Use Mojo enum types in the C++ USB interface

extensions/browser/api/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.
 
 import("//extensions/common/api/schema.gni")
 import("//tools/json_schema_compiler/json_schema_api.gni")
 
 source_set("api") {
   sources = [
     "api_resource.cc",
@@ skipping 84 matching lines @@
 
   # TODO(michaelpg): Move these deps to the individual APIs that require them.
   deps += [
     "//components/onc",
     "//components/storage_monitor",
     "//device/base",
     "//device/bluetooth",
     "//device/hid",
     "//device/power_save_blocker",
     "//device/serial",
-    "//device/usb",
   ]
 
   if (is_chromeos) {
     public_deps += [
       "//extensions/browser/api/clipboard",
       "//extensions/browser/api/diagnostics",
       "//extensions/browser/api/networking_config",
       "//extensions/browser/api/virtual_keyboard",
       "//extensions/browser/api/vpn_provider",
       "//extensions/browser/api/webcam_private",
@@ skipping 12 matching lines @@
   uncompiled_sources = extensions_api_uncompiled_sources
 
   deps = [
     ":api",
     "//device/serial",
     "//extensions/common/api",
     "//extensions/common/api/cast_channel:cast_channel_proto",
     "//skia",
   ]
 }