Mojo JS bindings: support auto-loading mojom.js deps.

mojo/public/tools/bindings/generators/js_templates/module.amd.tmpl

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 {%- if use_new_js_bindings %}
 
-"use strict";
+'use strict';
 
 (function() {
+  var mojomId = '{{module.path}}';
+  if (mojo.internal.isMojomLoaded(mojomId)) {
+    console.warn('The following mojom is loaded multiple times: ' + mojomId);
+    return;
+  }
+  mojo.internal.markMojomLoaded(mojomId);
+
   // TODO(yzshen): Define these aliases to minimize the differences between the
   // old/new modes. Remove them when the old mode goes away.
   var bindings = mojo;
   var codec = mojo.internal;
   var validator = mojo.internal;
+
 {%-   for import in imports %}
-  var {{import.unique_name}} = {{import.module.namespace}};
+  var {{import.unique_name}} =
+      mojo.internal.exposeNamespace('{{import.module.namespace}}');
+  if (mojo.config.autoLoadMojomDeps) {
+    mojo.internal.loadMojomIfNecessary(
+        '{{import.module.path}}',
+        new URL(
+            '{{import.module|get_relative_path(module)}}.js',
+            document.currentScript.src).href);
+  }
 {%-   endfor %}
 
 {% include "module_definition.tmpl" %}
 })();
 
 {%- else %}
 
 define("{{module.path}}", [
 {%- if module.path !=
          "mojo/public/interfaces/bindings/interface_control_messages.mojom" and
@@ skipping 18 matching lines @@
     , {{import.unique_name}}
 {%-   endfor -%}
 ) {
 
 {%- include "module_definition.tmpl" %}
 
   return exports;
 });
 
 {%- endif %}