Bug 1582740 - Default the 'Always check' checkbox to disabled until we load the default browser state to prevent accidental user changes. r=Gijs,preferences-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D62479

browser/components/preferences/main.inc.xhtml

@@ -40,6 +40,7 @@
 #ifdef HAVE_SHELL_SERVICE
   <vbox id="defaultBrowserBox">
     <checkbox id="alwaysCheckDefault" preference="browser.shell.checkDefaultBrowser"
+              disabled="true"
               data-l10n-id="always-check-default"/>
     <deck id="setDefaultPane">
       <hbox align="center" class="indent">

browser/components/preferences/main.js

@@ -1272,8 +1272,10 @@ var gMainPane = {
       let isDefault = shellSvc.isDefaultBrowser(false, true);
       setDefaultPane.selectedIndex = isDefault ? 1 : 0;
       let alwaysCheck = document.getElementById("alwaysCheckDefault");
-      alwaysCheck.disabled =
-        alwaysCheck.disabled || (isDefault && alwaysCheck.checked);
+      let alwaysCheckPref = Preferences.get(
+        "browser.shell.checkDefaultBrowser"
+      );
+      alwaysCheck.disabled = alwaysCheckPref.locked || isDefault;
     }
   },
 

browser/components/preferences/tests/browser_defaultbrowser_alwayscheck.js

@@ -106,6 +106,30 @@ add_task(async function clicking_make_default_checks_alwaysCheck_checkbox() {
   gBrowser.removeCurrentTab();
 });
 
+add_task(async function make_default_disabled_until_prefs_are_loaded() {
+  // Testcase with Firefox not set as the default browser
+  await BrowserTestUtils.openNewForegroundTab(gBrowser, "about:preferences");
+  await test_with_mock_shellservice({ isDefault: false }, async function() {
+    let alwaysCheck = content.document.getElementById("alwaysCheckDefault");
+    Assert.ok(
+      !alwaysCheck.disabled,
+      "'Always Check' is enabled after default browser updated"
+    );
+  });
+  gBrowser.removeCurrentTab();
+
+  // Testcase with Firefox set as the default browser
+  await BrowserTestUtils.openNewForegroundTab(gBrowser, "about:preferences");
+  await test_with_mock_shellservice({ isDefault: true }, async function() {
+    let alwaysCheck = content.document.getElementById("alwaysCheckDefault");
+    Assert.ok(
+      alwaysCheck.disabled,
+      "'Always Check' is still disabled after default browser updated"
+    );
+  });
+  gBrowser.removeCurrentTab();
+});
+
 registerCleanupFunction(function() {
   Services.prefs.unlockPref("browser.shell.checkDefaultBrowser");
   Services.prefs.setBoolPref(