Add ScopedKeepAlive to c/b/lifetime

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 <string>
+
+#include "base/macros.h"
+#include "chrome/browser/lifetime/keep_alive_registry.h"
+
+// Registers tokens with KeepAliveRegistry on creation and unregisters them
+// on destruction.
+//
+// These tokens should be descriptive of what the KeepAlive's
+// lifetime is tied to, to help with debugging.
+//
+// TODO(dgn)
+// When registering a token, indictations of which kind of optimizations would
+// be allowed during the KeepAlive's lifetime should be provided. This allows
+// to take some liberties with the state of the browser to optimize the resource
+// consumption.
+//
+// Use these objects with a scoped_ptr for easy management of the tokens.
+class ScopedKeepAlive {
+ public:
+  explicit ScopedKeepAlive(const std::string& token);
+  ~ScopedKeepAlive();
+
+ private:
+  std::string token_;

[sky, 2016/02/19 21:02:49]

const

[dgn, 2016/02/22 18:01:20]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(ScopedKeepAlive);
+};
+
+#endif  // CHROME_BROWSER_LIFETIME_SCOPED_KEEP_ALIVE_H_