Add calls to WrapCurrentThread and UnwrapCurrentThread.

Needed after the move of the rtc::Task class and its tests, because
webrtc in chrome is built with NO_MAIN_THREAD_WRAPPING.

BUG=708968

Review-Url: https://codereview.chromium.org/2803023002
Cr-Commit-Position: refs/heads/master@{#462802}
1 file changed