Update sync_test.cc to use GetSafeWeakWrapper.

When using GetSafeWeakWrapper, Detach() is called automatically, so
tests don't need to call it themselves.

Bug: 924960
Change-Id: Ie91abc37021f15be0420f3f47894b247810dee4f
Reviewed-on: https://chromium-review.googlesource.com/c/1466782
Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Lowell Manners <lowell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631620}
1 file changed