Add srcObject attribute of type MediaStream to HTMLMediaElement.

content/renderer/media/web_media_element_source_utils.cc

+// 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.
+
+#include "content/renderer/media/web_media_element_source_utils.h"
+
+#include "third_party/WebKit/public/platform/WebMediaPlayerSource.h"
+#include "third_party/WebKit/public/platform/WebMediaStream.h"
+#include "third_party/WebKit/public/web/WebMediaStreamRegistry.h"
+
+namespace content {
+
+blink::WebMediaStream GetWebMediaStreamFromWebMediaPlayerSource(
+    const blink::WebMediaPlayerSource& source) {
+  if (source.isMediaStream())
+    return source.getAsMediaStream();
+
+  if (source.isURL()) {
+    return blink::WebMediaStreamRegistry::lookupMediaStreamDescriptor(
+        source.getAsURL());
+  }
+
+  return blink::WebMediaStream();
+}
+
+}  // namespace content