Add base::test::ScopedTaskEnvironment::RunUntilIdle().

This method runs tasks on the main thread until no main thread
or TaskScheduler undelayed tasks remain.

R=gab@chromium.org,robliao@chromium.org
BUG=708584

Review-Url: https://codereview.chromium.org/2868093002
Cr-Commit-Position: refs/heads/master@{#470537}


CrOS-Libchrome-Original-Commit: f2b4d8358e465e016829cde71d11b736a105770d
3 files changed
tree: d6d1c871245f13333ce9ff0bf783e6b06335e0f7
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/