[Sensors] Implement sensor data polling

third_party/WebKit/Source/modules/sensor/SensorProxy.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/SensorProxy.h"
 
 #include "core/frame/LocalFrame.h"
 #include "modules/sensor/SensorProviderProxy.h"
 #include "platform/mojo/MojoHelper.h"
 
 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)
     , m_state(SensorProxy::Uninitialized)
     , m_reading()
 {
 }
 
 SensorProxy::~SensorProxy()
 {
 }
 
 void SensorProxy::dispose()
 {
     m_clientBinding.Close();
 }
 
 DEFINE_TRACE(SensorProxy)
 {
     visitor->trace(m_observers);
     visitor->trace(m_provider);
+    PageVisibilityObserver::trace(visitor);
 }
 
 void SensorProxy::addObserver(Observer* observer)
 {
     if (!m_observers.contains(observer))
         m_observers.add(observer);
 }
 
 void SensorProxy::removeObserver(Observer* observer)
 {
@@ skipping 39 matching lines @@
 {
     handleSensorError();
 }
 
 void SensorProxy::SensorReadingChanged()
 {
     for (Observer* observer : m_observers)
         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;
     m_sensor.reset();
     for (Observer* observer : m_observers)
         observer->onSensorError();
 }
 
 void SensorProxy::onSensorCreated(SensorReadBufferPtr buffer, SensorClientRequest clientRequest)
 {
@@ skipping 18 matching lines @@
         handleSensorError();
         return;
     }
 
     m_state = Initialized;
     for (Observer* observer : m_observers)
         observer->onSensorInitialized();
 }
 
 } // namespace blink