Translate flow thread coords to the nearest enclosing coord space when appropriate.

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

Index: third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp
diff --git a/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp b/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp
index e2fae001494443f1b73553c66da12291d449c651..5af30a3bff4a1202b6c641892aa9fdaf2a86ff2d 100644
--- a/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp
+++ b/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp
@@ -98,7 +98,7 @@ bool MultiColumnFragmentainerGroup::recalculateColumnHeight()
     return true; // Need another pass.
 }
 
-LayoutSize MultiColumnFragmentainerGroup::flowThreadTranslationAtOffset(LayoutUnit offsetInFlowThread) const
+LayoutSize MultiColumnFragmentainerGroup::flowThreadTranslationAtOffset(LayoutUnit offsetInFlowThread, CoordinateSpaceConversion mode) const
 {
     LayoutMultiColumnFlowThread* flowThread = m_columnSet.multiColumnFlowThread();
     unsigned columnIndex = columnIndexAtOffset(offsetInFlowThread);
@@ -107,6 +107,9 @@ LayoutSize MultiColumnFragmentainerGroup::flowThreadTranslationAtOffset(LayoutUn
     LayoutRect columnRect(columnRectAt(columnIndex));
     m_columnSet.flipForWritingMode(columnRect);
     LayoutSize translationRelativeToGroup = columnRect.location() - portionRect.location();
+    LayoutSize translationRelativeToFlowThread = translationRelativeToGroup + offsetFromColumnSet() + m_columnSet.topLeftLocationOffset() - flowThread->topLeftLocationOffset();
+    if (mode == CoordinateSpaceConversion::Containing)
+        return translationRelativeToFlowThread;
 
     LayoutSize enclosingTranslation;
     if (LayoutMultiColumnFlowThread* enclosingFlowThread = flowThread->enclosingFlowThread()) {
@@ -114,11 +117,11 @@ LayoutSize MultiColumnFragmentainerGroup::flowThreadTranslationAtOffset(LayoutUn
         // Translation that would map points in the coordinate space of the outermost flow thread to
         // visual points in the first column in the first fragmentainer group (row) in our multicol
         // container.
-        LayoutSize enclosingTranslationOrigin = enclosingFlowThread->flowThreadTranslationAtOffset(firstRow.blockOffsetInEnclosingFragmentationContext());
+        LayoutSize enclosingTranslationOrigin = enclosingFlowThread->flowThreadTranslationAtOffset(firstRow.blockOffsetInEnclosingFragmentationContext(), mode);
 
         // Translation that would map points in the coordinate space of the outermost flow thread to
         // visual points in the first column in this fragmentainer group.
-        enclosingTranslation = enclosingFlowThread->flowThreadTranslationAtOffset(blockOffsetInEnclosingFragmentationContext());
+        enclosingTranslation = enclosingFlowThread->flowThreadTranslationAtOffset(blockOffsetInEnclosingFragmentationContext(), mode);
 
         // What we ultimately return from this method is a translation that maps points in the
         // coordinate space of our flow thread to a visual point in a certain column in this
@@ -129,7 +132,7 @@ LayoutSize MultiColumnFragmentainerGroup::flowThreadTranslationAtOffset(LayoutUn
         enclosingTranslation -= enclosingTranslationOrigin;
     }
 
-    return enclosingTranslation + translationRelativeToGroup + offsetFromColumnSet() + m_columnSet.topLeftLocationOffset() - flowThread->topLeftLocationOffset();
+    return enclosingTranslation + translationRelativeToFlowThread;
 }
 
 LayoutUnit MultiColumnFragmentainerGroup::columnLogicalTopForOffset(LayoutUnit offsetInFlowThread) const
@@ -184,7 +187,7 @@ LayoutRect MultiColumnFragmentainerGroup::fragmentsBoundingBox(const LayoutRect&
     flowThread->flipForWritingMode(startColumnFlowThreadOverflowPortion);
     LayoutRect startColumnRect(boundingBoxInFlowThread);
     startColumnRect.intersect(startColumnFlowThreadOverflowPortion);
-    startColumnRect.move(flowThreadTranslationAtOffset(logicalTopInFlowThreadAt(startColumn)));
+    startColumnRect.move(flowThreadTranslationAtOffset(logicalTopInFlowThreadAt(startColumn), CoordinateSpaceConversion::Containing));
     if (startColumn == endColumn)
         return startColumnRect; // It all takes place in one column. We're done.
 
@@ -192,7 +195,7 @@ LayoutRect MultiColumnFragmentainerGroup::fragmentsBoundingBox(const LayoutRect&
     flowThread->flipForWritingMode(endColumnFlowThreadOverflowPortion);
     LayoutRect endColumnRect(boundingBoxInFlowThread);
     endColumnRect.intersect(endColumnFlowThreadOverflowPortion);
-    endColumnRect.move(flowThreadTranslationAtOffset(logicalTopInFlowThreadAt(endColumn)));
+    endColumnRect.move(flowThreadTranslationAtOffset(logicalTopInFlowThreadAt(endColumn), CoordinateSpaceConversion::Containing));
     return unionRect(startColumnRect, endColumnRect);
 }
 
@@ -251,7 +254,7 @@ void MultiColumnFragmentainerGroup::collectLayerFragments(PaintLayerFragments& f
         PaintLayerFragment fragment;
 
         // Set the physical translation offset.
-        fragment.paginationOffset = toLayoutPoint(flowThreadTranslationAtOffset(logicalTopInFlowThreadAt(i)));
+        fragment.paginationOffset = toLayoutPoint(flowThreadTranslationAtOffset(logicalTopInFlowThreadAt(i), CoordinateSpaceConversion::Visual));
 
         // Set the overflow clip rect that corresponds to the column.
         fragment.paginationClip = flowThreadPortionOverflowRectAt(i);