oobe: Check view in destructor before screen unbinding.

Fixed: 1136386
Change-Id: I9f6bf45c94fb8b26e05ecff5a5304e9eef857e81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2552396
Commit-Queue: Roman Aleksandrov <raleksandrov@google.com>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#830244}

chrome/browser/chromeos/login/screens/app_downloading_screen.cc

@@ -28,7 +28,8 @@ AppDownloadingScreen::AppDownloadingScreen(
 }
 
 AppDownloadingScreen::~AppDownloadingScreen() {
-  view_->Bind(nullptr);
+  if (view_)
+    view_->Bind(nullptr);
 }
 
 void AppDownloadingScreen::ShowImpl() {

chrome/browser/chromeos/login/screens/fingerprint_setup_screen.cc

@@ -112,7 +112,8 @@ FingerprintSetupScreen::FingerprintSetupScreen(
 }
 
 FingerprintSetupScreen::~FingerprintSetupScreen() {
-  view_->Bind(nullptr);
+  if (view_)
+    view_->Bind(nullptr);
 }
 
 bool FingerprintSetupScreen::MaybeSkip(WizardContext* context) {

chrome/browser/chromeos/login/screens/marketing_opt_in_screen.cc

@@ -97,7 +97,8 @@ MarketingOptInScreen::MarketingOptInScreen(
 }
 
 MarketingOptInScreen::~MarketingOptInScreen() {
-  view_->Bind(nullptr);
+  if (view_)
+    view_->Bind(nullptr);
 }
 
 bool MarketingOptInScreen::MaybeSkip(WizardContext* context) {

chrome/browser/chromeos/login/screens/pin_setup_screen.cc

@@ -57,7 +57,8 @@ PinSetupScreen::PinSetupScreen(PinSetupScreenView* view,
 }
 
 PinSetupScreen::~PinSetupScreen() {
-  view_->Bind(nullptr);
+  if (view_)
+    view_->Bind(nullptr);
 }
 
 bool PinSetupScreen::MaybeSkip(WizardContext* context) {

chrome/browser/chromeos/login/screens/sync_consent_screen.cc

@@ -101,7 +101,8 @@ SyncConsentScreen::SyncConsentScreen(SyncConsentScreenView* view,
 }
 
 SyncConsentScreen::~SyncConsentScreen() {
-  view_->Bind(NULL);
+  if (view_)
+    view_->Bind(nullptr);
 }
 
 void SyncConsentScreen::Init() {