[reland] Add a default task runner argument to the constructor of JsonPrefStore.

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>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram.h"
 #include "base/sequenced_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/task_runner_util.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/time/default_clock.h"
 #include "base/values.h"
 #include "components/prefs/pref_filter.h"

[gab, 2017/05/15 16:33:20]

rm

 
 // Result returned from internal read tasks.
 struct JsonPrefStore::ReadResult {
  public:
   ReadResult();
   ~ReadResult();
 
   std::unique_ptr<base::Value> value;
   PrefReadError error;
   bool no_dir;
@@ skipping 96 matching lines @@
     base::SequencedWorkerPool* worker_pool) {
   std::string token("json_pref_store-");
   token.append(filename.AsUTF8Unsafe());
   return worker_pool->GetSequencedTaskRunnerWithShutdownBehavior(
       worker_pool->GetNamedSequenceToken(token),
       base::SequencedWorkerPool::BLOCK_SHUTDOWN);
 }
 
 JsonPrefStore::JsonPrefStore(
     const base::FilePath& pref_filename,
-    const scoped_refptr<base::SequencedTaskRunner>& sequenced_task_runner,
+    scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner,
     std::unique_ptr<PrefFilter> pref_filter)
     : path_(pref_filename),
-      sequenced_task_runner_(sequenced_task_runner),
+      sequenced_task_runner_(std::move(sequenced_task_runner)),
       prefs_(new base::DictionaryValue()),
       read_only_(false),
-      writer_(pref_filename, sequenced_task_runner),
+      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_write_reply_(false),
       write_count_histogram_(writer_.commit_interval(), path_) {
   DCHECK(!path_.empty());
 }
 
@@ skipping 422 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;
 }