chromeos: call GetIdleTime from power manager client

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
 
 #include "base/callback.h"
 
 namespace chromeos {
 
-typedef base::Callback<void(int64_t)> CalculateIdleTimeCallback;
-
 // This interface defines interaction with the ChromeOS power library APIs.
 // Classes can add themselves as observers. Users can get an instance of this
 // library class like this: chromeos::CrosLibrary::Get()->GetPowerLibrary()
 class PowerLibrary {
  public:
   class Observer {
    public:
     virtual void SystemResumed() = 0;
 
    protected:
     virtual ~Observer() {}
   };
 
   virtual ~PowerLibrary() {}
 
   virtual void Init() = 0;
 
   virtual void AddObserver(Observer* observer) = 0;
   virtual void RemoveObserver(Observer* observer) = 0;
 
-  // Calculates idle time asynchronously. If it encounters some error,
-  // it returns -1.
-  virtual void CalculateIdleTime(CalculateIdleTimeCallback* callback) = 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_