Reland "media/gpu/VEA unittest: Test DMABuf-backed input buffers"

This adds the command line option, --natvie_input, that VEA unittest passes
DMABuf-backed video frame to VEA.
DMABufs are obtained by gbm though NativePixmap. To create NativePixmap on
Chrome OS, it needs to set up Ozone environment properly. Therefore, this change
also makes VEA unittest dependent on Ozone.

BUG=chromium:895230
TEST=VEA unittest on eve w/wo --native_input
TBR=posciak@chromium.org

Change-Id: I2998f0695813e5e1b77ae2136140eebc385636bf
Reviewed-on: https://chromium-review.googlesource.com/c/1329121
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Commit-Queue: Hirokazu Honda <hiroh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606880}
13 files changed