device/bluetooth: Improvements to GATT descriptor access API.

device/bluetooth/bluetooth_gatt_characteristic.h

 // Copyright 2014 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_GATT_CHARACTERISTIC_H_
 #define DEVICE_BLUETOOTH_BLUETOOTH_GATT_CHARACTERISTIC_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 120 matching lines @@
   virtual Properties GetProperties() const = 0;
 
   // Returns the bitmask of characteristic attribute permissions.
   virtual Permissions GetPermissions() const = 0;
 
   // Returns the list of GATT characteristic descriptors that provide more
   // information about this characteristic.
   virtual std::vector<BluetoothGattDescriptor*>
       GetDescriptors() const = 0;
 
+  // Returns the GATT characteristic descriptor with identifier |identifier| if
+  // it belongs to this GATT characteristic.
+  virtual BluetoothGattDescriptor* GetDescriptor(
+      const std::string& identifier) const = 0;
+
   // Adds a characteristic descriptor to the locally hosted characteristic
   // represented by this instance. This method only makes sense for local
   // characteristics and won't have an effect if this instance represents a
   // remote GATT service and will return false. This method takes ownership
   // of |descriptor|.
   virtual bool AddDescriptor(BluetoothGattDescriptor* descriptor) = 0;
 
   // For locally hosted characteristics, updates the characteristic's value.
   // This will update the value that is visible to remote devices and send out
   // any notifications and indications that have been configured. This method
@@ skipping 27 matching lines @@
   BluetoothGattCharacteristic();
   virtual ~BluetoothGattCharacteristic();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BluetoothGattCharacteristic);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_GATT_CHARACTERISTIC_H_