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diff --git a/layout/generic/nsLeafFrame.h b/layout/generic/nsLeafFrame.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 do not have child lists */
+
+#ifndef nsLeafFrame_h___
+#define nsLeafFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsIFrame.h"
+#include "nsDisplayList.h"
+
+/**
+ * Abstract class that provides simple fixed-size layout for leaf objects
+ * (e.g. images, form elements, etc.). Deriviations provide the implementation
+ * of the GetDesiredSize method. The rendering method knows how to render
+ * borders and backgrounds.
+ */
+class nsLeafFrame : public nsIFrame {
+ public:
+  NS_DECL_ABSTRACT_FRAME(nsLeafFrame)
+
+  // nsIFrame replacements
+  void BuildDisplayList(nsDisplayListBuilder* aBuilder,
+                        const nsDisplayListSet& aLists) override;
+
+  /**
+   * Both GetMinISize and GetPrefISize will return whatever GetIntrinsicISize
+   * returns.
+   */
+  virtual nscoord GetMinISize(gfxContext* aRenderingContext) override;
+  virtual nscoord GetPrefISize(gfxContext* aRenderingContext) override;
+
+  /**
+   * Our auto size is just intrinsic width and intrinsic height.
+   */
+  mozilla::LogicalSize ComputeAutoSize(
+      gfxContext* aRenderingContext, mozilla::WritingMode aWM,
+      const mozilla::LogicalSize& aCBSize, nscoord aAvailableISize,
+      const mozilla::LogicalSize& aMargin,
+      const mozilla::LogicalSize& aBorderPadding,
+      const mozilla::StyleSizeOverrides& aSizeOverrides,
+      mozilla::ComputeSizeFlags aFlags) override;
+
+  /**
+   * Each of our subclasses should provide its own Reflow impl:
+   */
+  virtual void Reflow(nsPresContext* aPresContext, ReflowOutput& aDesiredSize,
+                      const ReflowInput& aReflowInput,
+                      nsReflowStatus& aStatus) override = 0;
+
+  virtual bool IsFrameOfType(uint32_t aFlags) const override {
+    // We don't actually contain a block, but we do always want a
+    // computed width, so tell a little white lie here.
+    return nsIFrame::IsFrameOfType(aFlags &
+                                   ~(nsIFrame::eReplacedContainsBlock));
+  }
+
+ protected:
+  nsLeafFrame(ComputedStyle* aStyle, nsPresContext* aPresContext, ClassID aID)
+      : nsIFrame(aStyle, aPresContext, aID) {}
+
+  virtual ~nsLeafFrame();
+
+  /**
+   * Return the intrinsic isize of the frame's content area. Note that this
+   * should not include borders or padding and should not depend on the applied
+   * styles.
+   */
+  virtual nscoord GetIntrinsicISize() = 0;
+
+  /**
+   * Return the intrinsic bsize of the frame's content area.  This should not
+   * include border or padding.  This will only matter if the specified bsize
+   * is auto.  Note that subclasses must either implement this or override
+   * Reflow and ComputeAutoSize; the default Reflow and ComputeAutoSize impls
+   * call this method.
+   */
+  virtual nscoord GetIntrinsicBSize();
+
+  /**
+   * Set aDesiredSize to be the available size
+   */
+  void SizeToAvailSize(const ReflowInput& aReflowInput,
+                       ReflowOutput& aDesiredSize);
+};
+
+#endif /* nsLeafFrame_h___ */