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

chrome/browser/ui/chrome_pages.cc

Index: chrome/browser/ui/chrome_pages.cc
diff --git a/chrome/browser/ui/chrome_pages.cc b/chrome/browser/ui/chrome_pages.cc
index 179c0bb9bc2c8e19209f385eda61c6e9e92b2df9..2800acd0e130714213d9b78f925a610d51d059a7 100644
--- a/chrome/browser/ui/chrome_pages.cc
+++ b/chrome/browser/ui/chrome_pages.cc
@@ -215,6 +215,14 @@ void ShowSlow(Browser* browser) {
 #endif
 }
 
+std::string GetLegacySettingsHost() {
+  return kChromeUISettingsLegacyHost;
+}
+
+std::string GetMdSettingsHost() {
+  return kChromeUIMdSettingsHost;
+}
+
 GURL GetSettingsUrl(const std::string& sub_page) {
   std::string url = std::string(kChromeUISettingsURL) + sub_page;
 #if defined(OS_CHROMEOS)