Update GrSwizzle to only store key and not string.

Change-Id: Ieaba188e620e5c1f1d423109e628b0ca78f3afe0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/257394
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
diff --git a/src/gpu/effects/generated/GrSimpleTextureEffect.cpp b/src/gpu/effects/generated/GrSimpleTextureEffect.cpp
index fd8362a..9c1ad14 100644
--- a/src/gpu/effects/generated/GrSimpleTextureEffect.cpp
+++ b/src/gpu/effects/generated/GrSimpleTextureEffect.cpp
@@ -31,7 +31,10 @@
                 "%s = %s * sample(%s, %s).%s;\n", args.fOutputColor, args.fInputColor,
                 fragBuilder->getProgramBuilder()->samplerVariable(args.fTexSamplers[0]),
                 sk_TransformedCoords2D_0.c_str(),
-                fragBuilder->getProgramBuilder()->samplerSwizzle(args.fTexSamplers[0]).c_str());
+                fragBuilder->getProgramBuilder()
+                        ->samplerSwizzle(args.fTexSamplers[0])
+                        .asString()
+                        .c_str());
     }
 
 private: