[Sensors] Implement sensor data polling

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

Index: third_party/WebKit/Source/modules/sensor/SensorProxy.cpp
diff --git a/third_party/WebKit/Source/modules/sensor/SensorProxy.cpp b/third_party/WebKit/Source/modules/sensor/SensorProxy.cpp
index 7b84ebc67fd698dda12789e0dae0914b0348f5b0..c2d3edc23efeaa470a7eb8c46722fc11f80bcb8c 100644
--- a/third_party/WebKit/Source/modules/sensor/SensorProxy.cpp
+++ b/third_party/WebKit/Source/modules/sensor/SensorProxy.cpp
@@ -12,8 +12,9 @@ using namespace device::mojom::blink;
 
 namespace blink {
 
-SensorProxy::SensorProxy(SensorType sensorType, SensorProviderProxy* provider)
-    : m_type(sensorType)
+SensorProxy::SensorProxy(SensorType sensorType, Page* page, SensorProviderProxy* provider)
+    : PageVisibilityObserver(page)
+    , m_type(sensorType)
     , m_mode(ReportingMode::CONTINUOUS)
     , m_provider(provider)
     , m_clientBinding(this)
@@ -35,6 +36,7 @@ DEFINE_TRACE(SensorProxy)
 {
     visitor->trace(m_observers);
     visitor->trace(m_provider);
+    PageVisibilityObserver::trace(visitor);
 }
 
 void SensorProxy::addObserver(Observer* observer)
@@ -94,6 +96,18 @@ void SensorProxy::SensorReadingChanged()
         observer->onSensorReadingChanged();
 }
 
+void SensorProxy::pageVisibilityChanged()
+{
+    if (!isInitialized())
+        return;
+
+    if (page()->visibilityState() != PageVisibilityStateVisible) {
+        m_sensor->Suspend();
+    } else {
+        m_sensor->Resume();
+    }
+}
+
 void SensorProxy::handleSensorError()
 {
     m_state = Uninitialized;