Re-landing perf improvement for libjingle logging after reverting the general change.
This contains only a part of r8635 that I just reverted to unblock the roll.

TBR=perkj@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/42259004

Cr-Commit-Position: refs/heads/master@{#8643}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8643 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed