rename AudioSystem::newAudioSessionId()

Rename AudioSystem::newAudioSessionId() to
AudioSystem::newAudioUniqueId() as it can be used
also for I/O handles.

Bug: 12378680.
Change-Id: I611ea3b5eb57a4b0774437f477ee87dc4ccc2cc2
diff --git a/media/libmedia/AudioSystem.cpp b/media/libmedia/AudioSystem.cpp
index fd5824b..0d61885 100644
--- a/media/libmedia/AudioSystem.cpp
+++ b/media/libmedia/AudioSystem.cpp
@@ -427,11 +427,11 @@
     return result;
 }
 
-int AudioSystem::newAudioSessionId()
+audio_unique_id_t AudioSystem::newAudioUniqueId()
 {
     const sp<IAudioFlinger>& af = AudioSystem::get_audio_flinger();
-    if (af == 0) return AUDIO_SESSION_ALLOCATE;
-    return af->newAudioSessionId();
+    if (af == 0) return AUDIO_UNIQUE_ID_ALLOCATE;
+    return af->newAudioUniqueId();
 }
 
 void AudioSystem::acquireAudioSessionId(int audioSession, pid_t pid)