clang: don't build unused function
clang: don't build unused function

This function is not used when the tested #define isn't available.

TEST=compiles

Review URL: http://codereview.chromium.org/3290001

git-svn-id: http://src.chromium.org/svn/trunk/src@59247 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: a5c3402d8a37901362304218ec34c3537178ad58
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