Read characteristic implementation on macOS

device/bluetooth/bluetooth_low_energy_device_mac.h

 // Copyright 2015 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_LOW_ENERGY_DEVICE_MAC_H_
 #define DEVICE_BLUETOOTH_BLUETOOTH_LOW_ENERGY_DEVICE_MAC_H_
 
 #if defined(OS_IOS)
 #import <CoreBluetooth/CoreBluetooth.h>
 #else  // !defined(OS_IOS)
@@ skipping 78 matching lines @@
  protected:
   // BluetoothDevice override.
   std::string GetDeviceName() const override;
   void CreateGattConnectionImpl() override;
   void DisconnectGatt() override;
 
   // Methods used by BluetoothLowEnergyPeripheralBridge.
   void DidDiscoverPrimaryServices(NSError* error);
   void DidModifyServices(NSArray* invalidatedServices);
   void DidDiscoverCharacteristics(CBService* cb_service, NSError* error);
+  void DidUpdateValue(CBCharacteristic* characteristic, NSError* error);
 
   // Updates information about the device.
   virtual void Update(NSDictionary* advertisement_data, int rssi);
 
   static std::string GetPeripheralIdentifier(CBPeripheral* peripheral);
 
   // Hashes and truncates the peripheral identifier to deterministically
   // construct an address. The use of fake addresses is a temporary fix before
   // we switch to using bluetooth identifiers throughout Chrome.
   // http://crbug.com/507824
   static std::string GetPeripheralHashAddress(CBPeripheral* peripheral);
 
  private:
   friend class BluetoothAdapterMac;
   friend class BluetoothAdapterMacTest;
   friend class BluetoothLowEnergyPeripheralBridge;
   friend class BluetoothRemoteGattServiceMac;
   friend class BluetoothTestMac;
+  friend class BluetoothRemoteGattServiceMac;
 
   // Returns the Bluetooth adapter.
   BluetoothAdapterMac* GetMacAdapter();
 
   // Returns the CoreBluetooth Peripheral.
   CBPeripheral* GetPeripheral();
 
   // Returns BluetoothRemoteGattServiceMac based on the CBService.
   BluetoothRemoteGattServiceMac* GetBluetoothRemoteGattService(
       CBService* service) const;
@@ skipping 26 matching lines @@
 
   // The services (identified by UUIDs) that this device provides.
   std::set<BluetoothUUID> advertised_uuids_;
 
   DISALLOW_COPY_AND_ASSIGN(BluetoothLowEnergyDeviceMac);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_LOW_ENERGY_DEVICE_MAC_H_