[Mojo Video Capture] Simplify API and some cleanups

services/video_capture/public/interfaces/video_capture_device_descriptor.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;
+
+enum VideoCaptureApi {
+  LINUX_V4L2_SINGLE_PLANE,
+  WIN_MEDIA_FOUNDATION,
+  WIN_DIRECT_SHOW,
+  MACOSX_AVFOUNDATION,
+  MACOSX_DECKLINK,
+  ANDROID_API1,
+  ANDROID_API2_LEGACY,
+  ANDROID_API2_FULL,
+  ANDROID_API2_LIMITED,
+  ANDROID_TANGO,
+  UNKNOWN
+};
+
+enum VideoCaptureTransportType {
+  // For MACOSX_AVFOUNDATION Api, identifies devices that are built-in or USB.
+  MACOSX_USB_OR_BUILT_IN,
+  OTHER_TRANSPORT
+};
+
+struct VideoCaptureDeviceDescriptor {
+  string display_name;
+  string device_id;
+  string model_id;
+  VideoCaptureApi capture_api;
+  VideoCaptureTransportType transport_type;
+};