Fix preferred logical widths of orthogonal writing modes

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

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index d0c904e9c63fda921f0c2b284ff6d27d49e23845..7e972405786ba049268e822d5bf98dad21d6c168 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -133,12 +133,30 @@ void LayoutBox::willBeDestroyed()
     if (isOutOfFlowPositioned())
         LayoutBlock::removePositionedObject(this);
     removeFromPercentHeightContainer();
+    if (!documentBeingDestroyed() && isOrthogonalWritingModeRoot())
+        unmarkOrthogonalWritingModeRoot();
 
     ShapeOutsideInfo::removeInfo(*this);
 
     LayoutBoxModelObject::willBeDestroyed();
 }
 
+void LayoutBox::insertedIntoTree()
+{
+    LayoutBoxModelObject::insertedIntoTree();
+
+    if (isOrthogonalWritingModeRoot())
+        markOrthogonalWritingModeRoot();
+}
+
+void LayoutBox::willBeRemovedFromTree()
+{
+    if (!documentBeingDestroyed() && isOrthogonalWritingModeRoot())
+        unmarkOrthogonalWritingModeRoot();
+
+    LayoutBoxModelObject::willBeRemovedFromTree();
+}
+
 void LayoutBox::removeFloatingOrPositionedChildFromBlockLists()
 {
     ASSERT(isFloatingOrOutOfFlowPositioned());
@@ -223,8 +241,16 @@ void LayoutBox::styleDidChange(StyleDifference diff, const ComputedStyle* oldSty
     if (needsLayout() && oldStyle)
         removeFromPercentHeightContainer();
 
-    if (oldHorizontalWritingMode != isHorizontalWritingMode())
+    if (oldHorizontalWritingMode != isHorizontalWritingMode()) {
+        if (parent()) {

[esprehn, 2016/01/31 00:44:56]

The only times you go through here without a parent are:

you're the LayoutView, you're being first constructed before you get inserted,
so insertedIntoTree handles it.

Which case are you guarding here though?

[kojii, 2016/01/31 01:12:20]

This "if" avoids:
* Mark/unmark twice for when first constructed as you said.
* isOrthogonalWritingModeRoot() needs parent() to determine whether it's
orthogonal or not.
so insertedIntoTree() handles when constructed, while this code needs to handle
when styles were changed.

Did I miss something? I actually haven't gone though we always re-attach when
writing-mode is changed, and if that's the case, this code may not run at all.
Are you saying that's the case?

+            if (isOrthogonalWritingModeRoot())
+                markOrthogonalWritingModeRoot();
+            else
+                unmarkOrthogonalWritingModeRoot();
+        }
+
         clearPercentHeightDescendants();
+    }
 
     // If our zoom factor changes and we have a defined scrollLeft/Top, we need to adjust that value into the
     // new zoomed coordinate space.
@@ -3934,6 +3960,18 @@ void LayoutBox::markForPaginationRelayoutIfNeeded(SubtreeLayoutScope& layoutScop
         layoutScope.setChildNeedsLayout(this);
 }
 
+void LayoutBox::markOrthogonalWritingModeRoot()
+{
+    ASSERT(frameView());
+    frameView()->addOrthogonalWritingModeRoot(*this);
+}
+
+void LayoutBox::unmarkOrthogonalWritingModeRoot()
+{
+    ASSERT(frameView());
+    frameView()->removeOrthogonalWritingModeRoot(*this);
+}
+
 void LayoutBox::addVisualEffectOverflow()
 {
     if (!style()->hasVisualOverflowingEffect())