[CrOS Tether] Disconnect cleanly from active Tether networks when the user logs out or the Tether c…

chrome/browser/chromeos/tether/tether_service.cc

 // Copyright 2017 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.
 
 #include "chrome/browser/chromeos/tether/tether_service.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
@@ skipping 117 matching lines @@
 void TetherService::StopTether() {
   initializer_delegate_->ShutdownTether();
 }
 
 void TetherService::Shutdown() {
   if (shut_down_)
     return;
 
   shut_down_ = true;
 
+  // Remove all observers. This ensures that once Shutdown() is called, no more
+  // calls to UpdateTetherTechnologyState() will be triggered.
   power_manager_client_->RemoveObserver(this);
   session_manager_client_->RemoveObserver(this);
   cryptauth_service_->GetCryptAuthDeviceManager()->RemoveObserver(this);
   network_state_handler_->RemoveObserver(this, FROM_HERE);
   if (adapter_)
     adapter_->RemoveObserver(this);
   registrar_.RemoveAll();
 
-  UpdateTetherTechnologyState();
+  // Shut down the feature. Note that this does not change Tether's technology
+  // state in NetworkStateHandler because doing so could cause visual jank just
+  // as the user logs out.
+  StopTether();
 }
 
 void TetherService::SuspendImminent() {
   suspended_ = true;
   UpdateTetherTechnologyState();
 }
 
 void TetherService::SuspendDone(const base::TimeDelta& sleep_duration) {
   suspended_ = false;
   UpdateTetherTechnologyState();
@@ skipping 128 matching lines @@
 }
 
 bool TetherService::IsEnabledbyPreference() const {
   return profile_->GetPrefs()->GetBoolean(prefs::kInstantTetheringEnabled);
 }
 
 void TetherService::SetInitializerDelegateForTest(
     std::unique_ptr<InitializerDelegate> initializer_delegate) {
   initializer_delegate_ = std::move(initializer_delegate);
 }