Simple multi-url support for mojo apps

shell/test/pingable.mojom

Index: shell/test/pingable.mojom
diff --git a/services/icu_data/icu_data.mojom b/shell/test/pingable.mojom
similarity index 63%
copy from services/icu_data/icu_data.mojom
copy to shell/test/pingable.mojom
index 53f8ac5d047091be7948d9d587bcb090fa33cab6..20f6365acb7ed0871e680ed6c224bf8619ea743e 100644
--- a/services/icu_data/icu_data.mojom
+++ b/shell/test/pingable.mojom
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-module icu_data;
+module mojo;
 
-interface ICUData {
-  Map(string sha1hash) => (handle<shared_buffer>? icu_data);
+interface Pingable {
+  Ping(string message) => (string app_url, string message);
 };