Add logic for catching unsafe scoped_refptr conversions to T* in returns

tools/clang/rewrite_scoped_refptr/tests/temp-returned-as-raw-expected.cc

Index: tools/clang/rewrite_scoped_refptr/tests/temp-returned-as-raw-expected.cc
diff --git a/tools/clang/rewrite_scoped_refptr/tests/temp-returned-as-raw-expected.cc b/tools/clang/rewrite_scoped_refptr/tests/temp-returned-as-raw-expected.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1987bbb3586c3fd9ab4e17853cd939d874a6fa94
--- /dev/null
+++ b/tools/clang/rewrite_scoped_refptr/tests/temp-returned-as-raw-expected.cc
@@ -0,0 +1,22 @@
+// 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.
+
+#include "base/memory/ref_counted.h"
+
+struct Foo : public base::RefCounted<Foo> {
+  int dummy;
+};
+
+class Bar {
+  scoped_refptr<Foo> TestFunction();
+};
+
+scoped_refptr<Foo> CreateFoo();
+
+// An example of an unsafe conversion--the scoped_refptr will be destroyed by
+// the time function returns, since it's a temporary, so the returned raw
+// pointer may point to a deleted object.
+scoped_refptr<Foo> Bar::TestFunction() {
+  return CreateFoo();
+}