Make GrGLShaderBuilder responsible for enabling GLSL extensions

src/gpu/effects/GrEdgeEffect.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrEdgeEffect.h"
 #include "gl/GrGLEffect.h"
 #include "gl/GrGLSL.h"
@@ skipping 20 matching lines @@
 
         switch (type) {
         case GrEdgeEffect::kHairLine_EdgeType:
             builder->addVarying(kVec4f_GrSLType, "HairEdge", &vsName, &fsName);
 
             builder->fsCodeAppendf("\t\tedgeAlpha = abs(dot(vec3(%s.xy,1), %s.xyz));\n",
                                    builder->fragmentPosition(), fsName);
             builder->fsCodeAppendf("\t\tedgeAlpha = max(1.0 - edgeAlpha, 0.0);\n");
             break;
         case GrEdgeEffect::kQuad_EdgeType:
-            GrAssert(builder->ctxInfo().caps()->shaderDerivativeSupport());
+            SkAssertResult(builder->enableFeature(GrGLShaderBuilder::kStandardDerivatives_GLSLFeature));
             builder->addVarying(kVec4f_GrSLType, "QuadEdge", &vsName, &fsName);
 
             // keep the derivative instructions outside the conditional
             builder->fsCodeAppendf("\t\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
             builder->fsCodeAppendf("\t\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
             builder->fsCodeAppendf("\t\tif (%s.z > 0.0 && %s.w > 0.0) {\n", fsName, fsName);
             // today we know z and w are in device space. We could use derivatives
             builder->fsCodeAppendf("\t\t\tedgeAlpha = min(min(%s.z, %s.w) + 0.5, 1.0);\n", fsName,
                                    fsName);
             builder->fsCodeAppendf ("\t\t} else {\n");
             builder->fsCodeAppendf("\t\t\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
                                    "\t\t\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
                                     fsName, fsName);
             builder->fsCodeAppendf("\t\t\tedgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName,
                                    fsName);
             builder->fsCodeAppendf("\t\t\tedgeAlpha = "
                                    "clamp(0.5 - edgeAlpha / length(gF), 0.0, 1.0);\n\t\t}\n");
-            if (kES2_GrGLBinding == builder->ctxInfo().binding()) {
-                builder->fHeader.append("#extension GL_OES_standard_derivatives: enable\n");
-            }
             break;
         case GrEdgeEffect::kHairQuad_EdgeType:
-            GrAssert(builder->ctxInfo().caps()->shaderDerivativeSupport());
+            SkAssertResult(builder->enableFeature(GrGLShaderBuilder::kStandardDerivatives_GLSLFeature));
             builder->addVarying(kVec4f_GrSLType, "HairQuadEdge", &vsName, &fsName);
 
             builder->fsCodeAppendf("\t\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
             builder->fsCodeAppendf("\t\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
             builder->fsCodeAppendf("\t\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
                                    "\t\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
                                    fsName, fsName);
             builder->fsCodeAppendf("\t\tedgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName,
                                    fsName);
             builder->fsCodeAppend("\t\tedgeAlpha = sqrt(edgeAlpha*edgeAlpha / dot(gF, gF));\n");
             builder->fsCodeAppend("\t\tedgeAlpha = max(1.0 - edgeAlpha, 0.0);\n");
-            if (kES2_GrGLBinding == builder->ctxInfo().binding()) {
-                builder->fHeader.append("#extension GL_OES_standard_derivatives: enable\n");
-            }
             break;
         };
 
         SkString modulate;
         GrGLSLModulate4f(&modulate, inputColor, "edgeAlpha");
         builder->fsCodeAppendf("\t%s = %s;\n", outputColor, modulate.c_str());
 
         builder->vsCodeAppendf("\t%s = %s;\n", vsName, attrName->c_str());
     }
 
@@ skipping 40 matching lines @@
                                       GrTexture*[]) {
     // Only kHairLine works without derivative instructions.
     EdgeType edgeType;
     if (caps.shaderDerivativeSupport()) {
         edgeType = static_cast<EdgeType>(random->nextULessThan(kEdgeTypeCount));
     } else {
         edgeType = kHairLine_EdgeType;
     }
     return GrEdgeEffect::Create(edgeType);
 }