Additional IPC security documentation.

Talk about the special powers of WebUI renderers, and not-yet-shipped features.

Bug: 789374
Change-Id: I94e76ee58aec2ac0e5c8ca65cbf810e83f6c17e3
Reviewed-on: https://chromium-review.googlesource.com/798393
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521449}
1 file changed