[Mojo Video Capture] Stop service when last client disconnects.

services/video_capture/public/interfaces/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("//mojo/public/tools/bindings/mojom.gni")
 
 mojom("interfaces") {
   sources = [
     "device.mojom",
     "device_factory.mojom",
+    "device_factory_provider.mojom",
     "receiver.mojom",
-    "service.mojom",
   ]
 
   deps = [
     "//media/capture/mojo:capture_types",
     "//media/mojo/interfaces",
     "//ui/gfx/geometry/mojo",
   ]
 }
+
+mojom("constants") {
+  sources = [
+    "constants.mojom",
+  ]
+}