mus: Add UserActivityMonitor.

components/mus/public/interfaces/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("//mojo/public/tools/bindings/mojom.gni")
 
 mojom("interfaces") {
   sources = [
     "accelerator_registrar.mojom",
     "channel_handle.mojom",
     "clipboard.mojom",
     "command_buffer.mojom",
     "cursor.mojom",
     "display.mojom",
     "event_matcher.mojom",
     "gpu.mojom",
     "gpu_memory_buffer.mojom",
     "gpu_service.mojom",
     "mus_constants.mojom",
     "surface.mojom",
     "user_access_manager.mojom",
+    "user_activity_monitor.mojom",
     "window_manager.mojom",
     "window_manager_constants.mojom",
     "window_manager_window_tree_factory.mojom",
     "window_server_test.mojom",
     "window_tree.mojom",
     "window_tree_constants.mojom",
     "window_tree_host.mojom",
   ]
 
   import_dirs = [
     get_path_info("../../../..", "abspath"),
     "//mojo/services",
   ]
 
   public_deps = [
     "//cc/ipc:interfaces",
     "//gpu/ipc/common:interfaces",
     "//ui/events/mojo:interfaces",
     "//ui/gfx/geometry/mojo",
     "//ui/gfx/mojo",
     "//ui/platform_window/mojo:interfaces",
   ]
 }