aaudio: cleanup thread handling

Fix problem when an attempt is made to join the callback from the
callback. It used to leave mHasThread in the wrong state.
This was fixed in AAudioThread and in AudioStream.

Add "_l" suffix to functions that need to be locked.

Simplify the way that reference counted objects are passed to threads
using incStrong() and decStrong().

Bug: 171296283
Test: atest AAudioTestCases
Change-Id: I034049c4cb9021c6073fff441e49214ee898b804
diff --git a/media/libaaudio/src/legacy/AudioStreamTrack.cpp b/media/libaaudio/src/legacy/AudioStreamTrack.cpp
index 307904e..1d036d0 100644
--- a/media/libaaudio/src/legacy/AudioStreamTrack.cpp
+++ b/media/libaaudio/src/legacy/AudioStreamTrack.cpp
@@ -178,7 +178,7 @@
     // Did we get a valid track?
     status_t status = mAudioTrack->initCheck();
     if (status != NO_ERROR) {
-        releaseCloseFinal();
+        safeReleaseClose();
         ALOGE("open(), initCheck() returned %d", status);
         return AAudioConvert_androidToAAudioResult(status);
     }
@@ -293,7 +293,7 @@
     return;
 }
 
-aaudio_result_t AudioStreamTrack::requestStart() {
+aaudio_result_t AudioStreamTrack::requestStart_l() {
     if (mAudioTrack.get() == nullptr) {
         ALOGE("requestStart() no AudioTrack");
         return AAUDIO_ERROR_INVALID_STATE;
@@ -320,7 +320,7 @@
     return AAUDIO_OK;
 }
 
-aaudio_result_t AudioStreamTrack::requestPause() {
+aaudio_result_t AudioStreamTrack::requestPause_l() {
     if (mAudioTrack.get() == nullptr) {
         ALOGE("%s() no AudioTrack", __func__);
         return AAUDIO_ERROR_INVALID_STATE;
@@ -336,7 +336,7 @@
     return checkForDisconnectRequest(false);
 }
 
-aaudio_result_t AudioStreamTrack::requestFlush() {
+aaudio_result_t AudioStreamTrack::requestFlush_l() {
     if (mAudioTrack.get() == nullptr) {
         ALOGE("%s() no AudioTrack", __func__);
         return AAUDIO_ERROR_INVALID_STATE;
@@ -350,7 +350,7 @@
     return AAUDIO_OK;
 }
 
-aaudio_result_t AudioStreamTrack::requestStop() {
+aaudio_result_t AudioStreamTrack::requestStop_l() {
     if (mAudioTrack.get() == nullptr) {
         ALOGE("%s() no AudioTrack", __func__);
         return AAUDIO_ERROR_INVALID_STATE;