Add kRG_1616 and kAlpha_16 SkColorTypes

This also switches GrColorType::kR_16 to kAlpha_16 to more closely match raster.

Bug: skia:9121
Change-Id: I03c6e6c52c90aa4223478c5ea6c8b2ed8558f677
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/239930
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index af99ad8..41257f0 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -259,6 +259,10 @@
             return kRGBA_float_GrPixelConfig;
         case kRG_88_SkColorType:
             return kRG_88_GrPixelConfig;
+        case kRG_1616_SkColorType:
+            return kRG_1616_GrPixelConfig;
+        case kAlpha_16_SkColorType:
+            return kAlpha_16_GrPixelConfig;
     }
     SkASSERT(0);    // shouldn't get here
     return kUnknown_GrPixelConfig;
@@ -293,7 +297,6 @@
         case GrColorType::kRGB_888x:
         case GrColorType::kRG_88:
         case GrColorType::kBGRA_8888:
-        case GrColorType::kR_16:
         case GrColorType::kRG_1616:
         // Experimental (for Y416 and mutant P016/P010)
         case GrColorType::kRGBA_16161616:
@@ -312,6 +315,7 @@
         case GrColorType::kRGBA_F16_Clamped:
         case GrColorType::kAlpha_8:
         case GrColorType::kAlpha_8xxx:
+        case GrColorType::kAlpha_16:
         case GrColorType::kAlpha_F32xxx:
         case GrColorType::kGray_8xxx:
             return -1;