Simplify RecordTrack::stop()

Change-Id: Ib959c1e9dc9544d12277ce11bea445118b2e0521
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index f27d908..e2e023a 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -4031,8 +4031,9 @@
     }
 }
 
-bool AudioFlinger::RecordThread::stop_l(RecordThread::RecordTrack* recordTrack) {
+bool AudioFlinger::RecordThread::stop(RecordThread::RecordTrack* recordTrack) {
     ALOGV("RecordThread::stop");
+    AutoMutex _l(mLock);
     if (recordTrack != mActiveTrack.get() || recordTrack->mState == TrackBase::PAUSING) {
         return false;
     }