Remove forwarding headers in public/

Chromium has been updated to include from the new locations:
https://codereview.chromium.org/68683009/

BUG=none

Review URL: https://codereview.chromium.org/60033008

git-svn-id: svn://svn.chromium.org/blink/trunk@162076 bbb929c8-8fbe-4397-9dbb-9b2b20218538