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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef COMPONENTS_LANGUAGE_USAGE_METRICS_LANGUAGE_USAGE_METRICS_H_
      6 #define COMPONENTS_LANGUAGE_USAGE_METRICS_LANGUAGE_USAGE_METRICS_H_
      7 
      8 #include <set>
      9 #include <string>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/gtest_prod_util.h"
     13 
     14 namespace language_usage_metrics {
     15 
     16 // Methods to record language usage as UMA histograms.
     17 class LanguageUsageMetrics {
     18  public:
     19   // Records accept languages as a UMA histogram. |accept_languages| is a
     20   // case-insensitive comma-separated list of languages/locales of either xx,
     21   // xx-YY, or xx_YY format where xx is iso-639 language code and YY is iso-3166
     22   // country code. Country code is ignored. That is, xx and XX-YY are considered
     23   // identical and recorded once.
     24   static void RecordAcceptLanguages(const std::string& accept_languages);
     25 
     26   // Records the application language as a UMA histogram. |application_locale|
     27   // is a case-insensitive locale string of either xx, xx-YY, or xx_YY format.
     28   // Only the language part (xx in the example) is considered.
     29   static void RecordApplicationLanguage(const std::string& application_locale);
     30 
     31   // Parses |locale| and returns the language code. Returns 0 in case of errors.
     32   // The language code is calculated from two alphabets. For example, if
     33   // |locale| is 'en' which represents 'English', the codes of 'e' and 'n' are
     34   // 101 and 110 respectively, and the language code will be 101 * 256 + 100 =
     35   // 25966.
     36   // |locale| should consist of only lower-case letters. This function doesn't
     37   // check whether |locale| is valid locale or not strictly.
     38   static int ToLanguageCode(const std::string &locale);
     39 
     40  private:
     41   DISALLOW_IMPLICIT_CONSTRUCTORS(LanguageUsageMetrics);
     42 
     43   // Parses |accept_languages| and returns a set of language codes in
     44   // |languages|.
     45   static void ParseAcceptLanguages(const std::string& accept_languages,
     46                                    std::set<int>* languages);
     47 
     48   FRIEND_TEST_ALL_PREFIXES(LanguageUsageMetricsTest, ParseAcceptLanguages);
     49 };
     50 
     51 }  // namespace language_usage_metrics
     52 
     53 #endif  // COMPONENTS_LANGUAGE_USAGE_METRICS_LANGUAGE_USAGE_METRICS_H_
     54