Make it possible to run a test in sky_shell

sky/shell/BUILD.gn

 # Copyright 2015 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.
 
 common_deps = [
   "//base",
   "//base:i18n",
   "//build/config/sanitizers:deps",
   "//dart/runtime:libdart",
   "//mojo/common",
@@ skipping 163 matching lines @@
     ]
   }
 } else if (is_linux) {
   executable("shell") {
     output_name = "sky_shell"
 
     sources = [
       "linux/main.cc",
       "linux/platform_service_provider_linux.cc",
       "linux/platform_view_linux.cc",
+      "testing/test_runner.cc",
+      "testing/test_runner.h",
     ]
 
-    deps = common_deps + [ ":common" ]
+    deps = common_deps + [
+             ":common",
+             "//sky/services/testing",
+           ]
   }
 } else {
   assert(false, "Unsupported platform")
 }