Keep the split view activities topmost in z-order in Athena

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 99 matching lines @@
         'wm/public/window_list_provider_observer.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_list_provider_impl.cc',
         'wm/window_list_provider_impl.h',
         'wm/window_manager_impl.cc',
+        'wm/window_manager_impl.h',
         'wm/window_overview_mode.cc',
         'wm/window_overview_mode.h',
       ],
     },
     {
       'target_name': 'athena_content_lib',
       'type': 'static_library',
       'dependencies': [
         'athena_lib',
         '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
@@ skipping 131 matching lines @@
         'screen/screen_manager_unittest.cc',
         'test/athena_unittests.cc',
         'wm/split_view_controller_unittest.cc',
         'wm/window_list_provider_impl_unittest.cc',
         'wm/window_manager_unittest.cc',
       ],
     }
   ],
 }