I plan to do this late this week or earlier next week.

CL is up. https://codereview.chromium.org/2225723002
From testing, 2 input buffers improved the fps on oak and minnie. 3 input buffers did not improve the fps.

peach pit 8634.0.0 320x192 h264:
FPS of 1 input buffer: 973.55
2 input buffers: 976.199
3 input buffers: 966.006

elm-cheets 8667.0.0 320x192 h264:
989.196 1396.295 1395.97

minnie 8562.0.0	320x192 vp8:
984.168 1013.763 1038.44

nyan-big 8609.0.0 320x192 h264:
810.348 808.127 793.481

This is the command I tested FPS.
echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor >/dev/null
./video_encode_accelerator_unittest --test_stream_data=bear_320x192_40frames.yuv:320:192:1:out1.h264:200000:30:200000:30 --num_frames_to_encode=4000 --gtest_filter=EncoderPerf*

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bcdbb72470c705f4363a4cbe87eb8f9686b55088

commit bcdbb72470c705f4363a4cbe87eb8f9686b55088
Author: wuchengli <wuchengli@chromium.org>
Date: Mon Aug 08 05:59:59 2016

V4L2VideoEncodeAccelerator: increase the number of input buffers to 2.

The default number of input buffer was only one. When encoding
continuously, encoder would starve from input buffers. Change the
default number of input buffers to two to improve performance. From
testing, three input buffers do not improve the performance further.

BUG= chromium:627020 
TEST=Run VEA test on CrOS oak, veyron-minnie, nyan-big, and peach-pit.

Review-Url: https://codereview.chromium.org/2225723002
Cr-Commit-Position: refs/heads/master@{#410306}

[modify] https://crrev.com/bcdbb72470c705f4363a4cbe87eb8f9686b55088/media/gpu/v4l2_video_encode_accelerator.cc

bulk verified