beforeunload handlers can't specify message text in Chromium 51

[Chris Coulson]

Chromium has dropped the ability for beforeunload handlers to set the dialog message text. Instead, Chromium will display a stock message, making it behave the same as Firefox. This will affect Oxide too - beforeunload dialog components will be created with an empty message string.

I assume webbrowser-app already handles an empty message string by displaying its own text, but given that this API exists in Oxide, I wonder whether we should specify a stock message in Oxide and expose it via the existing API.

See:
https://chromium.googlesource.com/chromium/src.git/+/141dbc132f8aa2588fad4cf50fbfd7a319234b61
https://bugs.chromium.org/p/chromium/issues/detail?id=587940

[Olivier Tilloy (osomon)]

webbrowser-app currently doesn’t handle the empty mesage case. We could make it handle it, of course, but I think your proposal of exposing the stock message to the existing Oxide API makes sense, as it would mean no API/behaviour changes.

[Chris Coulson (chrisccoulson)]

Ok, I'll add a string to Oxide so that we don't break existing apps. I'll add a deprecation warning for this as well.

I'm just about to merge Chromium 51.0.2679.0 in to trunk. There are a couple of test failures until this is resolved.