Move willUseInputColor check to computeInvariantOutput

src/effects/SkLumaColorFilter.cpp

Index: src/effects/SkLumaColorFilter.cpp
diff --git a/src/effects/SkLumaColorFilter.cpp b/src/effects/SkLumaColorFilter.cpp
index d06a2132f4d664d75783517a529e458385cc2273..7750f04d7251fb2afb1062ae67cac58dccaae5f3 100644
--- a/src/effects/SkLumaColorFilter.cpp
+++ b/src/effects/SkLumaColorFilter.cpp
@@ -115,7 +115,8 @@ private:
 
     virtual void onComputeInvariantOutput(InvariantOutput* inout) const SK_OVERRIDE {
         // The output is always black. The alpha value for the color passed in is arbitrary.
-        inout->setToOther(kRGB_GrColorComponentFlags, GrColorPackRGBA(0, 0, 0, 0));
+        inout->setToOther(kRGB_GrColorComponentFlags, GrColorPackRGBA(0, 0, 0, 0),
+                          InvariantOutput::kWill_ReadInput);
     }
 };