Revert "Disabling ExtensionPrefStoreTest on valgrind bot as they have memory leak."
Revert "Disabling ExtensionPrefStoreTest on valgrind bot as they have memory leak."

This reverts commit 8bf6c8c414c2614440c11f75cb91c345eac32a46.

will be replaced with suppression

TBR=stuartmorgan@chromium.org

Review URL: http://codereview.chromium.org/2913010

git-svn-id: http://src.chromium.org/svn/trunk/src@52197 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 4f851eb784d74d82c34ef74de9443ee4183991b7
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