bluetooth: android: Implement Characteristic GetIdentifier, fix Service IDs too.

device/bluetooth/bluetooth_gatt_characteristic.h

Index: device/bluetooth/bluetooth_gatt_characteristic.h
diff --git a/device/bluetooth/bluetooth_gatt_characteristic.h b/device/bluetooth/bluetooth_gatt_characteristic.h
index f3a36e8928e58226c89036c7711a483985833c28..91d753f4d7dd172a78b96d7185db9d34934f23b7 100644
--- a/device/bluetooth/bluetooth_gatt_characteristic.h
+++ b/device/bluetooth/bluetooth_gatt_characteristic.h
@@ -117,8 +117,8 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothGattCharacteristic {
   // Identifier used to uniquely identify a GATT characteristic object. This is
   // different from the characteristic UUID: while multiple characteristics with
   // the same UUID can exist on a Bluetooth device, the identifier returned from
-  // this method is unique among all characteristics of a device. The contents
-  // of the identifier are platform specific.
+  // this method is unique among all characteristics on the adapter. The
+  // contents of the identifier are platform specific.
   virtual std::string GetIdentifier() const = 0;
 
   // The Bluetooth-specific UUID of the characteristic.