[Sensors] Handle default sensor configuration

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

Index: third_party/WebKit/Source/modules/sensor/Sensor.cpp
diff --git a/third_party/WebKit/Source/modules/sensor/Sensor.cpp b/third_party/WebKit/Source/modules/sensor/Sensor.cpp
index 6269f7162258b4d688ab5b11d14af4e8d0f7f4ac..e76e201911b10621df32d04af66242db8fe05f94 100644
--- a/third_party/WebKit/Source/modules/sensor/Sensor.cpp
+++ b/third_party/WebKit/Source/modules/sensor/Sensor.cpp
@@ -125,15 +125,7 @@ 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()
@@ -199,13 +191,22 @@ void Sensor::startListening()
         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()