Use the theme ID as as the cache-buster, making subsequent NNTP loads much faster.
Use the theme ID as as the cache-buster, making subsequent NNTP loads much faster.

BUG=18427
TEST=Install a few themes, verify that the NNTP never gets out of sync with the installed theme.

Review URL: http://codereview.chromium.org/159900

git-svn-id: http://src.chromium.org/svn/trunk/src@22462 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: a00e3a6dabc43f0206ce92366b9ba3f0ee77173b
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