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

BUG=skia:

Review URL: https://codereview.chromium.org/873333004
diff --git a/samplecode/SampleUnpremul.cpp b/samplecode/SampleUnpremul.cpp
index 889d067..7e5c950 100644
--- a/samplecode/SampleUnpremul.cpp
+++ b/samplecode/SampleUnpremul.cpp
@@ -7,7 +7,7 @@
 
 #include "gm.h"
 
-#include "Checkerboard.h"
+#include "sk_tool_utils.h"
 #include "Resources.h"
 #include "SampleCode.h"
 #include "SkBlurMask.h"
@@ -76,7 +76,7 @@
     }
 
     void onDrawBackground(SkCanvas* canvas) SK_OVERRIDE {
-        sk_tools::DrawCheckerboard(canvas, 0xFFCCCCCC, 0xFFFFFFFF, 12);
+        sk_tool_utils::draw_checkerboard(canvas, 0xFFCCCCCC, 0xFFFFFFFF, 12);
     }
 
     void onDrawContent(SkCanvas* canvas) SK_OVERRIDE {