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/src/core/SkRTree.cpp b/src/core/SkRTree.cpp
index b6ff29b..96f6b18 100644
--- a/src/core/SkRTree.cpp
+++ b/src/core/SkRTree.cpp
@@ -19,6 +19,8 @@
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
+SK_DEFINE_INST_COUNT(SkRTree)
+
 SkRTree* SkRTree::Create(int minChildren, int maxChildren, SkScalar aspectRatio) {
     if (minChildren < maxChildren && (maxChildren + 1) / 2 >= minChildren &&
         minChildren > 0 && maxChildren < static_cast<int>(SK_MaxU16)) {