Add an adapter layer (WMHelper) between exo and ash.

components/exo/BUILD.gn

 # Copyright 2015 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/ui.gni")
 import("//testing/test.gni")
 
 source_set("exo") {
   sources = [
     "buffer.cc",
@@ skipping 18 matching lines @@
     "sub_surface.cc",
     "sub_surface.h",
     "surface.cc",
     "surface.h",
     "surface_delegate.h",
     "surface_observer.h",
     "surface_property.h",
     "touch.cc",
     "touch.h",
     "touch_delegate.h",
+    "wm_helper.cc",
+    "wm_helper.h",
   ]
 
   deps = [
     "//ash",
     "//base",
     "//cc",
     "//cc/surfaces:surfaces",
     "//device/gamepad",
     "//gpu",
     "//gpu/command_buffer/client:gles2_interface",
@@ skipping 96 matching lines @@
   ]
 
   if (use_x11) {
     deps += [ "//tools/xdisplaycheck" ]
   }
 
   if (is_linux) {
     deps += [ "//components/exo/wayland:unit_tests" ]
   }
 }