[Mojo Video Capture] Cleanup naming of classes/files in services/video_capture

services/video_capture/public/interfaces/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 {
+struct DeviceDescriptor {
   string display_name;
   string device_id;
   string model_id;
   VideoCaptureApi capture_api;
   VideoCaptureTransportType transport_type;
 };