cc: Remove vectors from tiling eviction tile iterator.

cc/layers/picture_layer_impl.h

Index: cc/layers/picture_layer_impl.h
diff --git a/cc/layers/picture_layer_impl.h b/cc/layers/picture_layer_impl.h
index 0e5a64614f2445ed5b6e98aa8683996c15a6601a..d4af4785cfb6e71589e6ebcf5303e7fee5ede559 100644
--- a/cc/layers/picture_layer_impl.h
+++ b/cc/layers/picture_layer_impl.h
@@ -77,15 +77,33 @@ class CC_EXPORT PictureLayerImpl
     operator bool() const;
 
    private:
+    enum IterationStage {
+      EVENTUALLY,
+      EVENTUALLY_AND_REQUIRED_FOR_ACTIVATION,
+      SOON,
+      SOON_AND_REQUIRED_FOR_ACTIVATION,
+      NOW,
+      NOW_AND_REQUIRED_FOR_ACTIVATION
+    };
+
+    TilePriority::PriorityBin PriorityBinFromIterationStage(
+        IterationStage stage);
+    bool RequiredForActivationFromIterationStage(IterationStage stage);
+
+    PictureLayerTilingSet::TilingRange CurrentRange();
+    int CurrentTilingIndex();
+
     void AdvanceToNextIterator();
-    bool IsCorrectType(
-        PictureLayerTiling::TilingEvictionTileIterator* it) const;
+    bool AdvanceTiling();
+    bool AdvanceRange();
+    bool AdvanceStage();
 
-    std::vector<PictureLayerTiling::TilingEvictionTileIterator> iterators_;
-    size_t iterator_index_;
-    TilePriority::PriorityBin iteration_stage_;
-    bool required_for_activation_;
+    PictureLayerTiling::TilingEvictionTileIterator iterator_;
+    int current_range_offset_;
+    PictureLayerTilingSet::TilingRangeType current_tiling_range_type_;
+    IterationStage current_stage_;
 
+    TreePriority tree_priority_;
     PictureLayerImpl* layer_;
   };