We have a problem in the process on destroying WebContentsImpl because

chrome/browser/ui/tabs/tab_strip_model_unittest.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/ui/tabs/tab_strip_model.h"
 
 #include <map>
 #include <string>
 
 #include "base/files/file_path.h"
@@ skipping 40 matching lines @@
   // When |source| is deleted both |tab_to_delete| and |tab_strip| are deleted.
   // |tab_to_delete| and |tab_strip| may be NULL.
   DeleteWebContentsOnDestroyedObserver(WebContents* source,
                                        WebContents* tab_to_delete,
                                        TabStripModel* tab_strip)
       : WebContentsObserver(source),
         tab_to_delete_(tab_to_delete),
         tab_strip_(tab_strip) {
   }
 
-  virtual void WebContentsDestroyed(WebContents* web_contents) OVERRIDE {
+  virtual void WebContentsDestroyed() OVERRIDE {
     WebContents* tab_to_delete = tab_to_delete_;
     tab_to_delete_ = NULL;
     TabStripModel* tab_strip_to_delete = tab_strip_;
     tab_strip_ = NULL;
     delete tab_to_delete;
     delete tab_strip_to_delete;
   }
 
  private:
   WebContents* tab_to_delete_;
@@ skipping 2511 matching lines @@
   WebContents* moved_contents = strip_src.DetachWebContentsAt(1);
   EXPECT_EQ(contents2, moved_contents);
 
   // Attach the tab to the destination tab strip.
   strip_dst.AppendWebContents(moved_contents, true);
   EXPECT_TRUE(strip_dst.IsTabBlocked(0));
 
   strip_dst.CloseAllTabs();
   strip_src.CloseAllTabs();
 }