Adding a test case to ffmpeg_unittests for bug 62127.

      BUG=62127
TEST=ffmpeg_unittests

Review URL: http://codereview.chromium.org/4590003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@65269 0039d316-1c4b-4281-b951-d872f2087c98