The "collapsed" state was introduced so the user could interact with elements that could otherwise be overlapped by the megabar. Now we that we don't overlap anymore, this state seems unnecessary.

If you remove the collapsed state (which I find a good solution since this contast size changing is driving me crazy), are you going to keep the shadow? Or will the megabar only cast a shadow if it is focused?

And how would you show that the megabar is focused? With a blue border?

(In reply to trinywiky from comment #2)

And how would you show that the megabar is focused? With a blue border?

Removing the collapsed state means that it will be more obvious that the megabar is focused: if it is focused, it is in its expanded state. It will also retain its border.

Dao's patch still applies cleanly to central and meets all four bullet-point criteria for Megabar states in the new spec.

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&group_state=expanded&searchStr=linux%2Cx64%2Cdebug%2Cmochitests%2Cwith%2Cfission%2Cenabled%2Ctest-linux64%2Fdebug-mochitest-browser-chrome-fis-e10s-10%2Cm-fis%28bc10%29&revision=283c5335d006f25e97766ccc31bbf7725c15ee24&selectedJob=274620281

Failure log: https://treeherder.mozilla.org/logviewer.html#?job_id=274620281&repo=autoland

Backout link: https://hg.mozilla.org/integration/autoland/rev/565c9ca9735cff29f5de9b462ad00da331387107

[task 2019-11-05T13:45:24.645Z] 13:45:24 INFO - TEST-PASS | browser/components/urlbar/tests/browser/browser_urlbar_collapseOnChromeMousedown.js | The Urlbar should have the breakout-extend attribute. - true == true -
[task 2019-11-05T13:45:24.646Z] 13:45:24 INFO - Buffered messages finished
[task 2019-11-05T13:45:24.647Z] 13:45:24 INFO - TEST-UNEXPECTED-FAIL | browser/components/urlbar/tests/browser/browser_urlbar_collapseOnChromeMousedown.js | The Urlbar should not have the breakout-extend attribute. - false == true - JS frame :: chrome://mochitests/content/browser/browser/components/urlbar/tests/browser/browser_urlbar_collapseOnChromeMousedown.js :: <TOP_LEVEL> :: line 34
[task 2019-11-05T13:45:24.647Z] 13:45:24 INFO - Stack trace:
[task 2019-11-05T13:45:24.647Z] 13:45:24 INFO - chrome://mochitests/content/browser/browser/components/urlbar/tests/browser/browser_urlbar_collapseOnChromeMousedown.js:null:34
[task 2019-11-05T13:45:24.647Z] 13:45:24 INFO - chrome://mochikit/content/browser-test.js:Tester_execTest/<:1069
[task 2019-11-05T13:45:24.647Z] 13:45:24 INFO - chrome://mochikit/content/browser-test.js:Tester_execTest:1104
[task 2019-11-05T13:45:24.648Z] 13:45:24 INFO - chrome://mochikit/content/browser-test.js:nextTest/<:932
[task 2019-11-05T13:45:24.651Z] 13:45:24 INFO - chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:SimpleTest.waitForFocus/waitForFocusInner/focusedOrLoaded/<:805
[task 2019-11-05T13:45:24.651Z] 13:45:24 INFO - TEST-PASS | browser/components/urlbar/tests/browser/browser_urlbar_collapseOnChromeMousedown.js | The Urlbar should be focused. - true == true -

Dao is OoO so I'm going to see this through to landing. The failing test tested the behaviour being removed so the test can be removed. I've updated the revision on Phabricator.

https://hg.mozilla.org/mozilla-central/rev/8b79d4ccb76e