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

chrome/browser/chromeos/login/screens/hid_detection_screen.h

 // Copyright 2014 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_BROWSER_CHROMEOS_LOGIN_SCREENS_HID_DETECTION_SCREEN_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_HID_DETECTION_SCREEN_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 156 matching lines @@
 
   // Sends a notification to the Web UI of the status of available Bluetooth/USB
   // pointing device.
   void SendPointingDeviceNotification();
 
   // Sends a notification to the Web UI of the status of available Bluetooth/USB
   // keyboard device.
   void SendKeyboardDeviceNotification();
 
   // Helper method. Sets device name or placeholder if the name is empty.
-  void SetKeyboardDeviceName_(std::string name);
-
+  void SetKeyboardDeviceName_(const std::string& name);
 
   HIDDetectionView* view_;
 
   // Default bluetooth adapter, used for all operations.
   scoped_refptr<device::BluetoothAdapter> adapter_;
 
   InputServiceProxy input_service_proxy_;
 
   // The current device discovery session. Only one active discovery session is
   // kept at a time and the instance that |discovery_session_| points to gets
@@ skipping 19 matching lines @@
   bool showing_;
 
   base::WeakPtrFactory<HIDDetectionScreen> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HIDDetectionScreen);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_HID_DETECTION_SCREEN_H_