Valgrind: Suppress a small leak in ExtensionPrefsTest.
Valgrind: Suppress a small leak in ExtensionPrefsTest.

BUG=65642
TEST=Valgrind unit tests go green.
TBR=bauerb
Review URL: http://codereview.chromium.org/5556009

git-svn-id: http://src.chromium.org/svn/trunk/src@68375 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: b71eef9373b1fa48d1ab2494609b35c4cd881461
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser