chromeos: Add DisplayPowerServiceProvider.

chrome/browser/chromeos/power/output_observer.h

 // Copyright (c) 2012 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_OUTPUT_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_POWER_OUTPUT_OBSERVER_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "chromeos/dbus/power_manager_client.h"
 
 namespace chromeos {
 
 // This observer listens for when video outputs have been turned off so that the
 // corresponding CRTCs can be disabled to force the connected output off.
+// TODO(derat): Remove this class after powerd is calling the method
+// exported by DisplayPowerServiceProvider instead.
 class OutputObserver : public PowerManagerClient::Observer {
  public:
   // This class registers/unregisters itself as an observer in ctor/dtor.
   OutputObserver();
   virtual ~OutputObserver();
 
  private:
   // PowerManagerClient::Observer implementation.
   virtual void ScreenPowerSet(bool power_on, bool all_displays) OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(OutputObserver);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_POWER_OUTPUT_OBSERVER_H_