Mountain Lion: use the system download progress.

chrome/browser/download/download_status_updater.cc

Index: chrome/browser/download/download_status_updater.cc
diff --git a/chrome/browser/download/download_status_updater.cc b/chrome/browser/download/download_status_updater.cc
index 817e4184268926339bd599dc431f2ca5429911e2..fe40ef4aef63a4ca244db27277c2100a3623bb77 100644
--- a/chrome/browser/download/download_status_updater.cc
+++ b/chrome/browser/download/download_status_updater.cc
@@ -100,11 +100,31 @@ void DownloadStatusUpdater::UpdateItem(content::DownloadItem* download) {
     if (!ContainsKey(items_, download)) {
       items_.insert(download);
       download->AddObserver(this);
+      UpdateDownloadProgressForItemAdded(download);
+    } else {
+      UpdateDownloadProgressForItemProgressed(download);
     }
   } else {
     if (ContainsKey(items_, download)) {
+      UpdateDownloadProgressForItemRemoved(download);
       items_.erase(download);
       download->RemoveObserver(this);
     }
   }
 }
+
+// Non-Mac platforms track overall download progress via
+// UpdateAppIconDownloadProgress().
+#if !defined(OS_MACOSX)
+void DownloadStatusUpdater::UpdateDownloadProgressForItemAdded(
+    content::DownloadItem* download) {
+}
+
+void DownloadStatusUpdater::UpdateDownloadProgressForItemProgressed(
+    content::DownloadItem* download) {
+}
+
+void DownloadStatusUpdater::UpdateDownloadProgressForItemRemoved(
+    content::DownloadItem* download) {
+}
+#endif  // OS_MACOSX