NuPlayerDriver: acquire mLock when needed.

Bug: 24338126
Change-Id: Ic55d1a551c18255423423079b6c2bf045dea6e44
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerDriver.cpp b/media/libmediaplayerservice/nuplayer/NuPlayerDriver.cpp
index 018e668..3972b74 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerDriver.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerDriver.cpp
@@ -362,9 +362,9 @@
 }
 
 status_t NuPlayerDriver::setPlaybackSettings(const AudioPlaybackRate &rate) {
-    Mutex::Autolock autoLock(mLock);
     status_t err = mPlayer->setPlaybackSettings(rate);
     if (err == OK) {
+        Mutex::Autolock autoLock(mLock);
         if (rate.mSpeed == 0.f && mState == STATE_RUNNING) {
             mState = STATE_PAUSED;
             // try to update position