Add comments explaining about SCHED_FIFO

Test: builds OK
Change-Id: I7fa39defb081c27eb32abb241c0aa2a210744954
diff --git a/media/libaudioclient/AudioTrack.cpp b/media/libaudioclient/AudioTrack.cpp
index 97d3517..31044bb 100644
--- a/media/libaudioclient/AudioTrack.cpp
+++ b/media/libaudioclient/AudioTrack.cpp
@@ -1414,6 +1414,9 @@
 
     pid_t tid = -1;
     if (mFlags & AUDIO_OUTPUT_FLAG_FAST) {
+        // It is currently meaningless to request SCHED_FIFO for a Java thread.  Even if the
+        // application-level code follows all non-blocking design rules, the language runtime
+        // doesn't also follow those rules, so the thread will not benefit overall.
         if (mAudioTrackThread != 0 && !mThreadCanCallJava) {
             tid = mAudioTrackThread->getTid();
         }
@@ -2948,6 +2951,7 @@
             mPausedInt = false;
         }
         if (mPausedInt) {
+            // TODO use futex instead of condition, for event flag "or"
             if (mPausedNs > 0) {
                 (void) mMyCond.waitRelative(mMyLock, mPausedNs);
             } else {