Tweak STE::HasIncompleteUndelayedTasksForTesting() to provide side-effects visibility guarantees.

R=fdoray@chromium.org

Bug: 708584
Change-Id: I4a84351a3c4556f960628be140f1545208e02988
Reviewed-on: https://chromium-review.googlesource.com/847431
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: Fran├žois Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#526822}
3 files changed