Allow one-sided scan count down sampling
Allow one-sided scan count down sampling

Change-Id: I164add43e9d75af82312b464a176cdf0045ef9e1

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom