Update gradient colorizers to take coords instead of colors.

Gradient layout FPs were passing a position to their colorizers via
sk_InColor.x. This worked, but it makes more sense to pass coordinates
to children by sampling the child at explicit coordinates.

Change-Id: I60520f2e54e04bc9c4d8562e6b2256b95e0de5b4
Bug: skia:10548
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/307217
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
diff --git a/src/gpu/gradients/generated/GrClampedGradientEffect.cpp b/src/gpu/gradients/generated/GrClampedGradientEffect.cpp
index f7c57dd..2f5b0a3 100644
--- a/src/gpu/gradients/generated/GrClampedGradientEffect.cpp
+++ b/src/gpu/gradients/generated/GrClampedGradientEffect.cpp
@@ -51,8 +51,8 @@
                 args.fOutputColor, args.fOutputColor,
                 args.fUniformHandler->getUniformCStr(leftBorderColorVar), args.fOutputColor,
                 args.fUniformHandler->getUniformCStr(rightBorderColorVar));
-        SkString _input1767("t");
-        SkString _sample1767 = this->invokeChild(0, _input1767.c_str(), args);
+        SkString _coords1767("float2(t.xy)");
+        SkString _sample1767 = this->invokeChild(0, args, _coords1767.c_str());
         fragBuilder->codeAppendf(
                 R"SkSL(
     %s = %s;