Rework FocusManager as FocusClient.

ui/aura/aura.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 30 matching lines @@
         'client/default_capture_client.cc',
         'client/default_capture_client.h',
         'client/dispatcher_client.cc',
         'client/dispatcher_client.h',
         'client/drag_drop_client.cc',
         'client/drag_drop_client.h',
         'client/drag_drop_delegate.cc',
         'client/drag_drop_delegate.h',
         'client/event_client.cc',
         'client/event_client.h',
+        'client/focus_change_observer.h',
+        'client/focus_client.cc',
+        'client/focus_client.h',
         'client/screen_position_client.cc',
         'client/screen_position_client.h',
         'client/stacking_client.cc',
         'client/stacking_client.h',
         'client/tooltip_client.cc',
         'client/tooltip_client.h',
         'client/user_action_client.cc',
         'client/user_action_client.h',
         'client/visibility_client.cc',
         'client/visibility_client.h',
         'client/window_move_client.cc',
         'client/window_move_client.h',
         'client/window_types.h',
         'device_list_updater_aurax11.cc',
         'device_list_updater_aurax11.h',
         'dispatcher_win.cc',
         'display_util.cc',
         'display_util.h',
         'env.cc',
         'env.h',
         'env_observer.h',
-        'focus_change_observer.h',
         'focus_manager.cc',
         'focus_manager.h',
         'layout_manager.cc',
         'layout_manager.h',
         'remote_root_window_host_win.cc',
         'remote_root_window_host_win.h',
         'root_window_host.h',
         'root_window_host_delegate.h',
         'root_window_host_linux.cc',
         'root_window_host_linux.h',
@@ skipping 181 matching lines @@
         # osmesa GL implementation is used on linux.
         ['OS=="linux"', {
           'dependencies': [
             '<(DEPTH)/third_party/mesa/mesa.gyp:osmesa',
           ],
         }],
       ],
     },
   ],
 }