s/sk_tools::DrawCheckerboard/sk_tool_utils::draw_checkerboard/

BUG=skia:

Review URL: https://codereview.chromium.org/873333004
diff --git a/gm/xfermodeimagefilter.cpp b/gm/xfermodeimagefilter.cpp
index b90543f..0134bd3 100644
--- a/gm/xfermodeimagefilter.cpp
+++ b/gm/xfermodeimagefilter.cpp
@@ -6,7 +6,7 @@
  */
 
 #include "gm.h"
-#include "Checkerboard.h"
+#include "sk_tool_utils.h"
 #include "SkArithmeticMode.h"
 #include "SkOffsetImageFilter.h"
 #include "SkXfermodeImageFilter.h"
@@ -70,7 +70,7 @@
 
         fCheckerboard.allocN32Pixels(80, 80);
         SkCanvas checkerboardCanvas(fCheckerboard);
-        sk_tools::DrawCheckerboard(&checkerboardCanvas, 0xFFA0A0A0, 0xFF404040, 8);
+        sk_tool_utils::draw_checkerboard(&checkerboardCanvas, 0xFFA0A0A0, 0xFF404040, 8);
     }
 
     void onDraw(SkCanvas* canvas) SK_OVERRIDE {