Valgrind: Remove some unused suppressions, widen a suppression, and add a new one.

BUG=101146,181082,241932
TBR=groby
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/15370003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@200917 0039d316-1c4b-4281-b951-d872f2087c98