New helper for creating a color space from another, with linear gamma

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 49 matching lines @@
     /**
      *  Create a common, named SkColorSpace.
      */
     static sk_sp<SkColorSpace> NewNamed(Named);
 
     /**
      *  Create an SkColorSpace from an ICC profile.
      */
     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();
+
     GammaNamed gammaNamed() const { return fGammaNamed; }
 
     /**
      *  Returns the matrix used to transform src gamut to XYZ D50.
      */
     const SkMatrix44& xyz() const { return fToXYZD50; }
 
     /**
      *  Returns true if the color space gamma is near enough to be approximated as sRGB.
      */
@@ skipping 32 matching lines @@
 
 protected:
     SkColorSpace(GammaNamed gammaNamed, const SkMatrix44& toXYZD50, Named named);
 
     const GammaNamed fGammaNamed;
     const SkMatrix44 fToXYZD50;
     const Named      fNamed;
 };
 
 #endif