Use ComposColorFilter to collaps hierarchy (when possible).

src/core/SkImageFilter.cpp

 /*
  * Copyright 2012 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 "SkImageFilter.h"
 
 #include "SkBitmap.h"
@@ skipping 348 matching lines @@
     // loop, but then return false on the next filter.
     *dst = bounds;
     return true;
 }
 
 bool SkImageFilter::asFragmentProcessor(GrFragmentProcessor**, GrTexture*, const SkMatrix&,
                                         const SkIRect&) const {
     return false;
 }
 
-bool SkImageFilter::asColorFilter(SkColorFilter**) const {
-    return false;
-}
-
 #if SK_SUPPORT_GPU
 
 void SkImageFilter::WrapTexture(GrTexture* texture, int width, int height, SkBitmap* result) {
     SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
     result->setInfo(info);
     result->setPixelRef(SkNEW_ARGS(SkGrPixelRef, (info, texture)))->unref();
 }
 
 bool SkImageFilter::getInputResultGPU(SkImageFilter::Proxy* proxy,
                                       const SkBitmap& src, const Context& ctx,
@@ skipping 106 matching lines @@
 
 SkImageFilter::Cache* SkImageFilter::Cache::Create(size_t maxBytes) {
     return SkNEW_ARGS(CacheImpl, (maxBytes));
 }
 
 SK_DECLARE_STATIC_LAZY_PTR(SkImageFilter::Cache, cache, CreateCache);
 
 SkImageFilter::Cache* SkImageFilter::Cache::Get() {
     return cache.get();
 }