Initial import attempt, just to play with. Many things disabled/removed

ui/cc/TreeSynchronizer.h

Index: ui/cc/TreeSynchronizer.h
diff --git a/ui/cc/TreeSynchronizer.h b/ui/cc/TreeSynchronizer.h
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+++ b/ui/cc/TreeSynchronizer.h
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+/*
+ * Copyright (C) 2011 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1.  Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ * 2.  Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef TreeSynchronizer_h
+#define TreeSynchronizer_h
+
+#include <wtf/HashMap.h>
+#include <wtf/Noncopyable.h>
+#include <wtf/OwnPtr.h>
+#include <wtf/PassOwnPtr.h>
+
+namespace WebCore {
+
+class CCLayerImpl;
+class CCLayerTreeHostImpl;
+class LayerChromium;
+
+class TreeSynchronizer {
+WTF_MAKE_NONCOPYABLE(TreeSynchronizer);
+public:
+    // Accepts a LayerChromium tree and returns a reference to a CCLayerImpl tree that duplicates the structure
+    // of the LayerChromium tree, reusing the CCLayerImpls in the tree provided by oldCCLayerImplRoot if possible.
+    static PassOwnPtr<CCLayerImpl> synchronizeTrees(LayerChromium* layerRoot, PassOwnPtr<CCLayerImpl> oldCCLayerImplRoot, CCLayerTreeHostImpl*);
+
+private:
+    TreeSynchronizer(); // Not instantiable.
+
+    typedef HashMap<int, OwnPtr<CCLayerImpl> > OwnPtrCCLayerImplMap;
+    typedef HashMap<int, CCLayerImpl*> RawPtrCCLayerImplMap;
+
+    // Declared as static member functions so they can access functions on LayerChromium as a friend class.
+    static PassOwnPtr<CCLayerImpl> reuseOrCreateCCLayerImpl(RawPtrCCLayerImplMap& newLayers, OwnPtrCCLayerImplMap& oldLayers, LayerChromium*);
+    static void collectExistingCCLayerImplRecursive(OwnPtrCCLayerImplMap& oldLayers, PassOwnPtr<CCLayerImpl>);
+    static PassOwnPtr<CCLayerImpl> synchronizeTreeRecursive(RawPtrCCLayerImplMap& newLayers, OwnPtrCCLayerImplMap& oldLayers, LayerChromium*, CCLayerTreeHostImpl*);
+    static void updateScrollbarLayerPointersRecursive(const RawPtrCCLayerImplMap& newLayers, LayerChromium*);
+};
+
+} // namespace WebCore
+
+#endif // TreeSynchronizer_h