Fixed bug where Crostini icons didn't always load

This is an obvious coding error, the wrong variable was used for
checking if an iterator was empty. Depending upon if a specific bit was
set in that random memory location, then we'd get the right/wrong
behavior.

Bug: 842196
Test: Icons load (although they usually did before)
Change-Id: Ie52747f0b03e82ba2915df3f8ce9198a9a22452f
Reviewed-on: https://chromium-review.googlesource.com/1062199Reviewed-by: Timothy Loh <timloh@chromium.org>
Commit-Queue: Jeffrey Kardatzke <jkardatzke@google.com>
Cr-Commit-Position: refs/heads/master@{#559396}

chrome/browser/chromeos/crostini/crostini_registry_service.cc

@@ -448,7 +448,7 @@ void CrostiniRegistryService::MaybeRequestIcon(const std::string& app_id,
     }
   }
   const auto retry_iter = retry_icon_requests_.find(app_id);
-  if (retry_iter != active_icon_requests_.end()) {
+  if (retry_iter != retry_icon_requests_.end()) {
     if (retry_iter->second & (1 << scale_factor)) {
       // Icon request already setup to be retried when we are active.
       return;