GN: Build rules and fixes for (almost) all mojo unittest targets

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.
 
 group("mojo") {
   deps = [
+    ":tests",
     "//mojo/common",
     "//mojo/examples",
     "//mojo/public",
     "//mojo/services",
     "//mojo/shell:mojo_shell",
-    "//mojo/shell:mojo_shell_tests",
   ]
 }
 
+group("tests") {
+  deps = [
+    "//mojo/apps/js/test:mojo_apps_js_unittests",
+    "//mojo/common:mojo_common_unittests",
+    "//mojo/public/cpp/application/tests:mojo_public_application_unittests",
+    "//mojo/public/cpp/bindings/tests:mojo_public_bindings_unittests",
+    "//mojo/public/cpp/environment/tests:mojo_public_environment_unittests",
+    "//mojo/public/cpp/system/tests:mojo_public_system_unittests",
+    "//mojo/public/cpp/utility/tests:mojo_public_utility_unittests",
+    "//mojo/public/js/bindings/tests:mojo_js_unittests",
+    "//mojo/services/public/cpp/surfaces/tests:mojo_surfaces_lib_unittests",
+    "//mojo/shell:mojo_shell_tests",
+    "//mojo/system:mojo_system_unittests",
+  ]
+}
+
 if (is_android) {
   import("//build/config/android/rules.gni")
 
   generate_jni("jni_headers") {
     sources = [
       "android/javatests/src/org/chromium/mojo/MojoTestCase.java",
       "android/system/src/org/chromium/mojo/system/impl/CoreImpl.java",
       "services/native_viewport/android/src/org/chromium/mojo/PlatformViewportAndroid.java",
     ]
 
     jni_package = "mojo"
   }
 }