cc: Implement tiling iterator based on pyramid sequence.

cc/tiles/tiling_set_raster_queue_required.h

Index: cc/tiles/tiling_set_raster_queue_required.h
diff --git a/cc/tiles/tiling_set_raster_queue_required.h b/cc/tiles/tiling_set_raster_queue_required.h
index 4573d0409395fa8101f1021401a9ecd4139bc291..8accaf10986512e64f52056962313b78a27408a0 100644
--- a/cc/tiles/tiling_set_raster_queue_required.h
+++ b/cc/tiles/tiling_set_raster_queue_required.h
@@ -35,8 +35,13 @@ class CC_EXPORT TilingSetRasterQueueRequired {
     explicit TilingIterator(PictureLayerTiling* tiling,
                             TilingData* tiling_data,
                             const gfx::Rect& rect);
+    TilingIterator(const TilingIterator& other);
+    TilingIterator(TilingIterator&& other);
     ~TilingIterator();
 
+    TilingIterator& operator=(const TilingIterator& other);
+    TilingIterator& operator=(TilingIterator&& other);
+
     bool done() const { return !current_tile_.tile(); }
     const PrioritizedTile& operator*() const { return current_tile_; }
     TilingIterator& operator++();