Implement standalone event tracing in AppRTCDemo.

webrtc/base/event_tracer.h

Index: webrtc/base/event_tracer.h
diff --git a/webrtc/base/event_tracer.h b/webrtc/base/event_tracer.h
index cfc6e9e472ed79c6d0375c739269dca36b361e4f..51c8cfdc49d1001f06844e8ff01eeae2e26a91fd 100644
--- a/webrtc/base/event_tracer.h
+++ b/webrtc/base/event_tracer.h
@@ -26,6 +26,8 @@
 #ifndef WEBRTC_BASE_EVENT_TRACER_H_
 #define WEBRTC_BASE_EVENT_TRACER_H_
 
+#include <stdio.h>
+
 namespace webrtc {
 
 typedef const unsigned char* (*GetCategoryEnabledPtr)(const char* name);
@@ -68,4 +70,16 @@ class EventTracer {
 
 }  // namespace webrtc
 
+namespace rtc {
+namespace tracing {
+// Set up internal event tracer.
+void SetupInternalTracer();
+bool StartInternalCapture(const char* filename);
+void StartInternalCaptureToFile(FILE* file);
+void StopInternalCapture();
+// Make sure we run this, this will tear down the internal tracing.
+void ShutdownInternalTracer();
+}  // namespace tracing
+}  // namespace rtc
+
 #endif  // WEBRTC_BASE_EVENT_TRACER_H_