[sensors] [win] Fix ambient light not working properly Windows 10.

device/generic_sensor/platform_sensor_reader_win.cc

Index: device/generic_sensor/platform_sensor_reader_win.cc
diff --git a/device/generic_sensor/platform_sensor_reader_win.cc b/device/generic_sensor/platform_sensor_reader_win.cc
index 7f292b1fb2a197de00216dad2075d5a865c44c2b..f1a9eebd37365658937d81a5052751aa1e8bfdca 100644
--- a/device/generic_sensor/platform_sensor_reader_win.cc
+++ b/device/generic_sensor/platform_sensor_reader_win.cc
@@ -242,7 +242,8 @@ PlatformSensorReaderWin::PlatformSensorReaderWin(
       sensor_active_(false),
       client_(nullptr),
       sensor_(sensor),
-      event_listener_(new EventListener(this)) {
+      event_listener_(new EventListener(this)),
+      weak_factory_(this) {
   DCHECK(init_params_);
   DCHECK(!init_params_->reader_func.is_null());
   DCHECK(sensor_);
@@ -273,24 +274,26 @@ bool PlatformSensorReaderWin::StartSensor(
   if (!SetReportingInterval(configuration))
     return false;
 
-  // Set event listener.
   if (!sensor_active_) {
-    base::win::ScopedComPtr<ISensorEvents> sensor_events;
-    HRESULT hr = event_listener_->QueryInterface(__uuidof(ISensorEvents),
-                                                 sensor_events.ReceiveVoid());
-
-    if (FAILED(hr) || !sensor_events)
-      return false;
-
-    if (FAILED(sensor_->SetEventSink(sensor_events.get())))
-      return false;
-
-    sensor_active_ = true;
+    task_runner_->PostTask(
+        FROM_HERE, base::Bind(&PlatformSensorReaderWin::ListenSensorEvent,
+                              weak_factory_.GetWeakPtr()));
   }
 
   return true;
 }
 
+void PlatformSensorReaderWin::ListenSensorEvent() {
+  base::AutoLock autolock(lock_);

[shalamov, 2016/11/15 07:31:19]

If it is accessed only on sensor thread, I think you can remove lock.

+  event_listener_->AddRef();
+  // Set event listener.
+  if (FAILED(sensor_->SetEventSink(event_listener_.get()))) {
+    SensorError();
+    StopSensor();
+  }
+  sensor_active_ = true;

[shalamov, 2016/11/15 07:31:19]

Should this be moved to:

if (!sensor_active_) {
  postTask();
  sensor_active_ = true;
}

then, 

if (FAILED(...)) {
  ...
  sensor_active_ = false;
}

Otherwise, we can post multiple tasks for ListenSensorEvent()

+}
+
 bool PlatformSensorReaderWin::SetReportingInterval(
     const PlatformSensorConfiguration& configuration) {
   base::win::ScopedComPtr<IPortableDeviceValues> props;