Code:    void ProcessStateChangesUnifiedPlan(
       WebRtcSetDescriptionObserver::States states) {
     DCHECK_EQ(sdp_semantics_, webrtc::SdpSemantics::kUnifiedPlan);
    handler_->OnModifyTransceivers(
        std::move(states.transceiver_states),
        action_ == PeerConnectionTracker::ACTION_SET_REMOTE_DESCRIPTION);
   }

Vulnerability Type: 
CWE ID: CWE-416
Summary: Insufficient checks of pointer validity in WebRTC in Google Chrome prior to 72.0.3626.81 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
Commit Message: 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}