Add mp4 and mp3 media perf test cases.

BUG=None
NOTRY=true
TEST=tools/perf/run_benchmark media.tough_media_cases

Review URL: https://codereview.chromium.org/61603009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236565 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236565