Include transform origin in the transform tree.

Source/platform/graphics/paint/DisplayItemPropertyTreeBuilder.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 "config.h"
 #include "platform/graphics/paint/DisplayItemPropertyTreeBuilder.h"
 
 #include "platform/graphics/paint/DisplayItem.h"
 #include "platform/graphics/paint/DisplayItemClipTree.h"
 #include "platform/graphics/paint/DisplayItemTransformTree.h"
@@ skipping 47 matching lines @@
         processEndItem(displayItem);
     m_currentIndex++;
 }
 
 namespace {
 
 enum TransformKind { NotATransform = 0, Only2DTranslation, RequiresTransformNode };
 enum ClipKind { NotAClip = 0, RequiresClipNode };
 
 struct BeginDisplayItemClassification {
+    // |transformOrigin| is irrelevant unless a non-translation matrix is
+    // provided.
     TransformKind transformKind = NotATransform;
     TransformationMatrix matrix;
+    FloatPoint3D transformOrigin;
+
     ClipKind clipKind = NotAClip;
     FloatRect clipRect;
 };
 
 // Classifies a begin display item based on how it affects the property trees.
 static BeginDisplayItemClassification classifyBeginItem(const DisplayItem& beginDisplayItem)
 {
     ASSERT(beginDisplayItem.isBegin());
 
     BeginDisplayItemClassification result;
     DisplayItem::Type type = beginDisplayItem.type();
     if (DisplayItem::isTransform3DType(type)) {
         const auto& begin3D = static_cast<const BeginTransform3DDisplayItem&>(beginDisplayItem);
         result.matrix = begin3D.transform();
+        result.transformOrigin = begin3D.transformOrigin();
         result.transformKind = result.matrix.isIdentityOr2DTranslation() ? Only2DTranslation : RequiresTransformNode;
     } else if (type == DisplayItem::BeginTransform) {
         const auto& begin2D = static_cast<const BeginTransformDisplayItem&>(beginDisplayItem);
         result.matrix = begin2D.transform();
         result.transformKind = begin2D.transform().isIdentityOrTranslation() ? Only2DTranslation : RequiresTransformNode;
     } else if (DisplayItem::isScrollType(type)) {
         const auto& beginScroll = static_cast<const BeginScrollDisplayItem&>(beginDisplayItem);
         const IntSize& offset = beginScroll.currentOffset();
         result.matrix.translate(-offset.width(), -offset.height());
         result.transformKind = Only2DTranslation;
@@ skipping 19 matching lines @@
     switch (classification.transformKind) {
     case NotATransform:
         break;
     case Only2DTranslation:
         // Adjust the offset associated with the current transform node.
         newState.offset += classification.matrix.to2DTranslation();
         break;
     case RequiresTransformNode:
         // Emit a transform node.
         newState.transformNode = m_transformTree->createNewNode(
-            newState.transformNode, classification.matrix);
+            newState.transformNode, classification.matrix, classification.transformOrigin);
         newState.offset = FloatSize();
         break;
     }
 
     switch (classification.clipKind) {
     case NotAClip:
         break;
     case RequiresClipNode:
         // Emit a clip node.
         FloatRect adjustedClipRect = classification.clipRect;
@@ skipping 32 matching lines @@
         rangeRecord.clipNodeIndex = current.clipNode;
         m_rangeRecords.append(rangeRecord);
     }
 
     // The current display item is a boundary.
     // The earliest the next range could begin is the next one.
     m_rangeBeginIndex = m_currentIndex + 1;
 }
 
 } // namespace blink