Implement Clipboard::ReadAvailableTypes for Linux.
Implement Clipboard::ReadAvailableTypes for Linux.

BUG=75237
TEST=Local testing.

Review URL: http://codereview.chromium.org/6825064

git-svn-id: http://src.chromium.org/svn/trunk/src@81809 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 1f10ad0d6763987e9b6793a5bcb70e4c63b43491
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