[Extensions] More bindings hardening

Revision 83a4b3aa72d98fe4176b4a54c8cea227ed966570 missed a few
(c/r/resources/extensions).

BUG=468931
BUG=591164

Review URL: https://codereview.chromium.org/1840453002

Cr-Commit-Position: refs/heads/master@{#383541}