Update Android instrumentation tests to use JUnit4.

BUG=webrtc:6597

Review-Url: https://codereview.webrtc.org/2627043002
Cr-Commit-Position: refs/heads/master@{#16011}

webrtc/sdk/android/api/org/webrtc/VideoFileRenderer.java

@@ -7,6 +7,7 @@
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
+
 package org.webrtc;
 
 import android.os.Handler;