/usr/share/xul-ext/firetray/chrome.manifest is in xul-ext-firetray 0.5.3~rc1+dfsg-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26  | content		firetray			chrome/content/
skin		firetray	classic/1.0	chrome/skin/
locale		firetray	de-DE		chrome/locale/de-DE/
locale		firetray	en-US		chrome/locale/en-US/
locale		firetray	es-AR		chrome/locale/es-AR/
locale		firetray	fr		chrome/locale/fr/
locale		firetray	hr-HR		chrome/locale/hr-HR/
locale		firetray	it		chrome/locale/it/
locale		firetray	nl		chrome/locale/nl/
locale		firetray	pl-PL		chrome/locale/pl-PL/
locale		firetray	ru-RU		chrome/locale/ru-RU/
locale		firetray	sk-SK		chrome/locale/sk-SK/
locale		firetray	zh-TW		chrome/locale/zh-TW/
resource	firetray			modules/
overlay	chrome://browser/content/browser.xul	chrome://firetray/content/overlay.xul
overlay	chrome://messenger/content/messenger.xul	chrome://firetray/content/overlay.xul
overlay	chrome://songbird/content/xul/mainScriptsOverlay.xul	chrome://firetray/content/overlay.xul
overlay	chrome://sunbird/content/calendar.xul	chrome://firetray/content/overlay.xul
overlay	chrome://navigator/content/navigator.xul	chrome://firetray/content/overlay.xul
overlay	chrome://chatzilla/content/chatzilla.xul	chrome://firetray/content/overlay.xul
overlay	chrome://zotero/content/standalone/standalone.xul	chrome://firetray/content/overlay.xul
component {a9c9cc52-4d6c-45c2-a73f-0be1bd60aaa6} components/firetray-clhandler.js
contract @mozilla.org/commandlinehandler/general-startup;1?type=firetray {a9c9cc52-4d6c-45c2-a73f-0be1bd60aaa6}
category command-line-handler m-firetray @mozilla.org/commandlinehandler/general-startup;1?type=firetray
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