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

content/test/gpu/gpu_test_config_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 "content/test/gpu/gpu_test_config.h"
 #include "content/public/common/gpu_info.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 class GPUTestConfigTest : public testing::Test {
  public:
@@ skipping 130 matching lines @@
 }
 
 TEST_F(GPUTestConfigTest, StringMatches) {
   GPUTestBotConfig config;
   config.set_os(GPUTestConfig::kOsWin7);
   config.set_build_type(GPUTestConfig::kBuildTypeRelease);
   config.AddGPUVendor(0x10de);
   config.set_gpu_device_id(0x0640);
   EXPECT_TRUE(config.IsValid());
 
-  EXPECT_TRUE(config.Matches(""));
+  EXPECT_TRUE(config.Matches(std::string()));
 
   // os matching
   EXPECT_TRUE(config.Matches("WIN"));
   EXPECT_TRUE(config.Matches("WIN7"));
   EXPECT_FALSE(config.Matches("MAC"));
   EXPECT_TRUE(config.Matches("WIN7 LINUX"));
 
   // gpu vendor matching
   EXPECT_TRUE(config.Matches("NVIDIA"));
   EXPECT_TRUE(config.Matches("NVIDIA AMD"));
@@ skipping 80 matching lines @@
 
 TEST_F(GPUTestConfigTest, LoadCurrentConfig) {
   GPUTestBotConfig config;
   content::GPUInfo gpu_info;
   gpu_info.gpu.vendor_id = 0x10de;
   gpu_info.gpu.device_id = 0x0640;
   EXPECT_TRUE(config.LoadCurrentConfig(&gpu_info));
   EXPECT_TRUE(config.IsValid());
 }