Use BrowserThread instead of BrowserProcessSubThread for cache thread.
Use BrowserThread instead of BrowserProcessSubThread for cache thread.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/4683006

git-svn-id: http://src.chromium.org/svn/trunk/src@65485 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 5519d418f48a1b003b61589a1f8a36a9b39c31ab
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