Track pid for each session

so they can be properly freed.

Change-Id: I6f389035bc29e74e7c367c1c6d0252b180f666b3
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 459d2ec..4799beb 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -193,9 +193,9 @@
 
     virtual int newAudioSessionId();
 
-    virtual void acquireAudioSessionId(int audioSession);
+    virtual void acquireAudioSessionId(int audioSession, pid_t pid);
 
-    virtual void releaseAudioSessionId(int audioSession);
+    virtual void releaseAudioSessionId(int audioSession, pid_t pid);
 
     virtual status_t queryNumberEffects(uint32_t *numEffects) const;