DevTools: Parallelize trace messages serialization.

base/debug/trace_event_impl.h

Index: base/debug/trace_event_impl.h
diff --git a/base/debug/trace_event_impl.h b/base/debug/trace_event_impl.h
index c80826c881ee6bf8af6d9eaf44ffa353dbffd46b..ab4d9416c9be4e225eb487ce85ac28925010dc26 100644
--- a/base/debug/trace_event_impl.h
+++ b/base/debug/trace_event_impl.h
@@ -710,7 +710,9 @@ class BASE_EXPORT TraceLog {
   // |generation| is used in the following callbacks to check if the callback
   // is called for the flush of the current |logged_events_|.
   void FlushCurrentThread(int generation);
-  void ConvertTraceEventsToTraceFormat(scoped_ptr<TraceBuffer> logged_events,
+  // Usually it runs on a different thread.
+  static void ConvertTraceEventsToTraceFormat(
+      scoped_ptr<TraceBuffer> logged_events,
       const TraceLog::OutputCallback& flush_output_callback);
   void FinishFlush(int generation);
   void OnFlushTimeout(int generation);