[Sensors] Handle default sensor configuration

third_party/WebKit/Source/modules/sensor/Sensor.cpp

 // 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 "modules/sensor/Sensor.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "device/generic_sensor/public/interfaces/sensor.mojom-blink.h"
 #include "modules/sensor/SensorErrorEvent.h"
@@ skipping 107 matching lines @@
 {
     if (m_state == Sensor::SensorState::ACTIVE || m_state == Sensor::SensorState::ACTIVATING)
         stopListening();
 }
 
 void Sensor::onSensorInitialized()
 {
     if (m_state != Sensor::SensorState::ACTIVATING)
         return;
 
-    m_configuration = createSensorConfig(m_sensorOptions);
-    if (!m_configuration) {
-        reportError();
-        return;
-    }
-
-    DCHECK(m_sensorProxy);
-    auto startCallback = WTF::bind(&Sensor::onStartRequestCompleted, wrapWeakPersistent(this));
-    m_sensorProxy->addConfiguration(m_configuration->Clone(), std::move(startCallback));
+    startListening();
 }
 
 void Sensor::onSensorReadingChanged()
 {
     if (m_polling)
         m_polling->onSensorReadingChanged();
 }
 
 void Sensor::onSensorError()
 {
@@ skipping 45 matching lines @@
 }
 
 void Sensor::startListening()
 {
     DCHECK(m_sensorProxy);
     updateState(Sensor::SensorState::ACTIVATING);
     if (!m_sensorReading)
         m_sensorReading = createSensorReading(m_sensorProxy);
 
     m_sensorProxy->addObserver(this);
-    if (m_sensorProxy->isInitialized()) {
-        auto callback = WTF::bind(&Sensor::onStartRequestCompleted, wrapWeakPersistent(this));
-        DCHECK(m_configuration);
-        m_sensorProxy->addConfiguration(m_configuration->Clone(), std::move(callback));
-    } else {
+    if (!m_sensorProxy->isInitialized()) {
         m_sensorProxy->initialize();
+        return;
     }
+
+    if (!m_configuration) {
+        DCHECK(m_sensorProxy->defaultConfig());

[timvolodine, 2016/09/12 16:37:08]

should this check be in sensorProxy itself, perhaps when the defaultConfig is
first obtained?
i.e. this should probably automatically hold when proxy is in 'initialized'
state (independent of whether m_configuration is null or not)

[Mikhail, 2016/09/12 17:08:10]

right, the DCHECK can be omitted I just put it to underline the fact that
default config != nullptr here.

+        m_configuration = createSensorConfig(m_sensorOptions, *m_sensorProxy->defaultConfig());
+        if (!m_configuration) { // Failed to create configuration.

[timvolodine, 2016/09/12 16:37:08]

when can this happen? maybe just DCHECK here?

[Mikhail, 2016/09/12 17:08:10]

can be DCHECK() (given options checks can/should be done in ctor)

+            reportError();
+            return;
+        }
+    }
+
+    auto startCallback = WTF::bind(&Sensor::onStartRequestCompleted, wrapWeakPersistent(this));
+    m_sensorProxy->addConfiguration(m_configuration->Clone(), std::move(startCallback));
 }
 
 void Sensor::stopListening()
 {
     DCHECK(m_sensorProxy);
     m_sensorReading = nullptr;
     updateState(Sensor::SensorState::IDLE);
 
     if (m_sensorProxy->isInitialized()) {
         auto callback = WTF::bind(&Sensor::onStopRequestCompleted, wrapWeakPersistent(this));
@@ skipping 45 matching lines @@
 
     if (m_state != Sensor::SensorState::ACTIVE
         || page()->visibilityState() != PageVisibilityStateVisible) {
         m_polling->stopPolling();
     } else {
         m_polling->startPolling();
     }
 }
 
 } // namespace blink