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

chrome/browser/chromeos/login/network_screen.cc

Index: chrome/browser/chromeos/login/network_screen.cc
diff --git a/chrome/browser/chromeos/login/network_screen.cc b/chrome/browser/chromeos/login/network_screen.cc
index 909d4bf04401a9ee7611ebbf5a43a258a425ad0d..f2bf26b854cd2b29b7f7400d93b9435fe35d85b3 100644
--- a/chrome/browser/chromeos/login/network_screen.cc
+++ b/chrome/browser/chromeos/login/network_screen.cc
@@ -37,10 +37,14 @@ NetworkScreen::NetworkScreen(ScreenObserver* 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();
 }
@@ -49,16 +53,19 @@ NetworkScreen::~NetworkScreen() {
 // 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 {
@@ -83,6 +90,11 @@ void NetworkScreen::Refresh() {
 ///////////////////////////////////////////////////////////////////////////////
 // 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()) {
@@ -124,7 +136,7 @@ void NetworkScreen::OnConnectionTimeout() {
   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(
@@ -163,8 +175,10 @@ void NetworkScreen::StopWaitingForConnection(const string16& network_id) {
   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) {
@@ -177,9 +191,10 @@ void NetworkScreen::WaitForConnection(const string16& network_id) {
   }
 
   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