Option for SkCodec to treat dst as all zeroes.

src/ports/SkImageGenerator_skia.cpp

 /*
  * Copyright 2015 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 "SkData.h"
 #include "SkImageDecoder.h"
 #include "SkImageGenerator.h"
@@ skipping 35 matching lines @@
     SkData* onRefEncodedData() SK_OVERRIDE {
         return SkRef(fData.get());
     }
 
     virtual bool onGetInfo(SkImageInfo* info) SK_OVERRIDE {
         *info = fInfo;
         return true;
     }
 
     virtual Result onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
+                               const Options&,
                                SkPMColor ctableEntries[], int* ctableCount) SK_OVERRIDE {
         SkMemoryStream stream(fData->data(), fData->size(), false);
         SkAutoTUnref<BareMemoryAllocator> allocator(SkNEW_ARGS(BareMemoryAllocator,
                                                                (info, pixels, rowBytes)));
         fDecoder->setAllocator(allocator);
         fDecoder->setRequireUnpremultipliedColors(kUnpremul_SkAlphaType == info.alphaType());
 
         SkBitmap bm;
         const SkImageDecoder::Result result = fDecoder->decode(&stream, &bm, info.colorType(),
                                                                SkImageDecoder::kDecodePixels_Mode);
@@ skipping 41 matching lines @@
 
     SkBitmap bm;
     stream.rewind();
     if (!decoder->decode(&stream, &bm, kUnknown_SkColorType, SkImageDecoder::kDecodeBounds_Mode)) {
         SkDELETE(decoder);
         return NULL;
     }
 
     return SkNEW_ARGS(SkImageDecoderGenerator, (bm.info(), decoder, data));
 }