chromeos: Request screen lock directly from session manager.

chrome/browser/chromeos/power/power_button_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_POWER_BUTTON_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_POWER_POWER_BUTTON_OBSERVER_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "chromeos/dbus/power_manager_client.h"
+#include "chromeos/dbus/session_manager_client.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
 namespace chromeos {
 
 // Listens for power button, login, and screen lock events and passes them to
 // the Aura shell's PowerButtonController class.
 class PowerButtonObserver : public content::NotificationObserver,
-                            public PowerManagerClient::Observer {
+                            public PowerManagerClient::Observer,
+                            public SessionManagerClient::Observer {
  public:
   // This class registers/unregisters itself as an observer in ctor/dtor.
   PowerButtonObserver();
   virtual ~PowerButtonObserver();
 
  private:
   // content::NotificationObserver implementation:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   // PowerManagerClient::Observer implementation.
   virtual void PowerButtonStateChanged(
       bool down, const base::TimeTicks& timestamp) OVERRIDE;
   virtual void LockButtonStateChanged(
       bool down, const base::TimeTicks& timestamp) OVERRIDE;
+
+  // SessionManagerClient::Observer implementation.
   virtual void LockScreen() OVERRIDE;
 
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(PowerButtonObserver);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_POWER_POWER_BUTTON_OBSERVER_H_