Preliminary paint property walk implementation for SPv2

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h
new file mode 100644
index 0000000000000000000000000000000000000000..0625eb49bbb7428a0c53e6ae73ef76f543cb4c75
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+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h
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+// 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 PaintPropertyTreeBuilder_h
+#define PaintPropertyTreeBuilder_h
+
+namespace blink {
+
+class FrameView;
+class LayoutBoxModelObject;
+
+// This class walks the whole layout tree, beginning from the root FrameView, across
+// frame boundaries. The walk will collect special things in the layout tree and create
+// paint property nodes for them. Special things include but not limit to: overflow clip,
+// transform, fixed-pos, animation, mask, filter, ... etc.
+// It expects to be invoked after layout clean, i.e. during InPaintPropertyUpdate phase.
+class PaintPropertyTreeBuilder {
+public:
+    void buildPropertyTrees(FrameView& rootFrame);
+
+private:
+    struct Context;
+
+    void walk(FrameView&, const Context&);
+    void walk(LayoutBoxModelObject&, const Context&);
+};
+
+} // namespace blink
+
+#endif // PaintPropertyTreeBuilder_h