Remove unused base::ScopedZxHandle.
Remove unused base::ScopedZxHandle.

Bug: chromium:852541
Change-Id: I60270c548ab3bd6f30c44a8e6a94cf3119eca7c4
Reviewed-on: https://chromium-review.googlesource.com/1159103
Reviewed-by: Mark Mentovai <f1b5a91d4d6ad523f2610114591c007e75d15084@chromium.org>

chromium/mini_chromium,chromium/mini_chromium,chromium/mini_chromium