Fix #2747: open/reopen container tabs in tab groups when appropriate

Firefox 137 introduced tab groups. Tab group web extension support is rolling out in Firefox 138 and later. Creating a new tab after the last tab in a tab group can inadvertently create the new tab outside of the tab group.

When a user opens a new tab that should be in a container, this patch will make sure that the new tab resides in the same tab group as the original tab.

src/js/background/assignManager.js

@@ -1,3 +1,11 @@
+/**
+ * Firefox does not yet have the `tabGroups` API, which exposes this constant
+ * to indicate that a tab is not in a tab group. But the Firefox `tabs` API
+ * currently returns this constant value for `Tab.groupId`.
+ * @see https://searchfox.org/mozilla-central/rev/3b95c8dbe724b10390c96c1b9dd0f12c873e2f2e/browser/components/extensions/schemas/tabs.json#235
+ */
+const TAB_GROUP_ID_NONE = -1;
+
 window.assignManager = {
   MENU_ASSIGN_ID: "open-in-this-container",
   MENU_REMOVE_ID: "remove-open-in-this-container",
@@ -326,7 +334,8 @@ window.assignManager = {
         options.url,
         tab.index + 1,
         tab.active,
-        openTabId
+        openTabId,
+        tab.groupId
       );
     } else {
       this.reloadPageInContainer(
@@ -336,7 +345,8 @@ window.assignManager = {
         tab.index + 1,
         tab.active,
         siteSettings.neverAsk,
-        openTabId
+        openTabId,
+        tab.groupId
       );
     }
     this.calculateContextMenu(tab);
@@ -727,7 +737,15 @@ window.assignManager = {
     });
   },
 
-  reloadPageInDefaultContainer(url, index, active, openerTabId) {
+  /**
+   * @param {string} url
+   * @param {number} index
+   * @param {boolean} active
+   * @param {number} [openerTabId]
+   * @param {number} [groupId]
+   * @returns {void}
+   */
+  reloadPageInDefaultContainer(url, index, active, openerTabId, groupId) {
     // To create a new tab in the default container, it is easiest just to omit the
     // cookieStoreId entirely.
     //
@@ -746,16 +764,58 @@ window.assignManager = {
     // does not automatically return to the original opener tab. To get this desired behaviour,
     // we MUST specify the openerTabId when creating the new tab.
     const cookieStoreId = "firefox-default";
-    browser.tabs.create({url, cookieStoreId, index, active, openerTabId});
+    this.createTabWrapper(url, cookieStoreId, index, active, openerTabId, groupId);
   },
 
-  reloadPageInContainer(url, currentUserContextId, userContextId, index, active, neverAsk = false, openerTabId = null) {
+
+  /**
+   * Wraps around `browser.tabs.create` and `browser.tabs.group` to create a
+   * tab and ensure that it ends up in the requested tab group, if applicable.
+   *
+   * @param {string} url
+   * @param {string} cookieStoreId
+   * @param {number} index
+   * @param {boolean} active
+   * @param {number} openerTabId
+   * @param {number} [groupId]
+   * @returns {Promise<Tab>}
+   */
+  async createTabWrapper(url, cookieStoreId, index, active, openerTabId, groupId) {
+    const newTab = await browser.tabs.create({
+      url,
+      cookieStoreId,
+      index,
+      active,
+      openerTabId,
+    });
+
+    if (groupId && groupId !== TAB_GROUP_ID_NONE && browser.tabs.group) {
+      // If the original tab was in a tab group, make sure that the reopened tab
+      // stays in the same tab group.
+      await browser.tabs.group({ groupId, tabIds: newTab.id });
+    }
+
+    return newTab;
+  },
+
+  /**
+   * @param {string} url
+   * @param {string} currentUserContextId
+   * @param {string} userContextId
+   * @param {number} index
+   * @param {boolean} active
+   * @param {boolean} [neverAsk=false]
+   * @param {number} [openerTabId=null]
+   * @param {number} [groupId]
+   * @returns {Promise<Tab>}
+   */
+  reloadPageInContainer(url, currentUserContextId, userContextId, index, active, neverAsk = false, openerTabId = null, groupId = undefined) {
     const cookieStoreId = backgroundLogic.cookieStoreId(userContextId);
     const loadPage = browser.runtime.getURL("confirm-page.html");
     // False represents assignment is not permitted
     // If the user has explicitly checked "Never Ask Again" on the warning page we will send them straight there
     if (neverAsk) {
-      return browser.tabs.create({url, cookieStoreId, index, active, openerTabId});
+      return this.createTabWrapper(url, cookieStoreId, index, active, openerTabId, groupId);
     } else {
       let confirmUrl = `${loadPage}?url=${this.encodeURLProperty(url)}&cookieStoreId=${cookieStoreId}`;
       let currentCookieStoreId;
@@ -763,13 +823,14 @@ window.assignManager = {
         currentCookieStoreId = backgroundLogic.cookieStoreId(currentUserContextId);
         confirmUrl += `&currentCookieStoreId=${currentCookieStoreId}`;
       }
-      return browser.tabs.create({
-        url: confirmUrl,
-        cookieStoreId: currentCookieStoreId,
-        openerTabId,
+      return this.createTabWrapper(
+        confirmUrl,
+        currentCookieStoreId,
         index,
-        active
-      }).then(() => {
+        active,
+        openerTabId,
+        groupId
+      ).then(() => {
         // We don't want to sync this URL ever nor clutter the users history
         browser.history.deleteUrl({url: confirmUrl});
       }).catch((e) => {