Add support for 3D colorLUTs to SkColorXform

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 8afbfb9f2f92d61110251a1c06adafc194d7817f..f0b10103f7494d17a97ccb4bbbdde447a8afaa61 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -896,10 +896,7 @@ Error ColorCodecSrc::draw(SkCanvas* canvas) const {
 
             std::unique_ptr<SkColorSpaceXform> xform = SkColorSpaceXform::New(srcSpace, dstSpace);
             if (!xform) {
-                // FIXME (msarett):
-                // I haven't implemented conversions for all of the images that I've uploaded for
-                // testing.  Once we support all of them, this should be a fatal error.
-                return Error::Nonfatal("Unimplemented color conversion.");
+                return "Unimplemented color conversion.";
             }
 
             uint32_t* row = (uint32_t*) bitmap.getPixels();