Add the internals of RtcEvent's subclasses

webrtc/logging/rtc_event_log/events/rtc_event_logging_started.h

Index: webrtc/logging/rtc_event_log/events/rtc_event_logging_started.h
diff --git a/webrtc/logging/rtc_event_log/events/rtc_event_logging_started.h b/webrtc/logging/rtc_event_log/events/rtc_event_logging_started.h
index e2acd867c188b6701543f7877a21e51005a0c88c..3e6c3514ddf63312c624d4eba26d01135390f5f4 100644
--- a/webrtc/logging/rtc_event_log/events/rtc_event_logging_started.h
+++ b/webrtc/logging/rtc_event_log/events/rtc_event_logging_started.h
@@ -12,14 +12,18 @@
 #define WEBRTC_LOGGING_RTC_EVENT_LOG_EVENTS_RTC_EVENT_LOGGING_STARTED_H_
 
 #include "webrtc/logging/rtc_event_log/events/rtc_event.h"
+#include "webrtc/typedefs.h"
 
 namespace webrtc {
 
 class RtcEventLoggingStarted final : public RtcEvent {
  public:
+  explicit RtcEventLoggingStarted(int64_t timestamp_us);
   ~RtcEventLoggingStarted() override = default;
 
   Type GetType() const override;
+
+  int64_t timestamp_us_;
 };
 
 }  // namespace webrtc