Bug 1572925 - Make sure that about:support doesn't list the URL decorations pref as an important locked preference; r=baku

Differential Revision: https://phabricator.services.mozilla.com/D42019

--HG--
extra : moz-landing-system : lando

toolkit/modules/Troubleshoot.jsm

@@ -114,6 +114,8 @@ PREFS_GETTERS[Ci.nsIPrefBranch.PREF_INT] = (prefs, name) =>
 PREFS_GETTERS[Ci.nsIPrefBranch.PREF_BOOL] = (prefs, name) =>
   prefs.getBoolPref(name);
 
+const kURLDecorationPref = "privacy.restrict3rdpartystorage.url_decorations";
+
 // Return the preferences filtered by PREFS_BLACKLIST and PREFS_WHITELIST lists
 // and also by the custom 'filter'-ing function.
 function getPrefList(filter) {
@@ -384,7 +386,13 @@ var dataProviders = {
   },
 
   lockedPreferences: function lockedPreferences(done) {
-    done(getPrefList(name => Services.prefs.prefIsLocked(name)));
+    // The URL Decoration pref isn't an important locked pref, so there is no
+    // good reason to report it.
+    done(
+      getPrefList(
+        name => name != kURLDecorationPref && Services.prefs.prefIsLocked(name)
+      )
+    );
   },
 
   graphics: function graphics(done) {

toolkit/modules/tests/browser/browser_Troubleshoot.js

@@ -285,6 +285,7 @@ const SNAPSHOT_SCHEMA = {
     lockedPreferences: {
       required: true,
       type: "object",
+      properties: {},
     },
     graphics: {
       required: true,