don't play in-thread notification sound in priority mode

Fixes #3337
Closes #5439

// FREEBIE

src/org/thoughtcrime/securesms/notifications/MessageNotifier.java

@@ -43,7 +43,6 @@ import org.thoughtcrime.securesms.ConversationActivity;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.crypto.MasterSecret;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
-import org.thoughtcrime.securesms.database.MessagingDatabase;
 import org.thoughtcrime.securesms.database.MessagingDatabase.SyncMessageId;
 import org.thoughtcrime.securesms.database.MmsSmsDatabase;
 import org.thoughtcrime.securesms.database.PushDatabase;
@@ -57,6 +56,7 @@ import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientFactory;
 import org.thoughtcrime.securesms.recipients.Recipients;
 import org.thoughtcrime.securesms.service.KeyCachingService;
+import org.thoughtcrime.securesms.util.ServiceUtil;
 import org.thoughtcrime.securesms.util.SpanUtil;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
 import org.whispersystems.signalservice.api.messages.SignalServiceEnvelope;
@@ -287,7 +287,9 @@ public class MessageNotifier {
   }
 
   private static void sendInThreadNotification(Context context, Recipients recipients) {
-    if (!TextSecurePreferences.isInThreadNotifications(context)) {
+    if (!TextSecurePreferences.isInThreadNotifications(context) ||
+        ServiceUtil.getAudioManager(context).getRingerMode() != AudioManager.RINGER_MODE_NORMAL)
+    {
       return;
     }