https://cs.chromium.org/chromium/src/media/test/data/mse_config_change.html

We use this test with vorbis/vp8, but that means we're always using software decoders. We should add an H264 variant of this test and get it running on the optional gpu bots we include for testing.

Another option is to get the VideoDecodeAccelerator unittests running on the optional GPU bots.

Tentatively assigned to Dan, though liberato@ or wolenetz@ might be interested as well.