base/threading: remove ScopedTracker placed for experiments

Now that it turns out jank doesn't matter here, let's remove
the experimental code to measure the jank.

BUG=495097

Review URL: https://codereview.chromium.org/1265583003

Cr-Commit-Position: refs/heads/master@{#341975}


CrOS-Libchrome-Original-Commit: 16beb4ed3de2131c961201a5c359462550e83496
1 file changed
tree: 85649ea7d35bf4e1217fbb29838862b5cad739a5
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/