Avoid a string copy for every CommandLine::HasSwitch query

base/command_line.cc

Index: base/command_line.cc
diff --git a/base/command_line.cc b/base/command_line.cc
index fb7c81376ba4bfce5936b4298989b2144862c0fb..6125667d3ec8e66dcead5ec8147fd5879bd6ad48 100644
--- a/base/command_line.cc
+++ b/base/command_line.cc
@@ -94,13 +94,15 @@ void AppendSwitchesAndArguments(CommandLine* command_line,
 }
 
 // Lowercase switches for backwards compatiblity *on Windows*.
-std::string LowerASCIIOnWindows(const std::string& string) {
 #if defined(OS_WIN)
+std::string LowerASCIIOnWindows(const std::string& string) {
   return StringToLowerASCII(string);
+}
 #elif defined(OS_POSIX)
+const std::string& LowerASCIIOnWindows(const std::string& string) {
   return string;
-#endif
 }
+#endif
 
 
 #if defined(OS_WIN)