Fix getting notified twice after subscribe to notifications and call readValue

device/bluetooth/bluez/bluetooth_remote_gatt_characteristic_bluez.cc

Index: device/bluetooth/bluez/bluetooth_remote_gatt_characteristic_bluez.cc
diff --git a/device/bluetooth/bluez/bluetooth_remote_gatt_characteristic_bluez.cc b/device/bluetooth/bluez/bluetooth_remote_gatt_characteristic_bluez.cc
index ce386daaa9a9019601770fc70ccdc2500d9a4f0c..5359b075d29813e90425e0c27d4ed872d0c4c0a8 100644
--- a/device/bluetooth/bluez/bluetooth_remote_gatt_characteristic_bluez.cc
+++ b/device/bluetooth/bluez/bluetooth_remote_gatt_characteristic_bluez.cc
@@ -45,6 +45,7 @@ BluetoothRemoteGattCharacteristicBlueZ::BluetoothRemoteGattCharacteristicBlueZ(
     : BluetoothGattCharacteristicBlueZ(object_path),
       has_notify_session_(false),
       service_(service),
+      characteristic_value_read_in_progress_(false),
       weak_ptr_factory_(this) {
   VLOG(1) << "Creating remote GATT characteristic with identifier: "
           << GetIdentifier() << ", UUID: " << GetUUID().canonical_value();
@@ -184,6 +185,8 @@ void BluetoothRemoteGattCharacteristicBlueZ::ReadRemoteCharacteristic(
           << GetIdentifier() << ", UUID: " << GetUUID().canonical_value()
           << ".";
 
+  characteristic_value_read_in_progress_ = true;

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

If the read fails then this never goes back to false. Could you write or update
current tests to make sure we are doing the right thing?

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

Done.

+
   bluez::BluezDBusManager::Get()
       ->GetBluetoothGattCharacteristicClient()
       ->ReadValue(object_path(), callback,