Mac: turn on file access checks for the UI thread.
Mac: turn on file access checks for the UI thread.

BUG=60211
TEST=bots

Review URL: http://codereview.chromium.org/4144003

git-svn-id: http://src.chromium.org/svn/trunk/src@64094 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 30aa6de7da4c3c53f40e0a814f2685e69cea15f8
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