I just spotted this in a test log from try:

08:46:47     INFO - Console message: [JavaScript Error: "listener[name] is not a function" {file: "resource:///modules/UrlbarController.jsm" line: 461}]
08:46:47     INFO - _notify@resource:///modules/UrlbarController.jsm:461:23
08:46:47     INFO - viewContextChanged@resource:///modules/UrlbarController.jsm:192:10
08:46:47     INFO - _on_TabSelect@resource:///modules/UrlbarInput.jsm:1112:21
08:46:47     INFO - handleEvent@resource:///modules/UrlbarInput.jsm:199:23
08:46:47     INFO - updateCurrentBrowser@chrome://browser/content/tabbrowser.js:1047:14
08:46:47     INFO - _setupEventListeners/<@chrome://browser/content/tabbrowser.js:4582:14
08:46:47     INFO - set selectedIndex@chrome://global/content/elements/tabbox.js:202:12
08:46:47     INFO - set selectedPanel@chrome://global/content/elements/tabbox.js:216:5
08:46:47     INFO - set_selectedIndex@chrome://global/content/bindings/tabbox.xml:176:15
08:46:47     INFO - set_selectedItem@chrome://global/content/bindings/tabbox.xml:201:39
08:46:47     INFO - set selectedTab@chrome://global/content/elements/tabbox.js:81:9
08:46:47     INFO - set selectedTab@chrome://browser/content/tabbrowser.js:266:5
08:46:47     INFO - _blurTab@chrome://browser/content/tabbrowser.js:3257:29
08:46:47     INFO - _beginRemoveTab@chrome://browser/content/tabbrowser.js:2957:10
08:46:47     INFO - removeTab@chrome://browser/content/tabbrowser.js:2865:15
08:46:47     INFO - Tester_waitForWindowsState@chrome://mochikit/content/browser-test.js:578:16
08:46:47     INFO - nextTest@chrome://mochikit/content/browser-test.js:902:10
08:46:47     INFO - async*testScope/test_finish/<@chrome://mochikit/content/browser-test.js:1407:25
08:46:47     INFO - run@chrome://mochikit/content/browser-test.js:1344:9

I suspect this is because bug 1496685 added a notification for onViewContextChanged to the UrlbarController but didn't add it as part of the listener function for UrlbarEventBufferer.

We should either add it there or make it optional.

https://hg.mozilla.org/mozilla-central/rev/60359928dd2c