Integrate registry_hash_store_contents with the rest of tracked prefs.

base/files/important_file_writer.h

 // 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.
 
 #ifndef BASE_FILES_IMPORTANT_FILE_WRITER_H_
 #define BASE_FILES_IMPORTANT_FILE_WRITER_H_
 
 #include <string>
 
 #include "base/base_export.h"
@@ skipping 79 matching lines @@
   // the most recent |serializer| will be used. This operation does not block.
   // |serializer| should remain valid through the lifetime of
   // ImportantFileWriter.
   void ScheduleWrite(DataSerializer* serializer);
 
   // Serialize data pending to be saved and execute write on backend thread.
   void DoScheduledWrite();
 
   // Registers |on_next_successful_write| to be called once, on the next
   // successful write event. Only one callback can be set at once.
   void RegisterOnNextSuccessfulWriteCallback(

[gab, 2016/08/03 18:19:34]

Similar to comment below, suggest updating this to:

  // Registers |on_next_successful_write_reply| to be invoked on the sequence
  // owning this ImportantFileWriter in reply to the next successful write.
  void RegisterOnNextSuccessfulWriteReply(
    const Closure& on_next_successful_write_reply);

[proberge, 2016/08/04 00:13:45]

Done.

       const Closure& on_next_successful_write);
 
+  // Registers |on_next_successful_write| to be called once, on the next
+  // successful write event. Multiple callbacks can be set at once.

[gab, 2016/08/03 18:19:34]

Your implementation only allows a single callback, not multiple.

[proberge, 2016/08/04 00:13:45]

Done.

+  void RegisterOnNextSuccessfulWriteBlockingCallback(

[gab, 2016/08/03 18:19:34]

The ImportantFileWriter doesn't have a notion of the "BlockingPool", it just so
happens that |task_runner_| is bound to it in the JsonPrefStore's use case (and
even the JsonPrefStore doesn't know that either, it comes as a generic
SequencedTaskRunner from the factory in chrome).

Suggest:

  // Registers |on_next_successful_write_callback| to be synchronously invoked
  // from WriteFileAtomically() on its next successful write (i.e. from
  // |task_runner_|).
  void RegisterOnNextSuccessfulWriteSynchronousCallback(
      const Closure& on_next_successful_write_callback);

[proberge, 2016/08/04 00:13:45]

Done.

+      const Closure& on_next_successful_write);
+
   TimeDelta commit_interval() const {
     return commit_interval_;
   }
 
  private:
   // Helper method for WriteNow().
   bool PostWriteTask(const Callback<bool()>& task);
 
   // If |result| is true and |on_next_successful_write_| is set, invokes
   // |on_successful_write_| and then resets it; no-ops otherwise.
   void ForwardSuccessfulWrite(bool result);
 
   // Invoked once and then reset on the next successful write event.
   Closure on_next_successful_write_;

[gab, 2016/08/03 18:19:34]

on_next_successful_write_reply_

[proberge, 2016/08/04 00:13:45]

Done.

 
+  // Invoked on the blocking pool and then reset on the next successful write
+  // event.
+  Closure blocking_on_next_successful_write_;

[gab, 2016/08/03 18:19:34]

// Invoked synchronously on the next successful write and reset on this
ImportantFileWriter's owning sequence in the reply to such a write.
Closure on_next_successful_write_callback_;

[proberge, 2016/08/04 00:13:45]

Done.

+
   // Path being written to.
   const FilePath path_;
 
   // TaskRunner for the thread on which file I/O can be done.
   const scoped_refptr<SequencedTaskRunner> task_runner_;
 
   // Timer used to schedule commit after ScheduleWrite.
   OneShotTimer timer_;
 
   // Serializer which will provide the data to be saved.
   DataSerializer* serializer_;
 
   // Time delta after which scheduled data will be written to disk.
   const TimeDelta commit_interval_;
 
   WeakPtrFactory<ImportantFileWriter> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ImportantFileWriter);
 };
 
 }  // namespace base
 
 #endif  // BASE_FILES_IMPORTANT_FILE_WRITER_H_