Check GetVisibleItem exists in GetFormattedURL

ios/chrome/browser/ui/toolbar/toolbar_model_impl_ios.mm

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ios/chrome/browser/ui/toolbar/toolbar_model_impl_ios.h"
 
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "components/toolbar/toolbar_model_impl.h"
 #include "ios/chrome/browser/bookmarks/bookmark_model_factory.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
@@ skipping 66 matching lines @@
 }
 
 bool ToolbarModelImplIOS::ShouldDisplayHintText() {
   Tab* current_tab = delegate_->GetCurrentTab();
   return [current_tab.webController wantsLocationBarHintText];
 }
 
 base::string16 ToolbarModelImplIOS::GetFormattedURL(size_t* prefix_end) const {
   base::string16 formatted_url = toolbar_model_->GetFormattedURL(prefix_end);
   Tab* current_tab = delegate_->GetCurrentTab();
+  if (!current_tab || !current_tab.webState ||
+      !current_tab.webState->GetNavigationManager() ||
+      !current_tab.webState->GetNavigationManager()->GetVisibleItem()) {
+    return formatted_url;
+  }
   GURL url =
       current_tab.webState->GetNavigationManager()->GetVisibleItem()->GetURL();
   if (reading_list::IsOfflineURL(url) &&
       GetSecurityLevel(true /*ignore_editing*/) ==
           security_state::SecurityLevel::NONE) {
     size_t removed = 0;
     formatted_url =
         reading_list::StripSchemeFromOnlineURL(formatted_url, &removed);
     if (prefix_end) {
       *prefix_end -= removed;
@@ skipping 19 matching lines @@
   return toolbar_model_->GetSecureVerboseText();
 }
 
 base::string16 ToolbarModelImplIOS::GetEVCertName() const {
   return toolbar_model_->GetEVCertName();
 }
 
 bool ToolbarModelImplIOS::ShouldDisplayURL() const {
   return toolbar_model_->ShouldDisplayURL();
 }