Add audio service support to BridgeContext

Bug: http://b.android.com/259326
Test: N/A
Change-Id: Ie43ccca49a5e77d82426b4f265e3c05dddfacad9

tools/layoutlib/bridge/src/com/android/layoutlib/bridge/android/BridgeContext.java

@@ -648,6 +648,10 @@ public class BridgeContext extends Context {
             return null;
         }
 
+        if (AUDIO_SERVICE.equals(service)) {
+            return null;
+        }
+
         throw new UnsupportedOperationException("Unsupported Service: " + service);
     }