Introduce resetLayout(), to offload layoutBlockFlow().

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 401 matching lines @@
   updateAfterLayout();
 
   if (isHTMLDialogElement(node()) && isOutOfFlowPositioned())
     positionDialog();
 
   clearNeedsLayout();
   updateIsSelfCollapsing();
 }
 
 DISABLE_CFI_PERF
-inline bool LayoutBlockFlow::layoutBlockFlow(bool relayoutChildren,
-                                             SubtreeLayoutScope& layoutScope) {
-  LayoutUnit oldLeft = logicalLeft();
-  bool logicalWidthChanged = updateLogicalWidthAndColumnWidth();
-  relayoutChildren |= logicalWidthChanged;
+void LayoutBlockFlow::resetLayout() {
+  if (!firstChild() && !isAnonymousBlock())
+    setChildrenInline(true);
+  setContainsInlineWithOutlineAndContinuation(false);
 
   rebuildFloatsFromIntruding();
 
-  LayoutState state(*this, logicalWidthChanged);
-
-  if (m_paginationStateChanged) {
-    // We now need a deep layout to clean up struts after pagination, if we
-    // just ceased to be paginated, or, if we just became paginated on the
-    // other hand, we now need the deep layout, to insert pagination struts.
-    m_paginationStateChanged = false;
-    state.setPaginationStateChanged();
-  }
-
   // We use four values, maxTopPos, maxTopNeg, maxBottomPos, and maxBottomNeg,
   // to track our current maximal positive and negative margins. These values
   // are used when we are collapsed with adjacent blocks, so for example, if you
   // have block A and B collapsing together, then you'd take the maximal
   // positive margin from both A and B and subtract it from the maximal negative
   // margin from both A and B to get the true collapsed margin. This algorithm
   // is recursive, so when we finish layout() our block knows its current
   // maximal positive/negative values.
   //
   // Start out by setting our margin values to our current margins. Table cells
   // have no margins, so we don't fill in the values for table cells.
   if (!isTableCell()) {
     initMaxMarginValues();
     setHasMarginBeforeQuirk(style()->hasMarginBeforeQuirk());
     setHasMarginAfterQuirk(style()->hasMarginAfterQuirk());
   }
 
-  if (state.isPaginated()) {
+  if (view()->layoutState()->isPaginated()) {
     setPaginationStrutPropagatedFromChild(LayoutUnit());
     setFirstForcedBreakOffset(LayoutUnit());
 
     // Start with any applicable computed break-after and break-before values
     // for this object. During child layout, breakBefore will be joined with the
     // breakBefore value of the first in-flow child, and breakAfter will be
     // joined with the breakAfter value of the last in-flow child. This is done
     // in order to honor the requirement that a class A break point [1] may only
     // exists *between* in-flow siblings (i.e. not before the first child and
     // not after the last child).
     //
     // [1] https://drafts.csswg.org/css-break/#possible-breaks
     setBreakBefore(LayoutBlock::breakBefore());
     setBreakAfter(LayoutBlock::breakAfter());
   }
+}
+
+DISABLE_CFI_PERF
+inline bool LayoutBlockFlow::layoutBlockFlow(bool relayoutChildren,
+                                             SubtreeLayoutScope& layoutScope) {
+  LayoutUnit oldLeft = logicalLeft();
+  bool logicalWidthChanged = updateLogicalWidthAndColumnWidth();
+  relayoutChildren |= logicalWidthChanged;
+
+  LayoutState state(*this, logicalWidthChanged);
+
+  if (m_paginationStateChanged) {

[szager1, 2016/11/30 20:33:28]

Should this be inside resetLayout?  Maybe pass a LayoutState to that method?

[mstensho (USE GERRIT), 2016/11/30 20:47:58]

This is something that ideally should only be done once per layoutBlock() call
(pagination state only changes when style changes, or when entering/leaving
print preview), but since LayoutState is created here in layoutBlockFlow(),
m_paginationStateChanged needs to be here as well. But I intend to move them
both to layoutBlock().

I could put it in resetLayout() temporarily in the meantime, of course. But the
code move from layoutBlockFlow() to layoutBlock() that I'm talking about is only
2-3 CLs down the road.

So I suggest that we keep it here for now, if that's fine with you.

+    // We now need a deep layout to clean up struts after pagination, if we
+    // just ceased to be paginated, or, if we just became paginated on the
+    // other hand, we now need the deep layout, to insert pagination struts.
+    m_paginationStateChanged = false;
+    state.setPaginationStateChanged();
+  }
+
+  LayoutUnit previousHeight = logicalHeight();
+  resetLayout();
 
   LayoutUnit beforeEdge = borderBefore() + paddingBefore();
   LayoutUnit afterEdge =
       borderAfter() + paddingAfter() + scrollbarLogicalHeight();
-  LayoutUnit previousHeight = logicalHeight();
   setLogicalHeight(beforeEdge);
 
-  if (!firstChild() && !isAnonymousBlock())
-    setChildrenInline(true);
-
   TextAutosizer::LayoutScope textAutosizerLayoutScope(this, &layoutScope);
 
   bool preferredLogicalWidthsWereDirty = preferredLogicalWidthsDirty();
 
-  // Reset the flag here instead of in layoutInlineChildren() in case that
-  // all inline children are removed from this block.
-  setContainsInlineWithOutlineAndContinuation(false);
   if (childrenInline())
     layoutInlineChildren(relayoutChildren, afterEdge);
   else
     layoutBlockChildren(relayoutChildren, layoutScope, beforeEdge, afterEdge);
 
   bool preferredLogicalWidthsBecameDirty =
       !preferredLogicalWidthsWereDirty && preferredLogicalWidthsDirty();
   if (preferredLogicalWidthsBecameDirty) {
     // The only thing that should dirty preferred widths at this point is the
     // addition of overflow:auto scrollbars in a descendant. To avoid a
@@ skipping 4031 matching lines @@
   return LayoutBlock::invalidatePaintIfNeeded(paintInvalidationState);
 }
 
 void LayoutBlockFlow::invalidateDisplayItemClients(
     PaintInvalidationReason invalidationReason) const {
   BlockFlowPaintInvalidator(*this).invalidateDisplayItemClients(
       invalidationReason);
 }
 
 }  // namespace blink