arc: bluetooth: Always acquire a NotifySession

components/arc/bluetooth/arc_bluetooth_bridge.cc

Index: components/arc/bluetooth/arc_bluetooth_bridge.cc
diff --git a/components/arc/bluetooth/arc_bluetooth_bridge.cc b/components/arc/bluetooth/arc_bluetooth_bridge.cc
index 29b92d8ec94873772774a9f6a54966bd295babc2..897d8cd0d17822e24a3e39bbdc63258508537184 100644
--- a/components/arc/bluetooth/arc_bluetooth_bridge.cc
+++ b/components/arc/bluetooth/arc_bluetooth_bridge.cc
@@ -1099,11 +1099,6 @@ void ArcBluetoothBridge::RegisterForGattNotification(
     return;
   }
 
-  if (characteristic->IsNotifying()) {
-    callback.Run(mojom::BluetoothGattStatus::GATT_SUCCESS);
-    return;
-  }
-
   characteristic->StartNotifySession(

[puthik_chromium, 2016/07/28 22:40:31]

The notifying session is always acquire here.

       base::Bind(&ArcBluetoothBridge::OnGattNotifyStartDone,
                  weak_factory_.GetWeakPtr(), callback,
@@ -1126,12 +1121,16 @@ void ArcBluetoothBridge::DeregisterForGattNotification(
     return;
   }
 
+  std::string char_id_str = characteristic->GetIdentifier();
+
   if (!characteristic->IsNotifying()) {

[ortuno, 2016/07/28 22:56:00]

IsNotifying() will always be true as long as there is a client holding a
NotifySession. If arc has a notify session then this will always be true. The
callback for Stop will always be called so you can just call stop on your notify
session.

[puthik_chromium, 2016/07/28 23:11:12]

Since this is always true. Changed to DCHECK.

     callback.Run(mojom::BluetoothGattStatus::GATT_SUCCESS);
+    LOG(WARNING) << __func__ << ("Notification is stopped");

[ortuno, 2016/07/28 22:21:06]

I don't think this solves the problem. You are still not acquiring a
NotifySession if any other clients e.g. a website, have a NotifySession. Once
other clients drops their sessions notifications will stop.

[puthik_chromium, 2016/07/28 22:40:31]

This is the Deregister function. I think delete the if
(characteristic->IsNotifying()) in Register function above should solve the
problem.

[ortuno, 2016/07/28 22:56:00]

Ah my bad. You are right.

+    if (notification_session_.find(char_id_str) != notification_session_.end())
+      notification_session_.erase(char_id_str);
     return;
   }
 
-  std::string char_id_str = characteristic->GetIdentifier();
   std::unique_ptr<BluetoothGattNotifySession> notify =
       std::move(notification_session_[char_id_str]);
   notification_session_.erase(char_id_str);