Adds support for embedViewManagerClient() to IFrame.

sky/tests/services/resources/iframe-vmc.js

+#!mojo mojo:js_content_handler
+
+define("main", [
+  "console",
+  "mojo/public/js/bindings",
+  "mojo/services/public/js/application",
+  "mojo/services/view_manager/public/interfaces/view_manager.mojom",
+  "services/js/test/echo_service.mojom",
+], function(console, bindings, application, viewManagerMojom, echoServiceMojom) {
+
+  const Application = application.Application;
+  const ViewManagerClient = viewManagerMojom.ViewManagerClient;
+  const EchoService = echoServiceMojom.EchoService;
+
+  var serviceImpl;
+  var success = new Promise(function(resolve) {
+    serviceImpl = {
+      onEmbed: function() {
+        resolve({value: "success"});
+      },
+      echoString: function(s) {
+        return success;
+      },
+    }
+  });
+
+  class IFrameVMCApp extends Application {
+    acceptConnection(initiatorURL, initiatorServiceExchange) {
+      var factory = function() { return serviceImpl; }
+      initiatorServiceExchange.provideService(ViewManagerClient, factory);
+      initiatorServiceExchange.provideService(EchoService, factory);
+    }
+  }
+
+  return IFrameVMCApp;
+});