Make a mojo:apptests GN meta-target, add apptests.

mojo/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("//build/config/ui.gni")
 
 group("mojo") {
   # Meta-target, don't link into production code.
   testonly = true
   deps = [
@@ skipping 21 matching lines @@
     "//third_party/mojo/src/mojo/edk/system:mojo_message_pipe_perftests",
     "//third_party/mojo/src/mojo/edk/system:mojo_system_unittests",
     "//third_party/mojo/src/mojo/edk/test:mojo_public_application_unittests",
     "//third_party/mojo/src/mojo/edk/test:mojo_public_bindings_unittests",
     "//third_party/mojo/src/mojo/edk/test:mojo_public_environment_unittests",
     "//third_party/mojo/src/mojo/edk/test:mojo_public_system_perftests",
     "//third_party/mojo/src/mojo/edk/test:mojo_public_system_unittests",
     "//third_party/mojo/src/mojo/edk/test:mojo_public_utility_unittests",
   ]
 }
+
+# TODO(GYP): Not included in the mojo group meta-target; missing gyp targets.
+#            See the gn_all and gn_only comments in //src/BUILD.gn.
+group("apptests") {
+  testonly = true
+  deps = []
+  if (!is_component_build) {
+    deps += [
+      "//mojo/services/clipboard:apptests",
+      "//mojo/services/html_viewer:apptests",
+      "//mojo/services/network:apptests",
+      "//mojo/services/view_manager:mojo_view_manager_client_apptests",
+      "//mojo/services/view_manager:view_manager_service_apptests",
+      "//mojo/services/window_manager:window_manager_apptests",
+    ]
+  }
+}