We don't use boxBlurY.

src/opts/SkBlurImage_opts_SSE4.cpp

 /*
  * Copyright 2014 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkBlurImage_opts_SSE4.h"
 #include "SkColorPriv.h"
@@ skipping 76 matching lines @@
             dptr += dstStrideX;
         }
         src += srcStrideY;
         dst += dstStrideY;
     }
 }
 
 } // namespace
 
 bool SkBoxBlurGetPlatformProcs_SSE4(SkBoxBlurProc* boxBlurX,
-                                    SkBoxBlurProc* boxBlurY,
                                     SkBoxBlurProc* boxBlurXY,
                                     SkBoxBlurProc* boxBlurYX) {
     *boxBlurX = SkBoxBlur_SSE4<kX, kX>;
-    *boxBlurY = SkBoxBlur_SSE4<kY, kY>;
     *boxBlurXY = SkBoxBlur_SSE4<kX, kY>;
     *boxBlurYX = SkBoxBlur_SSE4<kY, kX>;
     return true;
 }
 
 #else // SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE41
 
 bool SkBoxBlurGetPlatformProcs_SSE4(SkBoxBlurProc* boxBlurX,
-                                    SkBoxBlurProc* boxBlurY,
                                     SkBoxBlurProc* boxBlurXY,
                                     SkBoxBlurProc* boxBlurYX) {
     sk_throw();
     return false;
 }
 
 
 #endif