Add application/xml and text/xml to the list of content types that we allow switching using http header.
Add application/xml and text/xml to the list of content types
that we allow switching using http header.

BUG=56269
TEST=none


Review URL: http://codereview.chromium.org/3397025

git-svn-id: http://src.chromium.org/svn/trunk/src@60488 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 146ad3304b35e0b0b063b6535f299b3d48494647
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