Enforce correct mime-type on some files formats (especially images).
Enforce correct mime-type on some files formats (especially images).

TEST=none
BUG=none
Review URL: http://codereview.chromium.org/147221

git-svn-id: http://src.chromium.org/svn/trunk/src@19437 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: a6a405e39f776f01b650f115f8354b2c6b5dfe2e
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