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

chrome/browser/webdata/web_database_unittest.cc

 // Copyright (c) 2011 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 <list>
 #include <map>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 73 matching lines @@
 
   if (timestamps1.size() != timestamps2.size()) {
     return timestamps1.size() < timestamps2.size();
   }
 
   std::set<base::Time>::iterator it;
   for (it = timestamps1.begin(); it != timestamps1.end(); it++) {
     timestamps2.erase(*it);
   }
 
-  return timestamps2.size() != 0U;
+  return !timestamps2.empty();
 }
 
 void AutoFillProfile31FromStatement(const sql::Statement& s,
                                     AutoFillProfile* profile,
                                     string16* label,
                                     int* unique_id,
                                     int64* date_modified) {
   DCHECK(profile);
   DCHECK(label);
   DCHECK(unique_id);
@@ skipping 3060 matching lines @@
 
     // Check that the country code is properly converted.
     sql::Statement s(connection.GetUniqueStatement(
         "SELECT country_code FROM autofill_profiles"));
 
     ASSERT_TRUE(s.Step());
     std::string country_code = s.ColumnString(0);
     EXPECT_EQ("US", country_code);
   }
 }