We have a problem in the process on destroying WebContentsImpl because

chrome/browser/safe_browsing/client_side_detection_host.cc

 // Copyright (c) 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 "chrome/browser/safe_browsing/client_side_detection_host.h"
 
 #include <vector>
 
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
@@ skipping 461 matching lines @@
     if (entry->GetPageType() == content::PAGE_TYPE_INTERSTITIAL)
       entry = web_contents()->GetController().GetLastCommittedEntry();
     if (!entry)
       return false;
   }
 
   base::string16 value;
   return entry->GetExtraData(kSafeBrowsingMatchKey, &value);
 }
 
-void ClientSideDetectionHost::WebContentsDestroyed(WebContents* tab) {
-  DCHECK(tab);
+void ClientSideDetectionHost::WebContentsDestroyed() {
   // Tell any pending classification request that it is being canceled.
   if (classification_request_.get()) {
     classification_request_->Cancel();
   }
   // Cancel all pending feature extractions.
   feature_extractor_.reset();
 }
 
 void ClientSideDetectionHost::OnPhishingPreClassificationDone(
     bool should_classify) {
@@ skipping 244 matching lines @@
     ui_manager_->RemoveObserver(this);
 
   ui_manager_ = ui_manager;
   if (ui_manager)
     ui_manager_->AddObserver(this);
 
   database_manager_ = database_manager;
 }
 
 }  // namespace safe_browsing