Need to examine the *bottom* of fragmented content.

third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 703 matching lines @@
             paginationStrut += logicalTop + marginBeforeIfFloating();
             setPaginationStrutPropagatedFromChild(paginationStrut);
             if (childBlockFlow)
                 childBlockFlow->setPaginationStrutPropagatedFromChild(LayoutUnit());
         } else {
             child.setPaginationStrut(paginationStrut);
             newLogicalTop += paginationStrut;
         }
     }
 
-    paginatedContentWasLaidOut(newLogicalTop);
+    paginatedContentWasLaidOut(newLogicalTop + child.logicalHeight());
 
     // Similar to how we apply clearance. Go ahead and boost height() to be the place where we're going to position the child.
     setLogicalHeight(logicalHeight() + (newLogicalTop - logicalTop));
 
     // Return the final adjusted logical top.
     return newLogicalTop;
 }
 
 static bool shouldSetStrutOnBlock(const LayoutBlockFlow& block, const RootInlineBox& lineBox, LayoutUnit lineLogicalOffset, int lineIndex, LayoutUnit pageLogicalHeight)
 {
@@ skipping 39 matching lines @@
     if (!pageLogicalHeight)
         return;
     LayoutUnit remainingLogicalHeight = pageRemainingLogicalHeightForOffset(logicalOffset, AssociateWithLatterPage);
     int lineIndex = lineCount(&lineBox);
     if (remainingLogicalHeight < lineHeight || (shouldBreakAtLineToAvoidWidow() && lineBreakToAvoidWidow() == lineIndex)) {
         LayoutUnit paginationStrut = calculatePaginationStrutToFitContent(logicalOffset, remainingLogicalHeight, lineHeight);
         LayoutUnit newLogicalOffset = logicalOffset + paginationStrut;
         // The new offset may require us to insert a new row for columns (fragmentainer group).
         // Give the multicol machinery an opportunity to do so (before checking the height of a
         // column that wouldn't have existed yet otherwise).
-        paginatedContentWasLaidOut(newLogicalOffset);
+        paginatedContentWasLaidOut(newLogicalOffset + lineHeight);
         // Moving to a different page or column may mean that its height is different.
         pageLogicalHeight = pageLogicalHeightForOffset(newLogicalOffset);
         if (lineHeight > pageLogicalHeight) {
             // Too tall to fit in one page / column. Give up. Don't push to the next page / column.
             // TODO(mstensho): Get rid of this. This is just utter weirdness, but the other browsers
             // also do something slightly similar, although in much more specific cases than we do here,
             // and printing Google Docs depends on it.
             return;
         }
 
@@ skipping 40 matching lines @@
         LayoutUnit strut = remainingLogicalHeight + totalLogicalOffset - pageLogicalHeight;
         if (strut > 0) {
             // The block starts in a previous column or page. Set a strut on the block if there's
             // room for the top border, padding and (if it's a float) margin and the line in one
             // column or page.
             if (totalLogicalOffset + lineHeight <= pageLogicalHeight)
                 setPaginationStrutPropagatedFromChild(strut);
         }
     }
 
-    paginatedContentWasLaidOut(logicalOffset);
+    paginatedContentWasLaidOut(logicalOffset + lineHeight);
 }
 
 LayoutUnit LayoutBlockFlow::adjustForUnsplittableChild(LayoutBox& child, LayoutUnit logicalOffset) const
 {
     if (child.paginationBreakability() == AllowAnyBreaks)
         return logicalOffset;
     LayoutUnit childLogicalHeight = logicalHeightForChild(child);
     // Floats' margins do not collapse with page or column boundaries.
     if (child.isFloating())
         childLogicalHeight += marginBeforeForChild(child) + marginAfterForChild(child);
@@ skipping 2268 matching lines @@
     FrameView* frameView = document().view();
     LayoutUnit top = (style()->position() == FixedPosition) ? 0 : frameView->scrollOffset().height();
     int visibleHeight = frameView->visibleContentRect(IncludeScrollbars).height();
     if (size().height() < visibleHeight)
         top += (visibleHeight - size().height()) / 2;
     setY(top);
     dialog->setCentered(top);
 }
 
 } // namespace blink