GitLab

Creating external semaphore and importing semaphores from file handle
are not cost free, so we try to reuse semaphores when it is possible.

Bug: 1004772,1004774,1107558
Change-Id: I3eb0ffd635424487de413162ca2585d7cc7b1265
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2283485
Commit-Queue: Peng Huang <penghuang@chromium.org>
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790695}