[translate] Add translate ranker model loader.

chrome/browser/translate/translate_ranker_factory.h

+// 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 CHROME_BROWSER_TRANSLATE_TRANSLATE_RANKER_FACTORY_H_
+#define CHROME_BROWSER_TRANSLATE_TRANSLATE_RANKER_FACTORY_H_
+
+#include "base/macros.h"
+#include "base/memory/singleton.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+namespace translate {
+class TranslateRanker;
+
+class TranslateRankerFactory : public BrowserContextKeyedServiceFactory {
+ public:
+  static TranslateRankerFactory* GetInstance();
+  static translate::TranslateRanker* GetForBrowserContext(
+      content::BrowserContext* browser_context);
+
+ private:
+  friend struct base::DefaultSingletonTraits<TranslateRankerFactory>;
+
+  TranslateRankerFactory();
+  ~TranslateRankerFactory() override;
+
+  // BrowserContextKeyedServiceFactory:
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* context) const override;
+  content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(TranslateRankerFactory);
+};
+
+}  // namespace translate
+
+#endif  // CHROME_BROWSER_TRANSLATE_TRANSLATE_RANKER_FACTORY_H_