Multimedia: hardware acceleration integration

Close for FF 6.0.4 and GG 7.0.0

Step 2.1:  Add the following lines to local.conf (or local.dev.inc) to use v4l2 device for hw accelerated video decoding. Perform steps below before building code using bitbake.

I verified the hw accelerated video decoding works on Renesas R-car m3 board.

Steps to be taken -

1) Use gstreamer and v4l2apps patches from https://github.com/igel-oss/meta-browser-hwdecode/tree/igalia-chromium71 by adding

the meta-browser-hwdecode path to BBLAYERS in conf/bblayers.conf like that -

BBLAYERS ?= " \  ${AGL_CORE_DEPENDENCY_LAYERS} \  ${AGL_CORE_LAYERS} \  ${AGL_APPFW_LAYERS} \  ${YOCTO_LAYERS} \  /home/msisov/code/meta-browser-hwdecode \
"

2) Add several components to image install in conf/local.conf -

IMAGE_INSTALL_append = " v4l-gst libv4l libv4l-dev"

3) bitbake agl-demo-platform-wam.

4) Create a dummy V4L2 device file under /dev

$ touch /dev/video-gst

$ chsmack -a * /dev/video-gst

5) Link to the video decoder device file that Chromium uses

$ ln -s /dev/video-gst /dev/video-dec

$ chsmack -a * /dev/video-dec

6) (bug in r-car layer) change /etc/gstvspfilter.conf to point to right path:

input-device-name=/dev/video8
output-device-name=/dev/video9

7) When playing a video, verify that GpuVideoDecoder is used in about://media-internals

 [Renesas R-car m3] Patches are backported from the ozone-wayland-dev branch to chromium 68. https://github.com/Igalia/chromium68/pull/10

Next: verifying on the Renesas board.