[CrNet] Properly setup net log.

ios/crnet/crnet_net_log.h

-// Copyright 2015 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_CRNET_CRNET_NET_LOG_H_
-#define IOS_CRNET_CRNET_NET_LOG_H_
-
-#include "base/memory/scoped_ptr.h"
-#include "base/threading/thread_checker.h"
-#include "net/log/net_log.h"
-
-namespace base {
-class FilePath;
-class DictionaryValue;
-}
-
-namespace net {
-class WriteToFileNetLogObserver;
-}
-
-// CrNet-specific NetLog subclass.
-// This class can be used as a NetLog where needed; it logs all log entries to
-// the file specified in Start().
-class CrNetNetLog : public net::NetLog {
- public:
-  enum Mode {
-    LOG_ALL_BYTES,
-    LOG_STRIP_PRIVATE_DATA,
-  };
-
-  CrNetNetLog();
-  ~CrNetNetLog() override;
-
-  // Starts logging to the file named |log_file|. If |mode| is LOG_ALL_BYTES,
-  // logs all network traffic, including raw bytes. If |mode| is
-  // LOG_STRIP_PRIVATE_DATA, strips cookies and other private data, and does
-  // not log raw bytes.
-  bool Start(const base::FilePath& log_file, Mode mode);
-
-  // Stops logging.
-  void Stop();
-
- private:
-  // Underlying file writer. This observer observes NetLog events and writes
-  // them back to the file this class is logging to.
-  scoped_ptr<net::WriteToFileNetLogObserver> write_to_file_observer_;
-
-  base::ThreadChecker thread_checker_;
-};
-
-#endif  // IOS_CRNET_CRNET_NET_LOG_H