GitLab

Tear down all sub-components of the OzonePlatformScenic implementation
on MessageLoop destruction, to prevent components which set FIDL error-
handlers from observing ZX_ERR_CANCELED events.

MessagePumpFuchsia is also updated to print out the base::Location at
which the {ZxHandle|Fd}WatchController was created, to help in
diagnosing issues with failing asynchronous watch operations.

Bug: 927400
Change-Id: I91ad15b5a5f83c9e45b602a0647745813c55aef9
Reviewed-on: https://chromium-review.googlesource.com/c/1490953Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636197}