Change AccelerometerReader to a Singleton

chromeos/accelerometer/accelerometer_reader.cc

 // Copyright 2014 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 "chromeos/accelerometer/accelerometer_reader.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
+#include "base/memory/singleton.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/task_runner.h"
 #include "base/task_runner_util.h"
 #include "base/threading/sequenced_worker_pool.h"
 
 namespace chromeos {
 
@@ skipping 154 matching lines @@
     for (int j = 0; j < 3; ++j) {
       scale[i][j] = 0;
       index[i][j] = -1;
     }
   }
 }
 
 AccelerometerReader::ConfigurationData::~ConfigurationData() {
 }
 
-AccelerometerReader::AccelerometerReader()
-    : configuration_(new AccelerometerReader::Configuration()),
-      weak_factory_(this) {
-}
-
-AccelerometerReader::~AccelerometerReader() {
+// static
+AccelerometerReader* AccelerometerReader::GetInstance() {
+  return Singleton<AccelerometerReader,
+                   LeakySingletonTraits<AccelerometerReader>>::get();

[oshima, 2015/01/07 16:39:57]

why this needs to be leaky?

[jonross, 2015/01/12 15:15:46]

As discussed offline this is not necessary. Thanks for the clarification.

I've changed this to use a normal Singleton.

 }
 
 void AccelerometerReader::Initialize(
     scoped_refptr<base::TaskRunner> blocking_task_runner) {
   DCHECK(blocking_task_runner.get());
   task_runner_ = blocking_task_runner;
   // Asynchronously detect and initialize the accelerometer to avoid delaying
   // startup.
   base::PostTaskAndReplyWithResult(
       task_runner_.get(), FROM_HERE,
       base::Bind(&DetectAndReadAccelerometerConfiguration, configuration_),
       base::Bind(&AccelerometerReader::OnInitialized,
                  weak_factory_.GetWeakPtr(), configuration_));
 }
 
 void AccelerometerReader::AddObserver(Observer* observer) {
   observers_.AddObserver(observer);
 }
 
 void AccelerometerReader::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
+AccelerometerReader::AccelerometerReader()
+    : configuration_(new AccelerometerReader::Configuration()),
+      weak_factory_(this) {
+}
+
+AccelerometerReader::~AccelerometerReader() {
+}
+
 void AccelerometerReader::OnInitialized(
     scoped_refptr<AccelerometerReader::Configuration> configuration,
     bool success) {
   if (success)
     TriggerRead();
 }
 
 void AccelerometerReader::TriggerRead() {
   DCHECK(!task_runner_->RunsTasksOnCurrentThread());
 
@@ skipping 32 matching lines @@
 
   // Trigger another read after the current sampling delay.
   base::MessageLoop::current()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&AccelerometerReader::TriggerRead,
                  weak_factory_.GetWeakPtr()),
       base::TimeDelta::FromMilliseconds(kDelayBetweenReadsMs));
 }
 
 }  // namespace chromeos