[CrOS Tether] Create ble_constants.h/cc, which include common constants to be shared among multiple…

chromeos/components/tether/ble_constants.h

+// Copyright 2016 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.
+
+#ifndef CHROMEOS_COMPONENTS_TETHER_BLE_CONSTANTS_H_
+#define CHROMEOS_COMPONENTS_TETHER_BLE_CONSTANTS_H_
+
+#include <string>
+
+namespace chromeos {
+
+namespace tether {
+
+// The maximum number of devices to which to advertise concurrently. If more
+// than this number of devices are registered, other advertisements must be
+// stopped before new ones can be added.
+//
+// Note that this upper limit on concurrent advertisements is imposed due to a
+// hardware limit of advertisements (many devices have <10 total advertisement
+// slots).
+extern const int kMaxConcurrentAdvertisements;
+
+// The service UUID used for BLE advertisements.
+extern const char kAdvertisingServiceUuid[];
+
+}  // namespace tether
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_COMPONENTS_TETHER_BLE_CONSTANTS_H_