Updates language model on iOS.

ios/chrome/browser/translate/language_model_factory.cc

+// 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.
+
+#include "ios/chrome/browser/translate/language_model_factory.h"
+
+#include "base/memory/ptr_util.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "components/keyed_service/ios/browser_state_dependency_manager.h"
+#include "components/translate/core/browser/language_model.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state.h"
+
+namespace translate {
+
+// static
+LanguageModelFactory* LanguageModelFactory::GetInstance() {
+  return base::Singleton<LanguageModelFactory>::get();
+}
+
+// static
+translate::LanguageModel* LanguageModelFactory::GetForBrowserState(
+    ios::ChromeBrowserState* state) {

[martis, 2017/06/01 06:49:21]

In general, I think we should try to be as const-correct as possible.

Up to you, but method parameters and instance variables in this cc file could be
declared as e.g.
ios::ChromeBrowserState* const state
to stop you from accidentally overwriting them.

Same comment for instance variables in this class' unit tests.

[ramyasharma, 2017/06/02 07:20:24]

Thanks Michael. I have changed it in here. I am not sure what you mean in the
unit tests?

+  return static_cast<LanguageModel*>(
+      GetInstance()->GetServiceForBrowserState(state, true));
+}
+
+LanguageModelFactory::LanguageModelFactory()
+    : BrowserStateKeyedServiceFactory(
+          "LanguageModel",
+          BrowserStateDependencyManager::GetInstance()) {}
+
+LanguageModelFactory::~LanguageModelFactory() {}
+
+std::unique_ptr<KeyedService> LanguageModelFactory::BuildServiceInstanceFor(
+    web::BrowserState* context) const {
+  ios::ChromeBrowserState* browser_state =
+      ios::ChromeBrowserState::FromBrowserState(context);
+  return base::MakeUnique<translate::LanguageModel>(browser_state->GetPrefs());
+}
+}