Use more C++11 code in dbus/.

Use std::unique_ptr for MethodCall::FromRawMessage()
and Signal::FromRawMessage().
Use nullptr instead of NULL.
Use constexpr for constant in anonymous namespace in
ObjectProxy.

BUG=739622
TEST=Ran trybots.

Change-Id: I84fb7bc0318b09a77a44540575a97db6e5992db0
Reviewed-on: https://chromium-review.googlesource.com/658168
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Hidehiko Abe <hidehiko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501171}

CrOS-Libchrome-Original-Commit: 1156b4573400470b10f21e1043c65b9fad424d75
3 files changed
tree: 253a4caead85796f7a80e99bbd7ab165d0dc0148
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/