Add unit test for AutoRestorer<> on smart pointer types.

Test UnownedPtr<> and RetainPtr<>. We cannot operate against
std::unique_ptr<> because we need a copyable type. Add test for
self-reassignment on going out of scope. Move one test helper
class to testing/ so it can be shared among unit tests. Allow it
to recognize if it ever gets "destroyed", otherwise we can't be
sure Retain/Release applied in the correct order.

Change-Id: I13056094c70079f7283cbc7600948f81a64874b4
Reviewed-on: https://pdfium-review.googlesource.com/41690
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

0 files changed, 0 insertions, 0 deletions