Simplify mojo_shell since it's now only used for Mandoline.

mojo/application/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.
 
 # GYP version: mojo/mojo_base.gyp:mojo_application_chromium
 source_set("application") {
   sources = [
     "application_runner_chromium.cc",
     "application_runner_chromium.h",
   ]
@@ skipping 20 matching lines @@
     "//mojo/environment:chromium",
     "//third_party/mojo/src/mojo/public/interfaces/application",
     "//third_party/mojo_services/src/content_handler/public/interfaces",
     "//mojo/services/network/public/interfaces",
   ]
 }
 
 source_set("test_support") {
   testonly = true
   sources = [
+    "application_test_base_chromium.cc",
+    "application_test_base_chromium.h",
     "application_test_main_chromium.cc",
   ]
 
-  public_deps = [
-    "//third_party/mojo/src/mojo/public/cpp/application:test_support",
-  ]
   deps = [
     "//base",
     "//base/test:test_support",
+    "//third_party/mojo/src/mojo/public/cpp/application:application",
+    "//third_party/mojo/src/mojo/public/cpp/bindings",
+    "//third_party/mojo/src/mojo/public/cpp/environment",
+    "//third_party/mojo/src/mojo/public/cpp/system",
+    "//testing/gtest",
   ]
 }