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

ios/chrome/browser/tabs/tab.mm

Index: ios/chrome/browser/tabs/tab.mm
diff --git a/ios/chrome/browser/tabs/tab.mm b/ios/chrome/browser/tabs/tab.mm
index 7cbcff399c1da0581aadd62b0a1a1e515e391eaa..3bdb7a377ed8c55b69aae6b87b933118a8b4c700 100644
--- a/ios/chrome/browser/tabs/tab.mm
+++ b/ios/chrome/browser/tabs/tab.mm
@@ -481,9 +481,9 @@ - (instancetype)initWithBrowserState:(ios::ChromeBrowserState*)browserState
                               opener:(Tab*)opener
                          openedByDOM:(BOOL)openedByDOM
                                model:(TabModel*)parentModel {
-  std::unique_ptr<web::WebStateImpl> webState(
-      new web::WebStateImpl(browserState));
-  webState->GetNavigationManagerImpl().InitializeSession(openedByDOM);
+  web::WebState::CreateParams params(browserState);
+  params.opened_by_dom = openedByDOM;
+  std::unique_ptr<web::WebState> webState = web::WebState::Create(params);
   if ([opener navigationManager]) {
     web::SerializableUserDataManager* userDataManager =
         web::SerializableUserDataManager::FromWebState(webState.get());
@@ -1517,7 +1517,7 @@ - (void)reloadForDesktopUserAgent {
   // |originalUrl| will be empty if a page was open by DOM.
   GURL reloadURL(lastUserItem->GetOriginalRequestURL());
   if (reloadURL.is_empty()) {
-    DCHECK(sessionController.openedByDOM);
+    DCHECK(self.webState && self.webState->IsOpenedByDOM());
     reloadURL = lastUserItem->GetVirtualURL();
   }