InitialColumnHeightFinder needs to take all expected rows into account.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/MultiColumnFragmentainerGroup.h"
 
 #include "core/layout/ColumnBalancer.h"
 #include "core/layout/FragmentationContext.h"
 #include "core/layout/LayoutMultiColumnSet.h"
 
@@ skipping 62 matching lines @@
     if (!columnSet.isInitialHeightCalculated()) {
       // Initial balancing: Start with the lowest imaginable column height. Also
       // calculate the height of the tallest piece of unbreakable content.
       // Columns should never get any shorter than that (unless constrained by
       // max-height). Propagate this to our containing column set, in case there
       // is an outer multicol container that also needs to balance. After having
       // calculated the initial column height, the multicol container needs
       // another layout pass with the column height that we just calculated.
       InitialColumnHeightFinder initialHeightFinder(
           columnSet, logicalTopInFlowThread(), logicalBottomInFlowThread());
-      LayoutUnit tallestUnbreakableLogicalHeight =
-          initialHeightFinder.tallestUnbreakableLogicalHeight();
       columnSet.propagateTallestUnbreakableLogicalHeight(
-          tallestUnbreakableLogicalHeight);
-      newColumnHeight =
-          std::max(initialHeightFinder.initialMinimalBalancedHeight(),
-                   tallestUnbreakableLogicalHeight);
+          initialHeightFinder.tallestUnbreakableLogicalHeight());
+      newColumnHeight = initialHeightFinder.initialMinimalBalancedHeight();
     } else {
       // Rebalancing: After having laid out again, we'll need to rebalance if
       // the height wasn't enough and we're allowed to stretch it, and then
       // re-lay out.  There are further details on the column balancing
       // machinery in ColumnBalancer and its derivates.
       newColumnHeight = rebalanceColumnHeightIfNeeded();
     }
     setAndConstrainColumnHeight(newColumnHeight);
   } else {
     // The position of the column set may have changed, in which case height
@@ skipping 490 matching lines @@
 MultiColumnFragmentainerGroupList::addExtraGroup() {
   append(MultiColumnFragmentainerGroup(m_columnSet));
   return last();
 }
 
 void MultiColumnFragmentainerGroupList::deleteExtraGroups() {
   shrink(1);
 }
 
 }  // namespace blink