plumb SkInstCnt to all subclasses of GrRefCnt



git-svn-id: http://skia.googlecode.com/svn/trunk@4353 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrDrawTarget.cpp b/src/gpu/GrDrawTarget.cpp
index 39ea5bf..64dc815 100644
--- a/src/gpu/GrDrawTarget.cpp
+++ b/src/gpu/GrDrawTarget.cpp
@@ -15,6 +15,8 @@
 #include "GrTexture.h"
 #include "GrVertexBuffer.h"
 
+SK_DEFINE_INST_COUNT(GrDrawTarget)
+
 namespace {
 
 /**