Allow ImportantFileWriter to take in a pre-write callback.

components/prefs/json_pref_store.cc

 // 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 "components/prefs/json_pref_store.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <utility>
@@ skipping 155 matching lines @@
       sequenced_task_runner_(sequenced_task_runner),
       prefs_(new base::DictionaryValue()),
       read_only_(false),
       writer_(pref_filename, sequenced_task_runner),
       pref_filter_(std::move(pref_filter)),
       initialized_(false),
       filtering_in_progress_(false),
       pending_lossy_write_(false),
       read_error_(PREF_READ_ERROR_NONE),
       has_pending_successful_write_reply_(false),
-      has_pending_write_callback_(false),
+      has_pending_write_callbacks_(false),
       write_count_histogram_(writer_.commit_interval(), path_) {
   DCHECK(!path_.empty());
 }
 
 bool JsonPrefStore::GetValue(const std::string& key,
                              const base::Value** result) const {
   DCHECK(CalledOnValidThread());
 
   base::Value* tmp = nullptr;
   if (!prefs_->Get(key, &tmp))
@@ skipping 136 matching lines @@
 
   FOR_EACH_OBSERVER(PrefStore::Observer, observers_, OnPrefValueChanged(key));
 
   ScheduleWrite(flags);
 }
 
 void JsonPrefStore::RunOrScheduleNextSuccessfulWriteCallback(
     bool write_success) {
   DCHECK(CalledOnValidThread());
 
-  has_pending_write_callback_ = false;
+  has_pending_write_callbacks_ = false;
   if (has_pending_successful_write_reply_) {
     has_pending_successful_write_reply_ = false;
     if (write_success) {
       on_next_successful_write_reply_.Run();
     } else {
       RegisterOnNextSuccessfulWriteReply(on_next_successful_write_reply_);
     }
   }
 }
 
@@ skipping 13 matching lines @@
 }
 
 void JsonPrefStore::RegisterOnNextSuccessfulWriteReply(
     const base::Closure& on_next_successful_write_reply) {
   DCHECK(CalledOnValidThread());
   DCHECK(!has_pending_successful_write_reply_);
 
   has_pending_successful_write_reply_ = true;
   on_next_successful_write_reply_ = on_next_successful_write_reply;
 
-  // If there already is a pending callback, avoid erasing it; the reply will
-  // be used as we set |on_next_successful_write_reply_|. Otherwise, setup a
-  // reply with an  empty callback.
-  if (!has_pending_write_callback_) {
-    writer_.RegisterOnNextWriteCallback(base::Bind(
-        &PostWriteCallback,
-        base::Bind(&JsonPrefStore::RunOrScheduleNextSuccessfulWriteCallback,
-                   AsWeakPtr()),
-        base::Callback<void(bool success)>(),
-        base::SequencedTaskRunnerHandle::Get()));
+  // If there are pending callbacks, avoid erasing them; the reply will be used
+  // as we set |on_next_successful_write_reply_|. Otherwise, setup a reply with
+  // an empty callback.
+  if (!has_pending_write_callbacks_) {
+    writer_.RegisterOnNextWriteCallbacks(
+        base::Closure(),
+        base::Bind(
+            &PostWriteCallback,
+            base::Bind(&JsonPrefStore::RunOrScheduleNextSuccessfulWriteCallback,
+                       AsWeakPtr()),
+            base::Callback<void(bool success)>(),
+            base::SequencedTaskRunnerHandle::Get()));
   }
 }
 
-void JsonPrefStore::RegisterOnNextWriteSynchronousCallback(
-    const base::Callback<void(bool success)>& on_next_write_callback) {
+void JsonPrefStore::RegisterOnNextWriteSynchronousCallbacks(
+    OnWriteCallbackPair callbacks) {
   DCHECK(CalledOnValidThread());
-  DCHECK(!has_pending_write_callback_);
+  DCHECK(!has_pending_write_callbacks_);
 
-  has_pending_write_callback_ = true;
+  has_pending_write_callbacks_ = true;
 
-  writer_.RegisterOnNextWriteCallback(base::Bind(
-      &PostWriteCallback,
-      base::Bind(&JsonPrefStore::RunOrScheduleNextSuccessfulWriteCallback,
-                 AsWeakPtr()),
-      on_next_write_callback, base::SequencedTaskRunnerHandle::Get()));
+  writer_.RegisterOnNextWriteCallbacks(
+      callbacks.first,
+      base::Bind(
+          &PostWriteCallback,
+          base::Bind(&JsonPrefStore::RunOrScheduleNextSuccessfulWriteCallback,
+                     AsWeakPtr()),
+          callbacks.second, base::SequencedTaskRunnerHandle::Get()));
 }
 
 void JsonPrefStore::ClearMutableValues() {
   NOTIMPLEMENTED();
 }
 
 void JsonPrefStore::OnFileRead(std::unique_ptr<ReadResult> read_result) {
   DCHECK(CalledOnValidThread());
 
   DCHECK(read_result);
@@ skipping 53 matching lines @@
   CommitPendingWrite();
 }
 
 bool JsonPrefStore::SerializeData(std::string* output) {
   DCHECK(CalledOnValidThread());
 
   pending_lossy_write_ = false;
 
   write_count_histogram_.RecordWriteOccured();
 
-  if (pref_filter_)
-    pref_filter_->FilterSerializeData(prefs_.get());
+  if (pref_filter_) {
+    OnWriteCallbackPair callbacks =
+        pref_filter_->FilterSerializeData(prefs_.get());
+    if (!callbacks.first.is_null() || !callbacks.second.is_null())
+      RegisterOnNextWriteSynchronousCallbacks(callbacks);
+  }
 
   JSONStringValueSerializer serializer(output);
   // Not pretty-printing prefs shrinks pref file size by ~30%. To obtain
   // readable prefs for debugging purposes, you can dump your prefs into any
   // command-line or online JSON pretty printing tool.
   serializer.set_pretty_print(false);
   return serializer.Serialize(*prefs_);
 }
 
 void JsonPrefStore::FinalizeFileRead(
@@ skipping 117 matching lines @@
   DCHECK_EQ(31, num_buckets);
 
   // The histogram below is an expansion of the UMA_HISTOGRAM_CUSTOM_COUNTS
   // macro adapted to allow for a dynamically suffixed histogram name.
   // Note: The factory creates and owns the histogram.
   base::HistogramBase* histogram = base::Histogram::FactoryGet(
       histogram_name, min_value, max_value, num_buckets,
       base::HistogramBase::kUmaTargetedHistogramFlag);
   return histogram;
 }