Bug 1265208: Restore url if the value of inputed bar that had been inputting is empty upon switching tab. r=adw

Differential Revision: https://phabricator.services.mozilla.com/D118125

browser/components/urlbar/UrlbarInput.jsm

@@ -325,10 +325,11 @@ class UrlbarInput {
     let value = this.window.gBrowser.userTypedValue;
     let valid = false;
 
-    // Explicitly check for nulled out value. We don't want to reset the URL
-    // bar if the user has deleted the URL and we'd just put the same URL
-    // back. See bug 304198.
-    if (value === null) {
+    // Restore the selected browser's current URI if `value` is null or if it's
+    // an empty string and we're switching tabs. In the latter case, when the
+    // user makes the input empty, switches tabs, and switches back, we want the
+    // URI to become visible again so the user knows what URI they're viewing.
+    if (value === null || (!value && dueToTabSwitch)) {
       uri = uri || this.window.gBrowser.currentURI;
       // Strip off usernames and passwords for the location bar
       try {

browser/components/urlbar/tests/browser/browser_valueOnTabSwitch.js

@@ -77,8 +77,8 @@ add_task(async function() {
     await BrowserTestUtils.switchTab(gBrowser, deletedURLTab);
     is(
       gURLBar.value,
-      "",
-      'gURLBar.value should be "" after switching back to deletedURLTab'
+      testURL,
+      "gURLBar.value should be testURL after switching back to deletedURLTab"
     );
 
     await BrowserTestUtils.switchTab(gBrowser, fullURLTab);