Add new UMA stats to get a handle on Downloads UI Usage

chrome/browser/download/chrome_download_manager_delegate.cc

 // Copyright (c) 2011 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/chrome_download_manager_delegate.h"
 
 #include "base/callback.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/rand_util.h"
@@ skipping 528 matching lines @@
 // TODO(noelutz): This function currently works as a callback place holder.
 // Once we decide the hash check is reliable, we could move the
 // MaybeCompleteDownload in OnAllDataSaved to this function.
 void ChromeDownloadManagerDelegate::CheckDownloadHashDone(
     int32 download_id,
     bool is_dangerous_hash) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DVLOG(1) << "CheckDownloadHashDone, download_id: " << download_id
            << " is dangerous_hash: " << is_dangerous_hash;
 }
+
+void ChromeDownloadManagerDelegate::MarkDownloadOpened(int64 db_handle) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  download_history_->MarkDownloadOpened(db_handle);
+}