Adding vlc plugin for firefox.

I really wanted it to substitute the html5 player, or at least the direct
player for mp4/webm files in firefox, but I couldn't make it work. The
formats recognized by the firefox internal player were used in all cases. The
plugin worked for formats unknown by firefox.

https://support.mozilla.org/ca/questions/1089501

Nevertheless, as I wrote the nix recipe, I commit it. It may be of interest to
someone else.

pkgs/applications/networking/browsers/firefox/wrapper.nix

···
 , trezor-bridge, bluejeans, djview4, adobe-reader
 , google_talk_plugin, fribid, gnome3/*.gnome_shell*/
 , esteidfirefoxplugin
+, vlc_npapi
 }:
 
 ## configurability of the wrapper itself
···
       ++ lib.optional (cfg.enableBluejeans or false) bluejeans
       ++ lib.optional (cfg.enableAdobeReader or false) adobe-reader
       ++ lib.optional (cfg.enableEsteid or false) esteidfirefoxplugin
+      ++ lib.optional (cfg.enableVLC or false) vlc_npapi
      );
   libs = (if ffmpegSupport then [ ffmpeg ] else with gst_all; [ gstreamer gst-plugins-base ])
          ++ lib.optionals (cfg.enableQuakeLive or false)

pkgs/applications/video/vlc/plugin.nix

···
+{ stdenv, fetchgit, vlc, autoconf, automake, libtool, pkgconfig, npapi_sdk,
+libxcb, xlibsWrapper, gtk}:
+
+with stdenv.lib;
+
+stdenv.mkDerivation rec {
+  name = "vlc-plugin-${version}";
+  version = "2.2.2"; # This 2.2.2 builds fine with vlc 2.2.4
+
+  src = fetchgit {
+    url = "https://code.videolan.org/videolan/npapi-vlc.git";
+    rev = "5fa6fbc11cf5bad983f57656c0085e47e18fbf20";
+    sha256 = "18fbiy4r8rlw4fsgcxgzhi6qi9r48d0rmnp8hs994w2p94fa8kwd";
+  };
+
+  preConfigure = "sh autogen.sh";
+
+  buildInputs = [ vlc autoconf automake libtool pkgconfig npapi_sdk libxcb
+      xlibsWrapper gtk ];
+
+  enableParallelBuilding = true;
+
+  passthru = {
+    mozillaPlugin = "/lib/mozilla/plugins";
+  };
+
+  meta = with stdenv.lib; {
+    description = "Webplugins based on libVLC (for firefox, npapi)";
+    homepage = https://code.videolan.org/videolan/npapi-vlc;
+    platforms = platforms.linux;
+    license = licenses.gpl2Plus;
+  };
+}

pkgs/top-level/all-packages.nix

···
     libva = libva-full; # also wants libva-x11
   };
 
+  vlc_npapi = callPackage ../applications/video/vlc/plugin.nix {
+    gtk = gtk2;
+  };
+
   vlc_qt5 = qt5.vlc;
 
   vmpk = callPackage ../applications/audio/vmpk { };