Fix CodecSubset benches seg faults for kIndex8

bench/subset/SubsetZoomBench.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 "SubsetZoomBench.h"
 #include "SubsetBenchPriv.h"
 #include "SkData.h"
@@ skipping 59 matching lines @@
             int w = fSubsetWidth;
             int h = fSubsetHeight;
             do {
                 const int subsetStartX = SkTMax(0, centerX - w / 2);
                 const int subsetStartY = SkTMax(0, centerY - h / 2);
                 const int subsetWidth = SkTMin(w, info.width() - subsetStartX);
                 const int subsetHeight = SkTMin(h, info.height() - subsetStartY);
                 // Note that if we subsetted and scaled in a single step, we could use the
                 // same bitmap - as is often done in actual use cases.
                 SkBitmap bitmap;
-                bitmap.allocPixels(info.makeWH(subsetWidth, subsetHeight));
+                SkImageInfo subsetInfo = info.makeWH(subsetWidth, subsetHeight);
+                alloc_pixels(&bitmap, subsetInfo, colors, colorCount);
 
                 uint32_t bpp = info.bytesPerPixel();
                 scanlineDecoder->skipScanlines(subsetStartY);
                 for (int y = 0; y < subsetHeight; y++) {
                     scanlineDecoder->getScanlines(row.get(), 1, 0);
                     memcpy(bitmap.getAddr(0, y), row.get() + subsetStartX * bpp,
                             subsetWidth * bpp);
                 }
                 w <<= 1;
                 h <<= 1;
@@ skipping 17 matching lines @@
                 SkBitmap bitmap;
                 SkIRect rect = SkIRect::MakeXYWH(subsetStartX, subsetStartY, subsetWidth,
                         subsetHeight);
                 decoder->decodeSubset(&bitmap, rect, fColorType);
                 w <<= 1;
                 h <<= 1;
             } while (w < 2 * width || h < 2 * height);
         }
     }
 }