Fixes a regression in launching certain settings activities.

Some undocumented settings and class names are being used by NotificationManagerService.
Added compatibility activities to handle them.

Bug: 3258668
diff --git a/src/com/android/settings/SoundSettings.java b/src/com/android/settings/SoundSettings.java
index f5e9290..cc38c23 100644
--- a/src/com/android/settings/SoundSettings.java
+++ b/src/com/android/settings/SoundSettings.java
@@ -261,6 +261,8 @@
 
     // updateState in fact updates the UI to reflect the system state
     private void updateState(boolean force) {
+        if (getActivity() == null) return;
+
         final int ringerMode = mAudioManager.getRingerMode();
 
         // NB: in the UI we now simply call this "silent mode". A separate