Change mojo enums to be scoped enums in the generated C++ bindings.

components/web_view/frame_apptest.cc

Index: components/web_view/frame_apptest.cc
diff --git a/components/web_view/frame_apptest.cc b/components/web_view/frame_apptest.cc
index 0c7ce4f6d6157f770dac2f2cf0d96da19d5eb9dd..e9601393b3eac6cb6a62a3b8bec16c1f1fd225a2 100644
--- a/components/web_view/frame_apptest.cc
+++ b/components/web_view/frame_apptest.cc
@@ -316,7 +316,7 @@ class FrameTest : public mojo::test::ApplicationTestBase,
     request->url = mojo::String::From(application_impl()->url());
     request->originating_time_ticks = navigation_start_time.ToInternalValue();
     window_and_frame->server_frame()->RequestNavigate(
-        mojom::NAVIGATION_TARGET_TYPE_EXISTING_FRAME,
+        mojom::NavigationTargetType::EXISTING_FRAME,
         window_and_frame->window()->id(), std::move(request));
     return WaitForViewAndFrame();
   }