Cleanup: Pass std::string as const reference if possible

components/signin/core/common/profile_management_switches.cc

Index: components/signin/core/common/profile_management_switches.cc
diff --git a/components/signin/core/common/profile_management_switches.cc b/components/signin/core/common/profile_management_switches.cc
index 6d58837d6524fffdfd513194ed88e1a5fb44aeb4..768ae5cd9fec8e314c39382bd4f05c56eab05171 100644
--- a/components/signin/core/common/profile_management_switches.cc
+++ b/components/signin/core/common/profile_management_switches.cc
@@ -106,7 +106,7 @@ State GetProcessState() {
   return state;
 }
 
-bool CheckFlag(std::string command_switch, State min_state) {
+bool CheckFlag(const std::string& command_switch, State min_state) {
   // Individiual flag settings take precedence.
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(command_switch))
     return true;