Initial QuadTree implementation

src/core/SkQuadTreePicture.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkQuadTreePicture_DEFINED
+#define SkQuadTreePicture_DEFINED
+
+#include "SkPicture.h"
+#include "SkRect.h"
+
+/**
+ * Subclass of SkPicture that override the behavior of the
+ * kOptimizeForClippedPlayback_RecordingFlag by creating an SkQuadGrid
+ * structure rather than an R-Tree. The quad tree has generally faster
+ * tree creation time, but slightly slower query times, as compared to
+ * R-Tree, so some cases may be faster and some cases slower.
+ */
+class SK_API SkQuadTreePicture : public SkPicture {
+public:
+    SkQuadTreePicture(const SkIRect& bounds) : fBounds(bounds) {}
+    virtual SkBBoxHierarchy* createBBoxHierarchy() const SK_OVERRIDE;
+private:
+    SkIRect fBounds;
+};
+
+#endif