[Extensions] Fix a data race in ChromeExtensionMessageFilter.

extensions/browser/info_map.h

 // 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.
 
 #ifndef EXTENSIONS_BROWSER_INFO_MAP_H_
 #define EXTENSIONS_BROWSER_INFO_MAP_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 12 matching lines @@
 class ContentVerifier;
 class Extension;
 
 // Contains extension data that needs to be accessed on the IO thread. It can
 // be created/destroyed on any thread, but all other methods must be called on
 // the IO thread.
 class InfoMap : public base::RefCountedThreadSafe<InfoMap> {
  public:
   InfoMap();
 
-  const ExtensionSet& extensions() const { return extensions_; }
-  const ExtensionSet& disabled_extensions() const {
-    return disabled_extensions_;
-  }
+  const ExtensionSet& extensions() const;
+  const ExtensionSet& disabled_extensions() const;
 
   // Information about which extensions are assigned to which render processes.
   const ProcessMap& process_map() const { return process_map_; }
 
   // Callback for when new extensions are loaded.
   void AddExtension(const extensions::Extension* extension,
                     base::Time install_time,
                     bool incognito_enabled,
                     bool notifications_disabled);
 
@@ skipping 71 matching lines @@
 
   // Assignment of extensions to renderer processes.
   extensions::ProcessMap process_map_;
 
   scoped_refptr<ContentVerifier> content_verifier_;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_INFO_MAP_H_