Rewrite std::string("") to std::string(), Linux edition.

extensions/common/matcher/substring_set_matcher_unittest.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 "extensions/common/matcher/substring_set_matcher.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 99 matching lines @@
 
   // Test non-match
   // String    abcde
   // Pattern 1        fg
   TestOnePattern("abcde", "fg", false);
 
   // Test empty pattern and too long pattern
   // String    abcde
   // Pattern 1
   // Pattern 2 abcdef
-  TestTwoPatterns("abcde", "", "abcdef", true, false);
+  TestTwoPatterns("abcde", std::string(), "abcdef", true, false);
 }
 
 TEST(SubstringSetMatcherTest, RegisterAndRemove) {
   SubstringSetMatcher matcher;
 
   StringPattern pattern_1("a", 1);
   StringPattern pattern_2("b", 2);
   StringPattern pattern_3("c", 3);
 
   std::vector<const StringPattern*> patterns;
@@ skipping 27 matching lines @@
   matcher.UnregisterPatterns(patterns);
   EXPECT_TRUE(matcher.IsEmpty());
 }
 
 TEST(SubstringSetMatcherTest, TestEmptyMatcher) {
   SubstringSetMatcher matcher;
   std::set<int> matches;
   matcher.Match("abd", &matches);
   EXPECT_TRUE(matches.empty());
 }