Create helper functions to use in computeInvariantOutput calls

src/gpu/effects/GrCustomCoordsTextureEffect.cpp

Index: src/gpu/effects/GrCustomCoordsTextureEffect.cpp
diff --git a/src/gpu/effects/GrCustomCoordsTextureEffect.cpp b/src/gpu/effects/GrCustomCoordsTextureEffect.cpp
index e89e46cb5a34022eb5674dd8f9b09f086241033b..40ff1b1f77fbce32a96ebc2c2712868de36d867e 100644
--- a/src/gpu/effects/GrCustomCoordsTextureEffect.cpp
+++ b/src/gpu/effects/GrCustomCoordsTextureEffect.cpp
@@ -73,12 +73,11 @@ bool GrCustomCoordsTextureEffect::onIsEqual(const GrProcessor& other) const {
 }
 
 void GrCustomCoordsTextureEffect::onComputeInvariantOutput(InvariantOutput* inout) const {
-    if (inout->isOpaque() && GrPixelConfigIsOpaque(this->texture(0)->config())) {
-        inout->fValidFlags = kA_GrColorComponentFlag;
+    if (GrPixelConfigIsOpaque(this->texture(0)->config())) {
+        inout->mulByUnknownOpaqueColor();
     } else {
-        inout->fValidFlags = 0;
+        inout->mulByUnknownColor();
     }
-    inout->fIsSingleComponent = false;
 }
 
 const GrBackendGeometryProcessorFactory& GrCustomCoordsTextureEffect::getFactory() const {