gistfile1.txt

USE_COUNTER2_DEPRECATED_AppCache_PAGE

<https://telemetry.mozilla.org/new-pipeline/evo.html#!aggregates=bucket-0!bucket-1!bucket-2&cumulative=0&end_date=null&keys=&max_channel_version=release%252F52&measure=USE_COUNTER2_DEPRECATED_AppCache_PAGE&min_channel_version=release%252F44&processType=*&product=Firefox&sanitize=1&sort_keys=submissions&start_date=null&trim=1&use_submission_date=0>

Data is a bit hard to read, but it looks like usage is generally ~3%. IIRC, think this just measures if a manifest file was seen.

The number goes up quite a bit for Firefox Mobile (Android), FWIW.

We also have use counters for AppCache JS API methods and getters:
http://searchfox.org/mozilla-central/source/dom/base/UseCounters.conf#52

Looking at just a couple:

appcache.update:

<https://telemetry.mozilla.org/new-pipeline/evo.html#!aggregates=bucket-0!bucket-1!bucket-2&cumulative=0&end_date=null&keys=&max_channel_version=release%252F52&measure=USE_COUNTER2_OFFLINERESOURCELIST_UPDATE_PAGE&min_channel_version=release%252F49&processType=*&product=Firefox&sanitize=1&sort_keys=submissions&start_date=null&trim=1&use_submission_date=0>

Looks like it's ~2%.

appcache.status:

<https://telemetry.mozilla.org/new-pipeline/evo.html#!aggregates=bucket-0!bucket-1!bucket-2&cumulative=0&end_date=null&keys=&max_channel_version=release%252F52&measure=USE_COUNTER2_OFFLINERESOURCELIST_STATUS_getter_PAGE&min_channel_version=release%252F49&processType=*&product=Firefox&sanitize=1&sort_keys=submissions&start_date=null&trim=1&use_submission_date=0>

~2.5%

Wow. Those numbers are ~an order of magnitude higher than what we're seeing in Chrome for overall usage:

API calls

• Insecure: https://www.chromestatus.com/metrics/feature/timeline/popularity/1248
• Secure: https://www.chromestatus.com/metrics/feature/timeline/popularity/1246

manifest in a document

• Insecure: https://www.chromestatus.com/metrics/feature/timeline/popularity/1245
• Secure: https://www.chromestatus.com/metrics/feature/timeline/popularity/1246