[MediaSession, Test] Move MediaSession test data to all-platforms directory

content/content_shell_test_apk.isolate

 # Copyright (c) 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 {
   'conditions': [
     ['OS=="android"', {
       'variables': {
         'files': [
           '<(DEPTH)/content/test/data/android/',
+          '<(DEPTH)/content/test/data/media/session/',
           '<(DEPTH)/net/data/ssl/certificates/crit-codeSigning-chain.pem',
           '<(DEPTH)/net/data/ssl/certificates/eku-test-root.pem',
           '<(DEPTH)/net/data/ssl/certificates/invalid_key_usage_cert.der',
           '<(DEPTH)/net/data/ssl/certificates/non-crit-codeSigning-chain.pem',
           '<(DEPTH)/net/data/ssl/certificates/ok_cert.pem',
           '<(DEPTH)/net/data/ssl/certificates/root_ca_cert.pem',
         ],
       },
     }],
   ],
 }