mus: Remove unnecessary const from property TypeConverter templates

mash/wm/property_util.cc

 // 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.
 
 #include "mash/wm/property_util.h"
 
 #include <stdint.h>
 
 #include "components/mus/public/cpp/property_type_converters.h"
 #include "components/mus/public/cpp/window_property.h"
@@ skipping 94 matching lines @@
 mus::mojom::WindowType GetWindowType(mus::Window* window) {
   return GetWindowType(window->shared_properties());
 }
 
 mus::mojom::WindowType GetWindowType(
     const mus::Window::SharedProperties& properties) {
   const auto iter =
       properties.find(mus::mojom::WindowManager::kWindowType_Property);
   if (iter != properties.end()) {
     return static_cast<mus::mojom::WindowType>(
-        mojo::TypeConverter<int32_t, const std::vector<uint8_t>>::Convert(
-            iter->second));
+        mojo::ConvertTo<int32_t>(iter->second));
   }
   return mus::mojom::WindowType::POPUP;
 }
 
 }  // namespace wm
 }  // namespace mash