Block a trace event in the sequence manager from recursively PostTasking

BUG=956337
R=gab@chromium.org

Change-Id: Ib462640e9ff786cf5b777c7f34dfea8955b3bfb9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1575362
Commit-Queue: oysteine <oysteine@chromium.org>
Auto-Submit: oysteine <oysteine@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653879}
2 files changed