Add a basic stub Polymer settings page at chrome://md-settings.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 6986eeeea5fabe7323d3e6a3fc16beaf9c6160b1..39da3d91e8f920dd356e668c8c2831754d702700 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -1376,6 +1376,12 @@ bool PdfMaterialUIEnabled() {
   return false;
 }
 
+
+bool MdSettingsEnabled() {
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      ::switches::kEnableMaterialDesignSettings);
+}
+
 bool SettingsWindowEnabled() {
 #if defined(OS_CHROMEOS)
   return !base::CommandLine::ForCurrentProcess()->HasSwitch(