Enable extended desktop by default.

ash/display/display_controller.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 ASH_DISPLAY_DISPLAY_CONTROLLER_H_
 #define ASH_DISPLAY_DISPLAY_CONTROLLER_H_
 
 #include <map>
 #include <vector>
 
@@ skipping 66 matching lines @@
                                   const gfx::Point& location_in_root);
 
   // aura::DisplayObserver overrides:
   virtual void OnDisplayBoundsChanged(
       const gfx::Display& display) OVERRIDE;
   virtual void OnDisplayAdded(const gfx::Display& display) OVERRIDE;
   virtual void OnDisplayRemoved(const gfx::Display& display) OVERRIDE;
 
   // Is extended desktop enabled?
   static bool IsExtendedDesktopEnabled();
-  // Change the extended desktop mode. Used for testing.
-  static void SetExtendedDesktopEnabled(bool enabled);
 
  private:
   // Creates a root window for |display| and stores it in the |root_windows_|
   // map.
   aura::RootWindow* AddRootWindowForDisplay(const gfx::Display& display);
 
   void UpdateDisplayBoundsForLayout();
 
   std::map<int, aura::RootWindow*> root_windows_;
 
   SecondaryDisplayLayout secondary_display_layout_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayController);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_DISPLAY_CONTROLLER_H_