Add capability for SkColorXform to output half floats

src/core/SkOpts.h

Index: src/core/SkOpts.h
diff --git a/src/core/SkOpts.h b/src/core/SkOpts.h
index 2bf4bdabde47de1f51a2c537d3294c13c127e35f..7acceef6a62f5d032b7fcc4da5f16345d285c0b2 100644
--- a/src/core/SkOpts.h
+++ b/src/core/SkOpts.h
@@ -66,7 +66,7 @@ namespace SkOpts {
     // 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]);
@@ -77,6 +77,9 @@ namespace SkOpts {
                                              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]);
 
 }