Delete Tracked, and move Location to its own file.

base/task.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.
 
 #ifndef BASE_TASK_H_
 #define BASE_TASK_H_
 #pragma once
 
 #include "base/base_export.h"
 #include "base/debug/alias.h"
 #include "base/memory/raw_scoped_refptr_mismatch_checker.h"
 #include "base/memory/weak_ptr.h"
-#include "base/tracked.h"
 #include "base/tuple.h"
 
 namespace base {
 const size_t kDeadTask = 0xDEAD7A53;
 }
 
 // Task ------------------------------------------------------------------------
 //
 // A task is a generic runnable thingy, usually used for running code on a
 // different thread or for scheduling future tasks off of the message loop.
 
-class BASE_EXPORT Task : public tracked_objects::Tracked {
+class BASE_EXPORT Task {
  public:
   Task();
   virtual ~Task();
 
   // Tasks are automatically deleted after Run is called.
   virtual void Run() = 0;
 };
 
 class BASE_EXPORT CancelableTask : public Task {
  public:
@@ skipping 565 matching lines @@
   Task* task_;
   bool* should_leak_task_;
   static bool kTaskLeakingDefault;
 };
 
 }  // namespace subtle
 
 }  // namespace base
 
 #endif  // BASE_TASK_H_