make GR_TEST_UTILS=0 work

Change-Id: Icce35140ca08b65217b32e6b1ffc6ad2f38ab37f
Reviewed-on: https://skia-review.googlesource.com/7840
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
diff --git a/src/gpu/effects/GrDitherEffect.cpp b/src/gpu/effects/GrDitherEffect.cpp
index 24e3ba6..34a1565 100644
--- a/src/gpu/effects/GrDitherEffect.cpp
+++ b/src/gpu/effects/GrDitherEffect.cpp
@@ -50,9 +50,11 @@
 
 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(DitherEffect);
 
+#if GR_TEST_UTILS
 sk_sp<GrFragmentProcessor> DitherEffect::TestCreate(GrProcessorTestData*) {
     return DitherEffect::Make();
 }
+#endif
 
 //////////////////////////////////////////////////////////////////////////////