Properly show conversation settings

... when the backing shortcut is missing, so users can change
notification settings when the shortcut hasn't yet been recreated by the
app when setting up a new device

Test: Robotests (confirmed that the 2 controllers that used
mConversationInfo already tested for null), manual
Fixes: 203991823

Change-Id: I477c6b0aef0d978767788cbfc1bfadea4d36cda8

src/com/android/settings/notification/app/NotificationSettings.java

@@ -270,6 +270,9 @@ abstract public class NotificationSettings extends DashboardFragment {
         String conversationId = intent != null
                 ? intent.getStringExtra(Settings.EXTRA_CONVERSATION_ID) : null;
         mChannel = mBackend.getChannel(mPkg, mUid, channelId, conversationId);
+        if (mChannel == null) {
+            mBackend.getChannel(mPkg, mUid, channelId, null);
+        }
     }
 
     private void loadConversation() {