Add srcObject attribute of type MediaStream to HTMLMediaElement.

third_party/WebKit/Source/modules/mediastream/HTMLMediaElementMediaStream.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/mediastream/HTMLMediaElementMediaStream.h"
+
+#include "modules/mediastream/MediaStream.h"
+#include "modules/mediastream/URLMediaStream.h"
+
+namespace blink {
+
+HTMLMediaElementMediaStream::HTMLMediaElementMediaStream()
+    : m_srcObject(nullptr)
+{
+}
+
+// static
+MediaStream* HTMLMediaElementMediaStream::srcObject(HTMLMediaElement& element)
+{
+    HTMLMediaElementMediaStream& thisElement = HTMLMediaElementMediaStream::from(element);
+    return thisElement.m_srcObject;
+}
+
+// static
+void HTMLMediaElementMediaStream::setSrcObject(HTMLMediaElement& element, MediaStream* mediaStream)
+{
+    HTMLMediaElementMediaStream& thisElement = HTMLMediaElementMediaStream::from(element);
+    thisElement.m_srcObject = mediaStream;
+    AtomicString url(URLMediaStream::createObjectURL(element.getExecutionContext(), mediaStream));

[philipj_slow, 2016/03/21 11:13:13]

If this URL is never revoked, won't the mediaStream object simply leak? Getting
rid of this problem is one of the main benefits of srcObject over
createObjectURL, if it can be fixed.

[Guido Urdaneta, 2016/03/21 16:34:53]

What if we do revoke the URL? For example, when srcObject becomes null and
perhaps in other cases?

[philipj_slow, 2016/03/22 16:06:54]

Yes, if avoiding URLs is not possible right now, that'd be an improvement.

+    element.setSrcObjectURL(url);
+}
+
+HTMLMediaElementMediaStream& HTMLMediaElementMediaStream::from(HTMLMediaElement& element)
+{
+    HTMLMediaElementMediaStream* supplement = static_cast<HTMLMediaElementMediaStream*>(WillBeHeapSupplement<HTMLMediaElement>::from(element, supplementName()));
+    if (!supplement) {
+        supplement = new HTMLMediaElementMediaStream();
+        provideTo(element, supplementName(), adoptPtrWillBeNoop(supplement));
+    }
+    return *supplement;
+}
+
+const char* HTMLMediaElementMediaStream::supplementName()
+{
+    return "HTMLMediaElementMediaStream";
+}
+
+DEFINE_TRACE(HTMLMediaElementMediaStream)
+{
+    visitor->trace(m_srcObject);
+    WillBeHeapSupplement<HTMLMediaElement>::trace(visitor);
+}
+
+} // namespace blink