Change SkShader;asFragmentProcessor signature to no longer take skpaint\grcolor*

Committed: https://skia.googlesource.com/skia/+/ecfdc251be71f3d634e76afdd6375bf55fc061aa

Review URL: https://codereview.chromium.org/1316513002
diff --git a/src/effects/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index 9044284..4929071 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -517,7 +517,7 @@
 
 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrDisplacementMapEffect);
 
-GrFragmentProcessor* GrDisplacementMapEffect::TestCreate(GrProcessorTestData* d) {
+const GrFragmentProcessor* GrDisplacementMapEffect::TestCreate(GrProcessorTestData* d) {
     int texIdxDispl = d->fRandom->nextBool() ? GrProcessorUnitTest::kSkiaPMTextureIdx :
                                                GrProcessorUnitTest::kAlphaTextureIdx;
     int texIdxColor = d->fRandom->nextBool() ? GrProcessorUnitTest::kSkiaPMTextureIdx :