Add presubmit check and automatic update script for ExtensionPermission enum.

tools/extra_imports/changed_file_8.h

+// Copyright (c) 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.
+
+#ifndef MOCK_ENUM_H
+#define MOCK_ENUM_H
+
+// Here is our mock enum. Beyond testing it is completely meaningless.
+// MockEnum follows strict rules for valid modifications:
+//    1. NO reordering of entries
+//    2. NO deletions of entries
+//    3. New entries must be added just before mBoundary, never after
+//
+enum MockEnum {
+  mEntry1,
+  mEntry2,
+  mData1,
+  mData2,
+  mInsertion,
+  mEntry3,
+  mInfo1,
+  mData3,
+  mError1,
+  mFunction1,
+  mInfo2,
+  mData4,
+  mBoundary // Do not add below here
+};
+
+#endif