[ios] Adds a VoiceSearchController interface to the provider layer.

ios/public/provider/chrome/browser/voice/voice_search_prefs.h

Index: ios/public/provider/chrome/browser/voice/voice_search_prefs.h
diff --git a/ios/public/provider/chrome/browser/voice/voice_search_prefs.h b/ios/public/provider/chrome/browser/voice/voice_search_prefs.h
new file mode 100644
index 0000000000000000000000000000000000000000..83be1ddc8d28d7e0f3a82fad6ea89b6be9971226
--- /dev/null
+++ b/ios/public/provider/chrome/browser/voice/voice_search_prefs.h
@@ -0,0 +1,15 @@
+// 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_PUBLIC_PROVIDER_CHROME_BROWSER_VOICE_VOICE_SEARCH_PREFS_H_
+#define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_VOICE_VOICE_SEARCH_PREFS_H_
+
+namespace prefs {
+
+extern const char kVoiceSearchLocale[];
+extern const char kVoiceSearchTTS[];
+
+}  // namespace prefs
+
+#endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_VOICE_VOICE_SEARCH_PREFS_H_