For c++, Generate enum classes instead of enum from mojom.

examples/pdf_viewer/pdf_viewer.cc

 // 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.
 
 #include <string>
 
 #include "examples/bitmap_uploader/bitmap_uploader.h"
 #include "mojo/application/application_runner_chromium.h"
 #include "mojo/application/content_handler_factory.h"
 #include "mojo/data_pipe_utils/data_pipe_utils.h"
@@ skipping 88 matching lines @@
   void OnViewBoundsChanged(View* view,
                            const Rect& old_bounds,
                            const Rect& new_bounds) override {
     DCHECK(embedder_for_roots_.find(view) != embedder_for_roots_.end());
     DrawBitmap(embedder_for_roots_[view]);
   }
 
   void OnViewInputEvent(View* view, const EventPtr& event) override {
     DCHECK(embedder_for_roots_.find(view) != embedder_for_roots_.end());
     if (event->key_data &&
-        (event->action != EVENT_TYPE_KEY_PRESSED || event->key_data->is_char)) {
+        (event->action != EventType::KEY_PRESSED || event->key_data->is_char)) {
       return;
     }
     if ((event->key_data &&
-         event->key_data->windows_key_code == KEYBOARD_CODE_DOWN) ||
+         event->key_data->windows_key_code == KeyboardCode::DOWN) ||
         (event->pointer_data && event->pointer_data->vertical_wheel < 0)) {
       if (current_page_ < (page_count_ - 1)) {
         current_page_++;
         DrawBitmap(embedder_for_roots_[view]);
       }
     } else if ((event->key_data &&
-                event->key_data->windows_key_code == KEYBOARD_CODE_UP) ||
+                event->key_data->windows_key_code == KeyboardCode::UP) ||
                (event->pointer_data &&
                 event->pointer_data->vertical_wheel > 0)) {
       if (current_page_ > 0) {
         current_page_--;
         DrawBitmap(embedder_for_roots_[view]);
       }
     }
   }
 
   void OnViewDestroyed(View* view) override {
@@ skipping 81 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(PDFViewer);
 };
 
 }  // namespace examples
 }  // namespace mojo
 
 MojoResult MojoMain(MojoHandle application_request) {
   mojo::ApplicationRunnerChromium runner(new mojo::examples::PDFViewer());
   return runner.Run(application_request);
 }