Make the browser's FieldTrialList instance as leaky.

It needs to be persistent for the lifetime for the browser process
and there's no benefit to cleaning it up at process exit.

This fixes a use-after-free when some code would check the state
of a trial or base::Feature on a different thread while the browser
is shutting down (and the FieldTrialList would have been destroyed
already). See referenced bug for an example of this.

Bug: 809564
Change-Id: I017da800635d3a548b283e7b66e69b923e0d61b7
Reviewed-on: https://chromium-review.googlesource.com/907168
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535415}

CrOS-Libchrome-Original-Commit: 8495e2015f6d51b55e210dcaa7d8b8c7dfbeb75d
1 file changed
tree: 7b8d0f5bc886c1a06c5414d3a71861603973b8c0
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/