New Tab button should always make a new tab not in a group.

Bug: 978109
Change-Id: Ie59d4d378da2476d9e78fc20f5a6a8e5929e55f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1731763
Commit-Queue: Charlene Yan <cyan@chromium.org>
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683395}

chrome/browser/ui/views/tabs/browser_tab_strip_controller.cc

@@ -325,8 +325,7 @@ void BrowserTabStripController::CreateNewTab() {
       browser_view_->browser()->profile());
   reopen_tab_iph->NewTabOpened();
 
-  const auto group_id = model_->GetTabGroupForTab(model_->active_index());
-  model_->delegate()->AddTabAt(GURL(), -1, true, group_id);
+  model_->delegate()->AddTabAt(GURL(), -1, true);
 
 #if BUILDFLAG(ENABLE_LEGACY_DESKTOP_IN_PRODUCT_HELP)
   auto* new_tab_tracker =