Add presubmit script to verify that scaled resources are correct dimensions.

ui/resources/PRESUBMIT.py

Index: ui/resources/PRESUBMIT.py
diff --git a/ui/resources/PRESUBMIT.py b/ui/resources/PRESUBMIT.py
new file mode 100644
index 0000000000000000000000000000000000000000..ba38b7106a77cd562712e0035d42af9bf138083d
--- /dev/null
+++ b/ui/resources/PRESUBMIT.py
@@ -0,0 +1,47 @@
+# 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.
+
+"""Presubmit script for Chromium UI resources.
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into gcl/git cl, and see
+http://www.chromium.org/developers/web-development-style-guide for the rules
+we're checking against here.
+"""
+
+
+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 = []
+  resources = input_api.PresubmitLocalPath()
+
+  # List of paths with their associated scale factor. This is used to verify
+  # that the images modified in one are the correct scale of the other.
+  path_scales = [
+    [(1, 'default_100_percent/'), (2, 'default_200_percent/')],
+    [(1, 'touch_100_percent/'), (2, 'touch_200_percent/')],
+  ]
+
+  import sys
+  old_path = sys.path
+
+  try:
+    sys.path = [resources] + old_path
+    from resource_check import resource_scale_factors
+
+    for paths in path_scales:
+      results.extend(resource_scale_factors.ResourceScaleFactors(
+          input_api, output_api, paths).RunChecks())
+  finally:
+    sys.path = old_path
+
+  return results