GitLab

If an EventRewriter discards the event, callbacks should be run immediately.
Without this, the callback never gets run.

BUG=898658
TEST=covered by tests

Change-Id: Ia2644890750fe328506d4fce3f575f327c06cd1f
Reviewed-on: https://chromium-review.googlesource.com/c/1371216
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615636}