[iOS/GN] Fix compilation of "all" with gn.

mojo/edk/system/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("//testing/test.gni")
 import("../../../mojo/public/tools/bindings/mojom.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
@@ skipping 141 matching lines @@
 
 test("mojo_system_unittests") {
   sources = [
     "awakable_list_unittest.cc",
     "core_test_base.cc",
     "core_test_base.h",
     "core_unittest.cc",
     "message_pipe_unittest.cc",
     "options_validation_unittest.cc",
     "platform_handle_dispatcher_unittest.cc",
-    "platform_wrapper_unittest.cc",
     "shared_buffer_dispatcher_unittest.cc",
     "shared_buffer_unittest.cc",
     "wait_set_dispatcher_unittest.cc",
     "waiter_test_utils.cc",
     "waiter_test_utils.h",
     "waiter_unittest.cc",
     "watch_unittest.cc",
   ]
 
   if (!is_ios) {
     sources += [
       "data_pipe_unittest.cc",
       "multiprocess_message_pipe_unittest.cc",
+      "platform_wrapper_unittest.cc",
     ]
   }
 
   deps = [
     ":test_utils",
     "//base",
     "//base/test:test_support",
     "//mojo/edk/embedder:embedder_unittests",
     "//mojo/edk/system",
     "//mojo/edk/system/ports:tests",
@@ skipping 15 matching lines @@
       ":test_utils",
       "//base",
       "//base/test:test_support",
       "//mojo/edk/system",
       "//mojo/edk/test:run_all_perftests",
       "//mojo/edk/test:test_support",
       "//testing/gtest",
     ]
   }
 }