Introduce aura::Env controller to abstract away changes to aura::Env

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 62 matching lines @@
         'client/screen_position_client.cc',
         'client/screen_position_client.h',
         'client/visibility_client.cc',
         'client/visibility_client.h',
         'client/window_stacking_client.cc',
         'client/window_stacking_client.h',
         'client/window_tree_client.cc',
         'client/window_tree_client.h',
         'env.cc',
         'env.h',
+        'env_input_state_controller.cc',
+        'env_input_state_controller.h',
         'env_observer.h',
         'input_state_lookup.cc',
         'input_state_lookup.h',
         'input_state_lookup_win.cc',
         'input_state_lookup_win.h',
         'layout_manager.cc',
         'layout_manager.h',
         'mus/mus_util.cc',
         'mus/mus_util.h',
         'scoped_window_targeter.cc',
@@ skipping 212 matching lines @@
               'dependencies': [
                 '../../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }