This lets the embedder know when the iframe has valid pixels available. This is useful for things like https://github.com/mozilla-b2g/gaia/issues/4213 . To implement this, I think we'd want to - register a MozAfterPaint listener from BrowserElementChild when it's initialized - when the first MozAfterPaint event is dispatched, fire the "firstpaint" notification to the embedder - unhook the MozAfterPaint listener (they can cause some perf issues)

Hm ... need to be careful about about:blank here.

(In reply to Chris Jones [:cjones] [:warhammer] from comment #1) > Hm ... need to be careful about about:blank here. Yeah, I was just about to comment on that. :) But I think we can just check the location of the docshell/document.

> But I think we can just check the location of the docshell/document. ...unless http://foo.com can be painted before the docshell's location changes away from about:blank. I hope not, but I'm not sure.

If that were true, I think that many things other than this would be broken.

One way to find out, I guess. https://tbpl.mozilla.org/?tree=Try&rev=0f81ae103909 Anyone want to take bets on which platform will go randomorange? My money is on OSX.

No random oranges; just permaorange on opt builds on all platforms. :)

Second time's a charm? https://tbpl.mozilla.org/?tree=Try&rev=3ec505fdd543

Comment on attachment 657434 [details] [diff] [review] Part 1: Fire a "firstpaint" event in iframe mozbrowser. Stealing. >diff --git a/dom/browser-element/BrowserElementChild.js b/dom/browser-element/BrowserElementChild.js > function debug(msg) { >- //dump("BrowserElementChild - " + msg + "\n"); >+ // dump("BrowserElementChild - " + msg + "\n"); This is distracting, please remove. Looks good! r=me with nitfix

https://hg.mozilla.org/integration/mozilla-inbound/rev/0d060c3e7d65 https://hg.mozilla.org/integration/mozilla-inbound/rev/50e752beca26 I, um, forgot to put "r=cjones" in the commit messages. Oops.

10 demerits. 10 more and we bust you down to L2 ;).

https://hg.mozilla.org/mozilla-central/rev/0d060c3e7d65 https://hg.mozilla.org/mozilla-central/rev/50e752beca26