Remove dead code from update_client::Component.

components/update_client/component.h

 // Copyright 2017 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 COMPONENTS_UPDATE_CLIENT_COMPONENT_H_
 #define COMPONENTS_UPDATE_CLIENT_COMPONENT_H_
 
 #include <map>
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "base/version.h"
 #include "components/update_client/crx_downloader.h"
 #include "components/update_client/update_client.h"
 #include "components/update_client/update_response.h"
 #include "url/gurl.h"
 
-namespace base {
-class SingleThreadTaskRunner;
-}
 
 namespace update_client {
 
 struct CrxUpdateItem;
-class ComponentUnpacker;
 struct UpdateContext;
 
 // Describes a CRX component managed by the UpdateEngine. Each |Component| is
 // associated with an UpdateContext.
 class Component {
  public:
   using Events = UpdateClient::Observer::Events;
 
   using CallbackHandleComplete = base::Callback<void()>;
 
@@ skipping 268 matching lines @@
    public:
     explicit StateUpdating(Component* component);
     ~StateUpdating() override;
 
    private:
     // State overrides.
     void DoHandle() override;
 
     void InstallComplete(int error_category, int error_code, int extra_code1);
 
-    // Posts replies back to the main thread.
-    scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
-
-    // Unpacks one CRX.
-    scoped_refptr<ComponentUnpacker> unpacker_;
-
-    base::FilePath unpack_path_;
-
     DISALLOW_COPY_AND_ASSIGN(StateUpdating);
   };
 
   class StateUpdated : public State {
    public:
     explicit StateUpdated(Component* component);
     ~StateUpdated() override;
 
    private:
     // State overrides.
@@ skipping 91 matching lines @@
   base::Closure update_check_complete_;
 
   DISALLOW_COPY_AND_ASSIGN(Component);
 };
 
 using IdToComponentPtrMap = std::map<std::string, std::unique_ptr<Component>>;
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_COMPONENT_H_