chromeos: Add a stub implementation for SensorsSource.

chrome/browser/chromeos/dbus/power_manager_client.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_DBUS_POWER_MANAGER_CLIENT_H_
 #define CHROME_BROWSER_CHROMEOS_DBUS_POWER_MANAGER_CLIENT_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 
@@ skipping 27 matching lines @@
   // Decreases the screen brightness. |allow_off| controls whether or not
   // it's allowed to turn off the back light.
   virtual void DecreaseScreenBrightness(bool allow_off) = 0;
 
   // Increases the screen brightness.
   virtual void IncreaseScreenBrightness() = 0;
 
   // Creates the instance.
   static PowerManagerClient* Create(dbus::Bus* bus);
 
-  PowerManagerClient();
   virtual ~PowerManagerClient();
 
+ protected:
+  // Create() should be used instead.
+  PowerManagerClient();
+
+ private:
   DISALLOW_COPY_AND_ASSIGN(PowerManagerClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_DBUS_POWER_MANAGER_CLIENT_H_