[Sensors] Implement sensor data polling

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

Index: third_party/WebKit/Source/modules/sensor/SensorProxy.h
diff --git a/third_party/WebKit/Source/modules/sensor/SensorProxy.h b/third_party/WebKit/Source/modules/sensor/SensorProxy.h
index 401ae29b3f59ff6137304899ebbfe06c1d6a02d8..6c6a931a342b1a9eeebd6c967cad722441a68121 100644
--- a/third_party/WebKit/Source/modules/sensor/SensorProxy.h
+++ b/third_party/WebKit/Source/modules/sensor/SensorProxy.h
@@ -5,6 +5,7 @@
 #ifndef SensorProxy_h
 #define SensorProxy_h
 
+#include "core/page/PageVisibilityObserver.h"
 #include "device/generic_sensor/public/interfaces/sensor.mojom-blink.h"
 #include "device/generic_sensor/public/interfaces/sensor_provider.mojom-blink.h"
 #include "mojo/public/cpp/bindings/binding.h"
@@ -19,7 +20,9 @@ class SensorProviderProxy;
 // JS sensor instances of the same type (within a single frame).
 class SensorProxy final
     : public GarbageCollectedFinalized<SensorProxy>
-    , public device::mojom::blink::SensorClient {
+    , public device::mojom::blink::SensorClient
+    , public PageVisibilityObserver {

[haraken, 2016/09/08 11:07:13]

Sensor is already a PageVisibilityObserver. Can we avoid making SensorProxy a
PageVisibilityObserver?

[Mikhail, 2016/09/08 11:24:48]

Tim raised the same concern at https://codereview.chromium.org/2121313002/. 
Looks like I indeed need to find an alternate solution..

+    USING_GARBAGE_COLLECTED_MIXIN(SensorProxy);
     USING_PRE_FINALIZER(SensorProxy, dispose);
     WTF_MAKE_NONCOPYABLE(SensorProxy);
 public:
@@ -67,12 +70,15 @@ public:
 
 private:
     friend class SensorProviderProxy;
-    SensorProxy(device::mojom::blink::SensorType, SensorProviderProxy*);
+    SensorProxy(device::mojom::blink::SensorType, Page*, SensorProviderProxy*);
 
     // device::mojom::blink::SensorClient overrides.
     void RaiseError() override;
     void SensorReadingChanged() override;
 
+    // PageVisibilityObserver overrides.
+    void pageVisibilityChanged() override;
+
     // Generic handler for a fatal error.
     void handleSensorError();