Bug 1602396: Set focus to URLBar when an empty tab is moved to new window. r=adw

Differential Revision: https://phabricator.services.mozilla.com/D117522

browser/base/content/browser.js

@@ -2151,7 +2151,8 @@ var gBrowserInit = {
 
       if (
         (isBlankPageURL(uriToLoad) && !aboutWelcomeSkipUrlBarFocus) ||
-        uriToLoad == "about:privatebrowsing"
+        uriToLoad == "about:privatebrowsing" ||
+        this.getTabToAdopt()?.isEmpty
       ) {
         gURLBar.select();
         shouldRemoveFocusedAttribute = false;

browser/base/content/test/general/browser_bug495058.js

@@ -3,7 +3,12 @@
  * torn out into its own window.
  */
 
-const URIS = ["about:blank", "about:sessionrestore", "about:privatebrowsing"];
+const URIS = [
+  "about:blank",
+  "about:home",
+  "about:sessionrestore",
+  "about:privatebrowsing",
+];
 
 add_task(async function() {
   for (let uri of URIS) {
@@ -35,10 +40,14 @@ add_task(async function() {
       uri,
       uri + ": uri loaded in detached tab"
     );
+
+    const expectedActiveElement = tab.isEmpty
+      ? win.gURLBar.inputField
+      : win.gBrowser.selectedBrowser;
     Assert.equal(
       win.document.activeElement,
-      win.gBrowser.selectedBrowser,
-      uri + ": browser is focused"
+      expectedActiveElement,
+      uri + ": the active element is expected"
     );
     Assert.equal(win.gURLBar.value, "", uri + ": urlbar is empty");
     Assert.ok(win.gURLBar.placeholder, uri + ": placeholder text is present");