[Extensions] Code cleanup - const &s

chrome/common/extensions/command.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_COMMON_EXTENSIONS_COMMAND_H_
 #define CHROME_COMMON_EXTENSIONS_COMMAND_H_
 
 #include <map>
 #include <string>
 
@@ skipping 43 matching lines @@
              int index,
              base::string16* error);
 
   // Accessors:
   const std::string& command_name() const { return command_name_; }
   const ui::Accelerator& accelerator() const { return accelerator_; }
   const base::string16& description() const { return description_; }
   bool global() const { return global_; }
 
   // Setter:
-  void set_accelerator(ui::Accelerator accelerator) {
+  void set_accelerator(const ui::Accelerator& accelerator) {
     accelerator_ = accelerator;
   }
   void set_global(bool global) {
     global_ = global;
   }
 
  private:
   std::string command_name_;
   ui::Accelerator accelerator_;
   base::string16 description_;
   bool global_;
 };
 
 // A mapping of command name (std::string) to a command object.
 typedef std::map<std::string, Command> CommandMap;
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_COMMAND_H_