Fix linker error with mus_demo.

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")
 import("//testing/test.gni")
 
 component("aura") {
   sources = [
     "../wm/public/activation_change_observer.cc",
@@ skipping 137 matching lines @@
     "//cc/surfaces",
     "//gpu/ipc/client",
     "//mojo/public/cpp/system",
     "//net",
     "//services/service_manager/public/cpp",
     "//services/ui/public/cpp",
     "//services/ui/public/interfaces",
     "//skia",
     "//ui/base",
     "//ui/base/ime",
-    "//ui/compositor",
     "//ui/display",
     "//ui/events",
     "//ui/events:events_base",
     "//ui/events/platform",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/gl",
     "//ui/platform_window",
     "//ui/platform_window/mojo",
     "//ui/platform_window/stub",
   ]
 
+  public_deps = [
+    "//ui/compositor",
+  ]
+
   data_deps = [
     "//services/ui",
   ]
 
   if (use_x11) {
     configs += [
       "//build/config/linux:x11",
       "//build/config/linux:xrandr",
     ]
     deps += [
@@ skipping 179 matching lines @@
   ]
 
   if (is_linux) {
     deps += [ "//third_party/mesa" ]
   }
 
   data_deps = [
     "//third_party/mesa:osmesa",
   ]
 }