chromium: Implement handling of enableCUPS.

We also need to patch the compilation process, so it allows deprecated
declarations when building support for the cups backend. In addition, we also
need to add libgcrypt to dependencies as it's needed by the cups implementation.

pkgs/applications/networking/browsers/chromium/cups_allow_deprecated.patch

@@ -0,0 +1,14 @@
+diff --git a/printing/printing.gyp b/printing/printing.gyp
+index 19fa1b2..f11d76e 100644
+--- a/printing/printing.gyp
++++ b/printing/printing.gyp
+@@ -26,6 +26,9 @@
+       'include_dirs': [
+         '..',
+       ],
++      'cflags': [
++        '-Wno-deprecated-declarations',
++      ],
+       'sources': [
+         'backend/print_backend.cc',
+         'backend/print_backend.h',

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

@@ -26,6 +26,7 @@ let
     enableGnomeSupport = false;
     gnomeKeyringSupport = false;
     useProprietaryCodecs = false;
+    enableCUPS = false;
   };
 
   sourceInfo = import ./source.nix;
@@ -91,13 +92,15 @@ in stdenv.mkDerivation rec {
     glib gtk dbus_glib
     libXScrnSaver libXcursor mesa
   ] ++ stdenv.lib.optional config.gnomeKeyringSupport libgnome_keyring
-    ++ stdenv.lib.optionals config.enableGnomeSupport [ gconf libgcrypt ];
+    ++ stdenv.lib.optionals config.enableGnomeSupport [ gconf libgcrypt ]
+    ++ stdenv.lib.optional config.enableCUPS libgcrypt;
 
   opensslPatches = stdenv.lib.optional config.useOpenSSL openssl.patches;
 
   prePatch = "patchShebangs .";
 
-  patches = stdenv.lib.optional (!config.useSELinux) ./enable_seccomp.patch;
+  patches = stdenv.lib.optional (!config.useSELinux) ./enable_seccomp.patch
+         ++ stdenv.lib.optional config.enableCUPS ./cups_allow_deprecated.patch;
 
   postPatch = stdenv.lib.optionalString config.useOpenSSL ''
     cat $opensslPatches | patch -p1 -d third_party/openssl/openssl
@@ -113,7 +116,7 @@ in stdenv.mkDerivation rec {
     disable_nacl = !config.naclSupport;
     use_openssl = config.useOpenSSL;
     selinux = config.useSELinux;
-    use_cups = false;
+    use_cups = config.enableCUPS;
   } // stdenv.lib.optionalAttrs (stdenv.system == "x86_64-linux") {
     target_arch = "x64";
   } // stdenv.lib.optionalAttrs (stdenv.system == "i686-linux") {