event_router->RegisterObserver(this, api::tabs::OnAttached::kEventName);
event_router->RegisterObserver(this, api::tabs::OnRemoved::kEventName);
event_router->RegisterObserver(this, api::tabs::OnReplaced::kEventName);
+ event_router->RegisterObserver(this, api::tabs::OnZoomChange::kEventName);
// Windows API Events.
event_router->RegisterObserver(this, api::windows::OnCreated::kEventName);