Added NiceMock for MockRtcEventLog in several unittests where we don't care about the event logging.

BUG=webrtc:4741
R=stefan@webrtc.org

Review URL: https://codereview.webrtc.org/2121993002 .

Cr-Original-Commit-Position: refs/heads/master@{#13388}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: fa1d568730ed5dedbed840df0836d1a2fd7a19ee
4 files changed