Zero out return values in media binder calls

More specifically when handling:
* GET_STREAM_VOLUME in IAudioPolicyService, and
* GET_CURRENT_POSITION and GET_DURATION in IMediaPlayer

This prevents leaking uninitialized values across binder in error cases.

Bug: 23756261
Change-Id: I0ffd900ab12b685b0611259ade4a3efb1ec5defe
diff --git a/media/libmedia/IAudioPolicyService.cpp b/media/libmedia/IAudioPolicyService.cpp
index 12efa8a..6ffb98f 100644
--- a/media/libmedia/IAudioPolicyService.cpp
+++ b/media/libmedia/IAudioPolicyService.cpp
@@ -931,7 +931,7 @@
             audio_stream_type_t stream =
                     static_cast <audio_stream_type_t>(data.readInt32());
             audio_devices_t device = static_cast <audio_devices_t>(data.readInt32());
-            int index;
+            int index = 0;
             status_t status = getStreamVolumeIndex(stream, &index, device);
             reply->writeInt32(index);
             reply->writeInt32(static_cast <uint32_t>(status));
diff --git a/media/libmedia/IMediaPlayer.cpp b/media/libmedia/IMediaPlayer.cpp
index aa22b58..a29a7de 100644
--- a/media/libmedia/IMediaPlayer.cpp
+++ b/media/libmedia/IMediaPlayer.cpp
@@ -438,7 +438,7 @@
         } break;
         case GET_CURRENT_POSITION: {
             CHECK_INTERFACE(IMediaPlayer, data, reply);
-            int msec;
+            int msec = 0;
             status_t ret = getCurrentPosition(&msec);
             reply->writeInt32(msec);
             reply->writeInt32(ret);
@@ -446,7 +446,7 @@
         } break;
         case GET_DURATION: {
             CHECK_INTERFACE(IMediaPlayer, data, reply);
-            int msec;
+            int msec = 0;
             status_t ret = getDuration(&msec);
             reply->writeInt32(msec);
             reply->writeInt32(ret);