Simplify SkGpuBlurUtils::GaussianBlur method

src/effects/SkGpuBlurUtils.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkGpuBlurUtils_DEFINED
 #define SkGpuBlurUtils_DEFINED
 
 #if SK_SUPPORT_GPU
 #include "GrTextureProvider.h"
 
 class GrTexture;
 class GrContext;
 #endif
 
 struct SkRect;
 
 namespace SkGpuBlurUtils {
 
 #if SK_SUPPORT_GPU
   /**
     * Applies a 2D Gaussian blur to a given texture.
     * @param context         The GPU context
     * @param srcTexture      The source texture to be blurred.
-    * @param canClobberSrc   If true, srcTexture may be overwritten, and
-    *                        may be returned as the result.
     * @param gammaCorrect    Should blur be gamma-correct (sRGB to linear, etc...)
     * @param dstBounds       The destination bounds, relative to the source texture.
     * @param srcBounds       The source bounds, relative to the source texture. If non-null,
     *                        no pixels will be sampled outside of this rectangle.
     * @param sigmaX          The blur's standard deviation in X.
     * @param sigmaY          The blur's standard deviation in Y.
     * @return the blurred texture, which may be srcTexture reffed, or a
     * new texture.  It is the caller's responsibility to unref this texture.
     */
     GrTexture* GaussianBlur(GrContext* context,
                             GrTexture* srcTexture,
-                            bool canClobberSrc,
                             bool gammaCorrect,
                             const SkRect& dstBounds,
                             const SkRect* srcBounds,
                             float sigmaX,
                             float sigmaY);
 #endif
 
 };
 
 #endif