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: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@68375 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser