We have a problem in the process on destroying WebContentsImpl because

chrome/browser/chromeos/file_manager/app_installer.cc

 // Copyright 2013 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/chromeos/file_manager/app_installer.h"
 
 #include "content/public/browser/web_contents.h"
 
 class Profile;
 
 namespace file_manager {
 
 namespace {
 const char kWebContentsDestroyedError[] = "WebContents is destroyed.";
 }  // namespace
 
 class AppInstaller::WebContentsObserver
     : public content::WebContentsObserver {
 
  public:
   explicit WebContentsObserver(
       content::WebContents* web_contents,
       AppInstaller* parent)
       : content::WebContentsObserver(web_contents),
         parent_(parent) {
   }
 
  protected:
   // content::WebContentsObserver implementation.
-  virtual void WebContentsDestroyed(
-      content::WebContents* web_contents) OVERRIDE {
-    parent_->OnWebContentsDestroyed(web_contents);
+  virtual void WebContentsDestroyed() OVERRIDE {
+    parent_->OnWebContentsDestroyed(web_contents());
   }
 
  private:
   AppInstaller* parent_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(WebContentsObserver);
 };
 
 AppInstaller::AppInstaller(
     content::WebContents* web_contents,
@@ skipping 61 matching lines @@
   return true;
 }
 
 void AppInstaller::OnWebContentsDestroyed(
     content::WebContents* web_contents) {
   callback_.Run(false, kWebContentsDestroyedError);
   AbortInstall();
 }
 
 }  // namespace file_manager