Added PRESUBMIT.py for binary_size tools.

tools/binary_size/PRESUBMIT.py

+#!/usr/bin/env python

[Primiano Tucci (use gerrit), 2014/05/22 09:30:38]

The PRESUBMIT.py shouldn't have a shbang and should not be executable (e.g.
chmod a-x before reuploading)

+# 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.
+
+"""binary_size presubmit script
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into gcl.
+"""
+
+def _RunUnitTests(input_api, output_api):

[Primiano Tucci (use gerrit), 2014/05/22 09:30:38]

Is there an actual reason why you didn't just copy over the one from deps2git as
I suggested you in the previous CL?
I didn't just pick a random one. I suggested that one because that is well done!
:)

+  # Skip if nothing to do
+  run_unit_test_path = input_api.os_path.join(
+    input_api.PresubmitLocalPath(), 'explain_binary_size_delta_unittest.py')

[Primiano Tucci (use gerrit), 2014/05/22 09:30:38]

We already have the mechanisms in place to run discover and run unittests, no
need to hard code the file name here (again, see deps2git).

+  cmd_name = 'explain_binary_size_delta_unittest'
+  if input_api.platform == 'win32':

[Primiano Tucci (use gerrit), 2014/05/22 09:30:38]

Neither we need platform specific black magic.

+    # Windows needs some help.
+    cmd = [input_api.python_executable, run_unit_test_path]
+  else:
+    cmd = [run_unit_test_path]
+
+  if input_api.is_committing:
+    message_type = output_api.PresubmitError
+  else:
+    message_type = output_api.PresubmitPromptWarning
+
+  test_cmd = input_api.Command(
+    name=cmd_name,
+    cmd=cmd,
+    kwargs={},
+    message=message_type)
+  if input_api.verbose:
+    print('Running ' + cmd_name)
+  return input_api.RunTests([test_cmd])
+
+
+def CheckChangeOnUpload(input_api, output_api):
+  return _RunUnitTests(input_api, output_api)
+
+
+def CheckChangeOnCommit(input_api, output_api):
+  return _RunUnitTests(input_api, output_api)