Revert of Split Screen mode implementation.

athena/athena.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 51 matching lines @@
         'screen/background_controller.cc',
         'screen/background_controller.h',
         'screen/public/screen_manager.h',
         'screen/screen_accelerator_handler.cc',
         'screen/screen_accelerator_handler.h',
         'screen/screen_manager_impl.cc',
         'system/power_button_controller.cc',
         'system/power_button_controller.h',
         'system/public/system_ui.h', 
         'system/system_ui_impl.cc',
+        'wm/public/window_manager.h',
+        'wm/public/window_manager_observer.h',
         'wm/bezel_controller.cc',
         'wm/bezel_controller.h',
-        'wm/mru_window_tracker.cc',
-        'wm/mru_window_tracker.h',
-        'wm/public/window_list_provider.h',
-        'wm/public/window_manager.h',
-        'wm/public/window_manager_observer.h',
         'wm/split_view_controller.cc',
         'wm/split_view_controller.h',
         'wm/title_drag_controller.cc',
         'wm/title_drag_controller.h',
         'wm/window_manager_impl.cc',
         'wm/window_overview_mode.cc',
         'wm/window_overview_mode.h',
       ],
     },
     {
@@ skipping 83 matching lines @@
         'activity/activity_manager_unittest.cc',
         'home/home_card_unittest.cc',
         'input/accelerator_manager_unittest.cc',
         'screen/screen_manager_unittest.cc',
         'wm/window_manager_unittest.cc',
       ],
     }
   ],
 }