Potentially optimize some GrGLEffects for known input color values

src/effects/SkPerlinNoiseShader.cpp

Index: src/effects/SkPerlinNoiseShader.cpp
diff --git a/src/effects/SkPerlinNoiseShader.cpp b/src/effects/SkPerlinNoiseShader.cpp
index 549acbb76d94f0631f39bd1662bdc14ca26518ca..ed94733a524329f52cca4ec089ef59f44bde657a 100644
--- a/src/effects/SkPerlinNoiseShader.cpp
+++ b/src/effects/SkPerlinNoiseShader.cpp
@@ -531,7 +531,7 @@ public:
                           const GrDrawEffect&,
                           EffectKey,
                           const char* outputColor,
-                          const char* inputColor,
+                          const GrGLSLExpr4& inputColor,
                           const TransformedCoordsArray&,
                           const TextureSamplerArray&) SK_OVERRIDE;
 
@@ -556,7 +556,7 @@ public:
                           const GrDrawEffect&,
                           EffectKey,
                           const char* outputColor,
-                          const char* inputColor,
+                          const GrGLSLExpr4& inputColor,
                           const TransformedCoordsArray&,
                           const TextureSamplerArray&) SK_OVERRIDE;
 
@@ -754,7 +754,7 @@ void GrGLSimplexNoise::emitCode(GrGLShaderBuilder* builder,
                                 const GrDrawEffect&,
                                 EffectKey key,
                                 const char* outputColor,
-                                const char* inputColor,
+                                const GrGLSLExpr4& inputColor,
                                 const TransformedCoordsArray& coords,
                                 const TextureSamplerArray&) {
     sk_ignore_unused_variable(inputColor);
@@ -970,7 +970,7 @@ void GrGLPerlinNoise::emitCode(GrGLShaderBuilder* builder,
                                const GrDrawEffect&,
                                EffectKey key,
                                const char* outputColor,
-                               const char* inputColor,
+                               const GrGLSLExpr4& inputColor,
                                const TransformedCoordsArray& coords,
                                const TextureSamplerArray& samplers) {
     sk_ignore_unused_variable(inputColor);