Make GrGLEffects use an interface to append their code.

src/effects/gradients/SkGradientShader.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGradientShaderPriv.h"
 #include "SkLinearGradient.h"
 #include "SkRadialGradient.h"
@@ skipping 769 matching lines @@
                                          vsVaryingName,
                                          vsVaryingType);
 }
 
 void GrGLGradientEffect::emitColorLookup(GrGLShaderBuilder* builder,
                                          const char* gradientTValue,
                                          const char* outputColor,
                                          const char* inputColor,
                                          const GrGLShaderBuilder::TextureSampler& sampler) {
 
-    SkString* code = &builder->fFSCode;
-    code->appendf("\tvec2 coord = vec2(%s, %s);\n",
-                  gradientTValue,
-                  builder->getUniformVariable(fFSYUni).c_str());
-    code->appendf("\t%s = ", outputColor);
-    builder->appendTextureLookupAndModulate(code, inputColor, sampler, "coord");
-    code->append(";\n");
+    builder->fsCodeAppendf("\tvec2 coord = vec2(%s, %s);\n",
+                           gradientTValue,
+                           builder->getUniformVariable(fFSYUni).c_str());
+    builder->fsCodeAppendf("\t%s = ", outputColor);
+    builder->appendTextureLookupAndModulate(GrGLShaderBuilder::kFragment_ShaderType,
+                                            inputColor,
+                                            sampler,
+                                            "coord");
+    builder->fsCodeAppend(";\n");
 }
 
 /////////////////////////////////////////////////////////////////////
 
 GrGradientEffect::GrGradientEffect(GrContext* ctx,
                                    const SkGradientShaderBase& shader,
                                    const SkMatrix& matrix,
                                    SkShader::TileMode tileMode) {
     // TODO: check for simple cases where we don't need a texture:
     //GradientInfo info;
@@ skipping 81 matching lines @@
             (*stops)[i] = stop;
             stop = i < outColors - 1 ? stop + random->nextUScalar1() * (1.f - stop) : 1.f;
         }
     }
     *tm = static_cast<SkShader::TileMode>(random->nextULessThan(SkShader::kTileModeCount));
 
     return outColors;
 }
 
 #endif