Add missing #include around sequenced_worker_pool.h in //chrome

chrome/browser/task_manager/sampling/task_manager_impl.cc

 // Copyright 2015 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 "chrome/browser/task_manager/sampling/task_manager_impl.h"
 
 #include <algorithm>
 #include <string>
 #include <unordered_map>
 #include <unordered_set>
 #include <vector>
 
 #include "base/containers/adapters.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "build/build_config.h"
 #include "chrome/browser/task_manager/providers/browser_process_task_provider.h"
 #include "chrome/browser/task_manager/providers/child_process_task_provider.h"
 #include "chrome/browser/task_manager/providers/web_contents/web_contents_task_provider.h"
 #include "chrome/browser/task_manager/sampling/shared_sampler.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/gpu_data_manager.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
@@ skipping 543 matching lines @@
         groups_itr.second->AreBackgroundCalculationsDone();
   }
   if (are_all_processes_data_ready) {
     NotifyObserversOnRefreshWithBackgroundCalculations(GetTaskIdsList());
     for (const auto& groups_itr : task_groups_by_proc_id_)
       groups_itr.second->ClearCurrentBackgroundCalculationsFlags();
   }
 }
 
 }  // namespace task_manager