ProcessThreadImpl - hold the lock while checking thread_ and calling ProcessThreadAttached().
This is needed since DeRegisterModule is currently being called on arbitrary threads.

BUG=4508
R=perkj@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/48829004

Cr-Commit-Position: refs/heads/master@{#8924}
1 file changed