Reinstate removed but needed header files.

BUG=837308

Change-Id: Id8c91d2f4a12ed3a60da30e5e7104ec25414feee
Reviewed-on: https://chromium-review.googlesource.com/c/1391291
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618970}
14 files changed