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

ios/chrome/browser/pref_names.h

Index: ios/chrome/browser/pref_names.h
diff --git a/ios/chrome/browser/pref_names.h b/ios/chrome/browser/pref_names.h
index 6161bd1d77363f751ebee10deb9c00ff00dd108d..5eca97af12a7777ee53ec00baa9d0662539ec0a2 100644
--- a/ios/chrome/browser/pref_names.h
+++ b/ios/chrome/browser/pref_names.h
@@ -5,6 +5,10 @@
 #ifndef IOS_CHROME_BROWSER_PREF_NAMES_H_
 #define IOS_CHROME_BROWSER_PREF_NAMES_H_
 
+// TODO(rohitrao): Remove this include once embedders are migrated to use the
+// new pref header.
+#include "ios/public/provider/chrome/browser/voice/voice_search_prefs.h"
+
 namespace prefs {
 
 extern const char kAcceptLanguages[];
@@ -38,9 +42,6 @@ extern const char kNetworkPredictionWifiOnly[];
 extern const char kNtpShownBookmarksFolder[];
 extern const char kShowMemoryDebuggingTools[];
 
-extern const char kVoiceSearchLocale[];
-extern const char kVoiceSearchTTS[];
-
 extern const char kSigninLastAccounts[];
 extern const char kSigninLastAccountsMigrated[];
 extern const char kSigninSharedAuthenticationUserId[];