gpu: Add a couple of unit-tests for GpuService.

services/ui/gpu/BUILD.gn

 # Copyright 2016 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")
 import("//services/service_manager/public/service_manifest.gni")
 import("//testing/test.gni")
 
 source_set("gpu") {
   output_name = "mus_gpu"
@@ skipping 33 matching lines @@
   testonly = true
   deps = [
     ":mus_gpu_unittests",
   ]
 }
 
 test("mus_gpu_unittests") {
   deps = [
     ":gpu",
     "//base",
+    "//gpu",
     "//ipc",
     "//services/ui/common:run_all_service_tests",
+    "//services/ui/gpu/interfaces",
     "//testing/gtest",
     "//ui/gfx:memory_buffer",
     "//ui/gfx/geometry",
   ]
+
+  sources = [
+    "gpu_service_unittest.cc",
+  ]
 }
 
 service_manifest("mus_gpu_unittests_app_manifest") {
   name = "mus_gpu_unittests_app"
   source = "mus_gpu_unittests_app_manifest.json"
 }