[Linux] Fix base_unittests for GCC 4.5.1
[Linux] Fix base_unittests for GCC 4.5.1

This is upstreaming a Gentoo Linux patch.

I have encountered this tiny compile issue
when using a more recent GCC.

TEST=none
BUG=none
Review URL: http://codereview.chromium.org/5791001

git-svn-id: http://src.chromium.org/svn/trunk/src@68933 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 60eb6bc7374633217a236eada7090f8fecdef2b8
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