Set vertical orientation by default in TrackSelectionView

Horizontal orientation doesn't make sense. I thought about
overriding the setter to throw something, but it's probably
not worth the extra lines.

PiperOrigin-RevId: 234632530

demos/main/src/main/res/layout/track_selection_dialog_tab.xml

@@ -16,9 +16,10 @@
 <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="wrap_content">
+
   <com.google.android.exoplayer2.ui.TrackSelectionView
       android:id="@+id/download_dialog_track_selection_view"
-      android:orientation="vertical"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"/>
+
 </ScrollView>

library/ui/src/main/java/com/google/android/exoplayer2/ui/TrackSelectionView.java

@@ -87,6 +87,8 @@ public class TrackSelectionView extends LinearLayout {
   public TrackSelectionView(
       Context context, @Nullable AttributeSet attrs, @AttrRes int defStyleAttr) {
     super(context, attrs, defStyleAttr);
+    setOrientation(LinearLayout.VERTICAL);
+
     overrides = new SparseArray<>();
 
     // Don't save view hierarchy as it needs to be reinitialized with a call to init.

library/ui/src/main/res/layout/exo_track_selection_dialog.xml

@@ -18,7 +18,6 @@
     android:layout_height="match_parent">
 
   <com.google.android.exoplayer2.ui.TrackSelectionView android:id="@+id/exo_track_selection_view"
-      android:orientation="vertical"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"/>