--- a/uriloader/exthandler/nsExternalHelperAppService.cpp
+++ b/uriloader/exthandler/nsExternalHelperAppService.cpp
@@ -20,16 +20,17 @@
  * Portions created by the Initial Developer are Copyright (C) 1999
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
  *   Scott MacGregor <mscott@netscape.com>
  *   Bill Law <law@netscape.com>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Dan Mosedale <dmose@mozilla.org>
+ *   Myk Melez <myk@mozilla.org>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either of the GNU General Public License Version 2 or later (the "GPL"),
  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  * in which case the provisions of the GPL or the LGPL are applicable instead
  * of those above. If you wish to allow use of your version of this file only
  * under the terms of either the GPL or the LGPL, and not to allow others to
  * use your version of this file under the terms of the MPL, indicate your
@@ -1321,22 +1322,22 @@ nsresult nsExternalHelperAppService::Exp
       localFile->Remove(PR_FALSE);
   }
 
   mTemporaryFilesList.Clear();
 
   return NS_OK;
 }
 
-nsresult
+NS_IMETHODIMP
 nsExternalHelperAppService::GetProtocolHandlerInfo(const nsACString &aScheme, 
                                                    nsIHandlerInfo **aHandlerInfo)
 {
-  // XXX before we expose this to the UI, we need sort out our strategy re
-  // the "warning" and "exposed" prefs
+  // XXX Now that we've exposed this to the UI (bug 391150), is there anything
+  // we need to do to make it compatible with the "warning" and "exposed" prefs?
 
   // XXX enterprise customers should be able to turn this support off with a
   // single master pref (maybe use one of the "exposed" prefs here?)
 
   // nsIMIMEInfo is a superset of nsIHandlerInfo.  Furthermore, nsMimeInfoImpl
   // and subclasses have lots of good platform specific-knowledge of local
   // applications which we might need later.  For now, just use nsMIMEInfoImpl
   // instead of implementating a separate nsIHandlerInfo object.

--- a/uriloader/exthandler/nsExternalHelperAppService.h
+++ b/uriloader/exthandler/nsExternalHelperAppService.h
@@ -18,16 +18,17 @@
  * Netscape Communications, Inc.
  * Portions created by the Initial Developer are Copyright (C) 1999
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
  *   Scott MacGregor <mscott@netscape.com>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Dan Mosedale <dmose@mozilla.org>
+ *   Myk Melez <myk@mozilla.org>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either of the GNU General Public License Version 2 or later (the "GPL"),
  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  * in which case the provisions of the GPL or the LGPL are applicable instead
  * of those above. If you wish to allow use of your version of this file only
  * under the terms of either the GPL or the LGPL, and not to allow others to
  * use your version of this file under the terms of the MPL, indicate your
@@ -225,23 +226,16 @@ public:
                                        nsIFile ** aFile);
 
   /**
    * Helper routine used to test whether a given mime type is in our
    * mimeTypes.rdf data source
    */
   NS_HIDDEN_(PRBool) MIMETypeIsInDataSource(const char * aContentType);
 
-  /**
-   * Return the URI template for any configured web handler.  This will
-   * probably be replaced by something on nsIWebContentConverterService soon. 
-   */
-  NS_HIDDEN_(nsresult) GetProtocolHandlerInfo(const nsACString &aScheme,
-                                              nsIHandlerInfo **aHandlerInfo);
-
   virtual NS_HIDDEN_(nsresult) OSProtocolHandlerExists(const char *aScheme,
                                                        PRBool *aExists) = 0;
 
 protected:
   /**
    * Pointer to the datasource that contains the user override information.
    * @see InitDataSource
    */

--- a/uriloader/exthandler/nsIExternalProtocolService.idl
+++ b/uriloader/exthandler/nsIExternalProtocolService.idl
@@ -17,16 +17,17 @@
  *
  * The Initial Developer of the Original Code is
  * Netscape Communications, Inc.
  * Portions created by the Initial Developer are Copyright (C) 1999
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
  *   Scott MacGregor <mscott@netscape.com>
+ *   Myk Melez <myk@mozilla.org>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either of the GNU General Public License Version 2 or later (the "GPL"),
  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  * in which case the provisions of the GPL or the LGPL are applicable instead
  * of those above. If you wish to allow use of your version of this file only
  * under the terms of either the GPL or the LGPL, and not to allow others to
  * use your version of this file under the terms of the MPL, indicate your
@@ -37,49 +38,67 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
 #include "nsISupports.idl"
 
 interface nsIURI;
 interface nsIFile;
 interface nsIInterfaceRequestor;
+interface nsIHandlerInfo;
 
 /**
  * The external protocol service is used for finding and launching
  * web handlers (a la registerProtocolHandler in the HTML5 draft) or 
  * platform-specific applications for handling particular protocols.
  *
  * You can ask the external protocol service if it has an external
  * handler for a given protocol scheme. And you can ask it to load 
  * the url using the default handler.
  */
-[scriptable, uuid(01e9ce6e-1c81-4f1a-b128-2f2526ec40e3)]
+[scriptable, uuid(7968ffa9-bb51-4b2d-aad2-8ea46c15d27f)]
 interface nsIExternalProtocolService : nsISupports
 {
   /**
    * Check whether a handler for a specific protocol exists.
    * @param aProtocolScheme The scheme from a url: http, ftp, mailto, etc.
    * @return true if we have a handler and false otherwise.
+   * XXX shouldn't aProtocolScheme be an ACString like nsIURI::scheme?
    */
   boolean externalProtocolHandlerExists(in string aProtocolScheme);
 
   /**
    * Check whether a handler for a specific protocol is "exposed" as a visible
    * feature of the current application.
    *
    * An exposed protocol handler is one that can be used in all contexts.  A
    * non-exposed protocol handler is one that can only be used internally by the
    * application.  For example, a non-exposed protocol would not be loaded by the
    * application in response to a link click or a X-remote openURL command.
    * Instead, it would be deferred to the system's external protocol handler.
+   * XXX shouldn't aProtocolScheme be an ACString like nsIURI::scheme?
    */
   boolean isExposedProtocol(in string aProtocolScheme);
 
   /**
+   * Retrieve the handler for the given protocol.  If neither the application
+   * nor the OS knows about a handler for the protocol, the object this method
+   * returns will represent a default handler for unknown content.
+   * 
+   * @param aProtocolScheme the scheme from a URL: http, ftp, mailto, etc.
+   * 
+   * Note: aProtocolScheme should not include a trailing colon, which is part
+   * of the URI syntax, not part of the scheme itself (i.e. pass "mailto" not
+   * "mailto:").
+   * 
+   * @return the handler, if any; otherwise a default handler
+   */
+  nsIHandlerInfo getProtocolHandlerInfo(in ACString aProtocolScheme);
+
+  /**
    * Used to load a url via an external protocol handler (if one exists)
    *
    * @param aURL The url to load
    * @deprecated Use LoadURI instead (See Bug 389565 for removal)
    */
    void loadUrl (in nsIURI aURL);
 
   /**