Make performance_ui_tests.exe optional. For "Chrome" builds,

chrome/tools/build/win/FILES.cfg

 # -*- python -*-
 # ex: set syntax=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.
 
 # This is a buildbot configuration file containing a tagged list of files
 # processed by the stage/archive scripts. The known tags are:
 #
@@ skipping 530 matching lines @@
   },
   {
     'filename': 'chrome_frame_helper.dll',
     'buildtype': ['dev', 'official'],
     'filegroup': ['default', 'symsrc'],
   },
   # Perf testing binary:
   {
     'filename': 'performance_ui_tests.exe',
     'buildtype': ['official'],
+    'optional': ['official'],
   },
   {
     'filename': 'sync_unit_tests.exe',
     'buildtype': ['official'],
     'optional': ['official'],
   },
   # Metro files (currently official build only):
   {
     'filename': 'metro_driver.dll',
     'buildtype': ['official'],
@@ skipping 125 matching lines @@
     'buildtype': ['official'],
     'archive': 'chrome-win32-syms.zip',
   },
   {
     'filename': 'syzygy/asan_rtl.dll.pdb',
     'buildtype': ['official'],
     'archive': 'chrome-win32-syms.zip',
     'optional': ['official'],
   },
 ]