GTTF: Run perf tests serially

This makes media_perftests run serially
(see https://codereview.chromium.org/112633009).

Also update other perf tests (initially changed by
https://codereview.chromium.org/47023009/ and
https://codereview.chromium.org/52443004) now that we have
LaunchUnitTestsSerially (for consistency).

BUG=236893
R=dalecurtis@chromium.org, jamesr@chromium.org, piman@chromium.org

Review URL: https://codereview.chromium.org/128593002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244806 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244806