Use ByteStream in downloads system to decouple source and sink.

content/browser/download/download_net_log_parameters.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_NET_LOG_PARAMETERS_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_NET_LOG_PARAMETERS_H_
 #pragma once
 
 #include <string>
 
@@ skipping 163 matching lines @@
  protected:
   virtual ~FileOpenedParameters();
 
  private:
   const std::string file_name_;
   const int64 start_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(FileOpenedParameters);
 };
 
+// NetLog parameters when a DownloadFile is opened.
+class FileStreamDrainedParameters : public net::NetLog::EventParameters {
+ public:
+  FileStreamDrainedParameters(size_t stream_size,
+                            size_t num_buffers);
+  virtual base::Value* ToValue() const OVERRIDE;
+
+ protected:
+  virtual ~FileStreamDrainedParameters();
+
+ private:
+  const size_t stream_size_;
+  const size_t num_buffers_;
+
+  DISALLOW_COPY_AND_ASSIGN(FileStreamDrainedParameters);
+};
+
 // NetLog parameters when a DownloadFile is renamed.
 class FileRenamedParameters : public net::NetLog::EventParameters {
  public:
   FileRenamedParameters(
       const std::string& old_filename, const std::string& new_filename);
   virtual base::Value* ToValue() const OVERRIDE;
 
  protected:
   virtual ~FileRenamedParameters();
 
@@ skipping 16 matching lines @@
  private:
   const std::string operation_;
   const net::Error net_error_;
 
   DISALLOW_COPY_AND_ASSIGN(FileErrorParameters);
 };
 
 }  // namespace download_net_logs
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_NET_LOG_PARAMETERS_H_