[sensors] Ambient light sensor bindings implementation

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

Index: third_party/WebKit/Source/modules/sensor/SensorReading.cpp
diff --git a/third_party/WebKit/Source/modules/sensor/SensorReading.cpp b/third_party/WebKit/Source/modules/sensor/SensorReading.cpp
index 12c14881bc9af7be3a74f93e364ea500abd8c641..dddf6cd4c4b2fea8334a9413e471ea216c46c846 100644
--- a/third_party/WebKit/Source/modules/sensor/SensorReading.cpp
+++ b/third_party/WebKit/Source/modules/sensor/SensorReading.cpp
@@ -14,7 +14,6 @@ namespace blink {
 SensorReading::SensorReading(SensorProxy* sensorProxy)
     : m_sensorProxy(sensorProxy)
 {
-    DCHECK(m_sensorProxy);
 }
 
 DEFINE_TRACE(SensorReading)
@@ -22,6 +21,13 @@ DEFINE_TRACE(SensorReading)
     visitor->trace(m_sensorProxy);
 }
 
+SensorReading::~SensorReading() = default;
+
+bool SensorReading::isReadingUpdated(const SensorProxy::Reading& previous) const
+{
+    return false;
+}
+
 DOMHighResTimeStamp SensorReading::timeStamp(ScriptState* scriptState) const
 {
     LocalDOMWindow* window = scriptState->domWindow();
@@ -31,6 +37,9 @@ DOMHighResTimeStamp SensorReading::timeStamp(ScriptState* scriptState) const
     Performance* performance = DOMWindowPerformance::performance(*window);
     DCHECK(performance);
 
+    if (!m_sensorProxy)
+        return performance->now();
+
     return performance->monotonicTimeToDOMHighResTimeStamp(m_sensorProxy->reading().timestamp);
 }