net: Implement canceling of all async operations in FileStream.

content/browser/web_contents/web_drag_source_mac.mm

 // 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.
 
 #import "content/browser/web_contents/web_drag_source_mac.h"
 
 #include <sys/param.h>
 
 #include "base/bind.h"
 #include "base/file_path.h"
@@ skipping 66 matching lines @@
 }
 
 // This helper's sole task is to write out data for a promised file; the caller
 // is responsible for opening the file. It takes the drop data and an open file
 // stream.
 void PromiseWriterHelper(const WebDropData& drop_data,
                          FileStream* file_stream) {
   DCHECK(file_stream);
   file_stream->WriteSync(drop_data.file_contents.data(),
                          drop_data.file_contents.length());
-
-  if (file_stream)
-    file_stream->CloseSync();
 }
 
 }  // namespace
 
 
 @interface WebDragSource(Private)
 
 - (void)fillPasteboard;
 - (NSImage*)dragImage;
 
@@ skipping 364 matching lines @@
 - (NSImage*)dragImage {
   if (dragImage_)
     return dragImage_;
 
   // Default to returning a generic image.
   return content::GetContentClient()->GetNativeImageNamed(
       IDR_DEFAULT_FAVICON).ToNSImage();
 }
 
 @end  // @implementation WebDragSource (Private)