STR: 1. Start Firefox Nightly, and open a new tab. 2. Check Error Console. ACTUAL RESULTS: This warning appears in the error console: DEPRECATION WARNING: This path to event-emitter.js is deprecated. Please use require("devtools/shared/event-emitter") to load this module. You may find more details about this deprecation at: https://bugzil.la/912121 resource://gre/modules/devtools/event-emitter.js 33 null resource://gre/modules/devtools/event-emitter.js 21 null resource://gre/modules/devtools/event-emitter.js 12 null resource://app/modules/NewTabWebChannel.jsm 28 null resource://gre/modules/XPCOMUtils.jsm 198 XPCU_defineLazyGetter/<.get resource://app/modules/NewTabWebChannel.jsm 76 NewTabWebChannelImpl resource://app/modules/NewTabWebChannel.jsm 295 null resource://gre/modules/XPCOMUtils.jsm 273 XPCU_moduleLambda resource://gre/modules/XPCOMUtils.jsm 198 XPCU_defineLazyGetter/<.get resource://app/components/nsBrowserGlue.js 763 BG__finalUIStartup resource://app/components/nsBrowserGlue.js 274 BG_observe I'm not 100% sure, but I think this chains back to this code: >XPCOMUtils.defineLazyGetter(this, "EventEmitter", function() { > const {EventEmitter} = Cu.import("resource://gre/modules/devtools/event-emitter.js", {}); > return EventEmitter; >}); http://hg.mozilla.org/mozilla-central/annotate/6202ade0e6d6/browser/components/newtab/NewTabWebChannel.jsm#l27 Looks like this file (NewTabWebChannel.jsm) was only added last week, in bug 1239118.

Looks like we need to use the new path. Thanks for the bug.

Review commit: https://reviewboard.mozilla.org/r/42317/diff/#index_header See other reviews: https://reviewboard.mozilla.org/r/42317/

Comment on attachment 8734518 [details] MozReview Request: Bug 1259522 - use non-deprecated event-emitter.js resource path in NewTabWebChannel r?emtwo https://reviewboard.mozilla.org/r/42317/#review38863 Thanks for the quick fix! But, you should probably get review from someone who knows more about .js/.jsm than I do (I'm not sure I've ever touched a .jsm file). (Might make sense to get review from someone who was involved in bug 912121, the bug mentioned in the warning.) One thing I notice: the warning quoted in comment 0 says: Please use require("devtools/shared/event-emitter") to load this module. ...whereas your patch is still doing something else. (not using 'require', and using a path that ends with event-emitter.js instead of just event-emitter) I have no idea whether that difference is OK or not (which is why I'm not a good reviewer here :)). Hopefully you know whether that's OK though, & your next reviewer-choice will know as well.

Comment on attachment 8734518 [details] MozReview Request: Bug 1259522 - use non-deprecated event-emitter.js resource path in NewTabWebChannel r?emtwo Review request updated; see interdiff: https://reviewboard.mozilla.org/r/42317/diff/1-2/

Comment on attachment 8734518 [details] MozReview Request: Bug 1259522 - use non-deprecated event-emitter.js resource path in NewTabWebChannel r?emtwo https://reviewboard.mozilla.org/r/42317/#review40383

This has been fixed by bug 1259045.