Moves ShellObserver to ash/common

ash/display/screen_orientation_controller_chromeos.h

 // Copyright 2014 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_SCREEN_ORIENTATION_CONTROLLER_CHROMEOS_H_
 #define ASH_DISPLAY_SCREEN_ORIENTATION_CONTROLLER_CHROMEOS_H_
 
 #include <map>
 
 #include "ash/ash_export.h"
+#include "ash/common/shell_observer.h"
 #include "ash/display/window_tree_host_manager.h"
-#include "ash/shell_observer.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "chromeos/accelerometer/accelerometer_reader.h"
 #include "chromeos/accelerometer/accelerometer_types.h"
 #include "third_party/WebKit/public/platform/modules/screen_orientation/WebScreenOrientationLockType.h"
 #include "ui/aura/window_observer.h"
 #include "ui/display/display.h"
 #include "ui/wm/public/activation_change_observer.h"
 
 namespace aura {
@@ skipping 155 matching lines @@
   // Tracks all windows that have requested a lock, as well as the requested
   // orientation.
   std::map<aura::Window*, blink::WebScreenOrientationLockType> locking_windows_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenOrientationController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_SCREEN_ORIENTATION_CONTROLLER_CHROMEOS_H_