Browser Usage Telemetry¶
The BrowserUsageTelemetry.jsm module is the main module for measurements regarding the browser usage (e.g. tab and window counts, search counts, …).
The measurements recording begins right after the
SessionStore has finished restoring the session (i.e. restoring tabs/windows after Firefox starts).
Tab and window interactions¶
The usage telemetry module currently measures these interactions with the browser’s tabs and windows:
tab and window engagement: counts the number of non-private tabs and windows opened in a subsession, after the session is restored (see e.g.
URI loads: counts the number of page loads (doesn’t track and send the addresses, just the counts) directly triggered by the users (see
navigation events: at this time, this only counts the number of time a page load is triggered by a particular UI interaction (e.g. by searching through the URL bar, see
Please see Scalars.yaml for the full list of tracked interactions.
This telemetry records information about the positions of toolbar items and when the user interacts with them. It is submitted as scalar values along with the normal telemetry ping. There are a number of different parts to this telemetry:
For the purposes of this telemetry a set of areas are defined:
In the main browser UI:
menu-bar- The main menu.
menu-toolbar- The normally hidden toolbar that holds the main menu.
titlebar- The optional title bar.
tabs-bar- The area where tabs are displayed.
bookmarks-bar- The bookmarks toolbar.
app-menu- The main application (hamburger) menu.
tabs-context- The context menu shown from right-clicking a tab.
content-context- The context menu shown from right-clicking the web page.
widget-overflow-list- Items that have overflowed the available space.
pinned-overflow-menu- Items that the user has pinned to the toolbar overflow menu.
pageaction-urlbar- Page actions buttons in the address bar.
pageaction-panel- The page action (meatball) menu.
nav-bar-start- The area of the navigation toolbar before the address bar.
nav-bar-end- The area of the navigastion toolbar after the address bar.
about:preferencesthe different cagtegories are used:
In order to uniquely identify a visual element a set of heuristics are used:
If the element is one of the customizable toolbar items then that item’s ID is used.
If the DOM element has an ID set then that is used.
If the DOM element’s class contains one of
tab-close-buttonthen that is used.
If the DOM element has a
data-l10n-idattribute then that is used.
If there is still no identifier then this is repeated for the DOM element’s parent element.
The keyed scalar
browser.ui.toolbar_widgets records the position of widgets in
the UI. At startup the positions of widgets are collected and recorded by
setting the scalar key
<widget id>_pinned_<area> to true. The widget ID are
the IDs of the elements in the DOM. The area is one of the areas listed above
from the browser UI that can be customised.
For the areas that can be controlled the scalar keys
<area>_<off/on/newtab> are set.
newtab is special to the Bookmarks Toolbar and is used when the toolbar will only
be shown on the New Tab page.
browser.ui.customized_widgets records whenever the user moves a
widget around the toolbars or shows or hides some of the areas. When a change
occurs the scalar with the key
<widget id>_<action>_<old area>_<new area>_<reason>
is incremented. The action can be one of
area and new area are the previous and now locations of the widget. In the case
remove actions one of the areas will be
na. For areas that
can be shown or hidden the areas will be
on. The reason is a simple
string that indicates what caused the move to happen (drag, context menu, etc.).
browser.ui.interaction.<area> record how often the use
interacts with the browser. The area is one of those above with the addition of
keyboard for keyboard shortcuts.
When an interaction occurs the widget’s identifier is used as the key and the
scalar is incremented. If the widget is provided by an add-on then the add-on
identifier is dropped and an identifier of the form
addonX is used where X
is a number. The number used is stable for a single session. Everytime the user
moves or interacts with an add-on the same number is used but then the numbers
for each add-on may change after Firefox has been restarted.
browser.engagement.profile_count records how many profiles have
been used by the current Firefox installation. It reports a bucketed result,
which will be 0 if there is an error. The raw value will be reported for 1-10,
but above that, it will report 10 for 10-99, 100 for 100-999, 1000 for
1000-9999, and 10000 for any values greater than that.
The profile count data for an installation is stored in the root of the
update directory in a file called
profile_count_<install hash>.json. The
full path to the file will typically look something like
This value is meant to be resilient to re-installation, so that file will not be removed when Firefox is uninstalled.