athena: Add the concept of Activity and related managers.

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 12 matching lines @@
         # All .cc, .h under athena, except unittests
         'athena_export.h',
         'home/home_card_delegate_view.cc',
         'home/home_card_delegate_view.h',
         'home/home_card_impl.cc',
         'home/public/home_card.h',
         'screen/background_controller.cc',
         'screen/background_controller.h',
         'screen/public/screen_manager.h',
         'screen/screen_manager_impl.cc',
+        'task/public/task.h',
+        'task/public/task_manager.h',
+        'task/task_manager_impl.cc',
         'wm/public/window_manager.h',
         'wm/window_manager_impl.cc',
       ],
     },
   ],
 }