Trace loggging: Check for g_event_logger is not null before calling it.

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 cb7554a891f6db4dd566c6c3c4f4c92333adf652..24ab99acf14b3dba2228073aa78d8e3b408485fa 100644
--- a/webrtc/base/event_tracer.cc
+++ b/webrtc/base/event_tracer.cc
@@ -374,22 +374,30 @@ void SetupInternalTracer() {
 }
 
 void StartInternalCaptureToFile(FILE* file) {
-  g_event_logger->Start(file, false);
+  if (g_event_logger) {

[tkchin_webrtc, 2017/06/27 22:56:40]

I'm not sure how thread-safe this check is. Ask owner of the file?

[jtt_webrtc, 2017/06/28 17:44:25]

The only time g_event_logger is changed is when SetupInternalTracer or
ShutdownInternalTracer is called.
Since we're just checking if g_event_logger is not null, and if it is null, it
is okay if the logging is not called.

Adding owner to reviewers.

+    g_event_logger->Start(file, false);
+  }
 }
 
 bool StartInternalCapture(const char* filename) {
-  FILE* file = fopen(filename, "w");
-  if (!file) {
-    LOG(LS_ERROR) << "Failed to open trace file '" << filename
-                  << "' for writing.";
+  if (g_event_logger) {
+    FILE* file = fopen(filename, "w");
+    if (!file) {
+      LOG(LS_ERROR) << "Failed to open trace file '" << filename
+                    << "' for writing.";
+      return false;
+    }
+    g_event_logger->Start(file, true);
+    return true;
+  } else {
     return false;
   }
-  g_event_logger->Start(file, true);
-  return true;
 }
 
 void StopInternalCapture() {
-  g_event_logger->Stop();
+  if (g_event_logger) {
+    g_event_logger->Stop();
+  }
 }
 
 void ShutdownInternalTracer() {