Move window_manager service implementation to //services

mojo/services/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")
 
 group("services") {
   deps = [
     "//mojo/services/clipboard",
     "//mojo/services/gles2:lib",
@@ skipping 13 matching lines @@
 
   if (!is_android) {
     deps += ["//mojo/services/native_viewport"]
   }
 
   if (use_aura) {
     deps += [
       "//mojo/services/public/interfaces/view_manager",
       "//mojo/services/public/interfaces/window_manager",
       "//mojo/services/view_manager",
-      "//mojo/services/window_manager",
     ]
   }
 }