Package video capture skeleton as Mojo Shell Service

services/video_capture/public/interfaces/video_capture_device.mojom

 // 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.
 
 module video_capture.mojom;
 
 import "services/video_capture/public/interfaces/video_capture_device_client.mojom";
 import "services/video_capture/public/interfaces/video_capture_format.mojom";
 
 enum ResolutionChangePolicy {
   FIXED_RESOLUTION,
   FIXED_ASPECT_RATIO,
   ANY_WITHIN_LIMIT,
 };
 
 enum PowerLineFrequency {
   DEFAULT,
   HZ_50,
   HZ_60
 };
 
-// Note: The VideoCaptureDevice is stopped when the corresponding message pipe
-// is closed.
+// Represents access to a video capture device available on the machine.
+// Note: Instead of offering an explicit Stop() method, the VideoCaptureDevice
+// is stopped automatically when the corresponding message pipe is closed.
 interface VideoCaptureDevice {
   Start(VideoCaptureFormat requested_format,
         ResolutionChangePolicy resolution_change_policy,
         PowerLineFrequency power_line_frequency,
         VideoCaptureDeviceClient client);
 };