Remove unneeded GrGLSLTransformedCoordsArray type

Rename GrGLSLFragmentBuilder::ensureFSCoords2D to ensureCoords2D and make it take an arbitrary GrShaderVar.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2324663004

Review-Url: https://codereview.chromium.org/2324663004
diff --git a/src/gpu/effects/GrMatrixConvolutionEffect.cpp b/src/gpu/effects/GrMatrixConvolutionEffect.cpp
index 8f03190..a07b671 100644
--- a/src/gpu/effects/GrMatrixConvolutionEffect.cpp
+++ b/src/gpu/effects/GrMatrixConvolutionEffect.cpp
@@ -65,7 +65,7 @@
     const char* bias = uniformHandler->getUniformCStr(fBiasUni);
 
     GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
-    SkString coords2D = fragBuilder->ensureFSCoords2D(args.fCoords, 0);
+    SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);
     fragBuilder->codeAppend("vec4 sum = vec4(0, 0, 0, 0);");
     fragBuilder->codeAppendf("vec2 coord = %s - %s * %s;", coords2D.c_str(), kernelOffset, imgInc);
     fragBuilder->codeAppend("vec4 c;");