Add capability for SkColorXform to output half floats

src/core/SkOpts.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkOpts_DEFINED
 #define SkOpts_DEFINED
 
@@ skipping 48 matching lines @@
                         gray_to_RGB1,          // i.e. expand to color channels + an opaque alpha
                         grayA_to_RGBA,         // i.e. expand to color channels
                         grayA_to_rgbA,         // i.e. expand to color channels and premultiply
                         inverted_CMYK_to_RGB1, // i.e. convert color space
                         inverted_CMYK_to_BGR1; // i.e. convert color space
 
     // Blend ndst src pixels over dst, where both src and dst point to sRGB pixels (RGBA or BGRA).
     // If nsrc < ndst, we loop over src to create a pattern.
     extern void (*srcover_srgb_srgb)(uint32_t* dst, const uint32_t* src, int ndst, int nsrc);
 
-    // Color xform RGB1 pixels into SkPMColor order.
+    // Color xform RGB1 pixels.
     extern void (*color_xform_RGB1_to_2dot2) (uint32_t* dst, const uint32_t* src, int len,
                                               const float* const srcTables[3],
                                               const float srcToDstMatrix[12]);
     extern void (*color_xform_RGB1_to_srgb)(uint32_t* dst, const uint32_t* src, int len,
                                             const float* const srcTables[3],
                                             const float srcToDstMatrix[12]);
     extern void (*color_xform_RGB1_to_table)(uint32_t* dst, const uint32_t* src, int len,
                                              const float* const srcTables[3],
                                              const float srcToDstMatrix[12],
                                              const uint8_t* const dstTables[3]);
+    extern void (*color_xform_RGB1_to_linear)(uint64_t* dst, const uint32_t* src, int len,
+                                              const float* const srcTables[3],
+                                              const float srcToDstMatrix[12]);
 
 }
 
 #endif//SkOpts_DEFINED