[Sensors] Fix reading updates after page refresh

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 "core/dom/ExecutionContextTask.h"
 #include "core/dom/TaskRunnerHelper.h"
@@ skipping 52 matching lines @@
 
 void Sensor::start(ScriptState* scriptState, ExceptionState& exceptionState) {
   if (m_state != Sensor::SensorState::Idle &&
       m_state != Sensor::SensorState::Errored) {
     exceptionState.throwDOMException(
         InvalidStateError,
         "Cannot start because SensorState is not Idle or errored");
     return;
   }
 
   initSensorProxyIfNeeded();

[shalamov, 2017/01/20 09:25:32]

Should we pass / use execution context of a start() call in
initSensorProxyIfNeeded()? At the moment we use context that was provided in the
constructor.

[Mikhail, 2017/01/24 12:00:18]

Does it make any practical change? haraken@, wdyt?

 
   if (!m_sensorProxy) {
     exceptionState.throwDOMException(
         InvalidStateError, "The Sensor is no longer associated to a frame.");
     return;
   }
   m_lastUpdateTimestamp = WTF::monotonicallyIncreasingTime();
   startListening();
 }
 
@@ skipping 73 matching lines @@
     return;
 
   Document* document = toDocument(getExecutionContext());
   if (!document || !document->frame())
     return;
 
   auto provider = SensorProviderProxy::from(document->frame());
   m_sensorProxy = provider->getSensorProxy(m_type);
 
   if (!m_sensorProxy) {
-    m_sensorProxy = provider->createSensorProxy(m_type, document,
+    m_sensorProxy = provider->createSensorProxy(m_type, document->page(),

[shalamov, 2017/01/20 09:25:32]

should we throw "InvalidStateError" if context is no longer associated with a
page (page is null)?

[Mikhail, 2017/01/24 12:00:18]

page is used only in PageVisibilityObserver which can contain nullptr

                                                 createSensorReadingFactory());
   }
 }
 
 void Sensor::contextDestroyed(ExecutionContext*) {
   if (m_state == Sensor::SensorState::Activated ||
       m_state == Sensor::SensorState::Activating)
     stopListening();
 }
 
@@ skipping 116 matching lines @@
 void Sensor::notifyOnActivate() {
   dispatchEvent(Event::create(EventTypeNames::activate));
 }
 
 void Sensor::notifyError(DOMException* error) {
   dispatchEvent(
       SensorErrorEvent::create(EventTypeNames::error, std::move(error)));
 }
 
 }  // namespace blink