Add hairlines batch unit test

include/gpu/GrTestUtils.h

Index: include/gpu/GrTestUtils.h
diff --git a/include/gpu/GrTestUtils.h b/include/gpu/GrTestUtils.h
index 2786bb2e9abdb7897e7ebad9e64012df7fdf30a2..a98548bb2f9a9014f5b8807492d6d5702aa33eb0 100644
--- a/include/gpu/GrTestUtils.h
+++ b/include/gpu/GrTestUtils.h
@@ -16,6 +16,7 @@
 #include "SkRandom.h"
 
 class SkMatrix;
+class SkPath;
 class SkRRect;
 struct SkRect;
 
@@ -28,6 +29,7 @@ const SkMatrix& TestMatrixPreservesRightAngles(SkRandom*);
 const SkMatrix& TestMatrixRectStaysRect(SkRandom*);
 const SkRect& TestRect(SkRandom*);
 const SkRRect& TestRRectSimple(SkRandom*);
+const SkPath& TestPath(SkRandom*);
 
 }