Support scaling down image in signal-pixel mode

It can be done by assigning proper arguments to pixeldump.

BUG=chromium:598387
TEST=Called the API CacheFrameThumbnail() in the single-pixel mode.

Change-Id: Ib2eb57f0864f3bc3d12a6570cf3a238e77908c06
Reviewed-on: https://chromium-review.googlesource.com/349263
Commit-Ready: Tom Tam <waihong@google.com>
Tested-by: Tom Tam <waihong@google.com>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>
1 file changed