diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index b41d480..2aeb263 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -412,6 +412,7 @@
                                                   int target);
         virtual status_t    setParameters(const String8& keyValuePairs);
         virtual status_t    getTimestamp(AudioTimestamp& timestamp);
+        virtual void        signal(); // signal playback thread for a change in control block
 
         virtual status_t onTransact(
             uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags);