AshExecutionStatus {
   ASH_KEEP_RUNNING,
   ASH_TERMINATE,
 };
 
 // Helper function to activate the desktop from Ash mode. The
 // |ash_execution_status| parameter indicates if we should exit Ash after
 // activating desktop.
 void ActivateDesktopHelper(AshExecutionStatus ash_execution_status);
 
-// Windows 8 specific: Like AttemptRestart but if chrome is running
+// Windows 7/8 specific: Like AttemptRestart but if chrome is running
 // in desktop mode it starts in metro mode and vice-versa. The switching like
 // the restarting is controlled by a preference.
 void AttemptRestartWithModeSwitch();
 void AttemptRestartToDesktopMode();
+// Launches Chrome into Windows 8 metro mode on Windows 8. On Windows 7 it
+// launches Chrome into Windows ASH.
 void AttemptRestartToMetroMode();
 #endif
 
 // Attempt to exit by closing all browsers.  This is equivalent to
 // CloseAllBrowsers() on platforms where the application exits
 // when no more windows are remaining. On other platforms (the Mac),
 // this will additionally exit the application if all browsers are
 // successfully closed.
 //  Note that he exit process may be interrupted by download or
 // unload handler, and the browser may or may not exit.
@@ skipping 52 matching lines @@
 // processing required.
 void HandleAppExitingForPlatform();
 
 // Returns true if we can start the shutdown sequence for the browser, i.e. the
 // last browser window is being closed.
 bool ShouldStartShutdown(Browser* browser);
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_LIFETIME_APPLICATION_LIFETIME_H_