Make GrGLShaderBuilder::TextureSampler extract only required info from GrTextureAccess.

include/gpu/GrTextureAccess.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTextureAccess_DEFINED
 #define GrTextureAccess_DEFINED
 
@@ skipping 144 matching lines @@
 
     bool operator!= (const GrTextureAccess& other) const { return !(*this == other); }
 
     GrTexture* getTexture() const { return fTexture.get(); }
 
     /**
      * Returns a string representing the swizzle. The string is is null-terminated.
      */
     const char* getSwizzle() const { return fSwizzle; }
 
-    enum {
-        kR_SwizzleFlag = 0x1,
-        kG_SwizzleFlag = 0x2,
-        kB_SwizzleFlag = 0x4,
-        kA_SwizzleFlag = 0x8,
-
-        kRGB_SwizzleMask = (kR_SwizzleFlag |  kG_SwizzleFlag | kB_SwizzleFlag),
-    };
-
-    /** Returns a mask indicating which components are referenced in the swizzle. */
+    /** Returns a mask indicating which components are referenced in the swizzle. The return
+        is a bitfield of GrColorComponentFlags. */
     uint32_t swizzleMask() const { return fSwizzleMask; }
 
     const GrTextureParams& getParams() const { return fParams; }
 
 private:
     void setSwizzle(const char*);
 
     GrTextureParams         fParams;
     SkAutoTUnref<GrTexture> fTexture;
     uint32_t                fSwizzleMask;
     char                    fSwizzle[5];
 
     typedef GrNoncopyable INHERITED;
 };
 
 #endif