| Index: ios/shared/chrome/browser/tabs/BUILD.gn | 
| diff --git a/ios/shared/chrome/browser/tabs/BUILD.gn b/ios/shared/chrome/browser/tabs/BUILD.gn | 
| index c05b62261993c5f5e2ca66fbaa60e4bf0a0abc91..9dfe5783a74f445fdde4956270eec64468d4a43a 100644 | 
| --- a/ios/shared/chrome/browser/tabs/BUILD.gn | 
| +++ b/ios/shared/chrome/browser/tabs/BUILD.gn | 
| @@ -11,6 +11,7 @@ source_set("tabs") { | 
| "web_state_list_metrics_observer.h", | 
| "web_state_list_metrics_observer.mm", | 
| "web_state_list_observer.h", | 
| +    "web_state_list_observer.mm", | 
| "web_state_list_observer_bridge.h", | 
| "web_state_list_observer_bridge.mm", | 
| "web_state_list_order_controller.h", | 
|  |