Extract trace from TaskAnnotator::RunTask to its call sites

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 d4f9c546b58ae3e3ceabcd7e6b723ab85de81502..c4ca0fa2bed0c7e6f7e0da4ad9a58e52f3ee8b83 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)
@@ -473,10 +474,18 @@ void MessageLoop::RunTask(const PendingTask& pending_task) {
 
   HistogramEvent(kTaskRunEvent);
 
+  TRACE_EVENT_WITH_MEMORY_TAG2(
+      "toplevel",
+      "MessageLoop::PostTask",
+      pending_task.posted_from.function_name(),  // Name for memory tracking.
+      "src_file",
+      pending_task.posted_from.file_name(),
+      "src_func",
+      pending_task.posted_from.function_name());
+
   FOR_EACH_OBSERVER(TaskObserver, task_observers_,
                     WillProcessTask(pending_task));
-  task_annotator_.RunTask(
-      "MessageLoop::PostTask", "MessageLoop::RunTask", pending_task);
+  task_annotator_.RunTask("MessageLoop::RunTask", pending_task);
   FOR_EACH_OBSERVER(TaskObserver, task_observers_,
                     DidProcessTask(pending_task));