Make BBoxHierarchy ref-counted, fix leak in RTreeTest.
Review URL: https://codereview.appspot.com/6489108

git-svn-id: http://skia.googlecode.com/svn/trunk@5484 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/RTreeTest.cpp b/tests/RTreeTest.cpp
index 61e6b67..d60bf0c 100644
--- a/tests/RTreeTest.cpp
+++ b/tests/RTreeTest.cpp
@@ -82,6 +82,7 @@
     DataRect rects[NUM_RECTS];
     SkRandom rand;
     SkRTree* rtree = SkRTree::Create(MIN_CHILDREN, MAX_CHILDREN);
+    SkAutoUnref au(rtree);
     REPORTER_ASSERT(reporter, NULL != rtree);
 
     int expectedDepthMin = -1;