Remove unused (by clients) SkUnitMapper

This reverts commit 874423a81b5bc2541c7397e6ab00d5e7c9fdaf98.

TBR=scroggo

Author: reed@google.com

Review URL: https://codereview.chromium.org/288313009

git-svn-id: http://skia.googlecode.com/svn/trunk@14842 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/convexpolyclip.cpp b/gm/convexpolyclip.cpp
index b76335c..edafea2 100644
--- a/gm/convexpolyclip.cpp
+++ b/gm/convexpolyclip.cpp
@@ -46,7 +46,7 @@
                         colors, pos,
                         SK_ARRAY_COUNT(colors),
                         SkShader::kRepeat_TileMode,
-                        NULL, 0, &mat))->unref();
+                        0, &mat))->unref();
         canvas.drawRect(rect, paint);
         rect.inset(wScalar / 8, hScalar / 8);
         mat.preTranslate(6 * wScalar, 6 * hScalar);