Fix demo app when built using ASWB

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=131853683

demo/src/main/AndroidManifest.xml

@@ -30,7 +30,7 @@
       android:icon="@drawable/ic_launcher"
       android:largeHeap="true"
       android:allowBackup="false"
-      android:name=".DemoApplication">
+      android:name="com.google.android.exoplayer2.demo.DemoApplication">
 
     <activity android:name="com.google.android.exoplayer2.demo.SampleChooserActivity"
         android:configChanges="keyboardHidden"