CrOS App list: Notify observers upon target visibility change

Change-Id: I02cfd0ad68407b54c681a88505eaf12e84a14753
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1830357
Commit-Queue: Manu Cornet <manucornet@chromium.org>
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Auto-Submit: Manu Cornet <manucornet@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700924}

ash/app_list/app_list_controller_impl.cc

@@ -1295,12 +1295,16 @@ void AppListControllerImpl::NotifyAppListTargetVisibilityChanged(
     return;
   }
 
-  last_target_visible_ = real_target_visibility;
-  last_target_visible_display_id_ = display_id;
-
   // Notify chrome of target visibility changes.
   if (client_)
     client_->OnAppListTargetVisibilityChanged(real_target_visibility);
+
+  for (auto& observer : observers_)
+    observer.OnAppListTargetVisibilityChanged(real_target_visibility,
+                                              display_id);
+
+  last_target_visible_ = real_target_visibility;
+  last_target_visible_display_id_ = display_id;
 }
 
 ////////////////////////////////////////////////////////////////////////////////