Disable failing perf unit tests on chromeos.

tools/perf/profile_creators/cookie_profile_extender.py

 # Copyright 2015 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.
 import multiprocessing
 import os
-import sqlite3
+
+try:
+  import sqlite3  # Not present on ChromeOS DUT.
+except ImportError:
+  pass
 
 import page_sets
 
 from profile_creators import fast_navigation_profile_extender
 
 class CookieProfileExtender(
     fast_navigation_profile_extender.FastNavigationProfileExtender):
   """This extender fills in the cookie database.
 
   By default, Chrome purges the cookie DB down to 3300 cookies. However, it
@@ skipping 61 matching lines @@
     that this method will return a false negative."""
     cookie_db_path = os.path.join(self.profile_path, "Default", "Cookies")
     try:
       cookie_count = CookieProfileExtender._CookieCountInDB(cookie_db_path)
     except sqlite3.OperationalError:
       # There will occasionally be contention for the SQLite database. This
       # shouldn't happen often, so ignore the errors.
       return False
 
     return cookie_count > CookieProfileExtender._COOKIE_DB_EXPECTED_SIZE