Use the iossim executable in the ninja-iossim directory.

scripts/slave/runtest.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.
 
 """A tool to run a chrome test executable, used by the buildbot slaves.
 
   When this is run, the current directory (cwd) should be the outer build
   directory (e.g., chrome-release/build/).
 
@@ skipping 642 matching lines @@
   # simulator and launch it, then dump the test results to stdout.
 
   # Note that the first object (build_dir) returned from the following
   # method invocations is ignored because only the app executable is needed.
   _, app_exe_path = get_build_dir_and_exe_path_mac(
       options,
       options.target + '-iphonesimulator',
       test_name + '.app')
 
   _, test_exe_path = get_build_dir_and_exe_path_mac(options,
-                                                    options.target,
-                                                    'iossim')
+      os.path.join('ninja-iossim', options.target),
+      'iossim')
   command = [test_exe_path,
       '-d', device,
       '-s', ios_version,
       app_exe_path, '--'
   ]
   command.extend(args[1:])
 
   if list_parsers(options.annotate):
     return 0
   results_tracker = create_results_tracker(get_parsers()['gtest'], options)
@@ skipping 479 matching lines @@
         '%d new files were left in %s: Fix the tests to clean up themselves.'
         ) % ((new_temp_files - temp_files), tempfile.gettempdir())
     # TODO(maruel): Make it an error soon. Not yet since I want to iron out all
     # the remaining cases before.
     #result = 1
   return result
 
 
 if '__main__' == __name__:
   sys.exit(main())