Check weak pointers in RTCPeerConnectionHandler::WebRtcSetDescriptionObserverImpl

Bug: 912074
Change-Id: I8ba86751f5d5bf12db51520f985ef0d3dae63ed8
Reviewed-on: https://chromium-review.googlesource.com/c/1411916
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622945}
  static void DeleteReports(std::vector<Report*>* reports) {
    TRACE_EVENT0("webrtc", "StatsResponse::DeleteReports");
    for (auto* p : *reports)
      delete p;
    delete reports;
  }

  static void DeleteReports(std::vector<Report*>* reports) {
    TRACE_EVENT0("webrtc", "StatsResponse::DeleteReports");
    for (auto* p : *reports)
      delete p;
    delete reports;
  }
