Fix CodecSubset benches seg faults for kIndex8

bench/subset/SubsetTranslateBench.cpp

Index: bench/subset/SubsetTranslateBench.cpp
diff --git a/bench/subset/SubsetTranslateBench.cpp b/bench/subset/SubsetTranslateBench.cpp
index 620b6f4903b8da291ee0c8eb34809385825fb188..076901515ccf27bb7234e82972f78b3ec53303b6 100644
--- a/bench/subset/SubsetTranslateBench.cpp
+++ b/bench/subset/SubsetTranslateBench.cpp
@@ -68,7 +68,8 @@ void SubsetTranslateBench::onDraw(const int n, SkCanvas* canvas) {
             SkBitmap bitmap;
             // Note that we use the same bitmap for all of the subsets.
             // It might be larger than necessary for the end subsets.
-            bitmap.allocPixels(info.makeWH(fSubsetWidth, fSubsetHeight));
+            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) {