==== 33060 LOG STARTS ====
06:16:14.739 8638 worker/2 external/wpt/media-source/mediasource-remove.html output stderr lines:
06:16:14.739 8638   [10748:42243:0426/061614.724925:941258270774:WARNING:audio_sync_reader.cc(185)] ASR: No room in socket buffer.: Broken pipe
06:16:14.742 8602 [29858/57843] external/wpt/media-source/mediasource-remove.html failed unexpectedly (text diff)
06:16:14.741 8638 worker/2 external/wpt/media-source/mediasource-remove.html failed:
06:16:14.741 8638 worker/2  text diff
==== 33060 LOG ENDS ====

==== 33061 LOG STARTS ====
06:46:34.307 8640 worker/4 external/wpt/media-source/mediasource-remove.html output stderr lines:
06:46:34.307 8640   [06:46:34.026] vtDecompressionDuctCreate signalled err=-8973 (err) (Could not select and open decoder instance) at /SourceCache/CoreMedia_frameworks/CoreMedia-1562.235/Sources/VideoToolbox/VTDecompressionSession.c line 1181
06:46:34.307 8640   <<<< VTVideoEncoderSelection >>>> VTSelectAndCreateVideoEncoderInstanceInternal: no video encoder found for 'avc1'
06:46:34.307 8640   
06:46:34.307 8640   [06:46:34.088] VTSelectAndCreateVideoEncoderInstanceInternal signalled err=-12908 (err) (Video encoder not available) at /SourceCache/CoreMedia_frameworks/CoreMedia-1562.235/Sources/VideoToolbox/VTVideoEncoderSelection.c line 1245
06:46:34.307 8640   [06:46:34.088] VTCompressionSessionCreate signalled err=-12908 (err) (Could not select and open encoder instance) at /SourceCache/CoreMedia_frameworks/CoreMedia-1562.235/Sources/VideoToolbox/VTCompressionSession.c line 946
06:46:34.311 8601 [29201/57843] external/wpt/media-source/mediasource-remove.html failed unexpectedly (text diff)
06:46:34.309 8640 worker/4 external/wpt/media-source/mediasource-remove.html failed:
06:46:34.310 8640 worker/4  text diff
==== 33061 LOG ENDS ====

Build 33062 is again green.

Reopen as it come again:

On Mac10.10
external/wpt/media-source/mediasource-activesourcebuffers.html 
external/wpt/media-source/mediasource-activesourcebuffers.html 
external/wpt/media-source/mediasource-remove.html
external/wpt/media-source/mediasource-remove.html 

On Mac10.11 (retina)
external/wpt/media-source/mediasource-remove.html 
external/wpt/media-source/mediasource-remove.html 

https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.10/builds/33071
https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.11%20(retina)/builds/15186

The test has been disabled by alph@ already. Merge the issue.