Fix the //mojo/go:application target.

mojo/go/BUILD.gn

 # 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.
 
 import("rules.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 
 go_library("application") {
   sources = [
     "//mojo/public/go/application/application_impl.go",
     "//mojo/public/go/application/connection.go",
+    "//mojo/public/go/application/describer.go",
   ]
   deps = [
     ":bindings",
     ":system",
+    "//mojo/public/interfaces/application",
+    "//mojo/public/interfaces/bindings",
   ]
 }
 
 go_library("bindings") {
   sources = [
     "//mojo/public/go/bindings/async_waiter.go",
     "//mojo/public/go/bindings/connector.go",
     "//mojo/public/go/bindings/decoder.go",
     "//mojo/public/go/bindings/encoder.go",
     "//mojo/public/go/bindings/interface.go",
@@ skipping 72 matching lines @@
 
 # These are additional test mojoms beyond those in the target
 # //mojo/public/interfaces/bindings/tests:test_interfaces.
 # These are built without 'generate_type_info = true' and so
 # allow us to test the go code generation in this mode also.
 mojom("more_test_mojoms") {
   sources = [
     "tests/test_enums.mojom",
   ]
 }