country_names.cc: change SetLocaleString to take const ref instead of value

components/autofill/core/browser/country_names.h

 // Copyright 2016 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 COMPONENTS_AUTOFILL_CORE_BROWSER_COUNTRY_NAMES_H_
 #define COMPONENTS_AUTOFILL_CORE_BROWSER_COUNTRY_NAMES_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 15 matching lines @@
 // corresponding country codes.
 class CountryNames {
  public:
   // The first call to this function, causing the creation of CountryNames,
   // is expensive.
   static CountryNames* GetInstance();
 
   // Tells CountryNames, what is the application locale. Only the first supplied
   // value is used, further calls result in no changes.  Call this on the UI
   // thread, before first using CountryNames. |locale| must not be empty.
-  static void SetLocaleString(std::string locale);
+  static void SetLocaleString(const std::string& locale);
 
   // Returns the country code corresponding to |country|, which should be a
   // country code or country name localized to |locale_name|.
   const std::string GetCountryCode(const base::string16& country);
 
  protected:
   // Create CountryNames for |locale_name|. Protected for testing.
   explicit CountryNames(const std::string& locale_name);
 
   // Protected for testing.
@@ skipping 40 matching lines @@
   // The same as |localized_names_| but for the "en_US" locale. Empty if
   // "en_US" is the application locale already.
   const std::map<std::string, std::string> default_localized_names_;
 
   DISALLOW_COPY_AND_ASSIGN(CountryNames);
 };
 
 }  // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_CORE_BROWSER_COUNTRY_NAMES_H_