Build WebRTC with data channel only.

webrtc/logging/rtc_event_log/rtc_event_log.cc

Index: webrtc/logging/rtc_event_log/rtc_event_log.cc
diff --git a/webrtc/logging/rtc_event_log/rtc_event_log.cc b/webrtc/logging/rtc_event_log/rtc_event_log.cc
index 7469cf7c8529dc8514ec98f1874b204ed1998248..c287b87c5eb7f92ec4320b97aba09b41a3a648d8 100644
--- a/webrtc/logging/rtc_event_log/rtc_event_log.cc
+++ b/webrtc/logging/rtc_event_log/rtc_event_log.cc
@@ -605,15 +605,6 @@ bool RtcEventLog::ParseRtcEventLog(const std::string& file_name,
 
 #endif  // ENABLE_RTC_EVENT_LOG
 
-bool RtcEventLogNullImpl::StartLogging(rtc::PlatformFile platform_file,
-                                       int64_t max_size_bytes) {
-  // The platform_file is open and needs to be closed.
-  if (!rtc::ClosePlatformFile(platform_file)) {
-    LOG(LS_ERROR) << "Can't close file.";
-  }
-  return false;
-}
-
 // RtcEventLog member functions.
 std::unique_ptr<RtcEventLog> RtcEventLog::Create() {
 #ifdef ENABLE_RTC_EVENT_LOG