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

base/vlog_unittest.cc

Index: base/vlog_unittest.cc
diff --git a/base/vlog_unittest.cc b/base/vlog_unittest.cc
index ef7247f0e54f8ae367f4ec6df16bec0bcc685c96..3a508f47263ec305482d1bb00da2ef17280e1abb 100644
--- a/base/vlog_unittest.cc
+++ b/base/vlog_unittest.cc
@@ -16,12 +16,20 @@ namespace {
 
 TEST(VlogTest, NoVmodule) {
   int min_log_level = 0;
-  EXPECT_EQ(0, VlogInfo("", "", &min_log_level).GetVlogLevel("test1"));
-  EXPECT_EQ(0, VlogInfo("0", "", &min_log_level).GetVlogLevel("test2"));
-  EXPECT_EQ(0, VlogInfo("blah", "", &min_log_level).GetVlogLevel("test3"));
-  EXPECT_EQ(0, VlogInfo("0blah1", "", &min_log_level).GetVlogLevel("test4"));
-  EXPECT_EQ(1, VlogInfo("1", "", &min_log_level).GetVlogLevel("test5"));
-  EXPECT_EQ(5, VlogInfo("5", "", &min_log_level).GetVlogLevel("test6"));
+  EXPECT_EQ(0,
+            VlogInfo(std::string(), std::string(), &min_log_level)
+                .GetVlogLevel("test1"));
+  EXPECT_EQ(0,
+            VlogInfo("0", std::string(), &min_log_level).GetVlogLevel("test2"));
+  EXPECT_EQ(
+      0, VlogInfo("blah", std::string(), &min_log_level).GetVlogLevel("test3"));
+  EXPECT_EQ(
+      0,
+      VlogInfo("0blah1", std::string(), &min_log_level).GetVlogLevel("test4"));
+  EXPECT_EQ(1,
+            VlogInfo("1", std::string(), &min_log_level).GetVlogLevel("test5"));
+  EXPECT_EQ(5,
+            VlogInfo("5", std::string(), &min_log_level).GetVlogLevel("test6"));
 }
 
 TEST(VlogTest, MatchVlogPattern) {
@@ -92,7 +100,7 @@ TEST(VlogTest, VmoduleDirs) {
   const char kVModuleSwitch[] =
       "foo/bar.cc=1,baz\\*\\qux.cc=2,*quux/*=3,*/*-inl.h=4";
   int min_log_level = 0;
-  VlogInfo vlog_info("", kVModuleSwitch, &min_log_level);
+  VlogInfo vlog_info(std::string(), kVModuleSwitch, &min_log_level);
   EXPECT_EQ(0, vlog_info.GetVlogLevel("/foo/bar.cc"));
   EXPECT_EQ(0, vlog_info.GetVlogLevel("bar.cc"));
   EXPECT_EQ(1, vlog_info.GetVlogLevel("foo/bar.cc"));