Add srcObject attribute of type MediaStream to HTMLMediaElement.

third_party/WebKit/Source/modules/srcobject/HTMLMediaElementSrcObject.cpp

+// 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 "modules/srcobject/HTMLMediaElementSrcObject.h"
+
+#include "core/html/HTMLMediaElement.h"
+#include "modules/mediastream/MediaStream.h"
+#include "platform/mediastream/MediaStreamDescriptor.h"
+#include "public/platform/WebMediaElementSource.h"
+#include "public/platform/WebMediaStream.h"
+
+namespace blink {
+
+// static
+MediaStream* HTMLMediaElementSrcObject::srcObject(HTMLMediaElement& element)
+{
+    const WebMediaElementSource& source = element.getSrcObject();
+    if (source.isMediaStream()) {
+        MediaStreamDescriptor* descriptor = source.getAsMediaStream();
+        MediaStream* stream = static_cast<MediaStream*>(descriptor->client());

[philipj_slow, 2016/04/06 11:58:42]

Can you introduce a free function toMediaStream(MediaStreamDescriptor*) or a
MediaStreamDescriptor::getAsMediaStream() instead so that the static_cast is
together with the code that makes it obviously safe?

[Guido Urdaneta, 2016/04/06 16:34:55]

Done.

+        return stream;
+    }
+
+    return nullptr;
+}
+
+// static
+void HTMLMediaElementSrcObject::setSrcObject(HTMLMediaElement& element, MediaStream* mediaStream)
+{
+    if (!mediaStream) {
+        element.setSrcObject(WebMediaElementSource());
+        return;
+    }
+    WebMediaStream webStream = WebMediaStream(mediaStream->descriptor());
+    WebMediaElementSource webSource(webStream);
+    element.setSrcObject(webSource);
+}
+
+} // namespace blink