anchor.diff:  
     version = chromium.browser.version;
   
  -  # This is here because we want to add the widevine shared object at the last
  -  # minute in order to avoid a full rebuild of chromium. Additionally, this
  -  # isn't in `browser.nix` so we can avoid having to re-expose attributes of
  -  # the chromium derivation (see above: we introspect `sandboxExecutableName`).
  +  # We want users to be able to enableWideVine without rebuilding all of
  +  # chromium, so we have a separate derivation here that copies chromium
  +  # and adds the unfree libwidevinecdm.so.
     chromiumWV = let browser = chromium.browser; in if enableWideVine then
       runCommand (browser.name + "-wv") { version = browser.version; }
         ''
           mkdir -p $out
  -        cp -R ${browser}/* $out/
  -        chmod u+w $out/libexec/chromium*
  -        cp ${widevine}/lib/libwidevinecdm.so $out/libexec/chromium/
  -        # patchelf?
  +        cp -a ${browser}/* $out/
  +        chmod u+w $out/libexec/chromium
  +        if [[ ${channel} != "dev" ]]; then
  +          cp ${widevine}/lib/libwidevinecdm.so $out/libexec/chromium/
  +        else
  +          mkdir -p $out/libexec/chromium/WidevineCdm/_platform_specific/linux_x64
  +          cp ${widevine}/lib/libwidevinecdm.so $out/libexec/chromium/WidevineCdm/_platform_specific/linux_x64/
  +        fi
         ''
       else browser;
   in stdenv.mkDerivation {
  
positive.code:     phases = [ "unpackPhase" "patchPhase" "installPhase" "checkPhase" ];
  
      unpackCmd = let
        chan = if upstream-info.channel == "dev"    then "chrome-unstable"
          else if upstream-info.channel == "stable" then "chrome"
          else if upstream-info.channel == "beta" then "chrome-beta"
          else throw "Unknown chromium channel.";
      in ''
        mkdir -p plugins
        ar p "$src" data.tar.xz | tar xJ -C plugins --strip-components=4 \
          ./opt/google/${chan}/libwidevinecdm.so
      '';
  
      doCheck = true;
  
negative.code:   widevine = let upstream-info = chromium.upstream-info; in stdenv.mkDerivation {
      name = "chromium-binary-plugin-widevine";
  
      # The .deb file for Google Chrome
      src = upstream-info.binary;
  
      nativeBuildInputs = [ patchelfUnstable ];
  