Enable wakeup sensors.

SensorService should hold a wakelock till the app reads events from a wakeup sensor. Currently drivers hold a wakelock with a
timeout while delivering events from a wake up sensor like Significant Motion. This hack can be removed now.

Bug: 9774884
Change-Id: If3b5acb99c9cf0cd29012fcfa9d6b04c74133d01
diff --git a/libs/gui/SensorEventQueue.cpp b/libs/gui/SensorEventQueue.cpp
index c365671..c2eaf4e 100644
--- a/libs/gui/SensorEventQueue.cpp
+++ b/libs/gui/SensorEventQueue.cpp
@@ -144,6 +144,15 @@
     return mSensorEventConnection->setEventRate(sensor->getHandle(), ns);
 }
 
+void SensorEventQueue::sendAck(const ASensorEvent* events, int count) {
+    for (int i = 0; i < count; ++i) {
+        if (events[i].flags & WAKE_UP_SENSOR_EVENT_NEEDS_ACK) {
+            mSensorEventConnection->decreaseWakeLockRefCount();
+        }
+    }
+    return;
+}
+
 // ----------------------------------------------------------------------------
 }; // namespace android