Always destruct url request context getter on io thread....

chrome/browser/spellcheck_host.h

Index: chrome/browser/spellcheck_host.h
===================================================================
--- chrome/browser/spellcheck_host.h	(revision 32112)
+++ chrome/browser/spellcheck_host.h	(working copy)
@@ -64,6 +64,8 @@
   // Executed on the file thread.
   void InitializeInternal();
 
+  void InitializeOnFileThread();
+
   // Inform |observer_| that initialization has finished.
   void InformObserverOfInitialization();
 
@@ -82,6 +84,9 @@
                                   const ResponseCookies& cookies,
                                   const std::string& data);
 
+  // Saves |data_| to disk. Run on the file thread.
+  void SaveDictionaryData();
+
   // May be NULL.
   Observer* observer_;
 
@@ -104,9 +109,13 @@
   // once.
   bool tried_to_download_;
 
-  // Used for downloading the dictionary file.
-  scoped_refptr<URLRequestContextGetter> request_context_getter_;
+  // Data received from the dictionary download.
+  std::string data_;
 
+  // Used for downloading the dictionary file. We don't hold a reference, and
+  // it is only valid to use it on the UI thread.
+  URLRequestContextGetter* request_context_getter_;
+
   // Used for downloading the dictionary file.
   scoped_ptr<URLFetcher> fetcher_;
 };