Stop listening to database changes in conversation list when not visible.

app/src/main/java/org/thoughtcrime/securesms/conversationlist/ConversationListFragment.java

@@ -320,6 +320,7 @@ public class ConversationListFragment extends MainFragment implements ActionMode
     super.onStart();
     ConversationFragment.prepare(requireContext());
     ApplicationDependencies.getAppForegroundObserver().addListener(appForegroundObserver);
+    viewModel.onStart();
   }
 
   @Override
@@ -335,6 +336,7 @@ public class ConversationListFragment extends MainFragment implements ActionMode
   public void onStop() {
     super.onStop();
     ApplicationDependencies.getAppForegroundObserver().removeListener(appForegroundObserver);
+    viewModel.onStop();
   }
 
   @Override

app/src/main/java/org/thoughtcrime/securesms/conversationlist/ConversationListViewModel.java

@@ -96,8 +96,6 @@ class ConversationListViewModel extends ViewModel {
         return DatabaseFactory.getThreadDatabase(application).getArchivedConversationListCount() == 0;
       }
     });
-
-    ApplicationDependencies.getDatabaseObserver().registerConversationListObserver(observer);
   }
 
   public LiveData<Boolean> hasNoConversations() {
@@ -142,6 +140,14 @@ class ConversationListViewModel extends ViewModel {
     coldStart = false;
   }
 
+  void onStart() {
+    ApplicationDependencies.getDatabaseObserver().registerConversationListObserver(observer);
+  }
+
+  void onStop() {
+    ApplicationDependencies.getDatabaseObserver().unregisterObserver(observer);
+  }
+
   void onMegaphoneCompleted(@NonNull Megaphones.Event event) {
     megaphone.postValue(null);
     megaphoneRepository.markFinished(event);