MD Settings: break SettingsPageUIHandler to its own file

chrome/browser/ui/webui/settings/settings_default_browser_handler.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_SETTINGS_SETTINGS_DEFAULT_BROWSER_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_SETTINGS_DEFAULT_BROWSER_HANDLER_H_
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/shell_integration.h"
-#include "chrome/browser/ui/webui/settings/md_settings_ui.h"
+#include "chrome/browser/ui/webui/settings/settings_page_ui_handler.h"
 #include "components/prefs/pref_member.h"
 
 namespace base {
 class ListValue;
 }
 
 namespace content {
 class WebUI;
 }
 
@@ skipping 31 matching lines @@
 
   // Used to invalidate the DefaultBrowserWorker callback.
   base::WeakPtrFactory<DefaultBrowserHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultBrowserHandler);
 };
 
 }  // namespace settings
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_SETTINGS_DEFAULT_BROWSER_HANDLER_H_