Make SimpleEntryImpl::Close asynchronous.

net/disk_cache/simple/simple_entry_impl.h

 // Copyright (c) 2013 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.
 
 #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_
 #define NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_
 
 #include <string>
 
 #include "base/files/file_path.h"
@@ skipping 71 matching lines @@
   // OpenEntry(). Constructs the new SimpleEntryImpl (if |result| is net::OK)
   // and passes it back to the caller via |out_entry|. Also runs
   // |completion_callback|.
   static void CreationOperationComplete(
       const CompletionCallback& completion_callback,
       Entry** out_entry,
       SimpleSynchronousEntry* sync_entry);
 
   // Called after a SimpleSynchronousEntry has completed an asynchronous IO
   // operation, such as ReadData() or WriteData(). Calls |completion_callback|.
+  // If |entry| no longer exists, then it ensures |sync_entry| is closed.
   static void EntryOperationComplete(
       const CompletionCallback& completion_callback,
       base::WeakPtr<SimpleEntryImpl> entry,
+      SimpleSynchronousEntry* sync_entry,
       int result);
 
   // Called on construction and also after the completion of asynchronous IO to
   // initialize the IO thread copies of data returned by synchronous accessor
   // functions. Copies data from |synchronous_entry_| into |this|, so that
   // values can be returned during our next IO operation.
   void SetSynchronousData();
 
   base::WeakPtrFactory<SimpleEntryImpl> weak_ptr_factory_;
 
   // |path_| and |key_| are copied from the synchronous entry on construction,
   // and never updated as they are const.
   const base::FilePath path_;
   const std::string key_;
 
   // |last_used_|, |last_modified_| and |data_size_| are copied from the
   // synchronous entry at the completion of each item of asynchronous IO.
   base::Time last_used_;
   base::Time last_modified_;
   int32 data_size_[kSimpleEntryFileCount];
 
   // The |synchronous_entry_| is the worker thread object that performs IO on
-  // entries.
+  // entries. It's owned by this SimpleEntryImpl whenever
+  // |synchronous_entry_in_use_by_worker_| is false (i.e. when an operation
+  // is not pending on the worker pool). When an operation is pending on the
+  // worker pool, the |synchronous_entry_| is owned by itself.
   SimpleSynchronousEntry* synchronous_entry_;
 
   // Set to true when a worker operation is posted on the |synchronous_entry_|,
   // and false after. Used to insure thread safety by not allowing multiple
   // threads to access the |synchronous_entry_| simultaneously.
   bool synchronous_entry_in_use_by_worker_;
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_