[Android WebView] Prepare the copyrights scanner to run from presubmit scripts

android_webview/tools/PRESUBMIT.py

+# 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.
+
+def CheckChangeOnUpload(input_api, output_api):
+  return _CommonChecks(input_api, output_api)
+
+def CheckChangeOnCommit(input_api, output_api):
+  return _CommonChecks(input_api, output_api)
+
+def _CommonChecks(input_api, output_api):
+  """Checks common to both upload and commit."""
+  results = []
+
+  would_affect_tests = [
+    'PRESUBMIT.py',
+    'copyright_scanner.py',
+    'copyright_scanner_unittest.py'
+  ]
+  need_to_run_unittests = False
+  for f in input_api.AffectedFiles():
+    if any(t for t in would_affect_tests if f.LocalPath().endswith(t)):
+      need_to_run_unittests = True
+      break
+  tests = [input_api.os_path.join(
+    input_api.PresubmitLocalPath(), 'copyright_scanner_unittest.py')]
+  results.extend(
+    input_api.canned_checks.RunUnitTests(input_api, output_api, tests))
+  return results