fix for FB fetch on nexus 10 ES3.0

src/gpu/gl/builders/GrGLFragmentShaderBuilder.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGLFragmentShaderBuilder.h"
 #include "GrGLShaderStringBuilder.h"
 #include "GrGLProgramBuilder.h"
@@ skipping 153 matching lines @@
 }
 
 const char* GrGLFragmentShaderBuilder::dstColor() {
     fHasReadDstColor = true;
 
     GrGLGpu* gpu = fProgramBuilder->gpu();
     if (gpu->glCaps().fbFetchSupport()) {
         this->addFeature(1 << (GrGLFragmentShaderBuilder::kLastGLSLPrivateFeature + 1),
                          gpu->glCaps().fbFetchExtensionString());
 
-        // On ES 3.0 we have to declare this, and use the custom color output name
+        // Some versions of this extension string require declaring custom color output on ES 3.0+
         const char* fbFetchColorName = gpu->glCaps().fbFetchColorName();
-        if (gpu->glslGeneration() >= k330_GrGLSLGeneration) {
+        if (gpu->glCaps().fbFetchNeedsCustomOutput()) {
             this->enableCustomOutput();
             fOutputs[fCustomColorOutputIndex].setTypeModifier(GrShaderVar::kInOut_TypeModifier);
             fbFetchColorName = declared_color_output_name();
         }
         return fbFetchColorName;
     } else if (fProgramBuilder->fUniformHandles.fDstCopySamplerUni.isValid()) {
         return kDstCopyColorName;
     } else {
         return "";
     }
@@ skipping 110 matching lines @@
     }
 }
 
 void GrGLFragmentShaderBuilder::addVarying(GrGLVarying* v, GrSLPrecision fsPrec) {
     v->fFsIn = v->fVsOut;
     if (v->fGsOut) {
         v->fFsIn = v->fGsOut;
     }
     fInputs.push_back().set(v->fType, GrGLShaderVar::kVaryingIn_TypeModifier, v->fFsIn, fsPrec);
 }