Don't break key event stream when enabling a11y

Bug: 62862624
Test: Enable magnification, then enable TalkBack with the
a11y shortcut. Verify that volume keys work.
A11y service CTS, a11y units tests.

Change-Id: I729ab17d24f758b5ce534ffde43d2126a1f9536c

services/accessibility/java/com/android/server/accessibility/AccessibilityInputFilter.java

@@ -271,6 +271,7 @@ class AccessibilityInputFilter extends InputFilter implements EventStreamTransfo
 
     private void processKeyEvent(EventStreamState state, KeyEvent event, int policyFlags) {
         if (!state.shouldProcessKeyEvent(event)) {
+            super.onInputEvent(event, policyFlags);
             return;
         }
         mEventHandler.onKeyEvent(event, policyFlags);