USAGE_ASSISTANT/ACCESSIBILITY in audio policy manager

Add support for USAGE_ASSISTANT.
Fix stream type for USAGE_ACCESSIBILITY.

Test: enable Talkback, check volume; make
Bug: 30947943

Change-Id: Ie35adf0115dce1fac6d3deddc1e57e36b36913f6
diff --git a/include/media/AudioPolicyHelper.h b/include/media/AudioPolicyHelper.h
index 79231be..04f6a20 100644
--- a/include/media/AudioPolicyHelper.h
+++ b/include/media/AudioPolicyHelper.h
@@ -32,9 +32,11 @@
     switch (attr->usage) {
     case AUDIO_USAGE_MEDIA:
     case AUDIO_USAGE_GAME:
-    case AUDIO_USAGE_ASSISTANCE_ACCESSIBILITY:
     case AUDIO_USAGE_ASSISTANCE_NAVIGATION_GUIDANCE:
+    case AUDIO_USAGE_ASSISTANT:
         return AUDIO_STREAM_MUSIC;
+    case AUDIO_USAGE_ASSISTANCE_ACCESSIBILITY:
+        return AUDIO_STREAM_ACCESSIBILITY;
     case AUDIO_USAGE_ASSISTANCE_SONIFICATION:
         return AUDIO_STREAM_SYSTEM;
     case AUDIO_USAGE_VOICE_COMMUNICATION: