[Merge M-58] Adds ChineseScriptClassifier to predict zh-Hant or zh-Hans for input detected as zh.

components/translate/core/language_detection/chinese_script_classifier.h

Index: components/translate/core/language_detection/chinese_script_classifier.h
diff --git a/components/translate/core/language_detection/chinese_script_classifier.h b/components/translate/core/language_detection/chinese_script_classifier.h
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+++ b/components/translate/core/language_detection/chinese_script_classifier.h
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+// Copyright 2017 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_TRANSLATE_CORE_LANGUAGE_DETECTION_CHINESE_SCRIPT_CLASSIFIER_H_
+#define COMPONENTS_TRANSLATE_CORE_LANGUAGE_DETECTION_CHINESE_SCRIPT_CLASSIFIER_H_
+
+#include <memory>
+#include <string>
+#include "third_party/icu/source/i18n/unicode/translit.h"
+
+namespace translate {
+
+class ChineseScriptClassifier {
+ public:
+  // Initializes both the Hant-to-Hans ICU transliterator and the
+  // Hans-to-Hant ICU transliterator.
+  ChineseScriptClassifier();
+  ~ChineseScriptClassifier();
+
+  // Given Chinese text as input, returns either zh-Hant or zh-Hans.
+  // When the input is ambiguous, i.e. not completely zh-Hans and not
+  // completely zh-Hant, this function returns the closest language code
+  // matching the input.
+  //
+  // Behavior is undefined for non-Chinese input.
+  std::string Classify(const std::string& input) const;
+
+  // Returns true if the underlying transliterators were properly initialized
+  // by the constructor.
+  bool IsInitialized() const;
+
+ private:
+  // ICU Transliterator that does Hans to Hant conversion.
+  std::unique_ptr<icu::Transliterator> hans2hant_;
+
+  // ICU Transliterator that does Hant to Hans conversion.
+  std::unique_ptr<icu::Transliterator> hant2hans_;
+};
+
+}  // namespace translate
+
+#endif  // COMPONENTS_TRANSLATE_CORE_LANGUAGE_DETECTION_CHINESE_SCRIPT_CLASSIFIER_H_