Support profiling of tasks run as sequenced_tasks

base/tracking_info.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/tracking_info.h"
 
+#include <stddef.h>
 #include "base/tracked_objects.h"
 
 namespace base {
 
+TrackingInfo::TrackingInfo()
+    : birth_tally(NULL) {
+}
+
 TrackingInfo::TrackingInfo(
     const tracked_objects::Location& posted_from,
     base::TimeTicks delayed_run_time)
     : birth_tally(
           tracked_objects::ThreadData::TallyABirthIfActive(posted_from)),
       time_posted(TimeTicks::Now()),
       delayed_run_time(delayed_run_time) {
 }
 
 TrackingInfo::~TrackingInfo() {}
 
 }  // namespace base