Create a scanline decoder without creating a codec

bench/subset/SubsetTranslateBench.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SubsetTranslateBench.h"
 #include "SubsetBenchPriv.h"
 #include "SkData.h"
@@ skipping 42 matching lines @@
     return kNonRendering_Backend == backend;
 }
 
 void SubsetTranslateBench::onDraw(const int n, SkCanvas* canvas) {
     // When the color type is kIndex8, we will need to store the color table.  If it is
     // used, it will be initialized by the codec.
     int colorCount;
     SkPMColor colors[256];
     if (fUseCodec) {
         for (int count = 0; count < n; count++) {
-            SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(fStream->duplicate()));
-            const SkImageInfo info = codec->getInfo().makeColorType(fColorType);
+            SkAutoTDelete<SkScanlineDecoder> scanlineDecoder(
+                    SkScanlineDecoder::NewFromStream(fStream->duplicate()));
+            const SkImageInfo info = scanlineDecoder->getInfo().makeColorType(fColorType);
             SkAutoTDeleteArray<uint8_t> row(SkNEW_ARRAY(uint8_t, info.minRowBytes()));
-            SkAutoTDelete<SkScanlineDecoder> scanlineDecoder(codec->getScanlineDecoder(
-                    info, NULL, colors, &colorCount));
+            scanlineDecoder->start(info, NULL, colors, &colorCount);
 
             SkBitmap bitmap;
             // Note that we use the same bitmap for all of the subsets.
             // It might be larger than necessary for the end subsets.
             SkImageInfo subsetInfo = info.makeWH(fSubsetWidth, fSubsetHeight);
             alloc_pixels(&bitmap, subsetInfo, colors, colorCount);
 
             for (int x = 0; x < info.width(); x += fSubsetWidth) {
                 for (int y = 0; y < info.height(); y += fSubsetHeight) {
                     scanlineDecoder->skipScanlines(y);
@@ skipping 39 matching lines @@
                     const uint32_t currSubsetHeight = y + (int) fSubsetHeight > height ?
                             height - y : fSubsetHeight;
                     SkIRect rect = SkIRect::MakeXYWH(x, y, currSubsetWidth,
                             currSubsetHeight);
                     decoder->decodeSubset(&bitmap, rect, fColorType);
                 }
             }
         }
     }
 }