Revert "Track thread activities in order to diagnose hangs."

base/debug/task_annotator.cc

Index: base/debug/task_annotator.cc
diff --git a/base/debug/task_annotator.cc b/base/debug/task_annotator.cc
index 2747d63c2bf29aa3d356c8c750ff3784b943e66f..4ba4d91b887d8e55a609824e89b5223815a20097 100644
--- a/base/debug/task_annotator.cc
+++ b/base/debug/task_annotator.cc
@@ -4,7 +4,6 @@
 
 #include "base/debug/task_annotator.h"
 
-#include "base/debug/activity_tracker.h"
 #include "base/debug/alias.h"
 #include "base/pending_task.h"
 #include "base/trace_event/trace_event.h"
@@ -29,8 +28,6 @@ void TaskAnnotator::DidQueueTask(const char* queue_function,
 
 void TaskAnnotator::RunTask(const char* queue_function,
                             const PendingTask& pending_task) {
-  ScopedTaskRunActivity task_activity(pending_task);
-
   tracked_objects::TaskStopwatch stopwatch;
   stopwatch.Start();
   tracked_objects::Duration queue_duration =