Fix windows registry loader to carry over prefs from file thread correctly

chrome/browser/extensions/external_loader.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_EXTERNAL_LOADER_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTERNAL_LOADER_H_
 
 #include <memory>
 
 #include "base/files/file_path.h"
@@ skipping 51 matching lines @@
   // Notifies the provider that the list of extensions has been updated.
   virtual void OnUpdated(std::unique_ptr<base::DictionaryValue> updated_prefs);
 
   // Used for passing the list of extensions from the method that loads them
   // to |LoadFinished|. To ensure thread safety, the rules are the following:
   // if this value is written on another thread than the UI, then it should
   // only be written in a task that was posted from |StartLoading|. After that,
   // this task should invoke |LoadFinished| with a PostTask. This scheme of
   // posting tasks will avoid concurrent access and imply the necessary memory
   // barriers.
+  // TODO(lazyboy): To avoid |prefs_| getting unexpectedly overwritten before it
+  // is consumed, consider passing the prefs directly in LoadFinished().
   std::unique_ptr<base::DictionaryValue> prefs_;
 
  private:
   friend class base::RefCountedThreadSafe<ExternalLoader>;
 
   ExternalProviderImpl* owner_;  // weak
 
   DISALLOW_COPY_AND_ASSIGN(ExternalLoader);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTERNAL_LOADER_H_