Prase IDL files in common/extensions/api PRESUBMIT check.

chrome/common/extensions/api/test_presubmit/invalid_idl_4.idl

Index: chrome/common/extensions/api/test_presubmit/invalid_idl_4.idl
diff --git a/chrome/common/extensions/api/test_presubmit/invalid_idl_4.idl b/chrome/common/extensions/api/test_presubmit/invalid_idl_4.idl
new file mode 100644
index 0000000000000000000000000000000000000000..28b42ffff99c436922f1cea87c7f232de0417c26
--- /dev/null
+++ b/chrome/common/extensions/api/test_presubmit/invalid_idl_4.idl
@@ -0,0 +1,13 @@
+// Copyright 2013 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.
+
+// Tests an invalid IDL file.
+
+namespace test {
+  // Trailing comma in block.
+  enum TrailingComma {
+    name1,
+    name2,
+  };
+};