aura: Unify WindowTreeHost for some platforms

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 90 matching lines @@
         'window_observer.h',
         'window_targeter.cc',
         'window_targeter.h',
         'window_tracker.cc',
         'window_tracker.h',
         'window_tree_host.cc',
         'window_tree_host.h',
         'window_tree_host_mac.h',
         'window_tree_host_mac.mm',
         'window_tree_host_observer.h',
-        'window_tree_host_ozone.cc',
-        'window_tree_host_ozone.h',
-        'window_tree_host_win.cc',
-        'window_tree_host_win.h',
         'window_tree_host_x11.cc',
         'window_tree_host_x11.h',
       ],
       'conditions': [
         ['use_x11==1', {
           'dependencies': [
             '../../build/linux/system.gyp:x11',
             '../../build/linux/system.gyp:xrandr',
             '../../build/linux/system.gyp:xi',
             '../events/devices/events_devices.gyp:events_devices',
@@ skipping 10 matching lines @@
           'sources!': [
             'input_state_lookup.cc',
           ],
         }],
         ['use_ozone==1', {
           'dependencies': [
             '../ozone/ozone.gyp:ozone',
             '../ozone/ozone.gyp:ozone_base',
           ],
         }],
+        ['OS=="win" or use_ozone==1', {
+          'sources': [
+            'window_tree_host_impl.cc',
+            'window_tree_host_impl.h',
+          ],
+        }],
       ],
     },
     {
       # GN version: //ui/aura:test_support
       'target_name': 'aura_test_support',
       'type': 'static_library',
       'dependencies': [
         '../../skia/skia.gyp:skia',
         '../../testing/gtest.gyp:gtest',
         '../base/ime/ui_base_ime.gyp:ui_base_ime',
@@ skipping 179 matching lines @@
               'dependencies': [
                 '../../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }