Make invokeChild default to fInputColor, rather than half4(1)

By extension, this changes the default behavior of sample() in .fp
files. This lets us remove the explicit fInputColor/sk_InColor
arguments everywhere. Most sites that were using the default no
longer care what's passed, as the child is known to be a texture
effect that will ignore the input color. The few remaining sites
now explicitly pass half4(1) when necessary.

Change-Id: Ie4691b049f905d098e9befe8bd07706a496f2968
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/303356
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
diff --git a/src/gpu/effects/generated/GrRRectBlurEffect.cpp b/src/gpu/effects/generated/GrRRectBlurEffect.cpp
index 819eb4e..fd224ca 100644
--- a/src/gpu/effects/generated/GrRRectBlurEffect.cpp
+++ b/src/gpu/effects/generated/GrRRectBlurEffect.cpp
@@ -94,19 +94,18 @@
                 args.fUniformHandler->getUniformCStr(proxyRectVar),
                 args.fUniformHandler->getUniformCStr(blurRadiusVar),
                 args.fUniformHandler->getUniformCStr(cornerRadiusVar));
-        SkString _input9561(args.fInputColor);
-        SkString _sample9561 = this->invokeChild(0, _input9561.c_str(), args);
+        SkString _sample9561 = this->invokeChild(0, args);
         fragBuilder->codeAppendf(
                 R"SkSL(
 half4 inputColor = %s;)SkSL",
                 _sample9561.c_str());
-        SkString _coords9621("float2(texCoord)");
-        SkString _sample9621 = this->invokeChild(1, args, _coords9621.c_str());
+        SkString _coords9609("float2(texCoord)");
+        SkString _sample9609 = this->invokeChild(1, args, _coords9609.c_str());
         fragBuilder->codeAppendf(
                 R"SkSL(
 %s = inputColor * %s;
 )SkSL",
-                args.fOutputColor, _sample9621.c_str());
+                args.fOutputColor, _sample9609.c_str());
     }
 
 private: