@Override
  protected Bitmap alloc(int size) {
    return Bitmap.createBitmap(
        1,
        (int) Math.ceil(size / (double) BitmapUtil.RGB_565_BYTES_PER_PIXEL),
        Bitmap.Config.RGB_565);
  }
Allocate a bitmap that has a backing memory allocation of 'size' bytes. This is configuration
agnostic so the size is the actual size in bytes of the bitmap.

@param size the 'size' in bytes of the bitmap
@return a new bitmap with the specified size in memory
imagepipeline/src/main/java/com/facebook/imagepipeline/memory/BucketsBitmapPool.java