firefox: Enable userChrome in about:config

Enable "toolkit.legacyUserProfileCustomizations.stylesheets" in
about:config if userChrome or userContent is not empty.

modules/programs/firefox/mkFirefoxModule.nix

@@ -343,7 +343,12 @@ in {
 
     profiles = mkOption {
       inherit visible;
-      type = types.attrsOf (types.submodule ({ config, name, ... }: {
+      type = types.attrsOf (types.submodule ({ config, name, ... }:
+        let
+
+          profile = config;
+
+        in {
           options = {
             name = mkOption {
               type = types.str;
@@ -746,6 +751,12 @@ in {
             };
 
           };
+
+          config = {
+            settings."toolkit.legacyUserProfileCustomizations.stylesheets" =
+              mkIf (profile.userChrome != "" || profile.userContent != "") true;
+          };
+
         }));
       default = { };
       description = "Attribute set of ${name} profiles.";
@@ -801,7 +812,28 @@ in {
       }
 
       (mkNoDuplicateAssertion cfg.profiles "profile")
-    ] ++ (mapAttrsToList
+    ] ++ (
+
+      # Assert "toolkit.legacyUserProfileCustomizations.stylesheets" is enabled if userChrome/userContent is used.
+      let
+
+        assertProfile = userChromeAttr: profile:
+          profile.${userChromeAttr} != ""
+          -> (profile.settings."toolkit.legacyUserProfileCustomizations.stylesheets"
+            != false);
+
+        mkAssertion = userChromeAttr: {
+          assertion =
+            all (assertProfile userChromeAttr) (attrValues cfg.profiles);
+          message = ''
+            {option}`${userChromeAttr}` won't work with
+            {option}`settings."toolkit.legacyUserProfileCustomizations.stylesheets"` set to false.
+          '';
+        };
+
+      in [ (mkAssertion "userChrome") (mkAssertion "userContent") ]
+
+    ) ++ (mapAttrsToList
       (_: profile: mkNoDuplicateAssertion profile.containers "container")
       cfg.profiles);
 

tests/modules/programs/firefox/profile-settings-expected-containers.json

@@ -1 +1 @@
-{"identities":[{"color":"yellow","icon":"circle","name":"shopping","public":true,"userContextId":6},{"accessKey":"","color":"","icon":"","name":"userContextIdInternal.thumbnail","public":false,"userContextId":4294967294},{"accessKey":"","color":"","icon":"","name":"userContextIdInternal.webextStorageLocal","public":false,"userContextId":4294967295}],"lastUserContextId":6,"version":4}
+{"identities":[{"color":"yellow","icon":"circle","name":"shopping","public":true,"userContextId":0},{"accessKey":"","color":"","icon":"","name":"userContextIdInternal.thumbnail","public":false,"userContextId":4294967294},{"accessKey":"","color":"","icon":"","name":"userContextIdInternal.webextStorageLocal","public":false,"userContextId":4294967295}],"lastUserContextId":0,"version":4}

tests/modules/programs/firefox/profile-settings.nix

@@ -9,6 +9,9 @@ let
 
   firefoxMockOverlay = import ./setup-firefox-mock-overlay.nix modulePath;
 
+  userChromeExample = "#example-user-chrome { display: none; }";
+  userContentExample = "#example-user-content { display: none; }";
+
 in {
   imports = [ firefoxMockOverlay ];
 
@@ -154,12 +157,18 @@ in {
       id = 5;
       containers = {
         "shopping" = {
-          id = 6;
           icon = "circle";
           color = "yellow";
         };
       };
     };
+
+    profiles.userChrome = {
+      id = 6;
+      userChrome = userChromeExample;
+      userContent = userContentExample;
+    };
+
   } // {
 
     nmt.script = ''
@@ -173,10 +182,6 @@ in {
         home-files/${cfg.configPath}/test/user.js \
         ${./profile-settings-expected-user.js}
 
-      assertFileContent \
-        home-files/${cfg.configPath}/containers/containers.json \
-        ${./profile-settings-expected-containers.json}
-
       bookmarksUserJs=$(normalizeStorePaths \
         home-files/${cfg.configPath}/bookmarks/user.js)
 
@@ -210,6 +215,22 @@ in {
       assertFirefoxSearchContent \
         home-files/${cfg.configPath}/searchWithoutDefault/search.json.mozlz4 \
         ${./profile-settings-expected-search-without-default.json}
+
+      assertFileContent \
+        home-files/${cfg.configPath}/containers/containers.json \
+        ${./profile-settings-expected-containers.json}
+
+      assertFileContains \
+        home-files/.mozilla/firefox/userChrome/user.js \
+        'user_pref("toolkit.legacyUserProfileCustomizations.stylesheets", true)'
+
+      assertFileContains \
+        home-files/.mozilla/firefox/userChrome/chrome/userChrome.css \
+        '${userChromeExample}'
+
+      assertFileContains \
+        home-files/.mozilla/firefox/userChrome/chrome/userContent.css \
+        '${userContentExample}'
     '';
   });
 }