Implement rewrite logic for assigning a temporary scoped_refptr to T*.

tools/clang/rewrite_scoped_refptr/tests/temp-passed-as-raw-arg-original.cc

+// Copyright (c) 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.
+
+#include "scoped_refptr.h"
+
+struct Foo {
+  int dummy;
+};
+
+// A temporary scoped_refptr is unsafely passed as a function argument. Since
+// temporaries are destroyed at the end of the full expression, this is 'safe'
+// and can be rewritten to use get(). Currently, the tool just skips this case
+// though--hopefully this is rare enough that manual intervention is not really
+// required.
+scoped_refptr<Foo> GetBuggyFoo() {
+  return new Foo;
+}
+
+void Bar(Foo* f);
+
+void UseBuggyFoo() {
+  Bar(GetBuggyFoo());

[mdempsky, 2014/08/11 20:21:54]

Might be worth adding a concise "// BUG: Should be rewritten to
Bar(GetBuggyFoo().get())" comment right here in case someone later fixes this? 
It'll make them less likely to get thrown off by a test case that superficially
suggests something else is expected, and it'll also make it easier for reviewers
to know the change to expected is desirable.

[dcheng, 2014/08/11 21:01:00]

I've updated the comments for this and several other tests to indicate cases
that are purposely skipped, or otherwise need to change in the future.

+}