Replace uses of GR_DEBUG by SK_DEBUG.

BUG=None
R=bsalomon@google.com, robertphillips@google.com

Author: tfarina@chromium.org

Review URL: https://chromiumcodereview.appspot.com/23137022

git-svn-id: http://skia.googlecode.com/svn/trunk@10978 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrMemoryPool.cpp b/src/gpu/GrMemoryPool.cpp
index a770792..83119db 100644
--- a/src/gpu/GrMemoryPool.cpp
+++ b/src/gpu/GrMemoryPool.cpp
@@ -7,7 +7,7 @@
 
 #include "GrMemoryPool.h"
 
-#if GR_DEBUG
+#ifdef SK_DEBUG
     #define VALIDATE this->validate()
 #else
     #define VALIDATE