net: Implement canceling of all async operations in FileStream.

net/base/file_stream.h

Index: net/base/file_stream.h
===================================================================
--- net/base/file_stream.h	(revision 148849)
+++ net/base/file_stream.h	(working copy)
@@ -40,7 +40,9 @@
   // |net_log| is the net log pointer to use to create a |BoundNetLog|.  May be
   // NULL if logging is not needed.
   // The already opened file will not be automatically closed when FileStream
-  // is destructed.
+  // is destroyed.
+  // Note: new FileStream object takes ownership of the PlatformFile and will

[willchan no longer on Chromium, 2012/08/14 19:23:26]

Nit: grammar is a bit off. Either it should be "the new FileStream object" or
"new FileStream objects take"

+  // close it on destruction.
   FileStream(base::PlatformFile file, int flags, net::NetLog* net_log);
 
   // If the file stream was opened with Open() or OpenSync(), the underlying
@@ -62,7 +64,8 @@
   // Call this method to close the FileStream synchronously.
   // It is OK to call CloseSync() multiple times.  Redundant calls are
   // ignored. Note that if there are any pending async operations, they'll
-  // be aborted.
+  // be aborted and actual closing of the stream will happen asynchronously
+  // (to avoid races with async operation).
   virtual void CloseSync();
 
   // Call this method to open the FileStream asynchronously.  The remaining