Cleanup GPU gamut transformation code

include/gpu/GrColorSpaceXform.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrColorSpaceXform_DEFINED
 #define GrColorSpaceXform_DEFINED
 
-#include "SkImageInfo.h"
+#include "SkMatrix44.h"
 #include "SkRefCnt.h"
 
 class SkColorSpace;
-class SkMatrix44;
 
  /**
   * Represents a color gamut transformation (as a 4x4 color matrix)
   */
 class GrColorSpaceXform : public SkRefCnt {
 public:
-    GrColorSpaceXform(const SkMatrix44& srcToDst, SkAlphaType srcAlphaType);
+    GrColorSpaceXform(const SkMatrix44& srcToDst);
 
-    static sk_sp<GrColorSpaceXform> Make(SkColorSpace* src, SkColorSpace* dst,
-                                         SkAlphaType srcAlphaType);
+    static sk_sp<GrColorSpaceXform> Make(SkColorSpace* src, SkColorSpace* dst);
 
-    const float* srcToDst() { return fSrcToDst; }
-    SkAlphaType alphaType() const { return fSrcAlphaType; }
+    const SkMatrix44& srcToDst() { return fSrcToDst; }
 
     /**
      * GrGLSLFragmentProcessor::GenKey() must call this and include the returned value in its
      * computed key.
      */
     static uint32_t XformKey(GrColorSpaceXform* xform) {
-        if (!xform) {
-            return 0;
-        }
-        // Code generation just depends on whether the alpha type is premul or not
-        return kPremul_SkAlphaType == xform->fSrcAlphaType ? 1 : 2;
+        // Code generation changes if there is an xform, but it otherwise constant
+        return SkToBool(xform) ? 1 : 0;
     }
 
 private:
-    // We store the column-major form of the srcToDst matrix, for easy uploading to uniforms
-    float fSrcToDst[16];
-
-    // Alpha type of the source. If it's premul, we need special handling
-    SkAlphaType fSrcAlphaType;
+    SkMatrix44 fSrcToDst;
 };
 
 #endif