Add a pref checkbox to enable/disable screen lock for ChromeOs.

chrome/browser/chromeos/cros/power_library.h

 // Copyright (c) 2009 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_CROS_POWER_LIBRARY_H_
 #define CHROME_BROWSER_CHROMEOS_CROS_POWER_LIBRARY_H_
 #pragma once
 
 #include "base/observer_list.h"
 #include "base/singleton.h"
@@ skipping 25 matching lines @@
 
   // Whether there is a battery present.
   virtual bool battery_is_present() const = 0;
 
   // The amount of time until battery is empty.
   virtual base::TimeDelta battery_time_to_empty() const = 0;
 
   // The amount of time until battery is full.
   virtual base::TimeDelta battery_time_to_full() const = 0;
 
+  // Enable/disable screen lock for current session.
+  virtual void EnableScreenLock(bool enable) = 0;
+
   // Factory function, creates a new instance and returns ownership.
   // For normal usage, access the singleton via CrosLibrary::Get().
   static PowerLibrary* GetImpl(bool stub);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_CROS_POWER_LIBRARY_H_