Add |notify_client_on_reading_change| flag to sensor configuration

device/generic_sensor/sensor_impl.cc

 // 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.
 
 #include "device/generic_sensor/sensor_impl.h"
 
 #include <utility>
 
 #include "mojo/public/cpp/bindings/strong_binding.h"
 
 namespace device {
 
 SensorImpl::SensorImpl(scoped_refptr<PlatformSensor> sensor)
-    : sensor_(std::move(sensor)), suspended_(false) {
+    : sensor_(std::move(sensor)),
+      suspended_(false),
+      suppress_on_change_events_count_(0) {
   sensor_->AddClient(this);
 }
 
 SensorImpl::~SensorImpl() {
   sensor_->RemoveClient(this);
 }
 
 mojom::SensorClientRequest SensorImpl::GetClient() {
   return mojo::MakeRequest(&client_);
 }
 
 void SensorImpl::AddConfiguration(
     const PlatformSensorConfiguration& configuration,
     AddConfigurationCallback callback) {
   // TODO(Mikhail): To avoid overflowing browser by repeated AddConfigs
   // (maybe limit the number of configs per client).
-  std::move(callback).Run(sensor_->StartListening(this, configuration));
+  bool success = sensor_->StartListening(this, configuration);
+  if (success && configuration.suppress_on_change_events())
+    ++suppress_on_change_events_count_;
+  std::move(callback).Run(success);
 }
 
 void SensorImpl::GetDefaultConfiguration(
     GetDefaultConfigurationCallback callback) {
   std::move(callback).Run(sensor_->GetDefaultConfiguration());
 }
 
 void SensorImpl::RemoveConfiguration(
     const PlatformSensorConfiguration& configuration,
     RemoveConfigurationCallback callback) {
-  std::move(callback).Run(sensor_->StopListening(this, configuration));
+  bool success = sensor_->StopListening(this, configuration);
+  if (success && configuration.suppress_on_change_events())
+    --suppress_on_change_events_count_;
+  std::move(callback).Run(success);
 }
 
 void SensorImpl::Suspend() {
   suspended_ = true;
   sensor_->UpdateSensor();
 }
 
 void SensorImpl::Resume() {
   suspended_ = false;
   sensor_->UpdateSensor();
 }
 
 void SensorImpl::OnSensorReadingChanged() {
   DCHECK(!suspended_);
-  if (client_)
+  if (client_ && suppress_on_change_events_count_ == 0)
     client_->SensorReadingChanged();
 }
 
 void SensorImpl::OnSensorError() {
   DCHECK(!suspended_);
   if (client_)
     client_->RaiseError();
 }
 
 bool SensorImpl::IsNotificationSuspended() {
   return suspended_;
 }
 
 }  // namespace device