Define sample(null) as returning the inputColor unchanged.

This is more useful than returning half4(1), and there was no existing
code that passed null to sample(), so this will not be a breaking
change.

This change will allow us to replace this boilerplate:
  half4 color = (inputFP != null) ? sample(inputFP, sk_InColor)
                                  : sk_InColor;
With:
  half4 color = sample(inputFP, sk_InColor);

Change-Id: I7bb1580299af99afccbd3a5fdf4cb1d5c4c96da9
Bug: skia:10217
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/295002
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
diff --git a/src/gpu/effects/generated/GrAARectEffect.cpp b/src/gpu/effects/generated/GrAARectEffect.cpp
index 423bf02..580bc61 100644
--- a/src/gpu/effects/generated/GrAARectEffect.cpp
+++ b/src/gpu/effects/generated/GrAARectEffect.cpp
@@ -54,17 +54,15 @@
                 "alpha = 1.0 - alpha;\n}",
                 (int)_outer.edgeType,
                 (int)_outer.edgeType);
-        SkString _input1697 = SkStringPrintf("%s", args.fInputColor);
-        SkString _sample1697;
+        SkString _input1677 = SkStringPrintf("%s", args.fInputColor);
+        SkString _sample1677;
         if (_outer.inputFP_index >= 0) {
-            _sample1697 = this->invokeChild(_outer.inputFP_index, _input1697.c_str(), args);
+            _sample1677 = this->invokeChild(_outer.inputFP_index, _input1677.c_str(), args);
         } else {
-            _sample1697 = "half4(1)";
+            _sample1677 = _input1677;
         }
-        fragBuilder->codeAppendf("\nhalf4 inputColor = %s ? %s : %s;\n%s = inputColor * alpha;\n",
-                                 _outer.inputFP_index >= 0 ? "true" : "false",
-                                 _sample1697.c_str(),
-                                 args.fInputColor,
+        fragBuilder->codeAppendf("\nhalf4 inputColor = %s;\n%s = inputColor * alpha;\n",
+                                 _sample1677.c_str(),
                                  args.fOutputColor);
     }