Initialize ios/web_view translate with a system-wide URLRequestContext.

ios/web_view/internal/app/application_context_impl.h

+// 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.
+
+#ifndef IOS_WEB_VIEW_INTERNAL_APP_APPLICATION_CONTEXT_IMPL_H_
+#define IOS_WEB_VIEW_INTERNAL_APP_APPLICATION_CONTEXT_IMPL_H_
+
+#include <memory>
+#include <string>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/threading/thread_checker.h"
+#include "ios/web_view/internal/app/application_context.h"
+
+namespace ios_web_view {
+
+// Exposes application global state objects. This class is not a standard
+// singleton (from //base/memory/singleton.h) because it's creation relies on
+// on two parameters.
+class ApplicationContextImpl : public ApplicationContext {

[Eugene But (OOO till 7-30), 2017/05/25 00:39:11]

What is the reason in separating ApplicationContext and ApplicationContextImpl?

[michaeldo, 2017/05/25 21:49:54]

No reason any longer. I removed the _impl class from the BUILD.gn file but
forgot to delete the files :)

+ public:
+  ApplicationContextImpl(const base::CommandLine& command_line,
+                         const std::string& locale);
+  ~ApplicationContextImpl() override;
+
+  // Creates state tied to application threads.
+  void PreCreateThreads();
+
+  // Saves applicaiton context state.
+  void SaveState();
+
+  // Destroys state tied to application threads.
+  void PostDestroyThreads();
+
+  // ApplicationContext implementation.
+  PrefService* GetLocalState() override;
+  net_log::ChromeNetLog* GetNetLog() override;
+  net::URLRequestContextGetter* GetSystemURLRequestContext() override;
+  const std::string& GetApplicationLocale() override;
+  WebViewIOThread* GetWebViewIOThread() override;
+
+ private:
+  // Returns the path to the application level preferences.
+  static base::FilePath GetLocalStatePath();
+
+  // Sets the locale used by the application.
+  void SetApplicationLocale(const std::string& locale);
+
+  // Creates the application level preferences.
+  void CreateLocalState();
+
+  THREAD_CHECKER(thread_checker_);
+  std::unique_ptr<PrefService> local_state_;
+  std::unique_ptr<net_log::ChromeNetLog> net_log_;
+  std::unique_ptr<WebViewIOThread> web_view_io_thread_;
+  std::string application_locale_;
+
+  // Sequenced task runner for local state related I/O tasks.
+  const scoped_refptr<base::SequencedTaskRunner> local_state_task_runner_;
+
+  bool created_local_state_;
+
+  DISALLOW_COPY_AND_ASSIGN(ApplicationContextImpl);
+};
+
+}  // namespace ios_web_view
+
+#endif  // IOS_WEB_VIEW_INTERNAL_APP_APPLICATION_CONTEXT_IMPL_H_