ToneGenerator requests fast track

Also add comments to AudioTrack::set() parameter list

Change-Id: I28c76e9d813778d86b15d75cf7f01a17c258b6d9
diff --git a/media/libmedia/ToneGenerator.cpp b/media/libmedia/ToneGenerator.cpp
index 717d316..c93b6fd 100644
--- a/media/libmedia/ToneGenerator.cpp
+++ b/media/libmedia/ToneGenerator.cpp
@@ -1020,15 +1020,15 @@
     ALOGV("Create Track: %p", mpAudioTrack);
 
     mpAudioTrack->set(mStreamType,
-                      0,
+                      0,    // sampleRate
                       AUDIO_FORMAT_PCM_16_BIT,
                       AUDIO_CHANNEL_OUT_MONO,
-                      0,
-                      AUDIO_POLICY_OUTPUT_FLAG_NONE,
+                      0,    // frameCount
+                      AUDIO_POLICY_OUTPUT_FLAG_FAST,
                       audioCallback,
-                      this,
-                      0,
-                      0,
+                      this, // user
+                      0,    // notificationFrames
+                      0,    // sharedBuffer
                       mThreadCanCallJava);
 
     if (mpAudioTrack->initCheck() != NO_ERROR) {