
This patch adds an interface that allows modification of stun messages sent by TurnPort. A user can inject a TurnCustomizer on the RTCConfig and the TurnCustomizer will be invoked by TurnPort before sending message. This allows user to e.g add custom attributes as described in rtf5389. BUG=webrtc:8313 Change-Id: I6f4333e9f8ff7fd20f32677be19285f15e1180b6 Reviewed-on: https://webrtc-review.googlesource.com/7618 Reviewed-by: Guido Urdaneta <guidou@webrtc.org> Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org> Reviewed-by: Sami Kalliomäki <sakal@webrtc.org> Commit-Queue: Jonas Oreland <jonaso@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20233}