Add RELATIVE_ORIENTATION sensor implementation on macOS to //device/generic_sensor

device/generic_sensor/relative_orientation_fusion_algorithm.cc

Index: device/generic_sensor/relative_orientation_fusion_algorithm.cc
diff --git a/device/generic_sensor/relative_orientation_fusion_algorithm.cc b/device/generic_sensor/relative_orientation_fusion_algorithm.cc
new file mode 100644
index 0000000000000000000000000000000000000000..10da8ba60c7722712b1239065159107a571a3909
--- /dev/null
+++ b/device/generic_sensor/relative_orientation_fusion_algorithm.cc
@@ -0,0 +1,13 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "device/generic_sensor/relative_orientation_fusion_algorithm.h"
+
+namespace device {
+
+RelativeOrientationFusionAlgorithm::RelativeOrientationFusionAlgorithm() {}
+
+RelativeOrientationFusionAlgorithm::~RelativeOrientationFusionAlgorithm() {}
+
+}  // namespace device