Valgrind: Pass --gtest_shuffle option to gtest.

NOTRY=true

Review URL: https://codereview.chromium.org/86073006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237238 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237238