[MSE] YouTube video decode error when variant-switching
https://bugs.webkit.org/show_bug.cgi?id=135128

Reviewed by Brent Fulgham.

Source/WebCore:
Test: media/media-source/media-source-overlapping-decodetime.html

When variant-switching, the situation can arise where an existing sample with a presentation
timestamp of N and a decode timestamp of M, and a new sample with a presentation timestamp > N
and the same decode timestamp of M, will keep the new sample from being added to the SampleMap.
This can result in a decode error when samples depending on that new, missing sample are enqueued.

The MSE spec is silent on the issue of overlapping decode timestamps. However, it guarantees that
presentation timestamps are non-overlapping. So instead of using just the decode timestamp as a key
for storing the samples in decode order, use both the decode timestamp and the presentation timestamp.
That ensures that samples with different presentation times but equal decode times are both inserted
into the decode queue, and in the correct order.

* Modules/mediasource/SampleMap.cpp:
(WebCore::SampleIsRandomAccess::operator()): Update the parameter type to match the new KeyType.
(WebCore::SampleMap::addSample): Pass both decodeTime and presentationTime as the key to decodeOrder.
(WebCore::SampleMap::removeSample): Ditto.
(WebCore::DecodeOrderSampleMap::findSampleWithDecodeKey): Renamed from findSampleWithDecodeTime.
(WebCore::DecodeOrderSampleMap::reverseFindSampleWithDecodeKey): renamed from reverseFindSampleWithDecodeTime.
(WebCore::DecodeOrderSampleMap::findSyncSamplePriorToPresentationTime): Use renamed version of above.
(WebCore::DecodeOrderSampleMap::findSyncSampleAfterPresentationTime): Ditto.
(WebCore::DecodeOrderSampleMap::findDependentSamples): Ditto.
(WebCore::DecodeOrderSampleMap::findSampleWithDecodeTime): Deleted.
(WebCore::DecodeOrderSampleMap::reverseFindSampleWithDecodeTime): Deleted.
* Modules/mediasource/SampleMap.h:
* Modules/mediasource/SourceBuffer.cpp:
(WebCore::SourceBuffer::removeCodedFrames): Ditto.
(WebCore::SourceBuffer::sourceBufferPrivateDidReceiveSample): Ditto.
(WebCore::SourceBuffer::reenqueueMediaForTime): Ditto.

LayoutTests:
* media/media-source/media-source-overlapping-decodetime-expected.txt: Added.
* media/media-source/media-source-overlapping-decodetime.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@171316 268f45cc-cd09-0410-ab3c-d52691b4dbfc