[translate] Add translate ranker model loader.

chrome/browser/translate/translate_ranker_factory.cc

+// 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.
+
+#include "chrome/browser/translate/translate_ranker_factory.h"
+
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "components/translate/core/browser/translate_ranker_impl.h"
+#include "components/translate/core/common/translate_switches.h"
+#include "components/variations/variations_associated_data.h"
+#include "content/public/browser/browser_context.h"
+
+namespace translate {
+
+// static
+TranslateRankerFactory* TranslateRankerFactory::GetInstance() {
+  return base::Singleton<TranslateRankerFactory>::get();
+}
+
+// static
+translate::TranslateRanker* TranslateRankerFactory::GetForBrowserContext(
+    content::BrowserContext* browser_context) {
+  return static_cast<translate::TranslateRanker*>(
+      GetInstance()->GetServiceForBrowserContext(browser_context, true));
+}
+
+TranslateRankerFactory::TranslateRankerFactory()
+    : BrowserContextKeyedServiceFactory(
+          "TranslateRanker",
+          BrowserContextDependencyManager::GetInstance()) {}
+
+TranslateRankerFactory::~TranslateRankerFactory() {}
+
+KeyedService* TranslateRankerFactory::BuildServiceInstanceFor(
+    content::BrowserContext* browser_context) const {
+  return new TranslateRankerImpl(
+      TranslateRankerImpl::GetModelPath(browser_context->GetPath()),
+      TranslateRankerImpl::GetModelURL());
+}
+
+}  // namespace translate