Fixing a crash in ProximityAuthBleSystem.

This CL fixes a bug causing crashes in
proximity_auth::ProximityAuthBleSystem:

- BluetoothLowEnergyConnection::Disconnect() should only change its
status to DISCONNECTED after performing all operations. Otherwise, it
will trigger a notification to its observers, which may then destroy the
instance, causing a crash when |BluetoothLowEnergyConnection::Disconnect()|
resume executing.

BUG=506196

Review URL: https://codereview.chromium.org/1222563002

Cr-Commit-Position: refs/heads/master@{#337586}

1 files changed, 4 insertions, 1 deletions

diff --git a/components/proximity_auth/ble/bluetooth_low_energy_connection.cc b/components/proximity_auth/ble/bluetooth_low_energy_connection.cc
index 550cbf2..a6d732a 100644
--- a/components/proximity_auth/ble/bluetooth_low_energy_connection.cc
+++ b/components/proximity_auth/ble/bluetooth_low_energy_connection.cc
@@ -96,7 +96,6 @@ void BluetoothLowEnergyConnection::Disconnect() {
   if (sub_status_ != SubStatus::DISCONNECTED) {
     ClearWriteRequestsQueue();
     StopNotifySession();
-    SetSubStatus(SubStatus::DISCONNECTED);
     if (gatt_connection_) {
       PA_LOG(INFO) << "Disconnect from device "
                    << gatt_connection_->GetDeviceAddress();
@@ -104,6 +103,10 @@ void BluetoothLowEnergyConnection::Disconnect() {
       // Destroying BluetoothGattConnection also disconnects it.
       gatt_connection_.reset();
     }
+    // Only transition to the DISCONNECTED state after perfoming all necessary
+    // operations. Otherwise, it'll trigger observers that can pontentially
+    // destroy the current instance (causing a crash).
+    SetSubStatus(SubStatus::DISCONNECTED);
   }
 }