[MD Settings] Add feature to enable md-settings by default.

chrome/browser/ui/webui/uber/uber_ui.cc

 // 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.
 
 #include "chrome/browser/ui/webui/uber/uber_ui.h"
 
 #include "base/stl_util.h"
 #include "build/build_config.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/chrome_pages.h"
 #include "chrome/browser/ui/webui/chrome_web_ui_controller_factory.h"
 #include "chrome/browser/ui/webui/extensions/extensions_ui.h"
 #include "chrome/browser/ui/webui/log_web_ui_url.h"
 #include "chrome/browser/ui/webui/options/options_ui.h"
 #include "chrome/common/chrome_features.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/chrome_manifest_url_handlers.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/chromium_strings.h"
 #include "chrome/grit/generated_resources.h"
@@ skipping 30 matching lines @@
   // Hack alert: continue showing "Loading..." until a real title is set.
   source->AddLocalizedString("pageTitle", IDS_TAB_LOADING_TITLE);
 
   source->AddString("extensionsFrameURL", chrome::kChromeUIExtensionsFrameURL);
   source->AddString("extensionsHost", chrome::kChromeUIExtensionsHost);
   source->AddString("helpFrameURL", chrome::kChromeUIHelpFrameURL);
   source->AddString("helpHost", chrome::kChromeUIHelpHost);
   source->AddString("historyFrameURL", chrome::kChromeUIHistoryFrameURL);
   source->AddString("historyHost", chrome::kChromeUIHistoryHost);
   source->AddString("settingsFrameURL", chrome::kChromeUISettingsFrameURL);
-  source->AddString("settingsHost", chrome::kChromeUISettingsHost);
+  source->AddString("settingsHost", chrome::GetLegacySettingsHost());
 
   return source;
 }
 
 // Determines whether the user has an active extension of the given type.
 bool HasExtensionType(content::BrowserContext* browser_context,
                       const std::string& extension_type) {
   const extensions::ExtensionSet& extension_set =
       extensions::ExtensionRegistry::Get(browser_context)->enabled_extensions();
   for (extensions::ExtensionSet::const_iterator iter = extension_set.begin();
@@ skipping 170 matching lines @@
   // opens the default history page if one is uninstalled or disabled.
   UpdateHistoryNavigation(web_ui());
 }
 
 void UberFrameUI::OnExtensionUnloaded(
     content::BrowserContext* browser_context,
     const extensions::Extension* extension,
     extensions::UnloadedExtensionInfo::Reason reason) {
   UpdateHistoryNavigation(web_ui());
 }