Revert of DevTools: Parallelize trace messages serialization.

content/browser/tracing/tracing_controller_impl.cc

Index: content/browser/tracing/tracing_controller_impl.cc
diff --git a/content/browser/tracing/tracing_controller_impl.cc b/content/browser/tracing/tracing_controller_impl.cc
index 5f2a18f912a394ee3b8be350daf4575f091bb571..22de3f21037adb7a597099eaf70e8089577a2fa0 100644
--- a/content/browser/tracing/tracing_controller_impl.cc
+++ b/content/browser/tracing/tracing_controller_impl.cc
@@ -349,8 +349,7 @@
     // Flush asynchronously now, because we don't have any children to wait for.
     TraceLog::GetInstance()->Flush(
         base::Bind(&TracingControllerImpl::OnLocalTraceDataCollected,
-                   base::Unretained(this)),
-        true);
+                   base::Unretained(this)));
   }
 
   // Notify all child processes.
@@ -682,8 +681,7 @@
     // called with the last of the local trace data.
     TraceLog::GetInstance()->Flush(
         base::Bind(&TracingControllerImpl::OnLocalTraceDataCollected,
-                   base::Unretained(this)),
-        true);
+                   base::Unretained(this)));
     return;
   }