Implement GL support for buffer textures

src/gpu/gl/GrGLProgramDesc.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 "GrGLProgramDesc.h"
 
 #include "GrProcessor.h"
 #include "GrPipeline.h"
 #include "GrRenderTargetPriv.h"
 #include "SkChecksum.h"
 #include "gl/GrGLDefines.h"
 #include "gl/GrGLTexture.h"
 #include "gl/GrGLTypes.h"
 #include "glsl/GrGLSLFragmentProcessor.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
 #include "glsl/GrGLSLCaps.h"
 
 static uint8_t texture_target_key(GrGLenum target) {
     switch (target) {
         case GR_GL_TEXTURE_2D:
             return 0;
         case GR_GL_TEXTURE_EXTERNAL:
             return 1;
         case GR_GL_TEXTURE_RECTANGLE:
             return 2;
+        case GR_GL_TEXTURE_BUFFER:
+            return 3;
         default:
             SkFAIL("Unexpected texture target.");
             return 0;
     }
 }
 
 static void add_texture_key(GrProcessorKeyBuilder* b, const GrProcessor& proc,
                             const GrGLSLCaps& caps) {
     int numTextures = proc.numTextures();
     // Need two bytes per key (swizzle and target).
@@ skipping 134 matching lines @@
     } else {
         header->fIgnoresCoverage = 0;
     }
 
     header->fSnapVerticesToPixelCenters = pipeline.snapVerticesToPixelCenters();
     header->fColorEffectCnt = pipeline.numColorFragmentProcessors();
     header->fCoverageEffectCnt = pipeline.numCoverageFragmentProcessors();
     glDesc->finalize();
     return true;
 }