chromeos: power: Refactor RendererFreezer and add tests

chrome/browser/chromeos/power/freezer_cgroup_process_manager.h

+// Copyright 2014 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_CHROMEOS_POWER_FREEZER_CGROUP_PROCESS_MANAGER_H_
+#define CHROME_BROWSER_CHROMEOS_POWER_FREEZER_CGROUP_PROCESS_MANAGER_H_
+
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "chrome/browser/chromeos/power/renderer_freezer.h"
+
+namespace chromeos {
+
+// Manages all the processes in the freezer cgroup on Chrome OS.
+class FreezerCgroupProcessManager : public RendererFreezer::Delegate {
+ public:
+  FreezerCgroupProcessManager();
+  virtual ~FreezerCgroupProcessManager();
+
+  // RendererFreezer::Delegate overrides.
+  virtual bool FreezeRenderers() OVERRIDE;
+  virtual bool ThawRenderers() OVERRIDE;
+  virtual bool CanFreezeRenderers() OVERRIDE;
+
+ private:
+  bool WriteCommandToStateFile(const std::string& command);
+
+  base::FilePath state_path_;
+  bool enabled_;
+
+  DISALLOW_COPY_AND_ASSIGN(FreezerCgroupProcessManager);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_POWER_FREEZER_CGROUP_PROCESS_MANAGER_H_