Fix getting notified twice after subscribe to notifications and call readValue

device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm

Index: device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm
diff --git a/device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm b/device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm
index ae72118130f9cf810262344aa18969c4421c809d..c5d7c256befb2cb675fd15bf1239ac6f1bd33331 100644
--- a/device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm
+++ b/device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm
@@ -257,7 +257,6 @@ void BluetoothRemoteGattCharacteristicMac::DidUpdateValue(NSError* error) {
       callbacks.second.Run(error_code);
       return;
     }
-    UpdateValueAndNotify();

[ortuno, 2017/03/03 05:28:37]

Ah good old mac. There are actually no bots on the CQ that run our tests so we
need to run them manually for mac.  I believe this change will break a couple of
tests. More specifically the UpdateValueAndNotify() function does two things:

1. Updates value_
2. Send the event

Since we are no longer calling this function value_ is never updated.

[juncai, 2017/03/04 01:33:59]

Yes, it does break some device unit tests on Mac. Fixed it.

Done.

     callbacks.first.Run(value_);
   } else if (IsNotifying()) {
     UpdateValueAndNotify();