nsIBrowserSearchService in Firefox 3.0

 Adds a new search engine from the file at the supplied URI, optionally
 asking the user for confirmation first.  If a confirmation dialog is
 shown, it will offer the option to begin using the newly added engine
 right away; if no confirmation dialog is shown, the new engine will be
 used right away automatically.

 @param engineURL
        The URL to the search engine's description file.

 @param dataType
        An integer representing the plugin file format. Must be one
        of the supported search engine data types defined above.

 @param iconURL
        A URL string to an icon file to be used as the search engine's
        icon. This value may be overridden by an icon specified in the
        engine description file.

 @param confirm
        A boolean value indicating whether the user should be asked for
        confirmation before this engine is added to the list.  If this
        value is false, the engine will be added to the list upon successful
        load, but it will not be selected as the current engine.

 @throws NS_ERROR_FAILURE if the type is invalid, or if the description
         file cannot be successfully loaded.

 Adds a new search engine, without asking the user for confirmation and
 without starting to use it right away.

 @param name
        The search engine's name. Must be unique. Must not be null.

 @param iconURL
        Optional: A URL string pointing to the icon to be used to represent
        the engine.

 @param alias
        Optional: A unique shortcut that can be used to retrieve the
        search engine.

 @param description
        Optional: a description of the search engine.

 @param method
        The HTTP request method used when submitting a search query.
        Must be a case insensitive value of either "get" or "post".

 @param url
        The URL to which search queries should be sent.
        Must not be null.

 Returns an array of all default search engines.

 @returns an array of nsISearchEngine objects.

 Returns an engine with the specified alias.

 @param   alias
          The search engine's alias.
 @returns The corresponding nsISearchEngine object, or null if it doesn't
          exist.

 Returns an engine with the specified name.

 @param   aEngineName
          The name of the engine.
 @returns The corresponding nsISearchEngine object, or null if it doesn't
          exist.

 Returns an array of all installed search engines.

 @returns an array of nsISearchEngine objects.

 Returns an array of all installed search engines whose hidden attribute is
 false.

 @returns an array of nsISearchEngine objects.

 Moves a visible search engine.

 @param  engine
         The engine to move.
 @param  newIndex
         The engine's new index in the set of visible engines.

 @throws NS_ERROR_FAILURE if newIndex is out of bounds, or if engine is
         hidden.

 Removes the search engine. If the search engine is installed in a global
 location, this will just hide the engine. If the engine is in the user's
 profile directory, it will be removed from disk.

 @param  engine
         The engine to remove.

 Un-hides all engines installed in the directory corresponding to
 the directory service's NS_APP_SEARCH_DIR key. (i.e. the set of
 engines returned by getDefaultEngines)