Added PRESUBMIT.py for binary_size tools.

tools/binary_size/PRESUBMIT.py

-# Copyright 2013 The Chromium Authors. All rights reserved.
+# Copyright 2014 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.
 
-"""Top-level presubmit script for linux.
+"""binary_size presubmit script
 
-See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts for
-details on the presubmit API built into gcl.
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into gcl.
 """
 
-
 def CommonChecks(input_api, output_api):
-  import sys
-  def join(*args):
-    return input_api.os_path.join(input_api.PresubmitLocalPath(), *args)
-
   output = []
-  sys_path_backup = sys.path
-  try:
-    sys.path = [
-      join('..', 'linux'),
-    ] + sys.path
-    output.extend(input_api.canned_checks.RunPylint(input_api, output_api))
-  finally:
-    sys.path = sys_path_backup
-
+  output.extend(input_api.canned_checks.RunPylint(input_api, output_api))
   output.extend(
       input_api.canned_checks.RunUnitTestsInDirectory(
           input_api, output_api,
-          input_api.os_path.join(input_api.PresubmitLocalPath(), 'tests'),
-          whitelist=[r'.+_tests\.py$']))
+          input_api.PresubmitLocalPath(),
+          whitelist=[r'.+_unittest\.py$']))
 
   if input_api.is_committing:
     output.extend(input_api.canned_checks.PanProjectChecks(input_api,
                                                            output_api,
                                                            owners_check=False))
   return output
 
 
 def CheckChangeOnUpload(input_api, output_api):
   return CommonChecks(input_api, output_api)
 
 
 def CheckChangeOnCommit(input_api, output_api):
   return CommonChecks(input_api, output_api)