R-Tree -- Don't sort draw commands unless specified.

src/core/SkRTree.h

Index: src/core/SkRTree.h
diff --git a/src/core/SkRTree.h b/src/core/SkRTree.h
index 2d11f28a5739a21c69da94c999db80562196ced9..74073be072562b22bf19c0782ff5184956461c5a 100644
--- a/src/core/SkRTree.h
+++ b/src/core/SkRTree.h
@@ -54,8 +54,13 @@ public:
      * If you have some prior information about the distribution of bounds you're expecting, you
      * can provide an optional aspect ratio parameter. This allows the bulk-load algorithm to create
      * better proportioned tiles of rectangles.
+     * You can make the build loading algorithm avoid the sorting step by setting
+     * orderWhenBulkLoading to false. It will have a small impact on playback performance for
+     * inputs where consecutive boxes are close to each other. It will do much worse if the inputs
+     * are positioned randomly.
      */
-    static SkRTree* Create(int minChildren, int maxChildren, SkScalar aspectRatio = 1);
+    static SkRTree* Create(int minChildren, int maxChildren, SkScalar aspectRatio = 1,
+            bool orderWhenBulkLoading = true);
     virtual ~SkRTree();
 
     /**
@@ -144,7 +149,7 @@ private:
         }
     };
 
-    SkRTree(int minChildren, int maxChildren, SkScalar aspectRatio);
+    SkRTree(int minChildren, int maxChildren, SkScalar aspectRatio, bool orderWhenBulkLoading);
 
     /**
      * Recursively descend the tree to find an insertion position for 'branch', updates
@@ -184,6 +189,7 @@ private:
     SkChunkAlloc fNodes;
     SkTDArray<Branch> fDeferredInserts;
     SkScalar fAspectRatio;
+    bool fSortWhenBulkLoading;
 
     Node* allocateNode(uint16_t level);