Parse messages.json in ExtensionUnpacker (like we do for manifest)....

chrome/common/extensions/extension_unpacker.h

 // Copyright (c) 2009 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_COMMON_EXTENSIONS_EXTENSION_UNPACKER_H_
 #define CHROME_COMMON_EXTENSIONS_EXTENSION_UNPACKER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 28 matching lines @@
   // |extension_path| is the path to the extension we unpacked that wrote the
   // data. Returns true on success.
   static bool ReadImagesFromFile(const FilePath& extension_path,
                                  DecodedImages* images);
 
   const std::string& error_message() { return error_message_; }
   DictionaryValue* parsed_manifest() {
     return parsed_manifest_.get();
   }
   const DecodedImages& decoded_images() { return decoded_images_; }
+  DictionaryValue* parsed_catalogs() { return parsed_catalogs_.get(); }
 
  private:
   // Parse the manifest.json file inside the extension (not in the header).
   // Caller takes ownership of return value.
   DictionaryValue* ReadManifest();
 
+  // Parse all _locales/*/messages.json files inside the extension.
+  bool ReadAllMessageCatalogs(const std::string& default_locale);
+
   // Decodes the image at the given path and puts it in our list of decoded
   // images.
   bool AddDecodedImage(const FilePath& path);
 
+  // Parses the catalog at the given path and puts it in our list of parsed
+  // catalogs.
+  bool ReadMessageCatalog(const FilePath& message_path);
+
   // Set the error message.
   void SetError(const std::string& error);
 
   // The extension to unpack.
   FilePath extension_path_;
 
   // The place we unpacked the extension to.
   FilePath temp_install_dir_;
 
   // The parsed version of the manifest JSON contained in the extension.
   scoped_ptr<DictionaryValue> parsed_manifest_;
 
   // A list of decoded images and the paths where those images came from.  Paths
   // are relative to the manifest file.
   DecodedImages decoded_images_;
 
+  // Dictionary of relative paths and catalogs per path. Paths are in the form
+  // of _locales/locale, without messages.json base part.
+  scoped_ptr<DictionaryValue> parsed_catalogs_;
+
   // The last error message that was set.  Empty if there were no errors.
   std::string error_message_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionUnpacker);
 };
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_UNPACKER_H_