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

mojo/services/surfaces/public/cpp/surfaces_utils.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 "surfaces/public/cpp/surfaces_utils.h"
 
 #include "geometry/public/interfaces/geometry.mojom.h"
 
 namespace mojo {
 
@@ skipping 13 matching lines @@
   SharedQuadStatePtr sqs = SharedQuadState::New();
   sqs->content_to_target_transform = GetIdentityTransform();
   sqs->content_bounds = size.Clone();
   Rect rect;
   rect.width = size.width;
   rect.height = size.height;
   sqs->visible_content_rect = rect.Clone();
   sqs->clip_rect = rect.Clone();
   sqs->is_clipped = false;
   sqs->opacity = 1.f;
-  sqs->blend_mode = mojo::SK_XFERMODE_kSrc_Mode;
+  sqs->blend_mode = mojo::SkXfermode::kSrc_Mode;
   sqs->sorting_context_id = 0;
   return sqs.Pass();
 }
 
 PassPtr CreateDefaultPass(int id, const Rect& rect) {
   PassPtr pass = Pass::New();
   pass->id = id;
   pass->output_rect = rect.Clone();
   pass->damage_rect = rect.Clone();
   pass->transform_to_root_target = GetIdentityTransform();
   pass->has_transparent_background = false;
   return pass.Pass();
 }
 
 }  // namespace mojo