Implement GL support for buffer textures

include/gpu/GrTextureAccess.h

Index: include/gpu/GrTextureAccess.h
diff --git a/include/gpu/GrTextureAccess.h b/include/gpu/GrTextureAccess.h
index 237485a9e2798072c9339bb227477fb86181bbe2..047a86636eac35d9eb2ef12b9967bae4cac7b65e 100644
--- a/include/gpu/GrTextureAccess.h
+++ b/include/gpu/GrTextureAccess.h
@@ -33,6 +33,9 @@ public:
                              GrShaderFlags visibility = kFragment_GrShaderFlag,
                              GrSLPrecision = kDefault_GrSLPrecision);
 
+    // This constructor is only for textures that do not support texture params.
+    explicit GrTextureAccess(GrTexture*, GrShaderFlags visibility, GrSLPrecision);
+
     void reset(GrTexture*, const GrTextureParams&,
                GrShaderFlags visibility = kFragment_GrShaderFlag,
                GrSLPrecision = kDefault_GrSLPrecision);
@@ -42,6 +45,9 @@ public:
                GrShaderFlags visibility = kFragment_GrShaderFlag,
                GrSLPrecision = kDefault_GrSLPrecision);
 
+    // This version is only for textures that do not support texture params.
+    void reset(GrTexture*, GrShaderFlags visibility, GrSLPrecision);
+
     bool operator==(const GrTextureAccess& that) const {
         return this->getTexture() == that.getTexture() &&
                fParams == that.fParams &&
@@ -60,7 +66,10 @@ public:
      */
     const GrGpuResourceRef* getProgramTexture() const { return &fTexture; }
 
-    const GrTextureParams& getParams() const { return fParams; }
+    const GrTextureParams& getParams() const {
+        SkASSERT(this->getTexture()->supportsTextureParams());
+        return fParams;
+    }
 
 private: