Version: 53.0.2785.8, making connection to 52 or ealier.
OS: Any

What steps will reproduce the problem?
(1) Make a connection between Chrome 53 and 52 or earlier.
(2) Perform an ICE restart initiated by the opposite endpoint as which initiated the call. (If Chrome 53 initiated the call, Chrome 52 should initiate the ICE restart).

What is the expected output?

ICE restart works as expected. Connectivity isn't interrupted.

What do you see instead?

50% chance of connection being completely broken.

Please use labels and text to provide additional information.

This is happening because in M53 we stopped switching ICE roles every time an ICE restart occurred. The assumption was that if communicating with an old endpoint that DOES always switch ICE roles, the role conflict resolution mechanism would select a role.

However, a then-unknown bug causes the role conflict resolution mechanism to fail if an offer is sent in the reverse direction of the initial offer-answer. This could occur if, for example, Peer A initiated the call, but Peer B loses and regains Internet access and initiates an ICE restart.

When this occurs, there's a 50% chance of a failure. This is because a tiebreaker determines who switches their role in case of a conflict. M53 can switch its role properly, but M52 and earlier cannot.