Hooked up RtcEventLog. It lives in Voice Engine and pointers are propagated to ACM and Call.

An option was added to voe_cmd_test to make a RtcEventLog dump.

BUG=webrtc:4741

Review URL: https://codereview.webrtc.org/1267683002

Cr-Commit-Position: refs/heads/master@{#9901}

talk/media/webrtc/fakewebrtcvoiceengine.h

@@ -536,6 +536,7 @@ class FakeWebRtcVoiceEngine
     channels_[channel]->associate_send_channel = accociate_send_channel;
     return 0;
   }
+  webrtc::RtcEventLog* GetEventLog() { return nullptr; }
 
   // webrtc::VoECodec
   WEBRTC_FUNC(NumOfCodecs, ()) {