Moves common view_manager related aura files to mojo/aura

mojo/mojo_examples.gypi

 # Copyright 2013 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.
 
 {
   'targets': [
     {
       'target_name': 'mojo_sample_app',
       'type': 'shared_library',
       'dependencies': [
@@ skipping 194 matching lines @@
             'mojo_application',
             'mojo_aura_support',
             'mojo_common_lib',
             'mojo_environment_chromium',
             'mojo_geometry_bindings',
             'mojo_geometry_lib',
             'mojo_system_impl',
             'mojo_view_manager_bindings',
           ],
           'sources': [
-            'examples/aura_demo/context_factory_view_manager.cc',
-            'examples/aura_demo/context_factory_view_manager.h',
-            'examples/aura_demo/window_tree_host_view_manager.cc',
-            'examples/aura_demo/window_tree_host_view_manager.h',
             'examples/aura_demo/aura_demo.cc',
             'public/cpp/application/lib/mojo_main_chromium.cc',
           ],
         },
         {
           'target_name': 'mojo_aura_demo_init',
           'type': 'shared_library',
           'dependencies': [
             '../base/base.gyp:base',
             'mojo_application',
@@ skipping 112 matching lines @@
           ],
           'sources': [
             'examples/dbus_echo/dbus_echo_app.cc',
             'public/cpp/application/lib/mojo_main_standalone.cc',
           ],
         },
       ],
     }],
   ],
 }