bluetooth: mac: Initial BluetoothRemoteGattCharacteristicMac implementation

device/bluetooth/bluetooth_low_energy_device_mac.h

Index: device/bluetooth/bluetooth_low_energy_device_mac.h
diff --git a/device/bluetooth/bluetooth_low_energy_device_mac.h b/device/bluetooth/bluetooth_low_energy_device_mac.h
index c5e24b166a9ac59bf989c859daa9c454c1e890dd..9b972ba59f23fc02fcf74277e72717b1d2f8c01a 100644
--- a/device/bluetooth/bluetooth_low_energy_device_mac.h
+++ b/device/bluetooth/bluetooth_low_energy_device_mac.h
@@ -95,6 +95,7 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothLowEnergyDeviceMac
   // Methods used by BluetoothLowEnergyPeripheralBridge.
   void DidDiscoverPrimaryServices(NSError* error);
   void DidModifyServices(NSArray* invalidatedServices);
+  void DidDiscoverCharacteristics(CBService* cb_service, NSError* error);
 
   // Updates information about the device.
   virtual void Update(NSDictionary* advertisement_data, int rssi);
@@ -111,6 +112,7 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothLowEnergyDeviceMac
   friend class BluetoothAdapterMac;
   friend class BluetoothAdapterMacTest;
   friend class BluetoothLowEnergyPeripheralBridge;
+  friend class BluetoothRemoteGattServiceMac;
   friend class BluetoothTestMac;
 
   // Returns the Bluetooth adapter.