Bug 1538433 [wpt PR 15991] - MSE: Fix mediasource-changetype-play to …

…work with MseBufferByPts, a=testonly

Automatic update from web-platform-tests
MSE: Fix mediasource-changetype-play to work with MseBufferByPts

This web-platform-test exercises changeType as it splice-overlaps
pairs of audio or video media streams at varying offsets in the
presentation timeline. Splice-overlapping an out-of-order decode stream
(such as the test AVC MP4 media) at arbitrary times can, per spec, drop
significant decode dependencies from a partially-overlapped GOP such
that a buffered range gap could result.

This change is more careful about where it performs splice-overlaps when
the overlapped media is out-of-order-decode, adjusting the splice point
to be at or very near to the next overlapped keyframe. This prevents
removing out-of-order non-keyframes and their dependents from the
overlapped media such that no buffered range gap nor playback stall
should result.

Note that Chromium is sensitive to such out-of-order buffering overlaps
with the new, compliant, MseBufferByPts behavior. Fixing
w3c/media-source#160 could greatly simplify
this problem by allowing apps to explicitly control how the
user agent behaves at these small gaps.

BUG=807793

Change-Id: I020e244c230756eaa1804f81b58a577124a6a28b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1428601
Commit-Queue: Matthew Wolenetz <wolenetzchromium.org>
Reviewed-by: Dan Sanders <sandersdchromium.org>
Cr-Commit-Position: refs/heads/master{#643473}

--

wpt-commits: 27ad6759d421b95b4572f20cabaeb750b3eb9799
wpt-pr: 15991

UltraBlame original commit: fc846bf83bfdae75b97fec2fb139b4b88dc9be7f

testing/web-platform/tests/media-source/mediasource-changetype-play.html

@@ -135,10 +135,11 @@
 {
 async_test
 (
-function
 (
 test
 )
+=
+>
 {
 assert_true
 (
@@ -162,8 +163,6 @@
 test
 media
 "
-+
-audio_types
 )
 ;
 assert_true