1 files changed, 46 insertions, 0 deletions
diff --git a/layout/generic/FrameChildList.h b/layout/generic/FrameChildList.h
new file mode 100644
index 0000000000..e230f12d3f
--- /dev/null
+++ b/layout/generic/FrameChildList.h
@@ -0,0 +1,46 @@
+/* -*- 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 FrameChildList_h_
+#define FrameChildList_h_
+
+#include "mozilla/EnumSet.h"
+#include "nsFrameList.h"
+#include "nsTArray.h"
+
+class nsIFrame;
+
+namespace mozilla {
+namespace layout {
+
+// enum FrameChildListID lives in nsFrameList.h to solve circular dependencies.
+
+#ifdef DEBUG_FRAME_DUMP
+extern const char* ChildListName(FrameChildListID aListID);
+#endif
+
+using FrameChildListIDs = EnumSet<FrameChildListID>;
+
+class FrameChildList {
+ public:
+  FrameChildList(const nsFrameList& aList, FrameChildListID aID)
+      : mList(aList), mID(aID) {}
+  nsFrameList mList;
+  FrameChildListID mID;
+};
+
+}  // namespace layout
+}  // namespace mozilla
+
+inline void nsFrameList::AppendIfNonempty(
+    nsTArray<mozilla::layout::FrameChildList>* aLists,
+    mozilla::layout::FrameChildListID aListID) const {
+  if (NotEmpty()) {
+    aLists->EmplaceBack(*this, aListID);
+  }
+}
+
+#endif /* !defined(FrameChildList_h_) */