Remove unnecessary use_new_wrapper_types flag for some mojom targets.

media/midi/BUILD.gn

 # Copyright 2015 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/android/config.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//media/media_options.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
@@ skipping 155 matching lines @@
 
   if (use_udev) {
     deps += [ "//device/udev_linux" ]
   }
 }
 
 mojom("mojo") {
   sources = [
     "midi_service.mojom",
   ]
-  use_new_wrapper_types = true
 }
 
 test("midi_unittests") {
   sources = [
     "message_util_unittest.cc",
     "midi_manager_unittest.cc",
     "midi_manager_usb_unittest.cc",
     "midi_message_queue_unittest.cc",
     "usb_midi_descriptor_parser_unittest.cc",
     "usb_midi_input_stream_unittest.cc",
@@ skipping 23 matching lines @@
     sources += [ "midi_manager_alsa_unittest.cc" ]
   }
 
   if (use_x11) {
     deps += [ "//tools/xdisplaycheck" ]
   }
 
   # This target should not require the Chrome executable to run.
   assert_no_deps = [ "//chrome" ]
 }