Limit the number of history urls indexed for omnibox suggestions.

components/history/core/browser/url_database.cc

 // Copyright 2014 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 "components/history/core/browser/url_database.h"
 
 #include <limits>
 #include <string>
 #include <vector>
 
@@ skipping 230 matching lines @@
   enumerator->initialized_ = enumerator->statement_.is_valid();
   return enumerator->statement_.is_valid();
 }
 
 bool URLDatabase::InitURLEnumeratorForSignificant(URLEnumerator* enumerator) {
   DCHECK(!enumerator->initialized_);
   std::string sql("SELECT ");
   sql.append(kURLRowFields);
   sql.append(" FROM urls WHERE last_visit_time >= ? OR visit_count >= ? OR "
              "typed_count >= ?");
+  sql.append(
+      " ORDER BY typed_count DESC, last_visit_time DESC, visit_count "
+      "DESC");
   enumerator->statement_.Assign(GetDB().GetUniqueStatement(sql.c_str()));
   enumerator->statement_.BindInt64(
       0, AutocompleteAgeThreshold().ToInternalValue());
   enumerator->statement_.BindInt(1, kLowQualityMatchVisitLimit);
   enumerator->statement_.BindInt(2, kLowQualityMatchTypedLimit);
   enumerator->initialized_ = enumerator->statement_.is_valid();
   return enumerator->statement_.is_valid();
 }
 
 bool URLDatabase::AutocompleteForPrefix(const std::string& prefix,
@@ skipping 379 matching lines @@
 bool RowQualifiesAsSignificant(const URLRow& row,
                                const base::Time& threshold) {
   const base::Time& real_threshold =
       threshold.is_null() ? AutocompleteAgeThreshold() : threshold;
   return (row.typed_count() >= kLowQualityMatchTypedLimit) ||
          (row.visit_count() >= kLowQualityMatchVisitLimit) ||
          (row.last_visit() >= real_threshold);
 }
 
 }  // namespace history