Adds mojom structure for ui::Accelerator and struct traits

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/buildflag_header.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
@@ skipping 856 matching lines @@
     "//ui/strings",
     "//url",
   ]
 
   if (build_ime) {
     deps += [ "//ui/base/ime" ]
   }
 
   if (is_ios) {
     deps += [ "//ui/resources:ui_test_pak_bundle_data" ]
+  } else {
+    deps += [ "//ui/base/accelerators/mojo:unittests" ]
   }
 
   if (is_win) {
     sources += [
       "dragdrop/os_exchange_data_win_unittest.cc",
       "win/hwnd_subclass_unittest.cc",
       "win/open_file_name_win_unittest.cc",
       "win/osk_display_manager_unittest.cc",
     ]
 
@@ skipping 98 matching lines @@
 if (is_mac) {
   mac_framework_bundle("ui_unittests_framework") {
     testonly = true
     deps = [
       "//ui/resources:ui_test_pak_bundle_data",
     ]
     info_plist = "test/framework-Info.plist"
     output_name = "ui_unittests Framework"
   }
 }