Remove the "Settings" packaged app

chrome/browser/ui/webui/options/options_ui.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_OPTIONS_OPTIONS_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_OPTIONS_OPTIONS_UI_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 23 matching lines @@
 class PointerDeviceObserver;
 }  // namespace system
 }  // namespace chromeos
 #endif
 
 namespace options {
 
 // The base class handler of Javascript messages of options pages.
 class OptionsPageUIHandler : public content::WebUIMessageHandler {
  public:
-  // Key for identifying the Settings App localized_strings in loadTimeData.
-  static const char kSettingsAppKey[];
-
   OptionsPageUIHandler();
   ~OptionsPageUIHandler() override;
 
   // Is this handler enabled?
   virtual bool IsEnabled();
 
   // Collects localized strings for options page.
   virtual void GetLocalizedValues(base::DictionaryValue* localized_strings) = 0;
 
   virtual void PageLoadStarted() {}
@@ skipping 104 matching lines @@
 #endif
 
   base::Time load_start_time_;
 
   DISALLOW_COPY_AND_ASSIGN(OptionsUI);
 };
 
 }  // namespace options
 
 #endif  // CHROME_BROWSER_UI_WEBUI_OPTIONS_OPTIONS_UI_H_