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 {
+
+static const char* kSupplementName = "SourceBufferTrackBaseSupplement";
+
+// static
+SourceBufferTrackBaseSupplement* SourceBufferTrackBaseSupplement::fromIfExists(TrackBase& track)
+{
+    return static_cast<SourceBufferTrackBaseSupplement*>(Supplement<TrackBase>::from(track, kSupplementName));
+}
+
+// static
+SourceBufferTrackBaseSupplement& SourceBufferTrackBaseSupplement::from(TrackBase& track)
+{
+    SourceBufferTrackBaseSupplement* supplement = fromIfExists(track);
+    if (!supplement) {
+        supplement = new SourceBufferTrackBaseSupplement();
+        Supplement<TrackBase>::provideTo(track, kSupplementName, supplement);
+    }
+    return *supplement;
+}
+
+// static
+SourceBuffer* SourceBufferTrackBaseSupplement::sourceBuffer(TrackBase& track)
+{
+    SourceBufferTrackBaseSupplement* supplement = fromIfExists(track);
+    if (supplement)
+        return supplement->m_sourceBuffer;
+    return nullptr;
+}
+
+void SourceBufferTrackBaseSupplement::setSourceBuffer(TrackBase& track, SourceBuffer* sourceBuffer)
+{
+    from(track).m_sourceBuffer = sourceBuffer;
+}
+
+DEFINE_TRACE(SourceBufferTrackBaseSupplement)
+{
+    visitor->trace(m_sourceBuffer);
+    Supplement<TrackBase>::trace(visitor);
+}
+
+} // namespace blink
+