GitLab

Adds external/wpt tests for the SourceBuffer.changeType() method being
incubated in WICG/media-source spec repo's codec-switching branch.

BUG=605134

Change-Id: I52879fdff07473fbec6f5b44296dedd42619455c
Reviewed-on: https://chromium-review.googlesource.com/1111275
Commit-Queue: Matthew Wolenetz <wolenetz@chromium.org>
Reviewed-by: Dan Sanders <sandersd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569812}