chromium: add rtc_use_pipewire

This provides the browser flag #enable-webrtc-pipewire-capturer, which
adds support for screensharing on Wayland via xdg-desktop-portal.

The browser flag is disabled by default until a user enables it. At
least one other major distribution (Arch) enables this compile time
option, and so I believe it should be safe to enable by default.

This is also needed to support xdg-desktop-portal-wlr which was added in
https://github.com/NixOS/nixpkgs/pull/83485.

pkgs/applications/networking/browsers/chromium/common.nix

@@ -17,6 +17,7 @@
 , protobuf, speechd, libXdamage, cups
 , ffmpeg, libxslt, libxml2, at-spi2-core
 , jre
+, pipewire_0_2
 
 # optional dependencies
 , libgcrypt ? null # gnomeSupport || cupsSupport
@@ -132,6 +133,7 @@ let
       libXScrnSaver libXcursor libXtst libGLU libGL
       pciutils protobuf speechd libXdamage at-spi2-core
       jre
+      pipewire_0_2
     ] ++ optional useVaapi libva
       ++ optional gnomeKeyringSupport libgnome-keyring3
       ++ optionals gnomeSupport [ gnome.GConf libgcrypt ]
@@ -243,6 +245,8 @@ let
       # added later in the wrapped -wv build or downloaded from Google.
       enable_widevine = true;
       use_cups = cupsSupport;
+      # Provides the enable-webrtc-pipewire-capturer flag to support Wayland screen capture.
+      rtc_use_pipewire = true;
 
       treat_warnings_as_errors = false;
       is_clang = stdenv.cc.isClang;