Trace tracing Start/Stop events.

webrtc/base/event_tracer.cc

Index: webrtc/base/event_tracer.cc
diff --git a/webrtc/base/event_tracer.cc b/webrtc/base/event_tracer.cc
index 4174589d366a48cf4d20d7cc1bceb8fc0eb3ca4f..9e777a85cef0a30fd62670ee82802a2ac87ce856 100644
--- a/webrtc/base/event_tracer.cc
+++ b/webrtc/base/event_tracer.cc
@@ -139,6 +139,7 @@ class EventLogger final {
   }
 
   void Start(FILE* file, bool owned) {
+    RTC_DCHECK(thread_checker_.CalledOnValidThread());
     RTC_DCHECK(file);
     RTC_DCHECK(!output_file_);
     output_file_ = file;
@@ -158,9 +159,12 @@ class EventLogger final {
 
     // Finally start, everything should be set up now.
     logging_thread_.Start();
+    TRACE_EVENT_INSTANT0("webrtc", "EventLogger::Start");
   }
 
   void Stop() {
+    RTC_DCHECK(thread_checker_.CalledOnValidThread());
+    TRACE_EVENT_INSTANT0("webrtc", "EventLogger::Stop");
     // Try to stop. Abort if we're not currently logging.
     if (rtc::AtomicOps::CompareAndSwap(&g_event_logging_active, 1, 0) == 0)
       return;