Use Ringtone instead of MediaPlayer directly

(Copied from rhodey's PR)

Fixes #3340
Closes #3342

// FREEBIe

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

@@ -23,10 +23,14 @@ import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.database.Cursor;
+import android.media.AudioAttributes;
 import android.media.AudioManager;
 import android.media.MediaPlayer;
+import android.media.Ringtone;
+import android.media.RingtoneManager;
 import android.net.Uri;
 import android.os.AsyncTask;
+import android.os.Build;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.text.Spannable;
@@ -265,7 +269,6 @@ public class MessageNotifier {
   }
 
   private static void sendInThreadNotification(Context context, Recipients recipients) {
-    try {
     if (!TextSecurePreferences.isInThreadNotifications(context)) {
       return;
     }
@@ -288,29 +291,17 @@ public class MessageNotifier {
       return;
     }
 
-      MediaPlayer player = new MediaPlayer();
+    Ringtone ringtone = RingtoneManager.getRingtone(context, uri);
-      player.setAudioStreamType(AudioManager.STREAM_NOTIFICATION);
-      player.setDataSource(context, uri);
-      player.setLooping(false);
-      player.setVolume(0.25f, 0.25f);
-      player.prepare();
-
-      final AudioManager audioManager = ((AudioManager)context.getSystemService(Context.AUDIO_SERVICE));
-
-      audioManager.requestAudioFocus(null, AudioManager.STREAM_NOTIFICATION,
-                                     AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK);
 
-      player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
+    if (Build.VERSION.SDK_INT >= 21) {
-        @Override
+      ringtone.setAudioAttributes(new AudioAttributes.Builder().setContentType(AudioAttributes.CONTENT_TYPE_UNKNOWN)
-        public void onCompletion(MediaPlayer mp) {
+                                                               .setUsage(AudioAttributes.USAGE_NOTIFICATION_COMMUNICATION_INSTANT)
-          audioManager.abandonAudioFocus(null);
+                                                               .build());
+    } else {
+      ringtone.setStreamType(AudioManager.STREAM_NOTIFICATION);
     }
-      });
 
-      player.start();
+    ringtone.play();
-    } catch (IOException ioe) {
-      Log.w("MessageNotifier", ioe);
-    }
   }
 
   private static void appendPushNotificationState(@NonNull Context context,