In Chrome ASH on Windows 8 make sure that the browser object is closed before destroying it.

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 "chrome/browser/ui/host_desktop.h"
+
 namespace browser {
 
 // Starts a user initiated exit process. Called from Browser::Exit.
 // On platforms other than ChromeOS, this is equivalent to
 // CloseAllBrowsers() On ChromeOS, this tells session manager
 // that chrome is signing out, which lets session manager send
 // SIGTERM to start actual exit process.
 void AttemptUserExit();
 
 // Starts a user initiated restart process. On platforms other than
@@ skipping 26 matching lines @@
 // handle SIGTERM on chromeos which is a signal to force shutdown
 // the chrome.
 void ExitCleanly();
 #endif
 
 // Closes all browsers. If the session is ending the windows are closed
 // directly. Otherwise the windows are closed by way of posting a WM_CLOSE
 // message.
 void CloseAllBrowsers();
 
+// Closes all browsers of the type (Desktop/Ash) passed in.
+void CloseAllBrowsersOfType(chrome::HostDesktopType type);
+
 // Begins shutdown of the application when the desktop session is ending.
 void SessionEnding();
 
 // Tells the BrowserList to keep the application alive after the last Browser
 // closes. This is implemented as a count, so callers should pair their calls
 // to StartKeepAlive() with matching calls to EndKeepAlive() when they no
 // longer need to keep the application running.
 void StartKeepAlive();
 
 // Stops keeping the application alive after the last Browser is closed.
@@ skipping 15 matching lines @@
 // Called once the application is exiting.
 void OnAppExiting();
 
 // Called once the application is exiting to do any platform specific
 // processing required.
 void HandleAppExitingForPlatform();
 
 }  // namespace browser
 
 #endif  // CHROME_BROWSER_LIFETIME_APPLICATION_LIFETIME_H_