Add PPAPI test mock headers to *.isolate files.

chrome/interactive_ui_tests.isolate

 # Copyright 2013 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': [
     ['use_x11==0', {
       'variables': {
         'command': [
           '../testing/test_env.py',
           '<(PRODUCT_DIR)/interactive_ui_tests<(EXECUTABLE_SUFFIX)',
@@ skipping 30 matching lines @@
           '<(PRODUCT_DIR)/pyproto/google/',
         ],
       },
     }],
     ['OS=="linux" or OS=="mac" or OS=="win"', {
       'variables': {
         'files': [
           '../net/data/ssl/certificates/',
           '../net/tools/testserver/',
           '../ppapi/tests/test_case.html',
+          '../ppapi/tests/test_case.html.mock-http-headers',
           '../ppapi/tests/test_page.css',
+          '../ppapi/tests/test_page.css.mock-http-headers',
           '../testing/test_env.py',
           '../third_party/pyftpdlib/',
           '../third_party/pywebsocket/',
           '../third_party/tlslite/',
           '<(PRODUCT_DIR)/interactive_ui_tests<(EXECUTABLE_SUFFIX)',
           '<(PRODUCT_DIR)/resources.pak',
           '<(PRODUCT_DIR)/ui_test.pak',
           'test/data/',
         ],
         'read_only': 1,
@@ skipping 78 matching lines @@
           'browser/chromeos/login/test/https_forwarder.py',
         ],
       },
     }],
   ],
   'includes': [
     '../base/base.isolate',
     '../gin/v8.isolate',
   ],
 }