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.
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-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#8643}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: f696e49c9a19817dfbb6c766a6d98ac2336b14e8

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