While reviewing https://codereview.chromium.org/1678523003/#ps480001, I suspected and confirmed that SourceBuffer does *not* enqueue a task to fire an 'error' event on all appendBuffer() failures. (That patch set was suggesting adding direct calls to append algorithm failures from within initsegmentreceived algorithm.)

I suspect the route forward will probably be to change the WebSourceBuffer append interface to return a boolean indicating whether or not there was a failure during processing of the append. The caller in Blink can then execute the appendError() algorithm correctly (and the patch set I was reviewing, above, would just need to reply false from failed initsegmentreceived impl in Blink and let the engine later report failed append by returning false from WebSourceBuffer append.

Note: I used a locally morphed version of mediasource-gc-after-decode-error-crash.html layout test to observe absence of SourceBuffer 'error' event, and presence of video element 'error' event on decode error resulting from append.