Added callback to DownloadUrl() so we can find download failures.

chrome/browser/tab_contents/render_view_context_menu.cc

Index: chrome/browser/tab_contents/render_view_context_menu.cc
diff --git a/chrome/browser/tab_contents/render_view_context_menu.cc b/chrome/browser/tab_contents/render_view_context_menu.cc
index 8420bdf446268b9878bccfceba839f863193eb12..caa36874d348a4b3afb72ea006dff9991d24ac1c 100644
--- a/chrome/browser/tab_contents/render_view_context_menu.cc
+++ b/chrome/browser/tab_contents/render_view_context_menu.cc
@@ -1517,7 +1517,8 @@ void RenderViewContextMenu::ExecuteCommand(int id, int event_flags) {
                        false,  // Don't prefer_cache
                        -1,  // No POST id
                        save_info,
-                       source_web_contents_);
+                       source_web_contents_,
+                       DownloadManager::OnStartedCallback());
       break;
     }
 
@@ -1545,7 +1546,8 @@ void RenderViewContextMenu::ExecuteCommand(int id, int event_flags) {
                        true,  // prefer_cache
                        post_id,
                        save_info,
-                       source_web_contents_);
+                       source_web_contents_,
+                       DownloadManager::OnStartedCallback());
       break;
     }