Revert of Fix to make the start/stop functions for the Rtc Eventlog non-virtual. (patchset #2 id:40001 of https://codereview.webrtc.org/2107253002/ )

Reason for revert:
Reverting all CLs related to moving the eventlog, as they break Chromium tests.

Original issue's description:
> Fix to make the start/stop functions for the Rtc Eventlog non-virtual.
>
> This is needed to prevent the Chromium import bot from breaking.
>
> BUG=
> R=tommi@webrtc.org
>
> Committed: https://crrev.com/df6ecea8ac7c4c3bddeda089d5fb9eccdf38a0a6
> Cr-Commit-Position: refs/heads/master@{#13324}

TBR=tommi@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review-Url: https://codereview.webrtc.org/2111803002
Cr-Commit-Position: refs/heads/master@{#13339}
diff --git a/webrtc/api/peerconnectioninterface.h b/webrtc/api/peerconnectioninterface.h
index 382a4b4..93cfafd 100644
--- a/webrtc/api/peerconnectioninterface.h
+++ b/webrtc/api/peerconnectioninterface.h
@@ -495,15 +495,11 @@
   // operation fails the file will be closed. The logging will stop
   // automatically after 10 minutes have passed, or when the StopRtcEventLog
   // function is called.
-  // TODO(ivoc): Make this pure virtual when Chrome is updated.
   virtual bool StartRtcEventLog(rtc::PlatformFile file,
-                                int64_t max_size_bytes) {
-    return false;
-  }
+                                int64_t max_size_bytes) = 0;
 
   // Stops logging the RtcEventLog.
-  // TODO(ivoc): Make this pure virtual when Chrome is updated.
-  virtual void StopRtcEventLog() {}
+  virtual void StopRtcEventLog() = 0;
 
   // Terminates all media and closes the transport.
   virtual void Close() = 0;