During thread detach, delay final sweep until shutdown lock is held.

Otherwise we risk re-scheduling a lazy sweep if the thread has to go via
a safe point before proceeding to clean out and shut down.

R=haraken
BUG=357427

Review URL: https://codereview.chromium.org/850433002

git-svn-id: svn://svn.chromium.org/blink/trunk@188193 bbb929c8-8fbe-4397-9dbb-9b2b20218538
1 file changed
tree: 6db2fed525ea449a1440d9fec4c5498abbe0f081
  1. third_party/