Added download error descriptions to tooltips for Mac & Linux.

chrome/browser/ui/gtk/download/download_item_gtk.cc

Index: chrome/browser/ui/gtk/download/download_item_gtk.cc
diff --git a/chrome/browser/ui/gtk/download/download_item_gtk.cc b/chrome/browser/ui/gtk/download/download_item_gtk.cc
index 92be0bb60486a668509acc632f2d1dd09b1f256f..86d26aa2be295581eb96e3aed765efc9225b966d 100644
--- a/chrome/browser/ui/gtk/download/download_item_gtk.cc
+++ b/chrome/browser/ui/gtk/download/download_item_gtk.cc
@@ -335,6 +335,7 @@ void DownloadItemGtk::OnDownloadUpdated(DownloadItem* download) {
       break;
     case DownloadItem::INTERRUPTED:
       StopDownloadProgress();
+      UpdateTooltip();
 
       complete_animation_.Show();
       break;
@@ -476,11 +477,19 @@ void DownloadItemGtk::LoadIcon() {
 }
 
 void DownloadItemGtk::UpdateTooltip() {
-  string16 elided_filename = ui::ElideFilename(
-      get_download()->GetFileNameToReportUser(),
-      gfx::Font(), kTooltipMaxWidth);
-  gtk_widget_set_tooltip_text(body_.get(),
-                              UTF16ToUTF8(elided_filename).c_str());
+  string16 tooltip_text = ui::ElideFilename(
+      get_download()->GetFileNameToReportUser(), gfx::Font(), kTooltipMaxWidth);
+
+  if (get_download()->GetState() == content::DownloadItem::INTERRUPTED) {
+    content::DownloadInterruptReason reason = get_download()->GetLastReason();
+    DCHECK(reason != 0);
+
+    // Add the status on another line.
+    tooltip_text += ASCIIToUTF16("\n");
+    tooltip_text += DownloadItemModel::InterruptReasonStatusMessage(reason);
+  }
+
+  gtk_widget_set_tooltip_text(body_.get(), UTF16ToUTF8(tooltip_text).c_str());
 }
 
 void DownloadItemGtk::UpdateNameLabel() {