chrome style plugin: Don't crash when checking class weight.

tools/clang/plugins/tests/class_with_incomplete_type.h

Index: tools/clang/plugins/tests/class_with_incomplete_type.h
diff --git a/tools/clang/plugins/tests/class_with_incomplete_type.h b/tools/clang/plugins/tests/class_with_incomplete_type.h
new file mode 100644
index 0000000000000000000000000000000000000000..777cf24bef0ab32a220c839d6ccba11d4ca4beb0
--- /dev/null
+++ b/tools/clang/plugins/tests/class_with_incomplete_type.h
@@ -0,0 +1,18 @@
+// Copyright 2016 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.
+//
+// Make sure that the plugin doesn't crash when trying to calculate the weight
+// of a class that has fields of incomplete type.
+
+#ifndef CLASS_WITH_INCOMPLETE_TYPE_H_
+#define CLASS_WITH_INCOMPLETE_TYPE_H_
+
+struct B;
+
+struct A {
+  ~A();
+  B incomplete;
+};
+
+#endif  // CLASS_WITH_INCOMPLETE_TYPE_H_