Put transform tree building in DisplayItemPropertyTreeBuilder.

Source/platform/graphics/paint/DisplayItemClipTree.h

Index: Source/platform/graphics/paint/DisplayItemClipTree.h
diff --git a/Source/platform/graphics/paint/DisplayItemClipTree.h b/Source/platform/graphics/paint/DisplayItemClipTree.h
new file mode 100644
index 0000000000000000000000000000000000000000..86378479c540e1ba4eb15c5262aa98541ccb3a1b
--- /dev/null
+++ b/Source/platform/graphics/paint/DisplayItemClipTree.h
@@ -0,0 +1,47 @@
+// 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.
+
+#ifndef DisplayItemClipTree_h
+#define DisplayItemClipTree_h
+
+#include "platform/PlatformExport.h"
+#include "platform/geometry/FloatRect.h"
+#include "public/platform/WebDisplayItemClipTree.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+// Represents a hierarchy of rectangular clips which apply to ranges of a
+// display list and may be of interest to the compositor.
+//
+// This class is also the private implementation of WebDisplayItemClipTree.
+// For more detail, see WebDisplayItemClipTree.h.
+class PLATFORM_EXPORT DisplayItemClipTree {
+public:
+    using ClipNode = WebDisplayItemClipTree::ClipNode;
+    enum : size_t { kInvalidIndex = WebDisplayItemClipTree::kInvalidIndex };
+
+    DisplayItemClipTree();
+    ~DisplayItemClipTree();
+
+    size_t nodeCount() const { return m_nodes.size(); }
+    ClipNode& nodeAt(size_t index) { return m_nodes[index]; }
+    const ClipNode& nodeAt(size_t index) const { return m_nodes[index]; }
+
+    // Returns the new node index.
+    size_t createNewNode(size_t parentNodeIndex, size_t transformNodeIndex, const FloatRect& clipRect)
+    {
+        ASSERT(parentNodeIndex != kInvalidIndex);
+        ASSERT(transformNodeIndex != kInvalidIndex);
+        m_nodes.append(ClipNode(parentNodeIndex, transformNodeIndex, clipRect));
+        return m_nodes.size() - 1;
+    }
+
+private:
+    Vector<ClipNode> m_nodes;
+};
+
+} // namespace blink
+
+#endif // DisplayItemClipTree_h