Record keep alive registry's state in stability instrumentation

chrome/browser/lifetime/keep_alive_registry.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_KEEP_ALIVE_REGISTRY_H_
 #define CHROME_BROWSER_LIFETIME_KEEP_ALIVE_REGISTRY_H_
 
 #include <unordered_map>
+#include <vector>
 
 #include "base/macros.h"
 #include "base/memory/singleton.h"
 #include "base/observer_list.h"
 
 enum class KeepAliveOrigin;
 enum class KeepAliveRestartOption;
 class KeepAliveStateObserver;
 
 // Centralized registry that objects in the browser can use to
@@ skipping 67 matching lines @@
   // Number of registered keep alives that have KeepAliveRestartOption::ENABLED.
   int restart_allowed_count_;
 
   base::ObserverList<KeepAliveStateObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(KeepAliveRegistry);
 };
 
 
 #endif  // CHROME_BROWSER_LIFETIME_KEEP_ALIVE_REGISTRY_H_