Add KeepAliveStateObserver, add the Restart option

chrome/browser/lifetime/scoped_keep_alive.h

 // Copyright 2016 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_SCOPED_KEEP_ALIVE_H_
 #define CHROME_BROWSER_LIFETIME_SCOPED_KEEP_ALIVE_H_
 
 #include "base/macros.h"
 
 enum class KeepAliveOrigin;
+enum class KeepAliveRestartOption;
 
 // Registers with KeepAliveRegistry on creation and unregisters them
 // on destruction. Use these objects with a scoped_ptr for easy management.
 class ScopedKeepAlive {
  public:
-  explicit ScopedKeepAlive(KeepAliveOrigin origin);
+  explicit ScopedKeepAlive(KeepAliveOrigin origin,

[sky, 2016/02/26 22:13:25]

nit: no explicit.

[dgn, 2016/03/09 16:35:32]

Done.

+                           KeepAliveRestartOption restart);
   ~ScopedKeepAlive();
 
  private:
   const KeepAliveOrigin origin_;
+  const KeepAliveRestartOption restart_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedKeepAlive);
 };
 
 #endif  // CHROME_BROWSER_LIFETIME_SCOPED_KEEP_ALIVE_H_