Mountain Lion: use the system download progress.

chrome/browser/download/download_status_updater.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/download/download_status_updater.h"
 
 #include <vector>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 82 matching lines @@
 
 // React to a transition that a download associated with one of our
 // download managers has made.  Our goal is to have only IN_PROGRESS
 // items on our set list, as they're the only ones that have relevance
 // to GetProgress() return values.
 void DownloadStatusUpdater::UpdateItem(content::DownloadItem* download) {
   if (download->GetState() == content::DownloadItem::IN_PROGRESS) {
     if (!ContainsKey(items_, download)) {
       items_.insert(download);
       download->AddObserver(this);
+      UpdateDownloadProgressForItemStarted(download);
+    } else {
+      UpdateDownloadProgressForItemProgressed(download);
     }
   } else {
     if (ContainsKey(items_, download)) {
+      UpdateDownloadProgressForItemCompleted(download);
       items_.erase(download);
       download->RemoveObserver(this);
     }
   }
 }
+
+// All platforms track overall download progress via
+// UpdateAppIconDownloadProgress(); these allow for tracking the progress of
+// individual downloads.
+#if !defined(OS_MACOSX) && !defined(OS_WIN)
+void DownloadStatusUpdater::UpdateDownloadProgressForItemStarted(
+    content::DownloadItem* download) {
+}
+
+void DownloadStatusUpdater::UpdateDownloadProgressForItemProgressed(
+    content::DownloadItem* download) {
+}
+
+void DownloadStatusUpdater::UpdateDownloadProgressForItemCompleted(
+    content::DownloadItem* download) {
+}
+#endif  // OS_MACOSX