Move GrInvariantOutput out of GrProcessor and into its own class.

src/effects/gradients/SkGradientShader.cpp

Index: src/effects/gradients/SkGradientShader.cpp
diff --git a/src/effects/gradients/SkGradientShader.cpp b/src/effects/gradients/SkGradientShader.cpp
index 0d1730860af872f3c04fea08a95e6b22d481c6de..b1a3bf0d79b1d4133bc271a9df588158e962d97e 100644
--- a/src/effects/gradients/SkGradientShader.cpp
+++ b/src/effects/gradients/SkGradientShader.cpp
@@ -945,6 +945,7 @@ SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
 #if SK_SUPPORT_GPU
 
 #include "effects/GrTextureStripAtlas.h"
+#include "GrInvariantOutput.h"
 #include "GrTBackendProcessorFactory.h"
 #include "gl/builders/GrGLProgramBuilder.h"
 #include "SkGr.h"
@@ -1208,7 +1209,7 @@ bool GrGradientEffect::onIsEqual(const GrFragmentProcessor& processor) const {
     return false;
 }
 
-void GrGradientEffect::onComputeInvariantOutput(InvariantOutput* inout) const {
+void GrGradientEffect::onComputeInvariantOutput(GrInvariantOutput* inout) const {
     if (fIsOpaque) {
         inout->mulByUnknownOpaqueColor();
     } else {