Abandon offset support with texel buffers

include/gpu/GrBufferAccess.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrBufferAccess_DEFINED
 #define GrBufferAccess_DEFINED
 
 #include "GrBuffer.h"
 #include "GrGpuResourceRef.h"
 
 /**
  * Used to represent a texel buffer that will be read in a GrProcessor. It holds a GrBuffer along
  * with an associated offset and texel config.
  */
 class GrBufferAccess : public SkNoncopyable {
 public:
     /**
      * Must be initialized before adding to a GrProcessor's buffer access list.
      */
-    void reset(intptr_t offsetInBytes, GrPixelConfig texelConfig, GrBuffer* buffer,
+    void reset(GrPixelConfig texelConfig, GrBuffer* buffer,
                GrShaderFlags visibility = kFragment_GrShaderFlag) {
-        fOffsetInBytes = offsetInBytes;
         fTexelConfig = texelConfig;
         fBuffer.set(SkRef(buffer), kRead_GrIOType);
         fVisibility = visibility;
     }
 
     bool operator==(const GrBufferAccess& that) const {
-        return fOffsetInBytes == that.fOffsetInBytes &&
-               fTexelConfig == that.fTexelConfig &&
+        return fTexelConfig == that.fTexelConfig &&
                this->buffer() == that.buffer() &&
                fVisibility == that.fVisibility;
     }
 
     bool operator!=(const GrBufferAccess& that) const { return !(*this == that); }
 
-    intptr_t offsetInBytes() const { return fOffsetInBytes; }
     GrPixelConfig texelConfig() const { return fTexelConfig; }
     GrBuffer* buffer() const { return fBuffer.get(); }
     GrShaderFlags visibility() const { return fVisibility; }
 
     /**
      * For internal use by GrProcessor.
      */
     const GrGpuResourceRef* getProgramBuffer() const { return &fBuffer;}
 
 private:
-    intptr_t                      fOffsetInBytes;
     GrPixelConfig                 fTexelConfig;
     GrTGpuResourceRef<GrBuffer>   fBuffer;
     GrShaderFlags                 fVisibility;
 
     typedef SkNoncopyable INHERITED;
 };
 
 #endif