Record language usage as UMA histograms.

chrome/browser/language_usage_metrics.cc

+// Copyright (c) 2011 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.
+
+#include "chrome/browser/language_usage_metrics.h"
+
+#include <algorithm>
+
+#include "base/metrics/histogram.h"
+#include "base/string_tokenizer.h"
+#include "base/string_util.h"
+
+namespace {
+void RecordAcceptLanguage(Language language) {
+  UMA_HISTOGRAM_ENUMERATION("LanguageUsageMetrics.AcceptLanguage",
+                            language, NUM_LANGUAGES);
+}
+}  // namespace
+
+// static
+void LanguageUsageMetrics::RecordAcceptLanguages(
+    const std::string& accept_languages) {
+  // Rethink about the histogram memory costs when the number of languages
+  // becomes too large.
+  DCHECK_LE(NUM_LANGUAGES, 300);
+
+  std::set<Language> languages;
+  ParseAcceptLanguages(accept_languages, &languages);
+  std::for_each(languages.begin(), languages.end(), RecordAcceptLanguage);
+}
+
+// static
+void LanguageUsageMetrics::RecordApplicationLanguage(
+    const std::string& application_locale) {
+  const Language language = ToLanguage(application_locale);
+  if (language != UNKNOWN_LANGUAGE) {
+    UMA_HISTOGRAM_ENUMERATION("LanguageUsageMetrics.ApplicationLanguage",
+                              language, NUM_LANGUAGES);
+  }
+}
+
+// static
+void LanguageUsageMetrics::ParseAcceptLanguages(
+    const std::string& accept_languages, std::set<Language>* languages) {
+  languages->clear();
+  StringTokenizer locales(accept_languages, ",");
+  while (locales.GetNext()) {
+    const Language language = ToLanguage(locales.token());
+    if (language != UNKNOWN_LANGUAGE) {
+      languages->insert(language);
+    }
+  }
+}
+
+// static
+Language LanguageUsageMetrics::ToLanguage(const std::string& locale) {
+  StringTokenizer parts(locale, "-_");
+  if (!parts.GetNext()) {
+    return UNKNOWN_LANGUAGE;
+  }
+  const std::string language_part = parts.token();
+  Language language;
+  if (!LanguageFromCode(language_part.c_str(), &language)) {
+    return UNKNOWN_LANGUAGE;
+  }
+  return language;
+}