Fix use-after-free that resulted from r106949.

chrome/browser/tab_contents/spelling_menu_observer.cc

 // Copyright (c) 2011 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/tab_contents/spelling_menu_observer.h"
 
 #include <string>
 
 #include "base/json/json_reader.h"
 #include "base/json/string_escape.h"
@@ skipping 136 matching lines @@
   animation_timer_.Start(FROM_HERE, base::TimeDelta::FromSeconds(1),
       this, &SpellingMenuObserver::OnAnimationTimerExpired);
 
   return true;
 }
 
 void SpellingMenuObserver::OnURLFetchComplete(
     const content::URLFetcher* source) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  fetcher_.reset();
+  scoped_ptr<content::URLFetcher> clean_up_fetcher(fetcher_.release());
   animation_timer_.Stop();
 
   // Parse the response JSON and replace misspelled words in the |result_| text
   // with their suggestions.
   std::string data;
   source->GetResponseAsString(&data);
   succeeded_ = ParseResponse(source->GetResponseCode(), data);
   if (!succeeded_)
     result_ = l10n_util::GetStringUTF16(IDS_CONTENT_CONTEXT_SPELLING_CORRECT);
 
@@ skipping 97 matching lines @@
   loading_frame_ = (loading_frame_ + 1) & 3;
   string16 loading_message = loading_message_;
   for (int i = 0; i < loading_frame_; ++i)
     loading_message.push_back('.');
 
   // Update the menu item with the text. We disable this item to prevent users
   // from selecting it.
   proxy_->UpdateMenuItem(IDC_CONTENT_CONTEXT_SPELLING_SUGGESTION, false, false,
                          loading_message);
 }