rtc_event_log2text doesn't currently handle all possible RtcEvent-s. 1. This CL - to make sure events are not forgotten in the future, change the succession of if-statements to a switch, so that the compiler would complain if events are ever added, but are not handled here. 2. Next CL - add handling of currently-unhandled events. BUG=webrtc:8111 NOPRESUBMIT=True Change-Id: Ia4459b4e760eb0208823fdab69996de0e8420703 Reviewed-on: https://webrtc-review.googlesource.com/1242 Commit-Queue: Elad Alon <eladalon@webrtc.org> Reviewed-by: Elad Alon <eladalon@webrtc.org> Cr-Commit-Position: refs/heads/master@{#19861}