Add BackgroundModeOptimizer that can restart the browser

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"
 #include "build/build_config.h"
 
@@ skipping 67 matching lines @@
 // For ChromeOS, also request session manager to end the session.
 void NotifyAndTerminate(bool fast_path);
 
 #if !defined(OS_ANDROID)
 // Called once the application is exiting.
 void OnAppExiting();
 
 // Called once the application is exiting to do any platform specific
 // processing required.
 void HandleAppExitingForPlatform();
+
+// Calling |AttemptRestart| unconditionally sets some preference to be used

[sky, 2016/07/06 16:55:33]

nit: generally | is used for arguments and members, where as () is used for
functions, e.g. AttemptRestart().

[dgn, 2016/07/22 15:18:09]

Ack.

+// during the shutdown or start sequences. They normally get reset when they are
+// individually read and used. In case a restart is cancelled, this function
+// should be called to perform that reset.
+void ResetRestartPrefs();

[sky, 2016/07/06 16:55:33]

Can this move to browser_shutdown::SetTryingToQuit if quitting is false? Having
this public is confusing and not something we normally want folks calling,
right?

[dgn, 2016/07/22 15:18:09]

Good point, done.

 #endif  // !defined(OS_ANDROID)
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_LIFETIME_APPLICATION_LIFETIME_H_