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

content/browser/gpu/gpu_control_list_machine_model_info_unittest.cc

 // Copyright (c) 2013 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 "content/browser/gpu/gpu_control_list.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace content {
 
 class MachineModelInfoTest : public testing::Test {
@@ skipping 29 matching lines @@
       if (version_op[j] == "between")
         version2 = "5.4";
       MachineModelInfo info(name_op[i], "model",
                             version_op[j], version1, version2);
       EXPECT_TRUE(info.IsValid());
     }
   }
 }
 
 TEST_F(MachineModelInfoTest, ModelComparison) {
-  MachineModelInfo info("=", "model_a",
-                        ">", "3.4", "");
+  MachineModelInfo info("=", "model_a", ">", "3.4", std::string());
   EXPECT_TRUE(info.Contains("model_a", "4"));
   EXPECT_FALSE(info.Contains("model_b", "4"));
   EXPECT_FALSE(info.Contains("model_a", "3.2"));
 }
 
 }  // namespace content