Mojo JS Bindings: Update User's Guide, examples

examples/js/share_echo.js

+#!mojo:js_content_handler
+// Demonstrate using the ServiceProvider returned by the Shell
+// connectToApplication() method to provide a service to the
+// target application and to request a service from the target
+// application. To run this application with mojo_shell, set DIR
+// to be the absolute path for this directory, then:
+//   mojo_shell "file://$DIR/share_echo.js file://$DIR/share_echo_target.js"
+
+define("main", [
+  "console",
+  "mojo/services/public/js/application",
+  "examples/echo/echo_service.mojom",
+], function(console, application, echo) {
+
+  var Application = application.Application;
+  var EchoService = echo.EchoService;
+
+  class EchoServiceImpl {
+    echoString(s) {
+      return Promise.resolve({value: "ShareEcho: " + s});
+    }
+  }
+
+  class ShareEcho extends Application {
+    initialize(args) {
+      if (args.length != 2) {
+        console.log("Expected URL argument");
+        return;
+      }
+      var shareEchoTargetURL = args[1];
+      // The value of targetSP is-a JS ServiceProvider that's connected to the
+      // share_echo_target.js application. We provide our implementation of
+      // EchoService to the share_echo_target.js application and request its
+      // EchoService implementation.
+      var targetSP = this.shell.connectToApplication(shareEchoTargetURL);
+      targetSP.provideService(EchoService, EchoServiceImpl);
+      var echoService = targetSP.requestService(EchoService);
+      echoService.echoString("ShareEcho").then(function(response) {
+        console.log(response.value);
+      });
+    }
+  }
+
+  return ShareEcho;
+});