Cleanup GPU gamut transformation code

src/gpu/glsl/GrGLSLColorSpaceXformHelper.h

Index: src/gpu/glsl/GrGLSLColorSpaceXformHelper.h
diff --git a/src/gpu/glsl/GrGLSLColorSpaceXformHelper.h b/src/gpu/glsl/GrGLSLColorSpaceXformHelper.h
index cd516e8c8917ab0c338f9725495b713d981d3560..5e112f9f9173caa1cec723882add2e33b031cf5f 100644
--- a/src/gpu/glsl/GrGLSLColorSpaceXformHelper.h
+++ b/src/gpu/glsl/GrGLSLColorSpaceXformHelper.h
@@ -26,18 +26,15 @@ public:
             *handle = uniformHandler->addUniform(kFragment_GrShaderFlag, kMat44f_GrSLType,
                                                  kDefault_GrSLPrecision, "ColorXform",
                                                  &fXformMatrix);
-            fAlphaType = colorSpaceXform->alphaType();
         } else {
             fXformMatrix = nullptr;
         }
     }
 
     const char* getXformMatrix() const { return fXformMatrix; }
-    SkAlphaType alphaType() const { return fAlphaType; }
 
 private:
     const char* fXformMatrix;
-    SkAlphaType fAlphaType;
 };
 
 #endif