Introduce LayoutBox::paginationBreakability().

third_party/WebKit/Source/core/layout/LayoutBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 672 matching lines @@
     bool hasScrollableOverflowX() const { return scrollsOverflowX() && pixelSnappedScrollWidth() != pixelSnappedClientWidth(); }
     bool hasScrollableOverflowY() const { return scrollsOverflowY() && pixelSnappedScrollHeight() != pixelSnappedClientHeight(); }
     virtual bool scrollsOverflowX() const { return hasOverflowClip() && (style()->overflowX() == OSCROLL || hasAutoHorizontalScrollbar()); }
     virtual bool scrollsOverflowY() const { return hasOverflowClip() && (style()->overflowY() == OSCROLL || hasAutoVerticalScrollbar()); }
 
     // Elements such as the <input> field override this to specify that they are scrollable
     // outside the context of the CSS overflow style
     virtual bool isIntrinsicallyScrollable(ScrollbarOrientation orientation) const { return false; }
 
     bool hasUnsplittableScrollingOverflow() const;
-    bool isUnsplittableForPagination() const;
+
+    // Page / column breakability inside block-level objects.
+    enum PaginationBreakability {
+        AllowAnyBreaks, // No restrictions on breaking. May examine children to find possible break points.
+        ForbidBreaks, // Forbid breaks inside this object. Content cannot be split nicely into smaller pieces.
+        AvoidBreaks // Preferably avoid breaks. If not possible, examine children to find possible break points.
+    };
+    PaginationBreakability paginationBreakability() const;
 
     LayoutRect localCaretRect(InlineBox*, int caretOffset, LayoutUnit* extraWidthToEndOfLine = nullptr) override;
 
     virtual LayoutRect overflowClipRect(const LayoutPoint& location, OverlayScrollbarSizeRelevancy = IgnoreOverlayScrollbarSize) const;
     LayoutRect clipRect(const LayoutPoint& location) const;
     virtual bool hasControlClip() const { return false; }
     virtual LayoutRect controlClipRect(const LayoutPoint&) const { return LayoutRect(); }
 
     virtual void paintBoxDecorationBackground(const PaintInfo&, const LayoutPoint&) const;
     virtual void paintMask(const PaintInfo&, const LayoutPoint&) const;
@@ skipping 351 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != nullptr))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace blink
 
 #endif // LayoutBox_h