Add srcObject attribute of type MediaStream to HTMLMediaElement.

third_party/WebKit/public/blink_headers.gypi

 # Copyright 2015 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.
 
 {
   'variables': {
     'blink_public_sources': [
       "platform/callback/WebClosure.h",
       "platform/Platform.h",
       "platform/FilePathConversion.h",
@@ skipping 103 matching lines @@
       "platform/WebInbandTextTrackClient.h",
       "platform/WebInputEventResult.h",
       "platform/WebLayer.h",
       "platform/WebLayerPositionConstraint.h",
       "platform/WebLayerScrollClient.h",
       "platform/WebLayerTreeView.h",
       "platform/WebLayoutAndPaintAsyncCallback.h",
       "platform/WebLocalizedString.h",
       "platform/WebMediaConstraints.h",
       "platform/WebMediaDeviceInfo.h",
+      "platform/WebMediaElementSource.h",
       "platform/WebMediaKeySystemConfiguration.h",
       "platform/WebMediaKeySystemMediaCapability.h",
       "platform/WebMediaPlayer.h",
       "platform/WebMediaPlayerClient.h",
       "platform/WebMediaRecorderHandler.h",
       "platform/WebMediaRecorderHandlerClient.h",
       "platform/WebMediaSource.h",
       "platform/WebMediaStream.h",
       "platform/WebMediaStreamCenter.h",
       "platform/WebMediaStreamCenterClient.h",
@@ skipping 368 matching lines @@
       "web/modules/serviceworker/WebServiceWorkerContextClient.h",
       "web/modules/serviceworker/WebServiceWorkerContextProxy.h",
       "web/modules/serviceworker/WebServiceWorkerNetworkProvider.h",
       "web/modules/webmidi/WebMIDIClient.h",
       "web/modules/webmidi/WebMIDIOptions.h",
       "web/modules/webmidi/WebMIDIPermissionRequest.h",
       "web/win/WebFontRendering.h",
     ],
   },
 }