Revert 107895 - Fully enable about:tracking by default

base/tracking_info.h

-// 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.
-
-// This is a simple struct with tracking information that is stored
-// with a PendingTask (when message_loop is handling the task).
-// Only the information that is shared with the profiler in tracked_objects
-// are included in this structure.
-
-
-#ifndef BASE_TRACKING_INFO_H_
-#define BASE_TRACKING_INFO_H_
-
-#include "base/time.h"
-
-namespace tracked_objects {
-class Location;
-class Births;
-}
-
-namespace base {
-
-// This structure is copied around by value.
-struct BASE_EXPORT TrackingInfo {
-  TrackingInfo(const tracked_objects::Location& posted_from,
-               base::TimeTicks delayed_run_time);
-  ~TrackingInfo();
-
-  // Record of location and thread that the task came from.
-  tracked_objects::Births* birth_tally;
-
-  // Time when the related task was posted.
-  base::TimeTicks time_posted;
-
-  // The time when the task should be run.
-  base::TimeTicks delayed_run_time;
-};
-
-}  // namespace base
-
-#endif  // BASE_TRACKING_INFO_H_