Expand modulate, add, subtract, extract component glsl helpers.
Review URL: https://codereview.chromium.org/13895006

git-svn-id: http://skia.googlecode.com/svn/trunk@8755 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGLProgram.h b/src/gpu/gl/GrGLProgram.h
index 4221d73..578b4a9 100644
--- a/src/gpu/gl/GrGLProgram.h
+++ b/src/gpu/gl/GrGLProgram.h
@@ -125,14 +125,14 @@
      */
     bool genProgram(const GrEffectStage* stages[]);
 
-    void genInputColor(GrGLShaderBuilder* builder, SkString* inColor);
+    GrSLConstantVec genInputColor(GrGLShaderBuilder* builder, SkString* inColor);
+
+    GrSLConstantVec genInputCoverage(GrGLShaderBuilder* builder, SkString* inCoverage);
 
     void genGeometryShader(GrGLShaderBuilder* segments) const;
 
     typedef GrGLUniformManager::UniformHandle UniformHandle;
 
-    void genUniformCoverage(GrGLShaderBuilder* segments, SkString* inOutCoverage);
-
     // Creates a GL program ID, binds shader attributes to GL vertex attrs, and links the program
     bool bindOutputsAttribsAndLinkProgram(const GrGLShaderBuilder& builder,
                                           bool bindColorOut,