Add video frame refresh to MediaStream and VideoCapture stacks.

content/renderer/media/media_stream_video_source.cc

 // Copyright 2014 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.
 
 #include "content/renderer/media/media_stream_video_source.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 
@@ skipping 280 matching lines @@
                static_cast<int>(MediaStreamVideoSource::kDefaultHeight));
 
   return GetBestFormatBasedOnArea(formats, area);
 }
 
 }  // anonymous namespace
 
 // static
 MediaStreamVideoSource* MediaStreamVideoSource::GetVideoSource(
     const blink::WebMediaStreamSource& source) {
+  if (source.isNull() ||
+      source.getType() != blink::WebMediaStreamSource::TypeVideo) {
+    return nullptr;
+  }
   return static_cast<MediaStreamVideoSource*>(source.getExtraData());
 }
 
 // static, deprecated
 bool MediaStreamVideoSource::IsConstraintSupported(const std::string& name) {
   return std::find(kSupportedConstraints,
                    kSupportedConstraints + arraysize(kSupportedConstraints),
                    name) !=
          kSupportedConstraints + arraysize(kSupportedConstraints);
 }
@@ skipping 273 matching lines @@
       callback(callback) {
 }
 
 MediaStreamVideoSource::TrackDescriptor::TrackDescriptor(
     const TrackDescriptor& other) = default;
 
 MediaStreamVideoSource::TrackDescriptor::~TrackDescriptor() {
 }
 
 }  // namespace content