arc: bluetooth: Implement Gatt notify

components/arc/common/bluetooth.mojom

 // 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.
 
 module arc.mojom;
 
 [Extensible]
 enum BluetoothAdapterState {
   OFF = 0,
   ON
@@ skipping 303 matching lines @@
                                              bool connected);
   [MinVersion=1] OnSearchComplete@9(BluetoothAddress remote_addr,
                                     BluetoothGattStatus status);
   [MinVersion=1] OnGetGattDB@10(BluetoothAddress remote_addr,
                                 array<BluetoothGattDBElement> db);
   [MinVersion=1] OnServicesRemoved@11(BluetoothAddress remote_addr,
                                       uint16 start_handle,
                                       uint16 end_handle);
   [MinVersion=1] OnServicesAdded@12(BluetoothAddress remote_addr,
                                     array<BluetoothGattDBElement> db);
+  [MinVersion=2] OnGattNotify@13(BluetoothAddress remote_addr,
+                                 BluetoothGattServiceID service_id,
+                                 BluetoothGattID char_id,
+                                 bool is_notify,

[ortuno, 2016/06/21 23:23:06]

What purpose does is_notify serve? When is it true and when is it false?

It makes me really sad that there is not a single comment in all these
functions. This code is going to be really hard to maintain...

[puthik_chromium, 2016/06/23 02:53:34]

It's map to is_notify in here. It should be true for notify and false for
indicate. Now it is always true.
[1]
https://source.android.com/devices/halref/structbtgatt__notify__params__t.html

[ortuno, 2016/06/23 14:29:38]

I see. Does this have to match the android implementation? Otherwise I would use
an enum. We usually only use bools if the variable actually means false.

[puthik_chromium, 2016/06/23 18:36:30]

I would prefer to match it to android. It will make life easier when we need to
upgrade to Android N

+                                 array<uint8> value);
 };