Reland: Add mock_rtc_event_log.h.

Bug: webrtc:7642
Change-Id: I3f97a8b603e34819e1563b335c1eeb51f89b11ac
Reviewed-on: https://webrtc-review.googlesource.com/37081
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21480}
diff --git a/audio/BUILD.gn b/audio/BUILD.gn
index c6de08f..0fd0ac8 100644
--- a/audio/BUILD.gn
+++ b/audio/BUILD.gn
@@ -105,6 +105,7 @@
       "../call:mock_rtp_interfaces",
       "../call:rtp_interfaces",
       "../call:rtp_receiver",
+      "../logging:mocks",
       "../modules/audio_device:mock_audio_device",
       "../modules/audio_mixer:audio_mixer_impl",
       "../modules/audio_processing:audio_processing_statistics",