chromeos: Move EnableScreenLock to PowerManagerClient from PowerLibrary

chrome/browser/chromeos/cros/power_library.h

 // Copyright (c) 2011 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
 
 // TODO(sque): Move to chrome/browser/chromeos/system, crosbug.com/16558
 
@@ skipping 14 matching lines @@
     virtual ~Observer() {}
   };
 
   virtual ~PowerLibrary() {}
 
   virtual void Init() = 0;
 
   virtual void AddObserver(Observer* observer) = 0;
   virtual void RemoveObserver(Observer* observer) = 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_