Implement create attribute API functions for BTLE.

device/bluetooth/bluetooth_local_gatt_service.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_LOCAL_GATT_SERVICE_H_
 #define DEVICE_BLUETOOTH_BLUETOOTH_LOCAL_GATT_SERVICE_H_
 
 #include <stdint.h>
 #include <vector>
 
@@ skipping 132 matching lines @@
   // all of its associated attributes available on the local adapters GATT
   // database. Call Unregister to make this service no longer available.
   virtual void Register(const base::Closure& callback,
                         const ErrorCallback& error_callback) = 0;
 
   // Unregisters this GATT service. This will remove the service from the list
   // of services exposed by the adapter this service was registered on.
   virtual void Unregister(const base::Closure& callback,
                           const ErrorCallback& error_callback) = 0;
 
+  virtual BluetoothLocalGattCharacteristic* GetCharacteristic(
+      const std::string& identifier) = 0;
+
  protected:
   BluetoothLocalGattService();
   ~BluetoothLocalGattService() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BluetoothLocalGattService);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_LOCAL_GATT_SERVICE_H_