Remove prefixed EME.

media/test/data/eme_player_js/file_io_test_player.js

Index: media/test/data/eme_player_js/file_io_test_player.js
diff --git a/media/test/data/eme_player_js/file_io_test_player.js b/media/test/data/eme_player_js/file_io_test_player.js
index 5136e7d9a83a63c541659b3990bc34b532a2b718..fb0d025eac4b0762d51f5d0cbeed7290f228f7a2 100644
--- a/media/test/data/eme_player_js/file_io_test_player.js
+++ b/media/test/data/eme_player_js/file_io_test_player.js
@@ -15,9 +15,7 @@ FileIOTestPlayer.prototype.init = function() {
 
 FileIOTestPlayer.prototype.registerEventListeners = function() {
   // Returns a promise.
-  return PlayerUtils.registerEMEEventListeners(this).then(function(result) {
-    return PlayerUtils.registerPrefixedEMEEventListeners(this);
-  });
+  return PlayerUtils.registerEMEEventListeners(this);
 };
 
 handleMessage = function(message) {
@@ -38,8 +36,4 @@ handleMessage = function(message) {
   }
 };
 
-// Check message for prefixed API.
-FileIOTestPlayer.prototype.onWebkitKeyMessage = handleMessage;
-
-// Check message for unprefixed API.
 FileIOTestPlayer.prototype.onMessage = handleMessage;