Cleanup: Remove VersionUpdater::RelaunchBrowser interface method.

chrome/browser/ui/webui/help/version_updater_basic.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_UI_WEBUI_HELP_VERSION_UPDATER_BASIC_H_
 #define CHROME_BROWSER_UI_WEBUI_HELP_VERSION_UPDATER_BASIC_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "chrome/browser/ui/webui/help/version_updater.h"
 
 // Bare bones implementation just checks if a new version is ready.
 class VersionUpdaterBasic : public VersionUpdater {
  public:
   // VersionUpdater implementation.
   void CheckForUpdate(const StatusCallback& callback,
                       const PromoteCallback&) override;
-  void RelaunchBrowser() const override;
-
  protected:
   friend class VersionUpdater;
 
   // Clients must use VersionUpdater::Create().
   VersionUpdaterBasic() {}
   ~VersionUpdaterBasic() override {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(VersionUpdaterBasic);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_HELP_VERSION_UPDATER_BASIC_H_