Bluetooth: macOS: Adding logs

device/bluetooth/bluetooth_remote_gatt_characteristic_mac.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 DEVICE_BLUETOOTH_BLUETOOTH_REMOTE_GATT_CHARACTERISTIC_MAC_H_
 #define DEVICE_BLUETOOTH_BLUETOOTH_REMOTE_GATT_CHARACTERISTIC_MAC_H_
 
 #include "device/bluetooth/bluetooth_remote_gatt_characteristic.h"
 
 #include <unordered_map>
@@ skipping 117 matching lines @@
   // Stores SubscribeToNotifications request callbacks.
   PendingNotifyCallbacks subscribe_to_notification_callbacks_;
   // Stores UnsubscribeFromNotifications request callbacks.
   PendingNotifyCallbacks unsubscribe_from_notification_callbacks_;
   // Map of descriptors, keyed by descriptor identifier.
   std::unordered_map<std::string,
                      std::unique_ptr<BluetoothRemoteGattDescriptorMac>>
       gatt_descriptor_macs_;
 };
 
+// Stream operator for logging.
+DEVICE_BLUETOOTH_EXPORT std::ostream& operator<<(
+    std::ostream& out,
+    const BluetoothRemoteGattCharacteristicMac& characteristic);
+
 }  // namespace device
 
 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_REMOTE_GATT_CHARACTERISTIC_MAC_H_