Bug 1244068 - Part 1: Add enum to represent the style system backend type. r=dholbert

layout/style/StyleBackendType.h

@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_StyleBackendType_h
+#define mozilla_StyleBackendType_h
+
+namespace mozilla {
+
+/**
+ * Enumeration that represents one of the two supported style system backends.
+ */
+enum class StyleBackendType : int
+{
+  Gecko,
+  Servo
+};
+
+} // namespace mozilla
+
+#endif // mozilla_StyleBackendType_h

layout/style/moz.build

@@ -90,6 +90,7 @@ EXPORTS.mozilla += [
     'RuleProcessorCache.h',
     'SheetType.h',
     'StyleAnimationValue.h',
+    'StyleBackendType.h',
 ]
 
 EXPORTS.mozilla.dom += [