Add SourceBuffer implementations of Audio/VideoTracks

third_party/WebKit/Source/modules/mediasource/SourceBufferTrackBaseSupplement.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/mediasource/SourceBufferTrackBaseSupplement.h"
+
+#include "core/html/track/TrackBase.h"
+#include "modules/mediasource/SourceBuffer.h"
+
+namespace blink {
+
+const char* SourceBufferTrackBaseSupplement::SupplementName = "SourceBufferTrackBaseSupplement";
+
+SourceBufferTrackBaseSupplement::SourceBufferTrackBaseSupplement(TrackBase& trackBase, SourceBuffer* sourceBuffer)
+    : m_sourceBuffer(sourceBuffer)
+{
+    provideTo(trackBase, SupplementName, this);
+}
+
+// static
+SourceBuffer* SourceBufferTrackBaseSupplement::sourceBuffer(TrackBase& track)
+{
+    SourceBufferTrackBaseSupplement* supplement = static_cast<SourceBufferTrackBaseSupplement*>(HeapSupplement<TrackBase>::from(track, SupplementName));
+    if (supplement)
+        return supplement->m_sourceBuffer;
+    return nullptr;
+}
+
+
+DEFINE_TRACE(SourceBufferTrackBaseSupplement)
+{
+    visitor->trace(m_sourceBuffer);
+    HeapSupplement<TrackBase>::trace(visitor);
+}
+
+} // namespace blink
+