Make bicubic FP factories return const FPs

src/core/SkBitmapProcShader.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapProcShader.h"
 #include "SkBitmapProcState.h"
 #include "SkBitmapProvider.h"
@@ skipping 382 matching lines @@
                                             &doBicubic);
     GrTextureParams params(tm, textureFilterMode);
     SkAutoTUnref<GrTexture> texture(GrRefCachedBitmapTexture(context, fRawBitmap, params));
 
     if (!texture) {
         SkErrorInternals::SetError( kInternalError_SkError,
                                     "Couldn't convert bitmap to texture.");
         return nullptr;
     }
 
-    SkAutoTUnref<GrFragmentProcessor> inner;
+    SkAutoTUnref<const GrFragmentProcessor> inner;
     if (doBicubic) {
         inner.reset(GrBicubicEffect::Create(texture, matrix, tm));
     } else {
         inner.reset(GrSimpleTextureEffect::Create(texture, matrix, params));
     }
 
     if (kAlpha_8_SkColorType == fRawBitmap.colorType()) {
         return GrFragmentProcessor::MulOutputByInputUnpremulColor(inner);
     }
     return GrFragmentProcessor::MulOutputByInputAlpha(inner);
 }
 
 #endif