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

ui/wm/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")
+import("//testing/test.gni")
 
 component("wm") {
   sources = [
     "core/accelerator_delegate.h",
     "core/accelerator_filter.cc",
     "core/accelerator_filter.h",
     "core/base_focus_rules.cc",
     "core/base_focus_rules.h",
     "core/capture_controller.cc",
     "core/capture_controller.h",
@@ skipping 123 matching lines @@
     "//ui/aura:test_support",
     "//ui/base:test_support",
     "//ui/compositor:test_support",
     "//ui/events:test_support",
     "//ui/events/platform",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/gl",
   ]
 }