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

chrome/common/extensions/api/test_presubmit/invalid_idl_2.idl

Index: chrome/common/extensions/api/test_presubmit/invalid_idl_2.idl
diff --git a/chrome/common/extensions/api/test_presubmit/invalid_idl_2.idl b/chrome/common/extensions/api/test_presubmit/invalid_idl_2.idl
new file mode 100644
index 0000000000000000000000000000000000000000..72996ed3cbc1273e8dd7a9e5f6c38382025c9350
--- /dev/null
+++ b/chrome/common/extensions/api/test_presubmit/invalid_idl_2.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 {
+  // Unexpected symbol DOMString after symbol a.
+  dictionary MissingSemicolon {
+    DOMString a
+    DOMString b;
+  };
+};