Expand modulate, add, subtract, extract component glsl helpers.

src/gpu/gl/GrGLShaderVar.h

Index: src/gpu/gl/GrGLShaderVar.h
===================================================================
--- src/gpu/gl/GrGLShaderVar.h	(revision 8735)
+++ src/gpu/gl/GrGLShaderVar.h	(working copy)
@@ -268,46 +268,22 @@
         if (this->isArray()) {
             if (this->isUnsizedArray()) {
                 out->appendf("%s %s[]",
-                             TypeString(effectiveType),
+                             GrGLSLTypeString(effectiveType),
                              this->getName().c_str());
             } else {
                 GrAssert(this->getArrayCount() > 0);
                 out->appendf("%s %s[%d]",
-                             TypeString(effectiveType),
+                             GrGLSLTypeString(effectiveType),
                              this->getName().c_str(),
                              this->getArrayCount());
             }
         } else {
             out->appendf("%s %s",
-                         TypeString(effectiveType),
+                         GrGLSLTypeString(effectiveType),
                          this->getName().c_str());
         }
     }
 
-    static const char* TypeString(GrSLType t) {
-        switch (t) {
-            case kVoid_GrSLType:
-                return "void";
-            case kFloat_GrSLType:
-                return "float";
-            case kVec2f_GrSLType:
-                return "vec2";
-            case kVec3f_GrSLType:
-                return "vec3";
-            case kVec4f_GrSLType:
-                return "vec4";
-            case kMat33f_GrSLType:
-                return "mat3";
-            case kMat44f_GrSLType:
-                return "mat4";
-            case kSampler2D_GrSLType:
-                return "sampler2D";
-            default:
-                GrCrash("Unknown shader var type.");
-                return ""; // suppress warning
-        }
-    }
-
     void appendArrayAccess(int index, SkString* out) const {
         out->appendf("%s[%d]%s",
                      this->getName().c_str(),