1 files changed, 44 insertions, 0 deletions
diff --git a/layout/base/ScrollStyles.h b/layout/base/ScrollStyles.h
new file mode 100644
index 0000000000..473277a968
--- /dev/null
+++ b/layout/base/ScrollStyles.h
@@ -0,0 +1,44 @@
+/* -*- 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_ScrollStyles_h
+#define mozilla_ScrollStyles_h
+
+#include <stdint.h>
+
+// Forward declarations
+struct nsStyleDisplay;
+
+namespace mozilla {
+
+enum class StyleOverflow : uint8_t;
+
+struct ScrollStyles {
+  // Always one of Scroll, Hidden, or Auto.
+  StyleOverflow mHorizontal;
+  StyleOverflow mVertical;
+
+  ScrollStyles(StyleOverflow aH, StyleOverflow aV);
+
+  // NOTE: This ctor maps `visible` to `auto` and `clip` to `hidden`.
+  // It's used for styles that are propagated from the <body> and for
+  // scroll frames (which we create also for overflow:clip/visible in
+  // some cases, e.g. form controls).
+  enum MapOverflowToValidScrollStyleTag { MapOverflowToValidScrollStyle };
+  ScrollStyles(const nsStyleDisplay&, MapOverflowToValidScrollStyleTag);
+
+  bool operator==(const ScrollStyles& aStyles) const {
+    return aStyles.mHorizontal == mHorizontal && aStyles.mVertical == mVertical;
+  }
+  bool operator!=(const ScrollStyles& aStyles) const {
+    return !(*this == aStyles);
+  }
+  bool IsHiddenInBothDirections() const;
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_ScrollStyles_h