added extension hook when files have been checked

include/libtorrent/extensions.hpp

@@ -77,6 +77,10 @@ namespace libtorrent
 		// default behavior will be skipped
 		virtual bool on_pause() { return false; }
 		virtual bool on_resume() { return false;}
+
+		// this is called when the initial checking of
+		// files is completed.
+		virtual void on_files_checked() {}
 	};
 
 	struct TORRENT_EXPORT peer_plugin

src/torrent.cpp

@@ -2299,6 +2299,14 @@ namespace libtorrent
 #ifndef NDEBUG
 		m_initial_done = boost::get<0>(bytes_done());
 #endif
+
+#ifndef TORRENT_DISABLE_EXTENSIONS
+		for (extension_list_t::iterator i = m_extensions.begin()
+			, end(m_extensions.end()); i != end; ++i)
+		{
+			try { (*i)->on_files_checked(); } catch (std::exception&) {}
+		}
+#endif
 	}
 
 	alert_manager& torrent::alerts() const