Mac: Add tooltip to download item.

chrome/browser/cocoa/download_item_mac.mm

Index: chrome/browser/cocoa/download_item_mac.mm
diff --git a/chrome/browser/cocoa/download_item_mac.mm b/chrome/browser/cocoa/download_item_mac.mm
index 144b42db5b58d2278d4a4c181a60d623b06c38e8..7bc3b2586c6a8c4851570a730e504f98ea24e11b 100644
--- a/chrome/browser/cocoa/download_item_mac.mm
+++ b/chrome/browser/cocoa/download_item_mac.mm
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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.
 
@@ -39,6 +39,8 @@ void DownloadItemMac::OnDownloadUpdated(DownloadItem* download) {
     // another thread, so reload the icon if the download filename changes.
     LoadIcon();
     lastFilePath_ = download->full_path();
+
+    [item_controller_ updateToolTip];
   }
 
   switch (download->state()) {