Preliminary work on resuming downloads whose connections have expired.

net/base/file_stream_win.cc

Index: net/base/file_stream_win.cc
diff --git a/net/base/file_stream_win.cc b/net/base/file_stream_win.cc
index 234ddf93f6f4a659d4fe9c194a82a6589752fac1..62461ed51da316b8dffd68af39503a34e78eb69d 100644
--- a/net/base/file_stream_win.cc
+++ b/net/base/file_stream_win.cc
@@ -10,6 +10,7 @@
 #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 {
@@ -147,7 +148,13 @@ void FileStream::Close() {
 
   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;
   }
 }