Make FileSystemOperation's lifetime more explicit.

webkit/fileapi/file_system_operation.h

 // Copyright (c) 2010 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 WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_H_
 
 #include <vector>
 
 #include "base/file_path.h"
@@ skipping 15 matching lines @@
 
 namespace fileapi {
 
 class FileSystemCallbackDispatcher;
 class FileWriterDelegate;
 
 // This class is designed to serve one-time file system operation per instance.
 // Only one method(CreateFile, CreateDirectory, Copy, Move, DirectoryExists,
 // GetMetadata, ReadDirectory and Remove) may be called during the lifetime of
 // this object and it should be called no more than once.
+// This class is self-destructed and an instance automatically gets deleted
+// when its operation is finished.
 class FileSystemOperation {
  public:
+  // |dispatcher| will be owned by this class.
   FileSystemOperation(FileSystemCallbackDispatcher* dispatcher,
                       scoped_refptr<base::MessageLoopProxy> proxy);
   virtual ~FileSystemOperation();
 
   virtual void CreateFile(const FilePath& path,
                           bool exclusive);
 
   virtual void CreateDirectory(const FilePath& path,
                                bool exclusive,
                                bool recursive);
 
   virtual void Copy(const FilePath& src_path,
                     const FilePath& dest_path);
 
   virtual void Move(const FilePath& src_path,
                     const FilePath& dest_path);
 
   virtual void DirectoryExists(const FilePath& path);
 
   virtual void FileExists(const FilePath& path);
 
   virtual void GetMetadata(const FilePath& path);
 
   virtual void ReadDirectory(const FilePath& path);
 
   virtual void Remove(const FilePath& path, bool recursive);
 
-  virtual void Write(
-      scoped_refptr<URLRequestContext> url_request_context,
-      const FilePath& path, const GURL& blob_url, int64 offset);
+  virtual void Write(scoped_refptr<URLRequestContext> url_request_context,
+                     const FilePath& path,
+                     const GURL& blob_url,
+                     int64 offset);
 
   virtual void Truncate(const FilePath& path, int64 length);
 
   virtual void TouchFile(const FilePath& path,
-                 const base::Time& last_access_time,
-                 const base::Time& last_modified_time);
+                         const base::Time& last_access_time,
+                         const base::Time& last_modified_time);
 
   // Try to cancel the current operation [we support cancelling write or
   // truncate only].  Report failure for the current operation, then tell the
   // passed-in operation to report success.
   virtual void Cancel(FileSystemOperation* cancel_operation);
 
  protected:
 #ifndef NDEBUG
   enum OperationType {
     kOperationNone,
     kOperationCreateFile,
     kOperationCreateDirectory,
     kOperationCopy,
     kOperationMove,
     kOperationDirectoryExists,
     kOperationFileExists,
     kOperationGetMetadata,
     kOperationReadDirectory,
     kOperationRemove,
     kOperationWrite,
     kOperationTruncate,
     kOperationTouchFile,
     kOperationCancel,
   };
 
   // A flag to make sure we call operation only once per instance.
   OperationType pending_operation_;
 #endif
 
-  FileSystemCallbackDispatcher* dispatcher() const { return dispatcher_.get(); }
+  // Returns a destructive dispatcher which deletes the operation instance
+  // after any of its callback methods is called (except for DidWrite with
+  // complete=false cases).
+  FileSystemCallbackDispatcher* destructive_dispatcher() const {
+    return destructive_dispatcher_.get();
+  }
+
+  // Returns a non-destructive dispatcher.
+  FileSystemCallbackDispatcher* non_destructive_dispatcher() const;
 
  private:
   // Callback for CreateFile for |exclusive|=true cases.
   void DidEnsureFileExistsExclusive(base::PlatformFileError rv,
                                     bool created);
 
   // Callback for CreateFile for |exclusive|=false cases.
   void DidEnsureFileExistsNonExclusive(base::PlatformFileError rv,
                                        bool created);
 
@@ skipping 22 matching lines @@
 
   // Helper for Write().
   void OnFileOpenedForWrite(
       base::PlatformFileError rv,
       base::PassPlatformFile file,
       bool created);
 
   // Proxy for calling file_util_proxy methods.
   scoped_refptr<base::MessageLoopProxy> proxy_;
 
-  scoped_ptr<FileSystemCallbackDispatcher> dispatcher_;
+  scoped_ptr<FileSystemCallbackDispatcher> destructive_dispatcher_;
 
   base::ScopedCallbackFactory<FileSystemOperation> callback_factory_;
 
   // These are all used only by Write().
   friend class FileWriterDelegate;
   scoped_ptr<FileWriterDelegate> file_writer_delegate_;
   scoped_ptr<URLRequest> blob_request_;
   FileSystemOperation* cancel_operation_;
 
   DISALLOW_COPY_AND_ASSIGN(FileSystemOperation);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_H_