Add the beginning of a simple window manager that we'll support on Windows.

mash/wm/BUILD.gn

+# Copyright 2016 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("//services/service_manager/public/cpp/service.gni")
+import("//services/service_manager/public/service_manifest.gni")
+
+service("wm") {
+  sources = [
+    "main.cc",
+  ]
+
+  deps = [
+    ":lib",
+    "//services/service_manager/public/cpp",
+    "//ui/views/mus:for_mojo_application",
+  ]
+}
+
+source_set("lib") {
+  sources = [
+    "wm.cc",
+    "wm.h",
+  ]
+
+  deps = [
+    "//base",
+    "//services/service_manager/public/cpp",
+    "//services/ui/public/cpp",
+    "//services/ui/public/interfaces",
+    "//ui/display",
+    "//ui/gfx/geometry/mojo",
+  ]
+
+  data_deps = [
+    ":manifest",
+    "//services/ui",
+  ]
+}
+
+service_manifest("manifest") {
+  name = "wm"
+  source = "manifest.json"
+}