Add a development flag for the new material design Settings UI.

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index b002070e002b7313bb121eb505719d4325b574dd..1ce3e02870aa2acd1dbc8a392aae1585b61da1dd 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -1981,6 +1981,14 @@ const Experiment kExperiments[] = {
     SINGLE_VALUE_TYPE(
         switches::kEnableMessageCenterAlwaysScrollUpUponNotificationRemoval)
   },
+  {
+    "enable-md-settings",
+    IDS_FLAGS_ENABLE_MATERIAL_DESIGN_SETTINGS_NAME,
+    IDS_FLAGS_ENABLE_MATERIAL_DESIGN_SETTINGS_DESCRIPTION,
+    kOsDesktop,
+    SINGLE_VALUE_TYPE(
+        switches::kEnableMaterialDesignSettings)
+  },
 #endif
 #if defined(OS_CHROMEOS)
   {