Make FileStream::Seek async and add FileStream::SeekSync for sync operation

net/base/file_stream_win.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.
 
 // This file implements FileStream for Windows.
 
 #ifndef NET_BASE_FILE_STREAM_WIN_H_
 #define NET_BASE_FILE_STREAM_WIN_H_
 #pragma once
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/platform_file.h"
 #include "base/synchronization/waitable_event.h"
 #include "net/base/completion_callback.h"
 #include "net/base/file_stream_whence.h"
 #include "net/base/net_export.h"
 #include "net/base/net_log.h"
 
 class FilePath;
 
+namespace base {
+class WaitableEvent;
+}
+
 namespace net {
 
 class IOBuffer;
 
 class NET_EXPORT FileStreamWin {
  public:
   explicit FileStreamWin(net::NetLog* net_log);
   FileStreamWin(base::PlatformFile file, int flags, net::NetLog* net_log);
   ~FileStreamWin();
 
   // FileStream implementations.
   void Close(const CompletionCallback& callback);
   void CloseSync();
   int Open(const FilePath& path, int open_flags,
            const CompletionCallback& callback);
   int OpenSync(const FilePath& path, int open_flags);
   bool IsOpen() const;
-  int64 Seek(Whence whence, int64 offset);
+  int Seek(Whence whence, int64 offset,
+           const Int64CompletionCallback& callback);
+  int64 SeekSync(Whence whence, int64 offset);
   int64 Available();
   int Read(IOBuffer* buf, int buf_len, const CompletionCallback& callback);
   int ReadSync(char* buf, int buf_len);
   int ReadUntilComplete(char *buf, int buf_len);
   int Write(IOBuffer* buf, int buf_len, const CompletionCallback& callback);
   int WriteSync(const char* buf, int buf_len);
   int64 Truncate(int64 bytes);
   int Flush();
   void EnableErrorStatistics();
   void SetBoundNetLogSource(const net::BoundNetLog& owner_bound_net_log);
   base::PlatformFile GetPlatformFileForTesting();
 
  private:
   class AsyncContext;
-  friend class AsyncContext;
+
+  // A helper method for Seek.
+  void SeekFile(Whence whence, int64 offset, int64* result);
 
   // Called when the file_ is opened asynchronously. |result| contains the
   // result as a network error code.
-  void OnOpened(int* result);
+  void OnOpened(const CompletionCallback& callback, int* result);
 
   // Called when the file_ is closed asynchronously.
-  void OnClosed();
+  void OnClosed(const CompletionCallback& callback);
+
+  // Called when the file_ is seeked asynchronously.
+  void OnSeeked(const Int64CompletionCallback& callback, int64* result);
+
+  // Resets on_io_complete_ and WeakPtr's.
+  // Called in OnOpened, OnClosed and OnSeeked.
+  void ResetOnIOComplete();
 
   // Waits until the in-flight async open/close operation is complete.
   void WaitForIOCompletion();
 
   // This member is used to support asynchronous reads.  It is non-null when
   // the FileStreamWin was opened with PLATFORM_FILE_ASYNC.
   scoped_ptr<AsyncContext> async_context_;
 
   base::PlatformFile file_;
   int open_flags_;
   bool auto_closed_;
   bool record_uma_;
   net::BoundNetLog bound_net_log_;
   base::WeakPtrFactory<FileStreamWin> weak_ptr_factory_;
-  CompletionCallback callback_;
   scoped_ptr<base::WaitableEvent> on_io_complete_;
 
   DISALLOW_COPY_AND_ASSIGN(FileStreamWin);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_FILE_STREAM_WIN_H_