Fix possible buffer emission during an abort.

content/renderer/media/websourcebuffer_impl.cc

 // Copyright 2013 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 "content/renderer/media/websourcebuffer_impl.h"
 
 #include <limits>
 
 #include "base/float_util.h"
 #include "media/filters/chunk_demuxer.h"
@@ skipping 69 matching lines @@
 
   // Coded frame processing may update the timestamp offset. If the caller
   // provides a non-NULL |timestamp_offset| and frame processing changes the
   // timestamp offset, report the new offset to the caller. Do not update the
   // caller's offset otherwise, to preserve any pre-existing value that may have
   // more than microsecond precision.
   if (timestamp_offset && old_offset != timestamp_offset_)
     *timestamp_offset = timestamp_offset_.InSecondsF();
 }
 
 void WebSourceBufferImpl::abort() {

[wolenetz, 2014/05/06 00:04:32]

Upon further inspection of the MSE spec, and given the abort() for at least
mp2ts streams could cause further buffers to be processed by the coded frame
processing algorithm, it looks like the Blink interface for WSB::abort() needs
to pass a double* timestamp_offset, and we need to (conditionally) update it
only if we get a non-NULL ptr from Blink AND the abort() changed the TimeDelta
version of it. See ::append(), above, for a clear example of what I mean. Since
coded frame processing can change the timestamp offset, and since everything
below WSBI uses TimeDeltas (lower precision than Blink's double), we need to do
this. I've filed crbug.com/370229 accordingly. Please add a TODO(wolenetz) for
this here, referencing that bug.

[damienv1, 2014/05/06 00:29:00]

Added a comment which references this bug.

-  demuxer_->Abort(id_);
+  demuxer_->Abort(id_,
+                  append_window_start_, append_window_end_,
+                  &timestamp_offset_);
 }
 
 void WebSourceBufferImpl::remove(double start, double end) {
   DCHECK_GE(start, 0);
   DCHECK_GE(end, 0);
   demuxer_->Remove(id_, DoubleToTimeDelta(start), DoubleToTimeDelta(end));
 }
 
 bool WebSourceBufferImpl::setTimestampOffset(double offset) {
   if (demuxer_->IsParsingMediaSegment(id_))
@@ skipping 12 matching lines @@
   DCHECK_GE(end, 0);
   append_window_end_ = DoubleToTimeDelta(end);
 }
 
 void WebSourceBufferImpl::removedFromMediaSource() {
   demuxer_->RemoveId(id_);
   demuxer_ = NULL;
 }
 
 }  // namespace content