Make GrGLEffects use an interface to append their code.

src/effects/SkDisplacementMapEffect.cpp

Index: src/effects/SkDisplacementMapEffect.cpp
===================================================================
--- src/effects/SkDisplacementMapEffect.cpp	(revision 8005)
+++ src/effects/SkDisplacementMapEffect.cpp	(working copy)
@@ -409,36 +409,38 @@
     GrSLType cCoordsType = fColorEffectMatrix.emitCode(
                                 builder, key, vertexCoords, &cCoordsIn, NULL, "COLOR");
 
-    SkString* code = &builder->fFSCode;
     const char* dColor = "dColor";
     const char* cCoords = "cCoords";
     const char* nearZero = "1e-6"; // Since 6.10352e−5 is the smallest half float, use
                                    // a number smaller than that to approximate 0, but
                                    // leave room for 32-bit float GPU rounding errors.
 
-    code->appendf("\t\tvec4 %s = ", dColor);
-    builder->appendTextureLookup(code, samplers[0], dCoordsIn, dCoordsType);
-    code->append(";\n");
+    builder->fsCodeAppendf("\t\tvec4 %s = ", dColor);
+    builder->appendTextureLookup(GrGLShaderBuilder::kFragment_ShaderType,
+                                 samplers[0],
+                                 dCoordsIn,
+                                 dCoordsType);
+    builder->fsCodeAppend(";\n");
 
     // Unpremultiply the displacement
-    code->appendf("\t\t%s.rgb = (%s.a < %s) ? vec3(0.0) : clamp(%s.rgb / %s.a, 0.0, 1.0);",
-                  dColor, dColor, nearZero, dColor, dColor);
+    builder->fsCodeAppendf("\t\t%s.rgb = (%s.a < %s) ? vec3(0.0) : clamp(%s.rgb / %s.a, 0.0, 1.0);",
+                           dColor, dColor, nearZero, dColor, dColor);
 
-    code->appendf("\t\tvec2 %s = %s + %s*(%s.",
-                  cCoords, cCoordsIn, scaleUni, dColor);
+    builder->fsCodeAppendf("\t\tvec2 %s = %s + %s*(%s.",
+                           cCoords, cCoordsIn, scaleUni, dColor);
 
     switch (fXChannelSelector) {
       case SkDisplacementMapEffect::kR_ChannelSelectorType:
-        code->append("r");
+        builder->fsCodeAppend("r");
         break;
       case SkDisplacementMapEffect::kG_ChannelSelectorType:
-        code->append("g");
+        builder->fsCodeAppend("g");
         break;
       case SkDisplacementMapEffect::kB_ChannelSelectorType:
-        code->append("b");
+        builder->fsCodeAppend("b");
         break;
       case SkDisplacementMapEffect::kA_ChannelSelectorType:
-        code->append("a");
+        builder->fsCodeAppend("a");
         break;
       case SkDisplacementMapEffect::kUnknown_ChannelSelectorType:
       default:
@@ -447,30 +449,33 @@
 
     switch (fYChannelSelector) {
       case SkDisplacementMapEffect::kR_ChannelSelectorType:
-        code->append("r");
+        builder->fsCodeAppend("r");
         break;
       case SkDisplacementMapEffect::kG_ChannelSelectorType:
-        code->append("g");
+        builder->fsCodeAppend("g");
         break;
       case SkDisplacementMapEffect::kB_ChannelSelectorType:
-        code->append("b");
+        builder->fsCodeAppend("b");
         break;
       case SkDisplacementMapEffect::kA_ChannelSelectorType:
-        code->append("a");
+        builder->fsCodeAppend("a");
         break;
       case SkDisplacementMapEffect::kUnknown_ChannelSelectorType:
       default:
         SkASSERT(!"Unknown Y channel selector");
     }
-    code->append("-vec2(0.5));\t\t");
+    builder->fsCodeAppend("-vec2(0.5));\t\t");
 
     // FIXME : This can be achieved with a "clamp to border" texture repeat mode and
     //         a 0 border color instead of computing if cCoords is out of bounds here.
-    code->appendf(
+    builder->fsCodeAppendf(
         "%s = any(greaterThan(vec4(vec2(0.0), %s), vec4(%s, vec2(1.0)))) ? vec4(0.0) : ",
         outputColor, cCoords, cCoords);
-    builder->appendTextureLookup(code, samplers[1], cCoords, cCoordsType);
-    code->append(";\n");
+    builder->appendTextureLookup(GrGLShaderBuilder::kFragment_ShaderType,
+                                 samplers[1],
+                                 cCoords,
+                                 cCoordsType);
+    builder->fsCodeAppend(";\n");
 }
 
 void GrGLDisplacementMapEffect::setData(const GrGLUniformManager& uman, const GrEffectStage& stage) {