Move DataSourceUnwrapper to MidiIoWrapper class

DataSourceUnwrapper is now part of MidiIoWrapper class
This is prevent use of this class outside MidiIoWrapper methods

Bug: 145332185
Test: adb shell /data/local/tmp/ExtractorUnitTest -P /data/local/tmp/extractorRes/
Test: atest android.media.cts.MediaExtractorTest
Test: atest android.mediav2.cts.ExtractorTest

Change-Id: Ia898539fb95a1eb62b81f522599976fc477bfbee
diff --git a/media/libmedia/MidiIoWrapper.cpp b/media/libmedia/MidiIoWrapper.cpp
index 6d46363..e71ea2c 100644
--- a/media/libmedia/MidiIoWrapper.cpp
+++ b/media/libmedia/MidiIoWrapper.cpp
@@ -49,7 +49,7 @@
     mDataSource = nullptr;
 }
 
-class DataSourceUnwrapper {
+class MidiIoWrapper::DataSourceUnwrapper {
 
 public:
     explicit DataSourceUnwrapper(CDataSource *csource) {