Communicate audio session ID to downmixer

The audio downmixer effect might need the audio session Id, pass it
 from the track creation in AudioFlinger to the downmix effect
 creation in AudioMixer.

Change-Id: I5e29540542ae89cf4a0cdb537b3e67f04442a20a
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 5ffa5a6..c956861 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -1086,7 +1086,7 @@
 
         // Allocate a track name for a given channel mask.
         //   Returns name >= 0 if successful, -1 on failure.
-        virtual int             getTrackName_l(audio_channel_mask_t channelMask) = 0;
+        virtual int             getTrackName_l(audio_channel_mask_t channelMask, int sessionId) = 0;
         virtual void            deleteTrackName_l(int name) = 0;
 
         // Time to sleep between cycles when:
@@ -1202,7 +1202,7 @@
 
     protected:
         virtual     mixer_state prepareTracks_l(Vector< sp<Track> > *tracksToRemove);
-        virtual     int         getTrackName_l(audio_channel_mask_t channelMask);
+        virtual     int         getTrackName_l(audio_channel_mask_t channelMask, int sessionId);
         virtual     void        deleteTrackName_l(int name);
         virtual     uint32_t    idleSleepTimeUs() const;
         virtual     uint32_t    suspendSleepTimeUs() const;
@@ -1254,7 +1254,7 @@
         virtual     bool        checkForNewParameters_l();
 
     protected:
-        virtual     int         getTrackName_l(audio_channel_mask_t channelMask);
+        virtual     int         getTrackName_l(audio_channel_mask_t channelMask, int sessionId);
         virtual     void        deleteTrackName_l(int name);
         virtual     uint32_t    activeSleepTimeUs() const;
         virtual     uint32_t    idleSleepTimeUs() const;