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

content/browser/download/mock_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 "content/browser/download/mock_download_manager_delegate.h"
 
 MockDownloadManagerDelegate::~MockDownloadManagerDelegate() {
 }
 
 void MockDownloadManagerDelegate::Shutdown() {
@@ skipping 34 matching lines @@
 }
 
 bool MockDownloadManagerDelegate::GenerateFileHash() {
   return false;
 }
 
 void MockDownloadManagerDelegate::OnResponseCompleted(DownloadItem* item,
                                                       const std::string& hash) {
 }
 
+void MockDownloadManagerDelegate::MarkDownloadOpened(int64 db_handle) {
+}
+
 void MockDownloadManagerDelegate::AddItemToPersistentStore(DownloadItem* item) {
 }
 
 void MockDownloadManagerDelegate::UpdateItemInPersistentStore(
     DownloadItem* item) {
 }
 
 void MockDownloadManagerDelegate::UpdatePathForItemInPersistentStore(
     DownloadItem* item,
     const FilePath& new_path) {
@@ skipping 15 matching lines @@
 }
 
 void MockDownloadManagerDelegate::ChooseSavePath(
     const base::WeakPtr<SavePackage>& save_package,
     const FilePath& suggested_path,
     bool can_save_as_complete) {
 }
 
 void MockDownloadManagerDelegate::DownloadProgressUpdated() {
 }