Preliminary work on resuming downloads whose connections have expired.

net/base/file_stream_win.cc

 // Copyright (c) 2010 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.
 
 #include "net/base/file_stream.h"
 
 #include <windows.h>
 
 #include "base/file_path.h"
 #include "base/histogram.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
+#include "base/win_util.h"
 #include "net/base/net_errors.h"
 
 namespace net {
 
 // Ensure that we can just use our Whence values directly.
 COMPILE_ASSERT(FROM_BEGIN == FILE_BEGIN, bad_whence_begin);
 COMPILE_ASSERT(FROM_CURRENT == FILE_CURRENT, bad_whence_current);
 COMPILE_ASSERT(FROM_END == FILE_END, bad_whence_end);
 
 static void SetOffset(OVERLAPPED* overlapped, const LARGE_INTEGER& offset) {
@@ skipping 117 matching lines @@
   if (auto_closed_)
     Close();
 }
 
 void FileStream::Close() {
   if (file_ != INVALID_HANDLE_VALUE)
     CancelIo(file_);
 
   async_context_.reset();
   if (file_ != INVALID_HANDLE_VALUE) {
-    CloseHandle(file_);
+    if (!CloseHandle(file_)) {
+      DLOG(WARNING) << " Unable to close file with handle = "
+                    << file_ << ", due to error "
+                    << GetLastError() << " ("
+                    << win_util::FormatMessage(GetLastError())
+                    << ")";
+    }
     file_ = INVALID_HANDLE_VALUE;
   }
 }
 
 int FileStream::Open(const FilePath& path, int open_flags) {
   if (IsOpen()) {
     DLOG(FATAL) << "File is already open!";
     return ERR_UNEXPECTED;
   }
 
@@ skipping 175 matching lines @@
     DWORD error = GetLastError();
     LOG(WARNING) << "SetEndOfFile failed: " << error;
     return MapErrorCode(error);
   }
 
   // Success.
   return seek_position;
 }
 
 }  // namespace net