Add more specialized fragment builders

src/gpu/effects/GrMatrixConvolutionEffect.cpp

Index: src/gpu/effects/GrMatrixConvolutionEffect.cpp
diff --git a/src/gpu/effects/GrMatrixConvolutionEffect.cpp b/src/gpu/effects/GrMatrixConvolutionEffect.cpp
index ac7889d0b290a754985dbc2d1308edc01ed93060..ae8b9bf3705a2fb3e67f5dbcb4689e6c979c9021 100644
--- a/src/gpu/effects/GrMatrixConvolutionEffect.cpp
+++ b/src/gpu/effects/GrMatrixConvolutionEffect.cpp
@@ -61,7 +61,7 @@ void GrGLMatrixConvolutionEffect::emitCode(EmitArgs& args) {
     const char* gain = uniformHandler->getUniformCStr(fGainUni);
     const char* bias = uniformHandler->getUniformCStr(fBiasUni);
 
-    GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+    GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
     SkString coords2D = fragBuilder->ensureFSCoords2D(args.fCoords, 0);
     fragBuilder->codeAppend("vec4 sum = vec4(0, 0, 0, 0);");
     fragBuilder->codeAppendf("vec2 coord = %s - %s * %s;", coords2D.c_str(), kernelOffset, imgInc);