1 files changed, 47 insertions, 0 deletions
diff --git a/layout/generic/nsAtomicContainerFrame.h b/layout/generic/nsAtomicContainerFrame.h
new file mode 100644
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+++ b/layout/generic/nsAtomicContainerFrame.h
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+/* -*- 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/. */
+
+/* base class for rendering objects that need child lists but behave like leaf */
+
+#ifndef nsAtomicContainerFrame_h___
+#define nsAtomicContainerFrame_h___
+
+#include "nsContainerFrame.h"
+
+/**
+ * This class is for frames which need child lists but act like a leaf
+ * frame. In general, all frames of elements laid out according to the
+ * CSS box model would need child list for ::backdrop in case they are
+ * in fullscreen, while some of them still want leaf frame behavior.
+ */
+class nsAtomicContainerFrame : public nsContainerFrame
+{
+public:
+  NS_DECL_ABSTRACT_FRAME(nsAtomicContainerFrame)
+
+  // Bypass the nsContainerFrame/nsSplittableFrame impl of the following
+  // methods so we behave like a leaf frame.
+  bool IsLeaf() const override { return true; }
+  FrameSearchResult PeekOffsetNoAmount(bool aForward, int32_t* aOffset) override
+  {
+    return nsFrame::PeekOffsetNoAmount(aForward, aOffset);
+  }
+  FrameSearchResult PeekOffsetCharacter(bool aForward, int32_t* aOffset,
+                                        bool aRespectClusters = true) override
+  {
+    return nsFrame::PeekOffsetCharacter(aForward, aOffset, aRespectClusters);
+  }
+  nsSplittableType GetSplittableType() const override
+  {
+    return nsFrame::GetSplittableType();
+  }
+
+protected:
+  explicit nsAtomicContainerFrame(nsStyleContext* aContext)
+    : nsContainerFrame(aContext) {}
+};
+
+#endif // nsAtomicContainerFrame_h___