Fix memory leaks

These are `new`ed, but never passed to anything else. It looks like
simply stack allocating will do what we want here.

Caught by our static analyzer:

frameworks/av/media/libmediaplayer2/MediaPlayer2AudioOutput.cpp:524:5:
warning: Potential memory leak [clang-analyzer-cplusplus.NewDeleteLeaks]
frameworks/av/media/libmediaplayer2/MediaPlayer2AudioOutput.cpp:527:9:
warning: Potential memory leak [clang-analyzer-cplusplus.NewDeleteLeaks]
frameworks/av/media/libmediaplayer2/MediaPlayer2AudioOutput.cpp:529:9:
warning: Potential memory leak [clang-analyzer-cplusplus.NewDeleteLeaks]

Bug: None
Test: Ran the analyer again. It was happy.
Change-Id: I8f4cda4a5993f43ad50cf5a0d152ed7158d7c8e1

media/libmediaplayer2/MediaPlayer2AudioOutput.cpp

@@ -521,12 +521,15 @@ jobject MediaPlayer2AudioOutput::getRoutedDevice() {
 status_t MediaPlayer2AudioOutput::addAudioDeviceCallback(jobject jRoutingDelegate) {
     ALOGV("addAudioDeviceCallback");
     Mutex::Autolock lock(mLock);
-    jobject listener = (new JObjectHolder(
-            JAudioTrack::getListener(jRoutingDelegate)))->getJObject();
+
+    JObjectHolder listenerHolder{JAudioTrack::getListener(jRoutingDelegate)};
+    jobject listener = listenerHolder.getJObject();
     if (JAudioTrack::findByKey(mRoutingDelegates, listener) == nullptr) {
-        jobject handler = (new JObjectHolder(
-                JAudioTrack::getHandler(jRoutingDelegate)))->getJObject();
-        jobject routingDelegate = (new JObjectHolder(jRoutingDelegate))->getJObject();
+        JObjectHolder handlerHolder{JAudioTrack::getHandler(jRoutingDelegate)};
+        jobject handler = handlerHolder.getJObject();
+
+        JObjectHolder routingDelegateHolder = JObjectHolder(jRoutingDelegate);
+        jobject routingDelegate = routingDelegateHolder.getJObject();
         mRoutingDelegates.push_back(std::pair<jobject, jobject>(listener, routingDelegate));
         if (mJAudioTrack != nullptr) {
             return mJAudioTrack->addAudioDeviceCallback(routingDelegate, handler);