Cros: Add nullptr check in CaptivePortalView for WindowTitleForNetwork call

Bug: 1157195
Change-Id: Ic4daf299819b3854a7aef924268c8e698271de69
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2643380
Commit-Queue: Roman Sorokin [CET] <rsorokin@chromium.org>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#846089}

chrome/browser/chromeos/login/ui/captive_portal_view.cc

@@ -23,7 +23,7 @@ const char* CaptivePortalStartURL() {
 }
 
 base::string16 WindowTitleForNetwork(const chromeos::NetworkState* network) {
-  if (!network->name().empty()) {
+  if (network && !network->name().empty()) {
     return l10n_util::GetStringFUTF16(IDS_LOGIN_CAPTIVE_PORTAL_WINDOW_TITLE,
                                       base::ASCIIToUTF16(network->name()));
   } else {