Fix downloads db state=3 corruption using version=23

chrome/browser/history/download_database.h

 // 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.
 
 #ifndef CHROME_BROWSER_HISTORY_DOWNLOAD_DATABASE_H_
 #define CHROME_BROWSER_HISTORY_DOWNLOAD_DATABASE_H_
 
 #include <set>
 #include <string>
 
@@ skipping 52 matching lines @@
   // all downloads that are in progress or are waiting to be cancelled.
   bool RemoveDownloadsBetween(base::Time remove_begin, base::Time remove_end);
 
  protected:
   // Returns the database for the functions in this interface.
   virtual sql::Connection& GetDB() = 0;
 
   // Returns the meta-table object for the functions in this interface.
   virtual sql::MetaTable& GetMetaTable() = 0;
 
+  // Returns true if able to successfully rewrite the invalid values for the
+  // |state| field from 3 to 4. Returns false if there was an error fixing the
+  // database. See http://crbug.com/140687
+  bool MigrateDownloadsState();

[Randy Smith (Not in Mondays), 2012/08/07 20:36:16]

I'd be inclined to suggest this take an argument which is the DB version number
we're coming from, and you have conditionals inside of it to see if you need to
do the migration.

[benjhayden, 2012/08/08 01:11:52]

That's not the pattern in history_database.cc

[Randy Smith (Not in Mondays), 2012/08/08 01:52:25]

Ok.  

+
   // Creates the downloads table if needed.
   bool InitDownloadTable();
 
   // Used to quickly clear the downloads. First you would drop it, then you
   // would re-initialize it.
   bool DropDownloadTable();
 
  private:
   // TODO(rdsmith): Remove after http://crbug.com/96627 has been resolved.
   void CheckThread();
 
   bool EnsureColumnExists(const std::string& name, const std::string& type);
 
   bool owning_thread_set_;
   base::PlatformThreadId owning_thread_;
 
   int next_id_;
   int next_db_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadDatabase);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_DOWNLOAD_DATABASE_H_