Add SourceBuffer implementations of Audio/VideoTracks

third_party/WebKit/Source/modules/mediasource/AudioTrackSourceBuffer.h

Index: third_party/WebKit/Source/modules/mediasource/AudioTrackSourceBuffer.h
diff --git a/third_party/WebKit/Source/modules/mediasource/AudioTrackSourceBuffer.h b/third_party/WebKit/Source/modules/mediasource/AudioTrackSourceBuffer.h
new file mode 100644
index 0000000000000000000000000000000000000000..e85e069fd4c5836c823613c530a2950b4ec50c5f
--- /dev/null
+++ b/third_party/WebKit/Source/modules/mediasource/AudioTrackSourceBuffer.h
@@ -0,0 +1,22 @@
+// 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.
+
+#ifndef AudioTrackSourceBuffer_h
+#define AudioTrackSourceBuffer_h
+
+#include "modules/mediasource/SourceBufferTrackBaseSupplement.h"
+
+namespace blink {
+
+class AudioTrack;
+class SourceBuffer;
+
+class AudioTrackSourceBuffer final : public SourceBufferTrackBaseSupplement {

[philipj_slow, 2016/03/10 13:12:17]

Can this be simplified even further? It ought to be possible to have

class AudioTrackSourceBuffer {
  static SourceBuffer* sourceBuffer(AudioTrack&);
};

where the implementation cast AudioTrack& to TrackBase& and calls into a shared
"static SourceBuffer* TrackBase::sourceBuffer(TrackBase&)" that's used for both
audio and video tracks.

I tried to apply the patch locally to try it out myself first, but the CL
doesn't apply any longer. Can you rebase?

[servolk, 2016/03/11 02:00:57]

Yep. In fact we don't even need the sourceBuffer method here, since it's exactly
the same for A and V cases. And we can remove the constructors that do the
implicit casting from A/V tracks to TrackBase. Then we are left with just two
empty classes that are descendants of SourceBufferTrackBaseSupplement, and we
can just get rid of these two classes completely and instead just use
ImplementedAs=SourceBufferTrackBaseSupplement in the .idl files.

+public:
+    explicit AudioTrackSourceBuffer(AudioTrack&, SourceBuffer*);
+};
+
+} // namespace blink
+
+#endif