Added kSRGBLinear_Named color space, along with tests

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 13 matching lines @@
          *  By far the most common color space.
          *  This is the default space for images, unmarked content, and monitors.
          */
         kSRGB_Named,
 
         /**
          *  Very common wide gamut color space.
          *  Often used by images and monitors.
          */
         kAdobeRGB_Named,
+
+        /**
+         * Colorspace with the sRGB primaries, but a linear (1.0) gamma.

[msarett, 2016/09/27 20:53:52]

Might be interesting to comment on why this is interesting/commonly used to
justify that it belongs here.

+         */
+        kSRGBLinear_Named,
     };
 
     enum RenderTargetGamma : uint8_t {
         kLinear_RenderTargetGamma,
 
         /**
          *  Transfer function is the canonical sRGB curve, which has a short linear segment
          *  followed by a 2.4f exponential.
          */
         kSRGB_RenderTargetGamma,
@@ skipping 54 matching lines @@
      */
     static bool Equals(const SkColorSpace* src, const SkColorSpace* dst);
 
 protected:
     SkColorSpace(const SkMatrix44& toXYZD50);
 
     const SkMatrix44 fToXYZD50;
 };
 
 #endif