Hardware video decoding (V4L2) on ARM64

Hey! Quick question — does Thorium build with V4L2 video decode enabled on Linux? I'm on a Qualcomm ARM64 device (Adreno GPU, Venus decoder at `/dev/video1`), and I can't get hardware decoding to work no matter what flags I throw at it.

What I've checked:
- `chrome://gpu` shows the "Video Acceleration Information" section completely empty — no decode/encode codecs listed.
- The decoder itself is fine: GStreamer's `v4l2h264dec` uses `/dev/video1` without any issue.
- Looking at the binary, there's no `media/gpu/v4l2/*` decode code in there — only the V4L2 camera-capture bits and the `V4L2VideoDecoder` feature name string. So it looks like `use_v4l2_codec` isn't enabled.
- VA-API is the only hardware path available, but freedreno has no VA-API driver, so that fails too.

Fedora's aarch64 chromium does exactly this (`use_v4l2_codec=true`), and it works on these SoCs. Any chance Thorium could do the same? Thanks!