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

sql/mojo/vfs_unittest.cc

Index: sql/mojo/vfs_unittest.cc
diff --git a/sql/mojo/vfs_unittest.cc b/sql/mojo/vfs_unittest.cc
index e51f1bd1e11531a51b6831d875852c1a96ebb1f9..e53ea11cf75c2160666af614457251dacd6de430 100644
--- a/sql/mojo/vfs_unittest.cc
+++ b/sql/mojo/vfs_unittest.cc
@@ -58,12 +58,12 @@ class VFSTest : public mojo::test::ApplicationTestBase,
     filesystem::FileSystemClientPtr client;
     binding_.Bind(GetProxy(&client));
 
-    filesystem::FileError error = filesystem::FILE_ERROR_FAILED;
+    filesystem::FileError error = filesystem::FileError::FAILED;
     filesystem::DirectoryPtr directory;
     files_->OpenFileSystem("temp", GetProxy(&directory), std::move(client),
                            mojo::Capture(&error));
     ASSERT_TRUE(files_.WaitForIncomingResponse());
-    ASSERT_EQ(filesystem::FILE_ERROR_OK, error);
+    ASSERT_EQ(filesystem::FileError::OK, error);
 
     vfs_.reset(new ScopedMojoFilesystemVFS(std::move(directory)));
   }