Expose method to reset translate settings.

ios/web_view/internal/translate/cwv_translation_controller.mm

 // 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.
 
 #import "ios/web_view/internal/translate/cwv_translation_controller_internal.h"
 
 #include <string>
 
 #include "base/memory/ptr_util.h"
 #include "base/strings/string16.h"
 #include "base/strings/sys_string_conversions.h"
 #include "components/translate/core/browser/translate_download_manager.h"
 #include "components/translate/core/browser/translate_manager.h"
+#import "ios/web_view/internal/cwv_web_view_configuration_internal.h"
+#include "ios/web_view/internal/pref_names.h"
 #import "ios/web_view/internal/translate/cwv_translation_language_internal.h"
 #import "ios/web_view/internal/translate/web_view_translate_client.h"
+#include "ios/web_view/internal/web_view_browser_state.h"
 #import "ios/web_view/public/cwv_translation_controller_delegate.h"
 #import "ios/web_view/public/cwv_translation_policy.h"
 #include "ui/base/l10n/l10n_util.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 NSErrorDomain const CWVTranslationErrorDomain =
     @"org.chromium.chromewebview.TranslationErrorDomain";
@@ skipping 32 matching lines @@
 
 @implementation CWVTranslationController {
   ios_web_view::WebViewTranslateClient* _translateClient;
   std::unique_ptr<translate::TranslatePrefs> _translatePrefs;
 }
 
 @synthesize delegate = _delegate;
 @synthesize supportedLanguagesByCode = _supportedLanguagesByCode;
 @synthesize webState = _webState;
 
+#pragma mark - Class Methods
+
++ (void)resetTranslationPolicies {
+  CWVWebViewConfiguration* configuration =
+      [CWVWebViewConfiguration defaultConfiguration];
+  PrefService* prefService = configuration.browserState->GetPrefs();
+  translate::TranslatePrefs translatePrefs(prefService, prefs::kAcceptLanguages,
+                                           nullptr);
+  translatePrefs.ResetToDefaults();
+}
+
 #pragma mark - Internal Methods
 
 - (void)setWebState:(web::WebState*)webState {
   _webState = webState;
 
   ios_web_view::WebViewTranslateClient::CreateForWebState(_webState);
   _translateClient =
       ios_web_view::WebViewTranslateClient::FromWebState(_webState);
   _translateClient->set_translation_controller(self);
   _translatePrefs = _translateClient->translate_manager()
@@ skipping 176 matching lines @@
   }
   return _supportedLanguagesByCode;
 }
 
 - (CWVTranslationLanguage*)languageWithCode:(const std::string&)languageCode {
   NSString* languageCodeString = base::SysUTF8ToNSString(languageCode);
   return self.supportedLanguagesByCode[languageCodeString];
 }
 
 @end