Fix crasher due to const-ref to non-existing variable

chrome/browser/web_resource/web_resource_service.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/web_resource/web_resource_service.h"
 
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
@@ skipping 128 matching lines @@
       WebResourceUnpacker unpacker(json_data_);
       if (unpacker.Run()) {
         OnUnpackWebResourceSucceeded(*unpacker.parsed_json());
       } else {
         OnUnpackWebResourceFailed(unpacker.error_message());
       }
     }
   }
 
  private:
-  ~UnpackerClient() {}
+  virtual ~UnpackerClient() {}
 
   // UtilityProcessHost::Client
   virtual bool OnMessageReceived(const IPC::Message& message) {
     bool msg_is_ok = true;
     bool handled = true;
     IPC_BEGIN_MESSAGE_MAP_EX(WebResourceService::UnpackerClient, message,
                              msg_is_ok)
       IPC_MESSAGE_HANDLER(ChromeUtilityHostMsg_UnpackWebResource_Succeeded,
                           OnUnpackWebResourceSucceeded)
       IPC_MESSAGE_HANDLER(ChromeUtilityHostMsg_UnpackWebResource_Failed,
@@ skipping 34 matching lines @@
   void StartProcessOnIOThread(BrowserThread::ID thread_id) {
     UtilityProcessHost* host = new UtilityProcessHost(this, thread_id);
     // TODO(mrc): get proper file path when we start using web resources
     // that need to be unpacked.
     host->Send(new ChromeUtilityMsg_UnpackWebResource(json_data_));
   }
 
   scoped_refptr<WebResourceService> web_resource_service_;
 
   // Holds raw JSON string.
-  const std::string& json_data_;
+  std::string json_data_;
 
   // True if we got a response from the utility process and have cleaned up
   // already.
   bool got_response_;
 };
 
 WebResourceService::WebResourceService(
     PrefService* prefs,
     const char* web_resource_server,
     bool apply_locale_to_url,
@@ skipping 78 matching lines @@
 }
 
 void WebResourceService::UpdateResourceCache(const std::string& json_data) {
   UnpackerClient* client = new UnpackerClient(this, json_data);
   client->Start();
 
   // Set cache update time in preferences.
   prefs_->SetString(last_update_time_pref_name_,
       base::DoubleToString(base::Time::Now().ToDoubleT()));
 }