downloads: add the ability to undo download removal.

chrome/browser/history/download_database.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/history/download_database.h"
 
 #include <limits>
 #include <string>
 #include <vector>
 
@@ skipping 77 matching lines @@
 const int DownloadDatabase::kDangerTypeUserValidated = 6;
 const int DownloadDatabase::kDangerTypeDangerousHost = 7;
 const int DownloadDatabase::kDangerTypePotentiallyUnwanted = 8;
 
 int DownloadDatabase::StateToInt(DownloadItem::DownloadState state) {
   switch (state) {
     case DownloadItem::IN_PROGRESS: return DownloadDatabase::kStateInProgress;
     case DownloadItem::COMPLETE: return DownloadDatabase::kStateComplete;
     case DownloadItem::CANCELLED: return DownloadDatabase::kStateCancelled;
     case DownloadItem::INTERRUPTED: return DownloadDatabase::kStateInterrupted;
+    case DownloadItem::REMOVED:

[Dan Beam, 2014/11/13 02:51:16]

i'll change this if we decide to sync this status to the database

     case DownloadItem::MAX_DOWNLOAD_STATE:
       NOTREACHED();
       return DownloadDatabase::kStateInvalid;
   }
   NOTREACHED();
   return DownloadDatabase::kStateInvalid;
 }
 
 DownloadItem::DownloadState DownloadDatabase::IntToState(int state) {
   switch (state) {
@@ skipping 554 matching lines @@
 size_t DownloadDatabase::CountDownloads() {
   EnsureInProgressEntriesCleanedUp();
 
   sql::Statement statement(GetDB().GetCachedStatement(SQL_FROM_HERE,
       "SELECT count(*) from downloads"));
   statement.Step();
   return statement.ColumnInt(0);
 }
 
 }  // namespace history