firefox-fourier: ship RK3399 HW-decode default prefs (closes #8)

Three prefs that gate the patched VAAPI / V4L2-request code path are
'false' upstream and need to be 'true' for the libva-v4l2-request
backend to actually engage on RK3399 / panfrost EGL:

  widget.dmabuf.force-enabled
  media.hardware-video-decoding.force-enabled
  media.ffvpx-hw.enabled

Without them, Gecko's DMA-BUF probe silently fails (panfrost EGL
doesn't trip the right detection), the (Intel-tuned) HW-vs-SW cost
heuristic picks SW, and the FFvpx PDM never selects its HW-capable
variant for VP8/VP9. Net result: fresh profiles SW-decode despite the
0001..0004 unlock patches being applied.

Shipped as a vendor-default file at:
  /usr/lib/firefox-fourier/browser/defaults/preferences/rockchip-fourier-defaults.js

Lower precedence than user.js / about:config — power users debugging
HW decode can still flip them off without touching the package.

pkgrel 1 -> 2.

Closes: #8

arch/firefox-fourier/PKGBUILD

@@ -13,7 +13,7 @@
 
 pkgname=firefox-fourier
 pkgver=150.0.1
-pkgrel=1
+pkgrel=2
 pkgdesc='Firefox with V4L2 stateless HW video decode unlocked for mainline Linux Rockchip'
 arch=('aarch64' 'x86_64')
 url='https://www.mozilla.org/firefox'
@@ -87,8 +87,11 @@ source=(
   '0002-libwrapper-hwdevice-ctx-create.patch'
   '0003-ffmpegvideo-v4l2-request-route.patch'
   '0004-prefs-v4l2-request.patch'
+  # Vendor-default prefs that gate the patched VAAPI path on RK3399 —
+  # widget.dmabuf.force-enabled etc. See marfrit-packages#8 for evidence.
+  'rockchip-fourier-defaults.js'
 )
-sha256sums=('SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP')
+sha256sums=('SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP' 'SKIP')
 
 prepare() {
   cd "${srcdir}/firefox-${pkgver}"
@@ -160,4 +163,12 @@ export MOZ_X11_EGL="${MOZ_X11_EGL:-1}"
 exec /usr/lib/firefox-fourier/firefox-fourier "$@"
 LAUNCHER
   chmod 0755 "${pkgdir}/usr/bin/firefox-fourier"
+
+  # Vendor-default prefs (RK3399 HW-decode unlock) — closes #8.
+  # Lower precedence than user prefs / about:config; loaded by Firefox
+  # at startup from the package install dir. The 0004 patch covers
+  # media.ffmpeg.v4l2-request.enabled; this file covers the three
+  # additional prefs that gate the path to the patched code.
+  install -Dm644 "${srcdir}/rockchip-fourier-defaults.js" \
+    "${pkgdir}/usr/lib/firefox-fourier/browser/defaults/preferences/rockchip-fourier-defaults.js"
 }

arch/firefox-fourier/rockchip-fourier-defaults.js

@@ -0,0 +1,19 @@
+// firefox-fourier — RK3399 V4L2-stateless HW-decode default prefs.
+//
+// The patch series (0001..0004) builds the VAAPI / V4L2-request routing
+// path through libavcodec, but the resulting code path is gated by three
+// other prefs that are 'false' upstream because the relevant probes don't
+// fire on panfrost EGL or trip the Intel-tuned cost heuristic. Without
+// these, firefox-fourier silently SW-decodes on a fresh profile despite
+// having all the unlock patches applied.
+//
+// Filed via marfrit/marfrit-packages#8 — see that issue for MOZ_LOG
+// evidence on fresnel (Pinebook Pro / RK3399).
+//
+// These are *vendor* defaults: lower precedence than user.js and
+// about:config user prefs. Power users who want to disable HW decode for
+// debugging can flip them in user prefs without touching this file.
+
+pref("widget.dmabuf.force-enabled",                  true);
+pref("media.hardware-video-decoding.force-enabled",  true);
+pref("media.ffvpx-hw.enabled",                       true);