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

chromeos/dbus/fake_shill_manager_client.h

 // Copyright 2013 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 CHROMEOS_DBUS_FAKE_SHILL_MANAGER_CLIENT_H_
 #define CHROMEOS_DBUS_FAKE_SHILL_MANAGER_CLIENT_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 108 matching lines @@
   base::ListValue* GetEnabledServiceList(const std::string& property) const;
   void ScanCompleted(const std::string& device_path,
                      const base::Closure& callback);
 
   // Parses the command line for Shill stub switches and sets initial states.
   // Uses comma-separated name-value pairs (see SplitStringIntoKeyValuePairs):
   // interactive={delay} - sets delay in seconds for interactive UI
   // {wifi,cellular,etc}={on,off,disabled,none} - sets initial state for type
   void ParseCommandLineSwitch();
   bool ParseOption(const std::string& arg0, const std::string& arg1);
-  bool SetInitialNetworkState(std::string type_arg, std::string state_arg);
+  bool SetInitialNetworkState(const std::string& type_arg,
+                              const std::string& state_arg);
   std::string GetInitialStateForType(const std::string& type,
                                      bool* enabled);
 
   // Dictionary of property name -> property value
   base::DictionaryValue stub_properties_;
 
   // Dictionary of technology -> list of property dictionaries
   base::DictionaryValue stub_geo_networks_;
 
   // Seconds to delay interactive actions
@@ skipping 23 matching lines @@
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate its weak pointers before any other members are destroyed.
   base::WeakPtrFactory<FakeShillManagerClient> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeShillManagerClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_FAKE_SHILL_MANAGER_CLIENT_H_