[Cleanup] Migrate ImporterList to use the TaskScheduler API.

chrome/browser/importer/importer_list.h

 // Copyright (c) 2012 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 CHROME_BROWSER_IMPORTER_IMPORTER_LIST_H_
 #define CHROME_BROWSER_IMPORTER_IMPORTER_LIST_H_
 
 #include <stddef.h>
 
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/sequence_checker.h"
 #include "base/strings/string16.h"
 #include "chrome/common/importer/importer_data_types.h"
 
 // ImporterList detects installed browsers and profiles via
 // DetectSourceProfilesWorker(). ImporterList lives on the UI thread.
 class ImporterList {
  public:
   ImporterList();
   ~ImporterList();
 
@@ skipping 21 matching lines @@
  private:
   // Called when the source profiles are loaded. Copies the loaded profiles
   // in |profiles| and calls |profiles_loaded_callback|.
   void SourceProfilesLoaded(
       const base::Closure& profiles_loaded_callback,
       const std::vector<importer::SourceProfile>& profiles);
 
   // The list of profiles with the default one first.
   std::vector<importer::SourceProfile> source_profiles_;
 
+  SEQUENCE_CHECKER(sequence_checker_);
+
   base::WeakPtrFactory<ImporterList> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ImporterList);
 };
 
 #endif  // CHROME_BROWSER_IMPORTER_IMPORTER_LIST_H_