Bruce Reporter
	Description • 7 years ago

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0
Build ID: 20180104100157

Steps to reproduce:

1. On a fresh browser profile, install the webextension Nano Defender [1].

2. Open some tabs and let them load.

3. Restart the browser

4. Notice poor startup performance and see that Browser Console displays the following message:

[bug 1345098] Lazy browser prematurely inserted via 'messageManager' property access:
getter@chrome://browser/content/tabbrowser.xml:2428:45
getAllFrames@chrome://extensions/content/ext-webNavigation.js:181:15
call/result<@resource://gre/modules/ExtensionParent.jsm:774:57
withPendingBrowser@resource://gre/modules/ExtensionParent.jsm:437:26
async*call@resource://gre/modules/ExtensionParent.jsm:773:20
async*receiveMessage@resource://gre/modules/ExtensionParent.jsm:684:11

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[1] https://addons.mozilla.org/en-US/firefox/addon/real-nano-defender/

	Bruce Reporter
	Comment 2 • 7 years ago

Filed the bug on add-on dev's Github too: https://github.com/jspenguin2017/uBlockProtector/issues/798

	Kris Maglione [:kmag]
	Comment 3 • 7 years ago

This should probably be fixed in the add-on. It tries to query all frames in all tabs at startup. It should probably explicitly ignore lazy tabs.

Though maybe the API should explicitly ignore those too.

	Bruce Reporter
	Comment 4 • 7 years ago

(In reply to Kris Maglione [:kmag] (long backlog; ping on IRC if you're blocked) from comment #3)
> Though maybe the API should explicitly ignore those too.

According to the developer [1], that's what Chrome does. So the fact that Firefox is different from Chrome in this regard isn't currently documented and in general, there are apparently no guidelines on what devs need to do to avoid un-lazifying tabs.

With that in mind, should this be considered a browser bug or a documentation bug or still an add-on bug?

[1] https://github.com/jspenguin2017/uBlockProtector/issues/798#issuecomment-356441919

	Dão Gottwald [:dao]
	Comment 5 • 7 years ago

Pretty sure the API shouldn't de-lazify tabs by default.