Fix uninitialized variable.

Bug: 19020118
Change-Id: I0aceadfec6652d468a5a5d9eb5dcbf0845757ffa
diff --git a/media/libmedia/MidiIoWrapper.cpp b/media/libmedia/MidiIoWrapper.cpp
index 2181111..5197ce2 100644
--- a/media/libmedia/MidiIoWrapper.cpp
+++ b/media/libmedia/MidiIoWrapper.cpp
@@ -48,6 +48,8 @@
 }
 
 MidiIoWrapper::MidiIoWrapper(const sp<DataSource> &source) {
+    ALOGV("MidiIoWrapper(DataSource)");
+    mFd = -1;
     mDataSource = source;
     off64_t l;
     if (mDataSource->getSize(&l) == OK) {
@@ -76,7 +78,7 @@
 }
 
 int MidiIoWrapper::size() {
-    ALOGV("size() = %d", mLength);
+    ALOGV("size() = %d", int(mLength));
     return mLength;
 }