Add pref to enable/disable palette tray.

chrome/browser/extensions/api/settings_private/prefs_util.cc

Index: chrome/browser/extensions/api/settings_private/prefs_util.cc
diff --git a/chrome/browser/extensions/api/settings_private/prefs_util.cc b/chrome/browser/extensions/api/settings_private/prefs_util.cc
index 76337e8981ddb10403eb9517a842cbb093c41adb..c36ea6d095081fc3b567d75dc4d7461b03919927 100644
--- a/chrome/browser/extensions/api/settings_private/prefs_util.cc
+++ b/chrome/browser/extensions/api/settings_private/prefs_util.cc
@@ -254,13 +254,17 @@ const PrefsUtil::TypedPrefMap& PrefsUtil::GetWhitelistedKeys() {
   (*s_whitelist)["settings.enable_screen_lock"] =
       settings_private::PrefType::PREF_TYPE_BOOLEAN;
 
+  // Ash settings.
+  (*s_whitelist)["settings.enable_stylus_tools"] =
+      settings_private::PrefType::PREF_TYPE_BOOLEAN;
+  (*s_whitelist)["settings.launch_palette_on_eject_event"] =
+      settings_private::PrefType::PREF_TYPE_BOOLEAN;
+
   // Input method settings.
   (*s_whitelist)["settings.language.preload_engines"] =
       settings_private::PrefType::PREF_TYPE_STRING;
   (*s_whitelist)["settings.language.enabled_extension_imes"] =
       settings_private::PrefType::PREF_TYPE_STRING;
-  (*s_whitelist)["settings.launch_palette_on_eject_event"] =
-      settings_private::PrefType::PREF_TYPE_BOOLEAN;
 
   // Device settings.
   (*s_whitelist)["settings.touchpad.enable_tap_to_click"] =