Eliminate the archived history database and clean up related code.

chrome/browser/history/url_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/url_database.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 #include <vector>
@@ skipping 200 matching lines @@
 
 bool URLDatabase::CreateTemporaryURLTable() {
   return CreateURLTable(true);
 }
 
 bool URLDatabase::CommitTemporaryURLTable() {
   // See the comments in the header file as well as
   // HistoryBackend::DeleteAllHistory() for more information on how this works
   // and why it does what it does.
   //
+  // TODO(engedy): The following is not true any longer. Revise this part.
   // Note that the main database overrides this to additionally create the
   // supplimentary indices that the archived database doesn't need.
 
   // Swap the url table out and replace it with the temporary one.
   if (!GetDB().Execute("DROP TABLE urls")) {
     NOTREACHED() << GetDB().GetErrorMessage();
     return false;
   }
   if (!GetDB().Execute("ALTER TABLE temp_urls RENAME TO urls")) {
     NOTREACHED() << GetDB().GetErrorMessage();
     return false;
   }
 
-  // Create the index over URLs. This is needed for the main, in-memory, and
-  // archived databases, so we always do it. The supplimentary indices used by
-  // the main database are not created here. When deleting all history, they
-  // are created by HistoryDatabase::RecreateAllButStarAndURLTables().

[engedy, 2014/04/16 18:08:10]

Note: Removing this as there is no CreateSupplimentaryURLIndices() anymore.

Interestingly, RecreateAllTablesButURL() had not always been called after this
function, so there had been cases when the FavIcon index would not have been
created.

However, this is no longer an issue, as we only have a single index on the URLs
table, which is created by CreateMainURLIndex().

+  // Create the index over URLs. This is currently needed for both the main and
+  // the in-memory databases, so we always do it.
   CreateMainURLIndex();
 
   return true;
 }
 
 bool URLDatabase::InitURLEnumeratorForEverything(URLEnumerator* enumerator) {
   DCHECK(!enumerator->initialized_);
   std::string sql("SELECT ");
   sql.append(kURLRowFields);
   sql.append(" FROM urls");
@@ skipping 368 matching lines @@
   return GetDB().Execute(sql.c_str());
 }
 
 bool URLDatabase::CreateMainURLIndex() {
   // Index over URLs so we can quickly look up based on URL.
   return GetDB().Execute(
       "CREATE INDEX IF NOT EXISTS urls_url_index ON urls (url)");
 }
 
 }  // namespace history