Disk cache: Remove all non essential synchronization from the cache destructor.

net/disk_cache/file_win.cc

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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 "net/disk_cache/file.h"
 
 #include "base/file_path.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop.h"
 #include "net/base/net_errors.h"
 #include "net/disk_cache/disk_cache.h"
@@ skipping 245 matching lines @@
 // Static.
 void File::WaitForPendingIO(int* num_pending_io) {
   while (*num_pending_io) {
     // Asynchronous IO operations may be in flight and the completion may end
     // up calling us back so let's wait for them.
     MessageLoopForIO::IOHandler* handler = g_completion_handler.Pointer();
     MessageLoopForIO::current()->WaitForIOCompletion(100, handler);
   }
 }
 
+// Static.
+void File::DropPendingIO() {
+  // Nothing to do here.
+}
+
 }  // namespace disk_cache