Potentially optimize some GrGLEffects for known input color values

src/gpu/gl/GrGLEffect.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLEffect_DEFINED
 #define GrGLEffect_DEFINED
 
@@ skipping 61 matching lines @@
                             color is solid white, trans black, known to be opaque, etc.) that allows
                             the effect to communicate back similar known info about its output.
         @param samplers     One entry for each GrTextureAccess of the GrEffect that generated the
                             GrGLEffect. These can be passed to the builder to emit texture
                             reads in the generated code.
         */
     virtual void emitCode(GrGLShaderBuilder* builder,
                           const GrDrawEffect& drawEffect,
                           EffectKey key,
                           const char* outputColor,
-                          const char* inputColor,
+                          const GrGLSLExpr4& inputColor,
                           const TransformedCoordsArray& coords,
                           const TextureSamplerArray& samplers) = 0;
 
     /** A GrGLEffect instance can be reused with any GrEffect that produces the same stage
         key; this function reads data from a stage and uploads any uniform variables required
         by the shaders created in emitCode(). The GrEffect installed in the GrEffectStage is
         guaranteed to be of the same type that created this GrGLEffect and to have an identical
         EffectKey as the one that created this GrGLEffect. Effects that use local coords have
         to consider whether the GrEffectStage's coord change matrix should be used. When explicit
         local coordinates are used it can be ignored. */
@@ skipping 10 matching lines @@
 protected:
     const GrBackendEffectFactory& fFactory;
 
 private:
     friend class GrGLVertexEffect; // to set fIsVertexEffect
 
     bool fIsVertexEffect;
 };
 
 #endif