Eliminate the archived history database and clean up related code.

chrome/browser/history/url_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_URL_DATABASE_H_
 #define CHROME_BROWSER_HISTORY_URL_DATABASE_H_
 
 #include "base/basictypes.h"
 #include "chrome/browser/history/history_types.h"
 #include "chrome/browser/search_engines/template_url_id.h"
 #include "components/query_parser/query_parser.h"
 #include "sql/statement.h"
 
 class GURL;
 
 namespace sql {
 class Connection;
 }
 
 namespace history {
 
 class VisitDatabase;  // For friend statement.
 
 // Encapsulates an SQL database that holds URL info.  This is a subset of the
 // full history data.  We split this class' functionality out from the larger
 // HistoryDatabase class to support maintaining separate databases of URLs with
-// different capabilities (for example, in-memory, or archived).
+// different capabilities (for example, the in-memory database).
 //
 // This is refcounted to support calling InvokeLater() with some of its methods
 // (necessary to maintain ordering of DB operations).
 class URLDatabase {
  public:
   // Must call CreateURLTable() and CreateURLIndexes() before using to make
   // sure the database is initialized.
   URLDatabase();
 
   // This object must be destroyed on the thread where all accesses are
@@ skipping 66 matching lines @@
   // Adds a row to the temporary URL table. This must be called between
   // CreateTemporaryURLTable() and CommitTemporaryURLTable() (see those for more
   // info). The ID of the URL will change in the temporary table, so the new ID
   // is returned. Returns 0 on failure.
   URLID AddTemporaryURL(const URLRow& row) {
     return AddURLInternal(row, true);
   }
 
   // Ends the mass-deleting by replacing the original URL table with the
   // temporary one created in CreateTemporaryURLTable. Returns true on success.
-  //
-  // This function does not create the supplimentary indices. It is virtual so
-  // that the main history database can provide this additional behavior.
-  virtual bool CommitTemporaryURLTable();
+  bool CommitTemporaryURLTable();
 
   // Enumeration ---------------------------------------------------------------
 
   // A basic enumerator to enumerate urls database.
   class URLEnumeratorBase {
    public:
     URLEnumeratorBase();
     virtual ~URLEnumeratorBase();
 
    private:
@@ skipping 121 matching lines @@
 
   // Initialization functions. The indexing functions are separate from the
   // table creation functions so the in-memory database and the temporary tables
   // used when clearing history can populate the table and then create the
   // index, which is faster than the reverse.
   //
   // is_temporary is false when generating the "regular" URLs table. The expirer
   // sets this to true to generate the  temporary table, which will have a
   // different name but the same schema.
   bool CreateURLTable(bool is_temporary);
-  // We have two tiers of indices for the URL table. The main tier is used by
-  // all URL databases, and is an index over the URL itself.
+
+  // Creates the index over URLs so we can quickly look up based on URL.
   bool CreateMainURLIndex();
 
   // Ensures the keyword search terms table exists.
   bool InitKeywordSearchTermsTable();
 
   // Creates the indices used for keyword search terms.
   bool CreateKeywordSearchTermsIndices();
 
   // Deletes the keyword search terms table.
   bool DropKeywordSearchTermsTable();
@@ skipping 31 matching lines @@
 // the macro if you want to put this in the middle of an otherwise constant
 // string, it will save time doing string appends. If you have to build a SQL
 // string dynamically anyway, use the constant, it will save space.
 #define HISTORY_URL_ROW_FIELDS \
     " urls.id, urls.url, urls.title, urls.visit_count, urls.typed_count, " \
     "urls.last_visit_time, urls.hidden "
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_URL_DATABASE_H_