Name TaskScheduler's worker threads

In conjunction with https://codereview.chromium.org/1937323002/ this
makes TaskScheduler work with chrome://tracing.

Thread name will be comprised of 3 parts:
 [1] Thread Pool name, e.g. "TaskSchedulerBackgroudFileIO"
 [2] "Worker"
 [3] Thread Index in thread pool

This can make for long names, e.g.:
"TaskSchedulerBackgroudFileIOWorker3"
but I think a descriptive name is still preferable.

The one caveat is that WinDBG's implementation of thread name
currently truncates at 32 characters... I'm willing to live with
that for now until (if ever) we realize it's too annoying.

BUG=553459

Committed: https://crrev.com/a0813e0c0286ee6790433164957141e9f299bff7
Cr-Commit-Position: refs/heads/master@{#392351}

Review-Url: https://codereview.chromium.org/1951453002
Cr-Commit-Position: refs/heads/master@{#392395}


CrOS-Libchrome-Original-Commit: b39e39eeb679c3bf45a444e9e6d0c5e364a8cd17
5 files changed
tree: 69a6465fe59f62e9ae35daa83c0a096048ed8d30
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/