Port ui_base_test_support target GN build.

ui/base/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")
 
 if (is_android) {
   import("//build/config/android/config.gni")
 }
 
@@ skipping 494 matching lines @@
   }
 
   # TODO(GYP): Port this to GN.
   #if (use_system_icu) {
     # When using the system icu, the icu targets generate shim headers
     # which are included by public headers in the ui target, so we need
     # ui to be a hard dependency for all its users.
     #'hard_dependency': 1,
   #}
 }
+
+source_set("ui_base_test_support") {
+  sources = [
+    "test/ui_controls.h",
+    "test/ui_controls_aura.cc",
+    "test/ui_controls_internal_win.cc",
+    "test/ui_controls_internal_win.h",
+    "test/ui_controls_mac.mm",
+    "test/ui_controls_win.cc",
+  ]
+
+  deps = [
+    "//base",
+    "//skia",
+    "//testing/gtest",
+    "//ui/gfx",
+    "//ui/gfx/geometry",
+  ]
+
+  if (!is_ios) {
+    sources += [
+      "ime/dummy_input_method.cc",
+      "ime/dummy_input_method.h",
+      "ime/dummy_text_input_client.cc",
+      "ime/dummy_text_input_client.h",
+    ]
+  }
+}