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

chrome/browser/ui/chrome_pages.h

Index: chrome/browser/ui/chrome_pages.h
diff --git a/chrome/browser/ui/chrome_pages.h b/chrome/browser/ui/chrome_pages.h
index 8e3470bb4853c7bd0bbe157aae106c56d2acee98..a2ff6b5c7205e9faef36b76d98fbdf5075cece2e 100644
--- a/chrome/browser/ui/chrome_pages.h
+++ b/chrome/browser/ui/chrome_pages.h
@@ -57,6 +57,14 @@ void ShowHelpForProfile(Profile* profile, HelpSource source);
 void ShowPolicy(Browser* browser);
 void ShowSlow(Browser* browser);
 
+// For the transition to Material Design settings, Chrome needs to temporarily
+// support two different settings pages - "legacy" and "MD Settings". Depending
+// on a feature flag, chrome://settings will point to one of them, while the
+// other one is reachable via chrome://legacy-settings and chrome://md-settings,
+// respectively.
+std::string GetLegacySettingsHost();
+std::string GetMdSettingsHost();
+
 // Constructs a settings GURL for the specified |sub_page|.
 GURL GetSettingsUrl(const std::string& sub_page);