net: Implement canceling of all async operations in FileStream.

chrome/browser/sessions/session_backend.cc

 // 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.
 
 #include "chrome/browser/sessions/session_backend.h"
 
 #include <limits>
 
 #include "base/file_util.h"
 #include "base/memory/scoped_vector.h"
@@ skipping 331 matching lines @@
         return false;
       }
     }
   }
   file->FlushSync();
   return true;
 }
 
 SessionBackend::~SessionBackend() {
   if (current_session_file_.get()) {
-    // Close() performs file IO. crbug.com/112512.
+    // Destructor performs file IO because file is open in sync mode.
+    // crbug.com/112512.
     base::ThreadRestrictions::ScopedAllowIO allow_io;
-    current_session_file_->CloseSync();
+    current_session_file_.reset();
   }
 }
 
 void SessionBackend::ResetFile() {
   DCHECK(inited_);
   if (current_session_file_.get()) {
     // File is already open, truncate it. We truncate instead of closing and
     // reopening to avoid the possibility of scanners locking the file out
     // from under us once we close it. If truncation fails, we'll try to
     // recreate.
@@ skipping 33 matching lines @@
 }
 
 FilePath SessionBackend::GetCurrentSessionPath() {
   FilePath path = path_to_dir_;
   if (type_ == BaseSessionService::TAB_RESTORE)
     path = path.AppendASCII(kCurrentTabSessionFileName);
   else
     path = path.AppendASCII(kCurrentSessionFileName);
   return path;
 }