Moves transient window observer methods out of WindowObserver

ui/views/views.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,
   },
   'target_defaults': {
     'conditions': [
       ['use_aura==1', {
@@ skipping 249 matching lines @@
         'corewm/tooltip_aura.cc',
         'corewm/tooltip_aura.h',
         'corewm/tooltip_controller.cc',
         'corewm/tooltip_controller.h',
         'corewm/tooltip_win.cc',
         'corewm/tooltip_win.h',
         'corewm/transient_window_controller.cc',
         'corewm/transient_window_controller.h',
         'corewm/transient_window_manager.cc',
         'corewm/transient_window_manager.h',
+        'corewm/transient_window_observer.h',
         'corewm/transient_window_stacking_client.cc',
         'corewm/transient_window_stacking_client.h',
         'corewm/visibility_controller.cc',
         'corewm/visibility_controller.h',
         'corewm/window_animations.cc',
         'corewm/window_animations.h',
         'corewm/window_modality_controller.cc',
         'corewm/window_modality_controller.h',
         'corewm/window_util.cc',
         'corewm/window_util.h',
@@ skipping 844 matching lines @@
           'sources/': [
             # This is needed because the aura rule strips it from the default
             # sources list.
             ['include', '^../../content/app/startup_helper_win.cc'],
           ],
         }],
       ],
     },  # target_name: views_examples_with_content_exe
   ],
 }