Implement GL support for buffer textures

src/gpu/GrTextureAccess.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrTextureAccess.h"
 #include "GrColor.h"
 #include "GrTexture.h"
 
 GrTextureAccess::GrTextureAccess() {}
 
 GrTextureAccess::GrTextureAccess(GrTexture* texture, const GrTextureParams& params) {
     this->reset(texture, params);
 }
 
 GrTextureAccess::GrTextureAccess(GrTexture* texture,
                                  GrTextureParams::FilterMode filterMode,
                                  SkShader::TileMode tileXAndY,
                                  GrShaderFlags visibility,
                                  GrSLPrecision precision) {
     this->reset(texture, filterMode, tileXAndY, visibility, precision);
 }
 
+GrTextureAccess::GrTextureAccess(GrTexture* texture,
+                                 GrShaderFlags visibility,
+                                 GrSLPrecision precision) {
+    this->reset(texture, visibility, precision);
+}
+
 void GrTextureAccess::reset(GrTexture* texture,
                             const GrTextureParams& params,
                             GrShaderFlags visibility,
                             GrSLPrecision precision) {
     SkASSERT(texture);
+    SkASSERT(texture->supportsTextureParams());
     fTexture.set(SkRef(texture), kRead_GrIOType);
     fParams = params;
     fVisibility = visibility;
     fPrecision = precision;
 }
 
 void GrTextureAccess::reset(GrTexture* texture,
                             GrTextureParams::FilterMode filterMode,
                             SkShader::TileMode tileXAndY,
                             GrShaderFlags visibility,
                             GrSLPrecision precision) {
     SkASSERT(texture);
+    SkASSERT(texture->supportsTextureParams());
     fTexture.set(SkRef(texture), kRead_GrIOType);
     fParams.reset(tileXAndY, filterMode);
     fVisibility = visibility;
     fPrecision = precision;
 }
+
+void GrTextureAccess::reset(GrTexture* texture, GrShaderFlags visibility, GrSLPrecision precision) {
+    SkASSERT(texture);
+    SkASSERT(!texture->supportsTextureParams());
+    fTexture.set(SkRef(texture), kRead_GrIOType);
+    fVisibility = visibility;
+    fPrecision = precision;
+}