Additional checks/calls for cases when WebUI may be already gone but OOBE screen instance is not

chrome/browser/chromeos/login/network_screen.cc

 // Copyright (c) 2012 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/login/network_screen.h"
 
 #include "base/logging.h"
 #include "base/string16.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/chromeos/cros/cros_library.h"
@@ skipping 19 matching lines @@
 
 ///////////////////////////////////////////////////////////////////////////////
 // NetworkScreen, public:
 
 NetworkScreen::NetworkScreen(ScreenObserver* screen_observer,
                              NetworkScreenActor* actor)
     : WizardScreen(screen_observer),
       is_network_subscribed_(false),
       continue_pressed_(false),
       actor_(actor) {
-  actor_->SetDelegate(this);
+  DCHECK(actor_);
+  if (actor_)
+    actor_->SetDelegate(this);
 }
 
 NetworkScreen::~NetworkScreen() {
+  if (actor_)
+    actor_->SetDelegate(NULL);
   connection_timer_.Stop();
   UnsubscribeNetworkNotification();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // NetworkScreen, WizardScreen implementation:
 
 void NetworkScreen::PrepareToShow() {
-  actor_->PrepareToShow();
+  if (actor_)
+    actor_->PrepareToShow();
 }
 
 void NetworkScreen::Show() {
-  actor_->Show();
+  if (actor_)
+    actor_->Show();
   Refresh();
 }
 
 void NetworkScreen::Hide() {
-  actor_->Hide();
+  if (actor_)
+    actor_->Hide();
 }
 
 std::string NetworkScreen::GetName() const {
   return WizardController::kNetworkScreenName;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // NetworkScreen, NetworkLibrary::NetworkManagerObserver implementation:
 
 void NetworkScreen::OnNetworkManagerChanged(NetworkLibrary* network_lib) {
   UpdateStatus(network_lib);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // NetworkScreen, public:
 
 void NetworkScreen::Refresh() {
   SubscribeNetworkNotification();
   OnNetworkManagerChanged(chromeos::CrosLibrary::Get()->GetNetworkLibrary());
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // NetworkScreen, NetworkScreenActor::Delegate implementation:
 
+void NetworkScreen::OnActorDestroyed(NetworkScreenActor* actor) {
+  if (actor_ == actor)
+    actor_ = NULL;
+}
+
 void NetworkScreen::OnContinuePressed() {
   NetworkLibrary* network = CrosLibrary::Get()->GetNetworkLibrary();
   if (network && network->Connected()) {
     NotifyOnConnection();
   } else {
     continue_pressed_ = true;
     WaitForConnection(network_id_);
   }
 }
 
@@ skipping 21 matching lines @@
   UnsubscribeNetworkNotification();
   connection_timer_.Stop();
   get_screen_observer()->OnExit(ScreenObserver::NETWORK_CONNECTED);
 }
 
 void NetworkScreen::OnConnectionTimeout() {
   StopWaitingForConnection(network_id_);
   NetworkLibrary* network = CrosLibrary::Get()->GetNetworkLibrary();
   bool is_connected = network && network->Connected();
 
-  if (!is_connected) {
+  if (!is_connected && actor_) {
     // Show error bubble.
     actor_->ShowError(
         l10n_util::GetStringFUTF16(
             IDS_NETWORK_SELECTION_ERROR,
             l10n_util::GetStringUTF16(IDS_SHORT_PRODUCT_OS_NAME),
             network_id_));
   }
 }
 
 void NetworkScreen::UpdateStatus(NetworkLibrary* network) {
@@ skipping 18 matching lines @@
   bool is_connected = network && network->Connected();
   if (is_connected && continue_pressed_) {
     NotifyOnConnection();
     return;
   }
 
   continue_pressed_ = false;
   connection_timer_.Stop();
 
   network_id_ = network_id;
-  actor_->ShowConnectingStatus(false, network_id_);
-  actor_->EnableContinue(is_connected);
+  if (actor_) {
+    actor_->ShowConnectingStatus(false, network_id_);
+    actor_->EnableContinue(is_connected);
+  }
 }
 
 void NetworkScreen::WaitForConnection(const string16& network_id) {
   if (network_id_ != network_id || !connection_timer_.IsRunning()) {
     connection_timer_.Stop();
     connection_timer_.Start(FROM_HERE,
                             base::TimeDelta::FromSeconds(kConnectionTimeoutSec),
                             this,
                             &NetworkScreen::OnConnectionTimeout);
   }
 
   network_id_ = network_id;
-  actor_->ShowConnectingStatus(continue_pressed_, network_id_);
-
-  actor_->EnableContinue(false);
+  if (actor_) {
+    actor_->ShowConnectingStatus(continue_pressed_, network_id_);
+    actor_->EnableContinue(false);
+  }
 }
 
 }  // namespace chromeos