GN: Get os="chromeos" use_ozone=true to compile

ui/aura/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/ui.gni")
 
 component("aura") {
   sources = [
     "client/aura_constants.cc",
     "client/aura_constants.h",
@@ skipping 97 matching lines @@
   ]
 
   if (use_x11) {
     configs += [
       "//build/config/linux:x11",
       "//build/config/linux:xrandr",
     ]
     deps += [
       "//ui/events/platform/x11",
     ]
+  } else {
+    sources -= [
+      "window_tree_host_x11.cc",
+      "window_tree_host_x11.h",
+    ]
   }
 
   if (is_win) {
     sources -= [
       "input_state_lookup.cc",
     ]
 
     deps += [
       "//ui/metro_viewer",
       "//ipc",
     ]
   }
 
   if (use_ozone) {
     sources += [
       "window_tree_host_ozone.cc",
       "window_tree_host_ozone.h",
     ]
 
-    # TODO(GYP) enable when these targets exist.
-    #deps += [
-    #  "//ui/events/ozone",
-    #  "//ui/ozone",
-    #]
+    deps += [
+      "//ui/events/ozone:events_ozone",
+      "//ui/ozone",
+    ]
   }
 }
 
 source_set("test_support") {
   testonly = true
   sources = [
     "test/aura_test_base.cc",
     "test/aura_test_base.h",
     "test/aura_test_helper.cc",
     "test/aura_test_helper.h",
@@ skipping 144 matching lines @@
     "//ui/gfx/geometry",
     "//ui/gl",
   ]
 
   if (is_linux) {
     deps += [
       "//third_party/mesa",
     ]
   }
 }