Replace TestSimpleTaskRunner::GetPendingTasks with TakePendingTasks

TestSimpleTaskRunner::GetPendingTasks copies whole set of the pending
task for each invocation. That prevents a migration to the non-copyable
Callback.
This CL replaces it with newly added TakePendingTasks and others.

BUG=554299
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_precise_blink_rel

Review-Url: https://codereview.chromium.org/2331423002
Cr-Commit-Position: refs/heads/master@{#422699}


CrOS-Libchrome-Original-Commit: 2d1f91c1ed29c73b81cf6a037435489242bb7aa3
3 files changed
tree: 8382bf57a5c334da074b6f27d88a243fc5fd590a
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/