Be more restrictive about forcing relayout of children for pagination.

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

 /*
  * Copyright (C) 2011 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 14 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/layout/LayoutFlexibleBox.h"
 
 #include "core/frame/UseCounter.h"
 #include "core/layout/LayoutState.h"
+#include "core/layout/LayoutView.h"
 #include "core/layout/TextAutosizer.h"
 #include "core/paint/BlockPainter.h"
 #include "core/paint/PaintLayer.h"
 #include "core/style/ComputedStyle.h"
 #include "platform/LengthFunctions.h"
 #include "wtf/MathExtras.h"
 #include <limits>
 
 namespace blink {
 
@@ skipping 1807 matching lines @@
     mainAxisOffset += isHorizontalFlow() ? verticalScrollbarWidth()
                                          : horizontalScrollbarHeight();
 
   LayoutUnit totalMainExtent = mainAxisExtent();
   if (!shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
     totalMainExtent -= isHorizontalFlow() ? verticalScrollbarWidth()
                                           : horizontalScrollbarHeight();
   LayoutUnit maxAscent, maxDescent;  // Used when align-items: baseline.
   LayoutUnit maxChildCrossAxisExtent;
   bool shouldFlipMainAxis = !isColumnFlow() && !isLeftToRightFlow();
+  bool isPaginated = view()->layoutState()->isPaginated();
   for (size_t i = 0; i < children.size(); ++i) {
     const FlexItem& flexItem = children[i];
     LayoutBox* child = flexItem.box;
 
     DCHECK(!flexItem.box->isOutOfFlowPositioned());
 
     child->setMayNeedPaintInvalidation();
 
     setOverrideMainAxisContentSizeForChild(*child, flexItem.flexedContentSize);
     // The flexed content size and the override size include the scrollbar
@@ skipping 61 matching lines @@
     // on the left. This will be fixed later in flipForRightToLeftColumn.
     LayoutPoint childLocation(
         shouldFlipMainAxis ? totalMainExtent - mainAxisOffset - childMainExtent
                            : mainAxisOffset,
         crossAxisOffset + flowAwareMarginBeforeForChild(*child));
     setFlowAwareLocationForChild(*child, childLocation);
     mainAxisOffset += childMainExtent + flowAwareMarginEndForChild(*child);
 
     mainAxisOffset += justifyContentSpaceBetweenChildren(
         availableFreeSpace, distribution, children.size());
+
+    if (isPaginated)
+      updateFragmentationInfoForChild(*child);
   }
 
   if (isColumnFlow())
     setLogicalHeight(std::max(
         logicalHeight(), mainAxisOffset + flowAwareBorderEnd() +
                              flowAwarePaddingEnd() + scrollbarLogicalHeight()));
 
   if (style()->flexDirection() == FlowColumnReverse) {
     // We have to do an extra pass for column-reverse to reposition the flex
     // items since the start depends on the height of the flexbox, which we
@@ skipping 295 matching lines @@
       LayoutUnit originalOffset =
           lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
       LayoutUnit newOffset =
           contentExtent - originalOffset - lineCrossAxisExtent;
       adjustAlignmentForChild(*flexItem.box, newOffset - originalOffset);
     }
   }
 }
 
 }  // namespace blink