Use StringPiece for base CommandLine::HasSwitch

base/command_line.h

Index: base/command_line.h
diff --git a/base/command_line.h b/base/command_line.h
index 85d924a8d31dcf743507ceb518a1cddfb91579b7..8de490a7901ca890ce91c26798bd26413c2faa22 100644
--- a/base/command_line.h
+++ b/base/command_line.h
@@ -22,6 +22,7 @@
 
 #include "base/base_export.h"
 #include "base/strings/string16.h"
+#include "base/strings/string_piece.h"
 #include "build/build_config.h"
 
 namespace base {
@@ -143,7 +144,9 @@ class BASE_EXPORT CommandLine {
 
   // Returns true if this command line contains the given switch.
   // (Switch names are case-insensitive).
-  bool HasSwitch(const std::string& switch_string) const;
+  // The second override provides an optimized version to avoid inlining the
+  // codegen for the string allocation.
+  bool HasSwitch(const base::StringPiece& switch_string) const;
 
   // Returns the value associated with the given switch. If the switch has no
   // value or isn't present, this method returns the empty string.