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

chrome/browser/history/query_parser.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/query_parser.h"
 
 #include <algorithm>
 
 #include "base/i18n/break_iterator.h"
 #include "base/logging.h"
@@ skipping 227 matching lines @@
     }
   }
   return false;
 }
 
 QueryParser::QueryParser() {
 }
 
 // static
 bool QueryParser::IsWordLongEnoughForPrefixSearch(const string16& word) {
-  DCHECK(word.size() > 0);
+  DCHECK(!word.empty());
   size_t minimum_length = 3;
   // We intentionally exclude Hangul Jamos (both Conjoining and compatibility)
   // because they 'behave like' Latin letters. Moreover, we should
   // normalize the former before reaching here.
   if (0xAC00 <= word[0] && word[0] <= 0xD7A3)
     minimum_length = 2;
   return word.size() >= minimum_length;
 }
 
 // Returns true if the character is considered a quote.
@@ skipping 118 matching lines @@
     if (iter.IsWord()) {
       string16 word = iter.GetString();
       if (!word.empty()) {
         words->push_back(QueryWord());
         words->back().word = word;
         words->back().position = iter.prev();
       }
     }
   }
 }