HistoryService::Init() receives the list of languages

chrome/browser/history/history_service.h

 // Copyright (c) 2012 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 CHROME_BROWSER_HISTORY_HISTORY_SERVICE_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_SERVICE_H_
 
 #include <set>
+#include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_list.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 64 matching lines @@
 // thread that made the request.
 class HistoryService : public syncer::SyncableService,
                        public KeyedService,
                        public visitedlink::VisitedLinkDelegate {
  public:
   // Miscellaneous commonly-used types.
   typedef std::vector<PageUsageData*> PageUsageDataList;
 
   // Must call Init after construction. The |history::HistoryClient| object
   // must be valid for the whole lifetime of |HistoryService|.
-  explicit HistoryService(history::HistoryClient* client, Profile* profile);
+  HistoryService(history::HistoryClient* client, Profile* profile);
   // The empty constructor is provided only for testing.
   HistoryService();
 
   ~HistoryService() override;
 
   // Initializes the history service, returning true on success. On false, do
   // not call any other functions. The given directory will be used for storing
   // the history files.

[droger, 2015/02/04 16:42:46]

Should we comment about the expected format of the string?
I assume this is a comma-separated list?

-  bool Init(const history::HistoryDatabaseParams& history_database_params) {
-    return Init(false, history_database_params);
+  bool Init(const std::string& languages,
+            const history::HistoryDatabaseParams& history_database_params) {
+    return Init(false, languages, history_database_params);
   }
 
   // Triggers the backend to load if it hasn't already, and then returns whether
   // it's finished loading.
   // Note: Virtual needed for mocking.
   virtual bool BackendLoaded();
 
   // Returns true if the backend has finished loading.
   bool backend_loaded() const { return backend_loaded_; }
 
@@ skipping 438 matching lines @@
   // should be impossible for anybody else to call the service, even if it is
   // still in memory (pending requests may be holding a reference to us).
   void Cleanup();
 
   // Implementation of visitedlink::VisitedLinkDelegate.
   void RebuildTable(const scoped_refptr<URLEnumerator>& enumerator) override;
 
   // Low-level Init().  Same as the public version, but adds a |no_db| parameter
   // that is only set by unittests which causes the backend to not init its DB.
   bool Init(bool no_db,
+            const std::string& languages,
             const history::HistoryDatabaseParams& history_database_params);
 
   // Called by the HistoryURLProvider class to schedule an autocomplete, it
   // will be called back on the internal history thread with the history
   // database so it can query. See history_autocomplete.cc for a diagram.
   void ScheduleAutocomplete(const base::Callback<
       void(history::HistoryBackend*, history::URLDatabase*)>& callback);
 
   // Notification from the backend that it has finished loading. Sends
   // notification (NOTIFY_HISTORY_LOADED) and sets backend_loaded_ to true.
@@ skipping 264 matching lines @@
 
   history::DeleteDirectiveHandler delete_directive_handler_;
 
   // All vended weak pointers are invalidated in Cleanup().
   base::WeakPtrFactory<HistoryService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryService);
 };
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_SERVICE_H_