Cache the inverse matrix on SkColorSpace. Rename xyz() to toXYZ().

include/core/SkColorSpace.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 SkColorSpace_DEFINED
 #define SkColorSpace_DEFINED
 
@@ skipping 48 matching lines @@
     static sk_sp<SkColorSpace> NewICC(const void*, size_t);
 
     /**
      *  Create an SkColorSpace with the same gamut as this color space, but with linear gamma.
      */
     sk_sp<SkColorSpace> makeLinearGamma();
 
     /**
      *  Returns the matrix used to transform src gamut to XYZ D50.
      */
-    const SkMatrix44& xyz() const { return fToXYZD50; }
+    const SkMatrix44& toXYZD50() const { return fToXYZD50; }
 
     /**
      *  Returns true if the color space gamma is near enough to be approximated as sRGB.
      */
     bool gammaCloseToSRGB() const;
 
     /**
      *  Returns true if the color space gamma is linear.
      */
     bool gammaIsLinear() const;
@@ skipping 18 matching lines @@
      */
     static bool Equals(const SkColorSpace* src, const SkColorSpace* dst);
 
 protected:
     SkColorSpace(const SkMatrix44& toXYZD50);
 
     const SkMatrix44 fToXYZD50;
 };
 
 #endif