Handler settings page.

content/common/notification_type.h

Index: content/common/notification_type.h
diff --git a/content/common/notification_type.h b/content/common/notification_type.h
index f2428baaf37113123075a4510934f039b7e1e43f..d952f22dca58183722e2720a8aba7d86b2d6aaf7 100644
--- a/content/common/notification_type.h
+++ b/content/common/notification_type.h
@@ -1305,6 +1305,10 @@ class NotificationType {
     HIDE_KEYBOARD_INVOKED,
 #endif
 
+    // Protocol Handler Registry -----------------------------------------------
+    // Sent when a ProtocolHandlerRegistry is changed.
+    PROTOCOL_HANDLER_REGISTRY_CHANGED,
+
     // Count (must be last) ----------------------------------------------------
     // Used to determine the number of notification types.  Not valid as
     // a type parameter when registering for or posting notifications.