Change other usages of .size() to .empty() when applicable.

chrome/browser/history/history_types.cc

 // Copyright (c) 2010 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/history_types.h"
 
 #include <limits>
 
 #include "base/logging.h"
 #include "base/stl_util-inl.h"
@@ skipping 156 matching lines @@
                                           size_t* num_matches) const {
   URLToResultIndices::const_iterator found = url_to_results_.find(url);
   if (found == url_to_results_.end()) {
     if (num_matches)
       *num_matches = 0;
     return NULL;
   }
 
   // All entries in the map should have at least one index, otherwise it
   // shouldn't be in the map.
-  DCHECK(found->second->size() > 0);
+  DCHECK(!found->second->empty());
   if (num_matches)
     *num_matches = found->second->size();
   return &found->second->front();
 }
 
 void QueryResults::Swap(QueryResults* other) {
   std::swap(first_time_searched_, other->first_time_searched_);
   std::swap(reached_beginning_, other->reached_beginning_);
   results_.swap(other->results_);
   url_to_results_.swap(other->url_to_results_);
@@ skipping 209 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