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

net/dns/mapped_host_resolver_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 "net/dns/mapped_host_resolver.h"
 
 #include "net/base/address_list.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_log.h"
 #include "net/base/net_util.h"
 #include "net/base/test_completion_callback.h"
 #include "net/dns/mock_host_resolver.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace net {
 
 namespace {
 
 std::string FirstAddress(const AddressList& address_list) {
   if (address_list.empty())
-    return "";
+    return std::string();
   return address_list.front().ToString();
 }
 
 TEST(MappedHostResolverTest, Inclusion) {
   // Create a mock host resolver, with specific hostname to IP mappings.
   scoped_ptr<MockHostResolver> resolver_impl(new MockHostResolver());
   resolver_impl->rules()->AddSimulatedFailure("*google.com");
   resolver_impl->rules()->AddRule("baz.com", "192.168.1.5");
   resolver_impl->rules()->AddRule("foo.com", "192.168.1.8");
   resolver_impl->rules()->AddRule("proxy", "192.168.1.11");
@@ skipping 132 matching lines @@
   EXPECT_EQ(OK, rv);
   EXPECT_EQ("192.168.1.9:60", FirstAddress(address_list));
 }
 
 // Parsing bad rules should silently discard the rule (and never crash).
 TEST(MappedHostResolverTest, ParseInvalidRules) {
   scoped_ptr<MappedHostResolver> resolver(
       new MappedHostResolver(scoped_ptr<HostResolver>()));
 
   EXPECT_FALSE(resolver->AddRuleFromString("xyz"));
-  EXPECT_FALSE(resolver->AddRuleFromString(""));
+  EXPECT_FALSE(resolver->AddRuleFromString(std::string()));
   EXPECT_FALSE(resolver->AddRuleFromString(" "));
   EXPECT_FALSE(resolver->AddRuleFromString("EXCLUDE"));
   EXPECT_FALSE(resolver->AddRuleFromString("EXCLUDE foo bar"));
   EXPECT_FALSE(resolver->AddRuleFromString("INCLUDE"));
   EXPECT_FALSE(resolver->AddRuleFromString("INCLUDE x"));
   EXPECT_FALSE(resolver->AddRuleFromString("INCLUDE x :10"));
 }
 
 // Test mapping hostnames to resolving failures.
 TEST(MappedHostResolverTest, MapToError) {
@@ skipping 25 matching lines @@
                          BoundNetLog());
   EXPECT_EQ(ERR_IO_PENDING, rv);
   rv = callback2.WaitForResult();
   EXPECT_EQ(OK, rv);
   EXPECT_EQ("192.168.1.5:80", FirstAddress(address_list));
 }
 
 }  // namespace
 
 }  // namespace net