Chromium OS build for Raspberry Pi

We have done extensive refactoring and optimisations over the past few months. Beginning from this release, we will be producing more end-user friendly Chromium OS builds with the intention to be used on a daily basis. Releases going forward will be equipped with more enhancements and optimisations (thanks to the work we have done with FydeOS), yet still have the Chromium OS livery to keep the experience as close to vanilla as possible.

Highlights in this release

• Updated Chromium OS manifest to release-R86-13421.B
• Incorporates a 64bits kernel
• One unified image file to supports both Raspberry Pi 3B/B+ and 4B
• Optimised support for PNaCl, you could use Zoom (the Chrome app) with a separate USB camera to do conference calls
• Added support for Chromecast
• Added support for Linux(beta), note that we've only tested successfully this on Raspberry Pi 4B with 4GB RAM
• Added support for hardware video stream decoding for H.264 and vp8 (unsupported for vp9)
• Fixed sound output had to be forced on 3.5mm output on previous builds
• Fixed Chromium OS bootsplash not showing on previous builds
• Fixed stateful storage not able to automatically occupy the entire microSD card

Known issues

• Boot from USB is still unsupported - this image can only be booted from microSD
• The initial boot time takes longer, this is expected
• To enable Linux(beta) you'll need at least 2GB of RAM and 16GB of microSD capacity. It's only been tested on Raspberry Pi 4B with 4BG RAM.
• Hardware accelerated graphics for Linux(beta) (virgl) isn't supported yet

sha256sum(chromiumos_image_r86r1-rpi4b.img.xz):
9d5c70d9b3f6c38a0d9096927b04aa5e2947a10df1e7963220466c3b18834557