[WIP][Ozone] Support external touchscreens

ash/BUILD.gn

 # 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 
 gypi_values = exec_script(
     "//build/gypi_to_gn.py",
     [ rebase_path("ash.gyp") ],
@@ skipping 83 matching lines @@
       "display/resolution_notification_controller.cc",
       "display/resolution_notification_controller.h",
       "system/tray/media_security/media_capture_observer.h",
       "system/tray/media_security/multi_profile_media_tray_item.cc",
       "system/tray/media_security/multi_profile_media_tray_item.h",
     ]
   }
 
   if (!use_x11 || !is_chromeos) {
     sources -= [
-      "touch/touch_transformer_controller.cc",
+      "touch/touch_transformer_controller_x11.cc",
       "touch/touch_transformer_controller.h",
       "touch/touchscreen_util.cc",
       "touch/touchscreen_util.h",
     ]
   }
 
   if (!use_ozone) {
     sources -= [
       "host/ash_window_tree_host_ozone.cc",
+      "touch/touch_transformer_controller_ozone.cc",
     ]
   }
 }
 
 component("ash_with_content") {
   sources = [
     "content_support/ash_with_content_export.h",
     "content_support/gpu_support_impl.cc",
     "content_support/gpu_support_impl.h",
     "screensaver/screensaver_view.cc",
@@ skipping 245 matching lines @@
     "//content/test:test_support",
     "//skia",
     "//testing/gtest",
     "//ui/accessibility",
   ]
 
   if (is_chromeos) {
     deps += [ "//ui/display" ]
   }
 }