net: Make UploadDataStream::Init() asynchronous.

net/base/upload_bytes_element_reader.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 NET_BASE_UPLOAD_BYTES_ELEMENT_READER_H_
 #define NET_BASE_UPLOAD_BYTES_ELEMENT_READER_H_
 
 #include "base/compiler_specific.h"
 #include "net/base/upload_element_reader.h"
 
 namespace net {
 
 // An UploadElementReader implementation for bytes.
 class NET_EXPORT_PRIVATE UploadBytesElementReader : public UploadElementReader {
  public:
   UploadBytesElementReader(const char* bytes, int bytes_length);
   virtual ~UploadBytesElementReader();
 
   // UploadElementReader overrides:
+  virtual int Init(const CompletionCallback& callback) OVERRIDE;
   virtual int InitSync() OVERRIDE;
   virtual uint64 GetContentLength() const OVERRIDE;
   virtual uint64 BytesRemaining() const OVERRIDE;
   virtual int ReadSync(char* buf, int buf_length) OVERRIDE;
   virtual bool IsInMemory() const OVERRIDE;
 
  private:
   const char* bytes_;
   int bytes_length_;
   int offset_;
 
   DISALLOW_COPY_AND_ASSIGN(UploadBytesElementReader);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_UPLOAD_BYTES_ELEMENT_READER_H_