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

base/sys_info_posix.cc

Index: base/sys_info_posix.cc
diff --git a/base/sys_info_posix.cc b/base/sys_info_posix.cc
index 854f123d469a236c8e1ed6a674b2318bc4e5fdfc..57b7af6cfd5cca48ca5c0c8ca9b86960b435b2fe 100644
--- a/base/sys_info_posix.cc
+++ b/base/sys_info_posix.cc
@@ -55,7 +55,7 @@ std::string SysInfo::OperatingSystemName() {
   struct utsname info;
   if (uname(&info) < 0) {
     NOTREACHED();
-    return "";
+    return std::string();
   }
   return std::string(info.sysname);
 }
@@ -67,7 +67,7 @@ std::string SysInfo::OperatingSystemVersion() {
   struct utsname info;
   if (uname(&info) < 0) {
     NOTREACHED();
-    return "";
+    return std::string();
   }
   return std::string(info.release);
 }
@@ -78,7 +78,7 @@ std::string SysInfo::OperatingSystemArchitecture() {
   struct utsname info;
   if (uname(&info) < 0) {
     NOTREACHED();
-    return "";
+    return std::string();
   }
   std::string arch(info.machine);
   if (arch == "i386" || arch == "i486" || arch == "i586" || arch == "i686") {