GitLab

In a lot of filters in media code, Stop() has been folded into the dtor.
This model doesn't apply directly to DataSource because DataSource::Stop()
is called by the FFmpegDemuxer, but the DataSource is owned by
WebMediaPlayerImpl.

TBR=gbillock@chromium.org
BUG=349211
TEST=All existing tests pass.

Review URL: https://codereview.chromium.org/413243002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285479 0039d316-1c4b-4281-b951-d872f2087c98