Move chrome.power API from chrome/ to extensions/.

extensions/common/api/power.idl

 // Copyright (c) 2013 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.
 
 // Use the <code>chrome.power</code> API to override the system's power
 // management features.
 namespace power {
   [noinline_doc] enum Level {
     // Prevent the system from sleeping in response to user inactivity.
     system,
 
     // Prevent the display from being turned off or dimmed or the system
     // from sleeping in response to user inactivity.
     display
   };
 
   interface Functions {
     // Requests that power management be temporarily disabled. |level|
     // describes the degree to which power management should be disabled.
     // If a request previously made by the same app is still active, it
     // will be replaced by the new request.
     static void requestKeepAwake(Level level);
 
     // Releases a request previously made via requestKeepAwake().
     static void releaseKeepAwake();
   };
 };