[ios] Adds configuration helper files for voice search.

ios/chrome/browser/voice/speech_input_locale_config.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 IOS_CHROME_BROWSER_VOICE_SPEECH_INPUT_LOCALE_CONFIG_H_
+#define IOS_CHROME_BROWSER_VOICE_SPEECH_INPUT_LOCALE_CONFIG_H_
+
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+#include "ios/chrome/browser/voice/speech_input_locale.h"
+
+namespace voice {
+
+class SpeechInputLocaleConfig;
+
+// Configuration object supplying information about valid locales for Voice
+// Search.
+class SpeechInputLocaleConfig {
+ public:
+  // Returns a pointer to the singleton object.
+  static SpeechInputLocaleConfig* GetInstance();
+
+  // Returns the default locale as determined by the system language.
+  virtual SpeechInputLocale GetDefaultLocale() const = 0;
+
+  // Returns a reference to a vector of SpeechInputLocales sorted alphabetically
+  // by their display names.
+  virtual const std::vector<SpeechInputLocale>& GetAvailableLocales() const = 0;
+
+  // Returns the SpeechInputLocale to use for |locale_code|. If |locale_code| is
+  // not contained in GetAvailableLocales()'s return value, then the
+  // SpeechInputLocaleConfig will attempt to match with an appropriate subsitute
+  // (e.g. "en-NZ" => "en-AU").
+  virtual SpeechInputLocale GetLocaleForCode(
+      const std::string& locale_code) const = 0;
+
+  // Returns a reference to an alphabetically sorted vector containing language
+  // codes (e.g. "en", "fr") that can be used to trigger Text To Speech results.
+  virtual const std::vector<std::string>& GetTextToSpeechLanguages() const = 0;
+
+  // Returns whether the language portion of |locale_code| is an available
+  // TTS language.
+  virtual bool IsTextToSpeechEnabledForCode(
+      const std::string& locale_code) const = 0;
+
+ protected:
+  SpeechInputLocaleConfig() = default;
+  virtual ~SpeechInputLocaleConfig() = default;
+
+  DISALLOW_COPY_AND_ASSIGN(SpeechInputLocaleConfig);
+};
+
+}  // namespace voice
+
+#endif  // IOS_CHROME_BROWSER_VOICE_SPEECH_INPUT_LOCALE_CONFIG_H_