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

services/device_info/device_info.cc

Index: services/device_info/device_info.cc
diff --git a/services/device_info/device_info.cc b/services/device_info/device_info.cc
index 791bc3a6e8713a0285c9ca6e7ca40b0949f8cb75..c94bd0c61be4c2910e3fd35dcd16860490f19873 100644
--- a/services/device_info/device_info.cc
+++ b/services/device_info/device_info.cc
@@ -25,8 +25,8 @@ class DeviceInfo : public mojo::ApplicationDelegate,
   // We look for the 'DISPLAY' environment variable. If present, then we assume
   // it to be a desktop, else we assume it to be a commandline
   void GetDeviceType(const GetDeviceTypeCallback& callback) override {
-    callback.Run(getenv("DISPLAY") ? DEVICE_TYPE_DESKTOP
-                                   : DEVICE_TYPE_HEADLESS);
+    callback.Run(getenv("DISPLAY") ? DeviceInfo::DeviceType::DESKTOP
+                                   : DeviceInfo::DeviceType::HEADLESS);
   }
 
   // |ApplicationDelegate| override.