implement cef browser title setting callback

ports/cef/lib.rs

@@ -8,6 +8,7 @@
 #![feature(link_args)]
 #![feature(thread_local)]
 #![feature(core)]
+#![feature(convert)]
 #![feature(std_misc)]
 #![feature(rustc_private)]
 #![feature(collections)]

ports/cef/window.rs

@@ -340,18 +340,24 @@ impl WindowMethods for Window {
         let frame = browser.get_main_frame();
         let frame = frame.downcast();
         let mut title_visitor = frame.title_visitor.borrow_mut();
+        let str = match string {
+            Some(s) => {
+                let utf16_chars: Vec<u16> = Utf16Encoder::new(s.chars()).collect();
+                utf16_chars
+            }
+            None => vec![]
+        };
+
+        if check_ptr_exist!(browser.get_host().get_client(), get_display_handler) &&
+           check_ptr_exist!(browser.get_host().get_client().get_display_handler(), on_title_change) {
+            browser.get_host().get_client().get_display_handler().on_title_change((*browser).clone(), str.as_slice());
+        }
         match &mut *title_visitor {
-            &mut None => {}
+            &mut None => {},
             &mut Some(ref mut visitor) => {
-                match string {
+                visitor.visit(&str);
-                    None => visitor.visit(&[]),
-                    Some(string) => {
-                        let utf16_chars: Vec<u16> = Utf16Encoder::new(string.chars()).collect();
-                        visitor.visit(&utf16_chars)
-                    }
-                }
-            }
             }
+        };
     }
 
     fn set_page_url(&self, url: Url) {