crostini: Fix crash in guest user session

Bug: 836187
Change-Id: Id072e00ca0d6e4f278a43f34deea6880d2aa0536
Reviewed-on: https://chromium-review.googlesource.com/1026039Reviewed-by: Timothy Loh <timloh@chromium.org>
Reviewed-by: Jenny Zhang <jennyz@chromium.org>
Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553694}

chrome/browser/ui/ash/launcher/launcher_context_menu.cc

@@ -43,9 +43,11 @@ std::unique_ptr<LauncherContextMenu> LauncherContextMenu::Create(
   }
 
   // Create an CrostiniShelfContextMenu if the item is Crostini app.
-  if (crostini::CrostiniRegistryServiceFactory::GetForProfile(
-          controller->profile())
-          ->IsCrostiniShelfAppId(item->id.app_id)) {
+  crostini::CrostiniRegistryService* crostini_registry_service =
+      crostini::CrostiniRegistryServiceFactory::GetForProfile(
+          controller->profile());
+  if (crostini_registry_service &&
+      crostini_registry_service->IsCrostiniShelfAppId(item->id.app_id)) {
     return std::make_unique<CrostiniShelfContextMenu>(controller, item,
                                                       display_id);
   }

chrome/browser/ui/ash/launcher/launcher_controller_helper.cc

@@ -127,7 +127,7 @@ base::string16 LauncherControllerHelper::GetAppTitle(
 
   crostini::CrostiniRegistryService* registry_service =
       crostini::CrostiniRegistryServiceFactory::GetForProfile(profile);
-  if (registry_service->IsCrostiniShelfAppId(app_id)) {
+  if (registry_service && registry_service->IsCrostiniShelfAppId(app_id)) {
     std::unique_ptr<crostini::CrostiniRegistryService::Registration>
         registration = registry_service->GetRegistration(app_id);
     if (!registration)
@@ -204,7 +204,7 @@ void LauncherControllerHelper::LaunchApp(const ash::ShelfID& id,
 
   crostini::CrostiniRegistryService* registry_service =
       crostini::CrostiniRegistryServiceFactory::GetForProfile(profile_);
-  if (registry_service->IsCrostiniShelfAppId(app_id)) {
+  if (registry_service && registry_service->IsCrostiniShelfAppId(app_id)) {
     // This expects a valid app list id, which is fine as we only get here for
     // shelf entries associated with an actual app and not arbitrary Crostini
     // windows.