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

sync/syncable/syncable_unittest.cc

 // Copyright 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 <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/file_util.h"
 #include "base/files/file_path.h"
@@ skipping 2235 matching lines @@
   TestIdFactory factory_;
 };
 
 TEST_F(SyncableClientTagTest, TestClientTagClear) {
   Id server_id = factory_.NewServerId();
   EXPECT_TRUE(CreateWithDefaultTag(server_id, false));
   {
     WriteTransaction trans(FROM_HERE, UNITTEST, dir_.get());
     MutableEntry me(&trans, GET_BY_CLIENT_TAG, test_tag_);
     EXPECT_TRUE(me.good());
-    me.Put(UNIQUE_CLIENT_TAG, "");
+    me.Put(UNIQUE_CLIENT_TAG, std::string());
   }
   {
     ReadTransaction trans(FROM_HERE, dir_.get());
     Entry by_tag(&trans, GET_BY_CLIENT_TAG, test_tag_);
     EXPECT_FALSE(by_tag.good());
 
     Entry by_id(&trans, GET_BY_ID, server_id);
     EXPECT_TRUE(by_id.good());
     EXPECT_TRUE(by_id.Get(UNIQUE_CLIENT_TAG).empty());
   }
@@ skipping 27 matching lines @@
   EXPECT_TRUE(CreateWithDefaultTag(factory_.NewServerId(), true));
   EXPECT_FALSE(CreateWithDefaultTag(factory_.NewServerId(), true));
   EXPECT_FALSE(CreateWithDefaultTag(factory_.NewServerId(), false));
   EXPECT_FALSE(CreateWithDefaultTag(factory_.NewLocalId(), false));
   EXPECT_FALSE(CreateWithDefaultTag(factory_.NewLocalId(), true));
 }
 
 }  // namespace
 }  // namespace syncable
 }  // namespace syncer