Trace MessageLoop::RunTask execution

base/message_loop/message_loop.cc

Index: base/message_loop/message_loop.cc
diff --git a/base/message_loop/message_loop.cc b/base/message_loop/message_loop.cc
index 4fecbc5a60383ac5c5a6cd84b92edac99afa6223..b7577735f55705bc86e068a77feb053e2707cc03 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -19,6 +19,7 @@
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/thread_local.h"
 #include "base/time/time.h"
+#include "base/trace_event/trace_event.h"
 #include "base/tracked_objects.h"
 
 #if defined(OS_MACOSX)
@@ -454,6 +455,7 @@ bool MessageLoop::ProcessNextDelayedNonNestableTask() {
 
 void MessageLoop::RunTask(const PendingTask& pending_task) {
   DCHECK(nestable_tasks_allowed_);
+  TRACE_EVENT0("toplevel", "MessageLoop::RunTask.WithObservers");
 
 #if defined(OS_WIN)
   if (pending_task.is_high_res) {