Move the test template to //testing/test.gni (part 2)

ipc/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("//mojo/public/tools/bindings/mojom.gni")
+import("//testing/rules.gni")
 
 mojom("client_channel") {
   sources = [
     "client_channel.mojom",
   ]
 }
 
 component("mojo") {
   sources = [
     "client_channel.mojom",
@@ skipping 51 matching lines @@
     "//base/test:test_support_perf",
     "//base/third_party/dynamic_annotations",
     "//ipc",
     "//ipc:test_support",
     "//ipc/mojo",
     "//mojo/edk/system",
     "//mojo/environment:chromium",
     "//url",
   ]
 }