Slimming Paint phase 2 compositing algorithm plumbing & skeleton display list API.

Source/platform/graphics/paint/DisplayItemTransformTreeBuilder.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/DisplayItemTransformTreeBuilder.h"
 
 #include "platform/graphics/paint/DisplayItem.h"
+#include "platform/graphics/paint/DisplayItemList.h"
 #include "platform/graphics/paint/DisplayItemTransformTree.h"
 #include "platform/graphics/paint/Transform3DDisplayItem.h"
+#include "public/platform/WebDisplayList.h"
 
 namespace blink {
 
 DisplayItemTransformTreeBuilder::DisplayItemTransformTreeBuilder()
     : m_transformTree(adoptPtr(new DisplayItemTransformTree))
     , m_rangeBeginIndex(0)
     , m_currentIndex(0)
 {
     pushCurrentTransformNode(0 /* root node */, FloatSize());
 }
@@ skipping 28 matching lines @@
         *transform = begin3D.transform();
         if (transform->isIdentityOr2DTranslation())
             return Only2DTranslation;
         return RequiresTransformNode;
     }
     return NotATransform;
 }
 
 } // namespace
 
+void DisplayItemTransformTreeBuilder::build(const DisplayItemList& displayList, const WebDisplayListDiff& displayListDiff)
+{
+    // TODO(chrishtr): use |displayListDiff| to optimize.
+    for (const auto& displayItem : displayList.displayItems()) {
+        processDisplayItem(*displayItem);
+    }
+}
+
 void DisplayItemTransformTreeBuilder::processDisplayItem(const DisplayItem& displayItem)
 {
     if (displayItem.isBegin()) {
         TransformationMatrix matrix;
         switch (classifyBeginItem(displayItem, &matrix)) {
         case NotATransform:
             // Remember to ignore this begin later on.
             currentTransformNodeData().ignoredBeginCount++;
             break;
         case Only2DTranslation:
@@ skipping 33 matching lines @@
         const auto& current = currentTransformNodeData();
         m_transformTree->appendRangeRecord(m_rangeBeginIndex, m_currentIndex, current.transformNode, current.offset);
     }
 
     // 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