Revert "Make Chrome_DevToolsADBThread shutdown gracefully in tests"

This reverts commit db0240964c06bf7fdb3bf6b2645614e87fceefab.

Reason for revert:

ASAN is detecting use-after-free: See https://crbug.com/888994 and https://chromium-swarm.appspot.com/task?id=4028b7f2e7276110&refresh=10&show_raw=1

Original change's description:
> Make Chrome_DevToolsADBThread shutdown gracefully in tests
> 
> To land the BrowserUIThreadScheduler we need in tests for all threads
> to stop using base::PostTaskWithTraits before the scheduler is
> deleted. Currently this is true for the UI and IO threads but it's
> not true for Chrome_DevToolsADBThread.
> 
> This patch makes sure references retaining
> AndroidDeviceManager::HandlerThread are released in tests
> which triggers thread shutdown, fixing the problem.
> 
> Bug: 863341, 872372
> Change-Id: Iec737aac74fb62118d07b6cf878a14db055f5be5
> Reviewed-on: https://chromium-review.googlesource.com/1238468
> Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
> Reviewed-by: Finnur Thorarinsson <finnur@chromium.org>
> Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
> Commit-Queue: Alex Clarke <alexclarke@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#593850}

TBR=dgozman@chromium.org,finnur@chromium.org,mlamouri@chromium.org,alexclarke@chromium.org

Change-Id: I3490eaf6c70a85c9eb2e96dcb5b942bff85f4a7a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 863341, 872372
Reviewed-on: https://chromium-review.googlesource.com/1243084
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593904}
8 files changed