Use NullTaskRunner in BudgetPool tests.

Bug: 841735
Change-Id: I5a38422269e6635c6cc7b4880c1a9108b0bd3761
Reviewed-on: https://chromium-review.googlesource.com/1129231
Reviewed-by: Alexander Timin <altimin@chromium.org>
Commit-Queue: Greg Kraynov <kraynov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573330}
1 file changed