Last tranche of new SkColorTypes

This CL adds:
    kAlpha_F16_SkColorType
    kRG_F16_SkColorType
    kRGBA_16161616_SkColorType,

which should be it for a while.

Bug: skia:9121
Change-Id: I81b9d46a202a76e9b7d7ca86495d72dbdae32576
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/241357
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 41257f0..750e554 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -263,9 +263,14 @@
             return kRG_1616_GrPixelConfig;
         case kAlpha_16_SkColorType:
             return kAlpha_16_GrPixelConfig;
+        case kAlpha_F16_SkColorType:
+            return kAlpha_half_GrPixelConfig;
+        case kRG_F16_SkColorType:
+            return kRG_half_GrPixelConfig;
+        case kRGBA_16161616_SkColorType:
+            return kRGBA_16161616_GrPixelConfig;
     }
-    SkASSERT(0);    // shouldn't get here
-    return kUnknown_GrPixelConfig;
+    SkUNREACHABLE;
 }
 
 GrPixelConfig SkImageInfo2GrPixelConfig(const SkImageInfo& info) {