Upstream ios/showcase source code.

ios/showcase/test/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.
 
-# This empty target is there to help with upstreaming by removing a manual
-# step from the process (updating the //ios:all target). It will be changed
-# to a real target as part of upstreaming.
-group("all_tests") {
+source_set("test") {
   testonly = true
+  sources = [
+    "showcase_test_case.h",
+    "showcase_test_case.mm",
+  ]
+  deps = [
+    "//base",
+    "//ios/third_party/earl_grey",
+  ]
+  public_deps = [
+    "//build/config/ios:xctest",
+  ]
+  configs += [ "//build/config/compiler:enable_arc" ]
 }