Next round of GrGLSLFragmentProcessor-derived class cleanup

src/effects/SkArithmeticMode_gpu.cpp

Index: src/effects/SkArithmeticMode_gpu.cpp
diff --git a/src/effects/SkArithmeticMode_gpu.cpp b/src/effects/SkArithmeticMode_gpu.cpp
index 709f59d3d68b05255ed6870e077e348d68f186a1..d3fb6097f8559187fa84be783dd89152710ec56c 100644
--- a/src/effects/SkArithmeticMode_gpu.cpp
+++ b/src/effects/SkArithmeticMode_gpu.cpp
@@ -75,7 +75,7 @@ public:
                             arith.enforcePMColor());
     }
 
-    static void GenKey(const GrProcessor& proc, const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) {
+    static void GenKey(const GrProcessor& proc, const GrGLSLCaps&, GrProcessorKeyBuilder* b) {
         const GrArithmeticFP& arith = proc.cast<GrArithmeticFP>();
         uint32_t key = arith.enforcePMColor() ? 1 : 0;
         b->add32(key);