[cronet] make startNetLogToFile write to correct file

components/cronet/ios/cronet_environment.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 COMPONENTS_CRONET_IOS_CRONET_ENVIRONMENT_H_
 #define COMPONENTS_CRONET_IOS_CRONET_ENVIRONMENT_H_
 
 #include <list>
 #include <string>
 #include <vector>
@@ skipping 42 matching lines @@
   void Start();
 
   // The full user-agent.
   std::string user_agent();
 
   // Get global UMA histogram deltas.
   std::vector<uint8_t> GetHistogramDeltas();
 
   // Creates a new net log (overwrites existing file with this name). If
   // actively logging, this call is ignored.
-  void StartNetLog(base::FilePath::StringType file_name, bool log_bytes);
+  bool StartNetLog(base::FilePath::StringType file_name, bool log_bytes);
   // Stops logging and flushes file. If not currently logging this call is
   // ignored.
   void StopNetLog();
 
   void AddQuicHint(const std::string& host, int port, int alternate_port);
 
   // Setters and getters for |http2_enabled_|, |quic_enabled_|, and
   // |forced_quic_origin_|. These only have any effect before Start() is
   // called.
   void set_http2_enabled(bool enabled) { http2_enabled_ = enabled; }
@@ skipping 30 matching lines @@
 
  private:
   // Performs initialization tasks that must happen on the network thread.
   void InitializeOnNetworkThread();
 
   // Runs a closure on the file user blocking thread.
   void PostToFileUserBlockingThread(const tracked_objects::Location& from_here,
                                     const base::Closure& task);
 
   // Helper methods that start/stop net logging on the network thread.
-  void StartNetLogOnNetworkThread(const base::FilePath::StringType& file_name,
-                                  bool log_bytes);
+  void StartNetLogOnNetworkThread(base::ScopedFILE file, bool log_bytes);

[mef, 2016/11/17 15:58:48]

Add #include "base/files/scoped_file.h".

[lilyhoughton, 2016/11/22 20:48:42]

Done.

   void StopNetLogOnNetworkThread(base::WaitableEvent* log_stopped_event);
 
   // Returns the HttpNetworkSession object from the passed in
   // URLRequestContext or NULL if none exists.
   net::HttpNetworkSession* GetHttpNetworkSession(
       net::URLRequestContext* context);
 
   bool http2_enabled_;
   bool quic_enabled_;
   std::string accept_language_;
@@ skipping 17 matching lines @@
   bool user_agent_partial_;
   std::unique_ptr<net::NetLog> net_log_;
   std::unique_ptr<net::WriteToFileNetLogObserver> net_log_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(CronetEnvironment);
 };
 
 }  // namespace cronet
 
 #endif  // COMPONENTS_CRONET_IOS_CRONET_ENVIRONMENT_H_