Add a presubmit check to look for duplicate Valgrind/Heapchecker suppression names.

BUG=none
TEST=none
Review URL: http://codereview.chromium.org/3343020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@59405 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed