Add KeepAliveStateObserver, add the Restart option

chrome/browser/lifetime/keep_alive_state_observer.h

Index: chrome/browser/lifetime/keep_alive_state_observer.h
diff --git a/chrome/browser/lifetime/keep_alive_state_observer.h b/chrome/browser/lifetime/keep_alive_state_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..0e959b11982c93906598fc745ff3aebf2922e09b
--- /dev/null
+++ b/chrome/browser/lifetime/keep_alive_state_observer.h
@@ -0,0 +1,18 @@
+// 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_KEEP_ALIVE_STATE_OBSERVER_H_
+#define CHROME_BROWSER_LIFETIME_KEEP_ALIVE_STATE_OBSERVER_H_
+
+struct KeepAliveOptions;
+
+class KeepAliveStateObserver {
+ public:
+  virtual void OnKeepAliveRestartStateChanged(bool can_restart) = 0;
+
+ protected:
+  virtual ~KeepAliveStateObserver() {}
+};
+
+#endif  // CHROME_BROWSER_LIFETIME_KEEP_ALIVE_STATE_OBSERVER_H_