Revert of mojo filesystem: Simplify full file reading/writing.

components/filesystem/public/cpp/prefs/filesystem_json_pref_store.h

 // Copyright 2016 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 COMPONENTS_FILESYSTEM_PUBLIC_CPP_PREFS_FILESYSTEM_JSON_PREF_STORE_H_
 #define COMPONENTS_FILESYSTEM_PUBLIC_CPP_PREFS_FILESYSTEM_JSON_PREF_STORE_H_
 
 #include <stdint.h>
 
 #include <set>
@@ skipping 122 matching lines @@
   // Opens the filesystem and calls |callback| when completed, whether
   // successfully or unsuccessfully.
   void OpenFilesystem(base::Closure callback);
 
   // Callback method which verifies that there were no errors on opening the
   // filesystem, and if there aren't, invokes the passed in callback.
   void OnOpenFilesystem(base::Closure callback, FileError err);
 
   // Asynchronous implementation details of PerformWrite().
   void OnTempFileWriteStart();
-  void OnTempFileWrite(FileError err);
+  void OnTempFileOpened(FileError err);
+  void OnTempFileWrite(FileError err, uint32_t num_bytes_written);
+  void OnTempFileClosed(FileError err);
   void OnTempFileRenamed(FileError err);
 
   // Asynchronous implementation details of ReadPrefsAsync().
   void OnPreferencesReadStart();
+  void OnPreferencesFileOpened(FileError err);
   void OnPreferencesFileRead(FileError err, mojo::Array<uint8_t> contents);
 
   const std::string path_;
   mojo::Binding<filesystem::FileSystemClient> binding_;
   filesystem::FileSystemPtr filesystem_;
 
   // |directory_| is only bound after the first attempt to access the
   // |filesystem. See OpenFilesystem().
   DirectoryPtr directory_;
 
+  FilePtr preferences_file_;
+  FilePtr temporary_file_;
+
   scoped_ptr<base::DictionaryValue> prefs_;
 
   bool read_only_;
 
   scoped_ptr<PrefFilter> pref_filter_;
   base::ObserverList<PrefStore::Observer, true> observers_;
 
   scoped_ptr<ReadErrorDelegate> error_delegate_;
 
   bool initialized_;
   bool filtering_in_progress_;
   bool pending_lossy_write_;
   PrefReadError read_error_;
 
   DISALLOW_COPY_AND_ASSIGN(FilesystemJsonPrefStore);
 };
 
 }  // namespace filesystem
 
 #endif  // COMPONENTS_FILESYSTEM_PUBLIC_CPP_PREFS_FILESYSTEM_JSON_PREF_STORE_H_