[tab_grid] Hack-in new tab FAB action.

ios/clean/chrome/browser/ui/tab_grid/tab_grid_coordinator.mm

Index: ios/clean/chrome/browser/ui/tab_grid/tab_grid_coordinator.mm
diff --git a/ios/clean/chrome/browser/ui/tab_grid/tab_grid_coordinator.mm b/ios/clean/chrome/browser/ui/tab_grid/tab_grid_coordinator.mm
index 8fd156fa5e16cb9866aaf482eb8d8d5618594da0..ce8e600a284e8c6ae3ec015b1fd6c0d4c304887b 100644
--- a/ios/clean/chrome/browser/ui/tab_grid/tab_grid_coordinator.mm
+++ b/ios/clean/chrome/browser/ui/tab_grid/tab_grid_coordinator.mm
@@ -114,6 +114,13 @@
   _webStates.erase(_webStates.begin() + index);
 }
 
+- (void)createNewTabAtIndexPath:(NSIndexPath*)indexPath {
+  web::WebState::CreateParams webStateCreateParams(self.browserState);
+  std::unique_ptr<web::WebState> webState =
+      web::WebState::Create(webStateCreateParams);
+  _webStates.push_back(std::move(webState));
+}
+
 #pragma mark - TabGridCommands
 
 - (void)showTabGrid {