[TaskScheduler] DCHECK no TrackedRef obtained after count has already reached zero.

Follow-up to https://crbug.com/827615#c17

R=fdoray@chromium.org, wez@chromium.org

Bug: 827615
Change-Id: I873b3eadd6be973b4e0d7b962d7cd720a663198e
Reviewed-on: https://chromium-review.googlesource.com/1020372
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552241}

CrOS-Libchrome-Original-Commit: b65e8848f2cd5575bc38fe68259f6e002baf5eb1
1 file changed
tree: b8de78cd7cb3fa45ad304d28f9963e1fffd0267e
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/