Moved |openedByDOM| to WebState's CreateParams and public interface.

ios/chrome/browser/ui/browser_view_controller.mm

Index: ios/chrome/browser/ui/browser_view_controller.mm
diff --git a/ios/chrome/browser/ui/browser_view_controller.mm b/ios/chrome/browser/ui/browser_view_controller.mm
index e83a5c533d0229abb781bda7b73f1fea507fd3f9..2646f9ff7c33187338a2b38b269102db97fd9b76 100644
--- a/ios/chrome/browser/ui/browser_view_controller.mm
+++ b/ios/chrome/browser/ui/browser_view_controller.mm
@@ -172,7 +172,6 @@
 #include "ios/public/provider/chrome/browser/voice/voice_search_controller.h"
 #include "ios/public/provider/chrome/browser/voice/voice_search_controller_delegate.h"
 #include "ios/public/provider/chrome/browser/voice/voice_search_provider.h"
-#import "ios/web/navigation/crw_session_controller.h"
 #include "ios/web/navigation/navigation_manager_impl.h"
 #include "ios/web/public/active_state_manager.h"
 #include "ios/web/public/navigation_item.h"
@@ -2418,8 +2417,7 @@ - (void)closeWebState:(web::WebState*)webState {
   // Only allow a web page to close itself if it was opened by DOM, or if there
   // are no navigation items.
   Tab* tab = LegacyTabHelper::GetTabForWebState(webState);
-  DCHECK([[tab navigationManagerImpl]->GetSessionController() isOpenedByDOM] ||
-         ![tab navigationManager]->GetItemCount());
+  DCHECK(webState->HasOpener() || ![tab navigationManager]->GetItemCount());
 
   if (![self tabModel])
     return;