Expose method to reset translate settings.

ios/web_view/internal/web_view_browser_state.mm

 // Copyright 2014 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.
 
 #include "ios/web_view/internal/web_view_browser_state.h"
 
 #include <memory>
 
 #include "base/base_paths.h"
 #include "base/files/file_path.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
 #include "base/sequenced_task_runner.h"
 #include "base/threading/thread_restrictions.h"
 #include "components/pref_registry/pref_registry_syncable.h"
+#include "components/prefs/in_memory_pref_store.h"
 #include "components/prefs/json_pref_store.h"
 #include "components/prefs/pref_filter.h"
 #include "components/prefs/pref_service_factory.h"
 #include "components/translate/core/browser/translate_pref_names.h"
 #include "components/translate/core/browser/translate_prefs.h"
 #include "ios/web/public/web_thread.h"
 #include "ios/web_view/internal/pref_names.h"
 #include "ios/web_view/internal/web_view_url_request_context_getter.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
@@ skipping 23 matching lines @@
       web::WebThread::GetTaskRunnerForThread(web::WebThread::CACHE));
 
   // Initialize prefs.
   scoped_refptr<user_prefs::PrefRegistrySyncable> pref_registry =
       new user_prefs::PrefRegistrySyncable;
   RegisterPrefs(pref_registry.get());
   scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner =
       JsonPrefStore::GetTaskRunnerForFile(path_,
                                           web::WebThread::GetBlockingPool());
 
-  scoped_refptr<PersistentPrefStore> user_pref_store = new JsonPrefStore(
-      path_.Append(kPreferencesFilename), sequenced_task_runner, nullptr);
+  scoped_refptr<PersistentPrefStore> user_pref_store;
+  if (off_the_record) {
+    user_pref_store = new InMemoryPrefStore();

[Eugene But (OOO till 7-30), 2017/07/10 16:17:43]

nit: s/new/base::MakeUnique

[jzw1, 2017/07/10 18:51:40]

Does this mean you want to use std::unique_ptrs instead?

[Eugene But (OOO till 7-30), 2017/07/10 20:45:49]

Sorry, did not notice that this is not std::unique_ptrs

+  } else {
+    user_pref_store = new JsonPrefStore(path_.Append(kPreferencesFilename),
+                                        sequenced_task_runner, nullptr);
+  }
 
   PrefServiceFactory factory;
   factory.set_user_prefs(user_pref_store);
   prefs_ = factory.Create(pref_registry.get());
 
   base::ThreadRestrictions::SetIOAllowed(wasIOAllowed);
 }
 
 WebViewBrowserState::~WebViewBrowserState() = default;
 
@@ skipping 25 matching lines @@
   // TODO(crbug.com/679895): Find a good value for the kAcceptLanguages pref.
   // TODO(crbug.com/679895): Pass this value to the network stack somehow, for
   // the HTTP header.
   pref_registry->RegisterStringPref(prefs::kAcceptLanguages,
                                     l10n_util::GetLocaleOverride());
   pref_registry->RegisterBooleanPref(prefs::kEnableTranslate, true);
   translate::TranslatePrefs::RegisterProfilePrefs(pref_registry);
 }
 
 }  // namespace ios_web_view