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 4ba4d91b887d8e55a609824e89b5223815a20097..9cea91c6e19d26f53cbf046882af120ddff81661 100644
--- a/base/debug/task_annotator.cc
+++ b/base/debug/task_annotator.cc
@@ -5,6 +5,7 @@
 #include "base/debug/task_annotator.h"
 
 #include "base/debug/alias.h"
+#include "base/metrics/activity_tracker.h"
 #include "base/pending_task.h"
 #include "base/trace_event/trace_event.h"
 #include "base/tracked_objects.h"
@@ -28,6 +29,8 @@ void TaskAnnotator::DidQueueTask(const char* queue_function,
 
 void TaskAnnotator::RunTask(const char* queue_function,
                             const PendingTask& pending_task) {
+  ScopedTaskActivity activity(pending_task);
+
   tracked_objects::TaskStopwatch stopwatch;
   stopwatch.Start();
   tracked_objects::Duration queue_duration =