[Security docs] Note that heuristic API gating is hypothetical.

Bug: None
Change-Id: I1667617b44ee4bb999de3d0b18eacd56a84b9d79
Reviewed-on: https://chromium-review.googlesource.com/1079324
Reviewed-by: Andrew Whalley <awhalley@chromium.org>
Commit-Queue: Andrew Whalley <awhalley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562934}
1 file changed