Register default accelerometer sensor

Registers a default accelerometer with the Sensors HAL.

Bug: 111070257
Test: Builds, a_sns_test receives accel events
Change-Id: I2f016eb74b9b729854e771264f4c2f1adf025c09
diff --git a/sensors/2.0/default/Sensor.h b/sensors/2.0/default/Sensor.h
index 21ad10d..e467b56 100644
--- a/sensors/2.0/default/Sensor.h
+++ b/sensors/2.0/default/Sensor.h
@@ -66,6 +66,11 @@
     ISensorsEventCallback* mCallback;
 };
 
+class AccelSensor : public Sensor {
+   public:
+    AccelSensor(int32_t sensorHandle, ISensorsEventCallback* callback);
+};
+
 }  // namespace implementation
 }  // namespace V2_0
 }  // namespace sensors