Fix CodecSubset benches seg faults for kIndex8

All of the CodecSubset benches fail when the color type is
kIndex8.  We need to pass a color table to allocPixels()
when we want to decode to kIndex8 or it will throw a failure.

BUG=skia:

Review URL: https://codereview.chromium.org/1213983003

1 files changed, 2 insertions, 1 deletions

diff --git a/bench/subset/SubsetSingleBench.cpp b/bench/subset/SubsetSingleBench.cpp
index 68c94cd246..6c1da5c39e 100644
--- a/bench/subset/SubsetSingleBench.cpp
+++ b/bench/subset/SubsetSingleBench.cpp
@@ -70,7 +70,8 @@ void SubsetSingleBench::onDraw(const int n, SkCanvas* canvas) {
                     info, NULL, colors, &colorCount);
 
             SkBitmap bitmap;
-            bitmap.allocPixels(info.makeWH(fSubsetWidth, fSubsetHeight));
+            SkImageInfo subsetInfo = info.makeWH(fSubsetWidth, fSubsetHeight);
+            alloc_pixels(&bitmap, subsetInfo, colors, colorCount);
 
             scanlineDecoder->skipScanlines(fOffsetTop);
             uint32_t bpp = info.bytesPerPixel();