Implement GL support for buffer textures

src/gpu/glsl/GrGLSLProgramBuilder.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "glsl/GrGLSLProgramBuilder.h"
 
 #include "GrPipeline.h"
@@ skipping 222 matching lines @@
             ++fNumFragmentSamplers;
         }
         GrSLType samplerType = access.getTexture()->samplerType();
         if (kSamplerExternal_GrSLType == samplerType) {
             const char* externalFeatureString = this->glslCaps()->externalTextureExtensionString();
             // We shouldn't ever create a GrGLTexture that requires external sampler type
             SkASSERT(externalFeatureString);
             this->addFeature(visibility,
                              1 << GrGLSLShaderBuilder::kExternalTexture_GLSLPrivateFeature,
                              externalFeatureString);
+        } else if (kSamplerBuffer_GrSLType == samplerType) {
+            if (const char* extension = this->glslCaps()->bufferTextureExtensionString()) {
+                this->addFeature(visibility,
+                                 1 << GrGLSLShaderBuilder::kBufferTexture_GLSLPrivateFeature,
+                                 extension);
+            }
         }
         name.printf("Sampler%d", t);
         localSamplerUniforms[t] = this->uniformHandler()->addUniform(access.getVisibility(),
                                                                      samplerType,
                                                                      access.getPrecision(),
                                                                      name.c_str());
         outSamplers->emplace_back(localSamplerUniforms[t], access);
     }
 }
 
@@ skipping 110 matching lines @@
         delete fFragmentProcessors[i];
     }
 }
 
 void GrGLSLProgramBuilder::finalizeShaders() {
     this->varyingHandler()->finalize();
     fVS.finalize(kVertex_GrShaderFlag);
     fFS.finalize(kFragment_GrShaderFlag);
 
 }