Reland "Add SkImage::makeColorSpace() with correct transfer fn behavior"

Completes implementation for lazy and raster images.  gpu is
still a TODO.

Bug: skia:6553
Change-Id: I898e4464ffc91442c7f98669f1203dd5c203621b
Reviewed-on: https://skia-review.googlesource.com/15307
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>
diff --git a/gn/gm.gni b/gn/gm.gni
index 6d43b3a..eb81887 100644
--- a/gn/gm.gni
+++ b/gn/gm.gni
@@ -188,6 +188,7 @@
   "$_gm/localmatriximagefilter.cpp",
   "$_gm/localmatriximageshader.cpp",
   "$_gm/lumafilter.cpp",
+  "$_gm/makecolorspace.cpp",
   "$_gm/manypaths.cpp",
   "$_gm/matrixconvolution.cpp",
   "$_gm/matriximagefilter.cpp",