Express (GLSL expression, possibly known value) pairs as a class

src/gpu/gl/GrGLProgramDesc.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLProgramDesc_DEFINED
 #define GrGLProgramDesc_DEFINED
 
@@ skipping 95 matching lines @@
     // Specifies where the initial color comes from before the stages are applied.
     enum ColorInput {
         kSolidWhite_ColorInput,
         kTransBlack_ColorInput,
         kAttribute_ColorInput,
         kUniform_ColorInput,
 
         kColorInputCnt
     };
 
-    static GrSLConstantVec KnownColorInputValue(ColorInput ci) {
-        switch (ci) {
-            case GrGLProgramDesc::kTransBlack_ColorInput:
-                return kZeros_GrSLConstantVec;
-            case GrGLProgramDesc::kSolidWhite_ColorInput:
-                return kOnes_GrSLConstantVec;
-            default:
-                return kNone_GrSLConstantVec;
-        }
-    }
-
     enum CoverageOutput {
         // modulate color and coverage, write result as the color output.
         kModulate_CoverageOutput,
         // Writes color*coverage as the primary color output and also writes coverage as the
         // secondary output. Only set if dual source blending is supported.
         kSecondaryCoverage_CoverageOutput,
         // Writes color*coverage as the primary color output and also writes coverage * (1 - colorA)
         // as the secondary output. Only set if dual source blending is supported.
         kSecondaryCoverageISA_CoverageOutput,
         // Writes color*coverage as the primary color output and also writes coverage *
@@ skipping 93 matching lines @@
 
     // GrGLProgram and GrGLShaderBuilder read the private fields to generate code. TODO: Move all
     // code generation to GrGLShaderBuilder (and maybe add getters rather than friending).
     friend class GrGLProgram;
     friend class GrGLShaderBuilder;
     friend class GrGLFullShaderBuilder;
     friend class GrGLFragmentOnlyShaderBuilder;
 };
 
 #endif