Add "extensions_unittests" as a valid test specifier to chrome_tests.py.

tools/valgrind/chrome_tests.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 ''' Runs various chrome tests through valgrind_test.py.'''
 
 import glob
 import logging
 import multiprocessing
@@ skipping 642 matching lines @@
     "cloud_print_unittests": TestCloudPrint,
     "components": TestComponents,"components_unittests": TestComponents,
     "compositor": TestCompositor,"compositor_unittests": TestCompositor,
     "content": TestContent,      "content_unittests": TestContent,
     "content_browsertests": TestContentBrowser,
     "courgette": TestCourgette,  "courgette_unittests": TestCourgette,
     "crypto": TestCrypto,        "crypto_unittests": TestCrypto,
     "device": TestDevice,        "device_unittests": TestDevice,
     "display": TestDisplay,      "display_unittests": TestDisplay,
     "events": TestEvents,        "events_unittests": TestEvents,
-    "extensions": TestExtensions,
+    "extensions": TestExtensions, "extensions_unittests": TestExtensions,
     "ffmpeg": TestFFmpeg,        "ffmpeg_unittests": TestFFmpeg,
     "ffmpeg_regression_tests": TestFFmpegRegressions,
     "gcm": TestGCM,              "gcm_unit_tests": TestGCM,
     "gin": TestGin,              "gin_unittests": TestGin,
     "gfx": TestGfx,              "gfx_unittests": TestGfx,
     "google_apis": TestGoogleApis,
     "gpu": TestGPU,              "gpu_unittests": TestGPU,
     "ipc": TestIpc,              "ipc_tests": TestIpc,
     "installer_util": TestInstallerUtil,
     "interactive_ui": TestInteractiveUI,
@@ skipping 102 matching lines @@
 
   for t in options.test:
     tests = ChromeTests(options, args, t)
     ret = tests.Run()
     if ret: return ret
   return 0
 
 
 if __name__ == "__main__":
   sys.exit(_main())