Per https://bugzilla.mozilla.org/show_bug.cgi?id=1550625#c5 there is no mechanism available for FIDO U2F JS API operations on Android. The exposed API is FIDO2/WebAuthn-only. As such, Firefox cannot support FIDO U2F JS API operations on Android, and we should disable the u2f preference so that window.u2f is not set inappropriately.

Per https://bugzilla.mozilla.org/show_bug.cgi?id=1550625#c5 there is no
mechanism available for FIDO U2F JS API operations on Android. The exposed API
is FIDO2/WebAuthn-only. As such, Firefox cannot support FIDO U2F JS API
operations on Android, and we should disable the u2f preference so that
window.u2f is not set inappropriately.

Backed out changeset 8e8ea33ecb3d (Bug 1552602) for test_interfaces_secureContext.html failures

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&searchStr=android%2C4.3%2Capi16%2B%2Cdebug%2Cmochitests%2Cwithout%2Ce10s%2Ctest-android-em-4.3-arm7-api-16%2Fdebug-mochitest-1proc-44%2Cm-1proc%2844%29&fromchange=197df45a8076f497c59951d3ab818af9ba7eedcc&tochange=777492b75f9745bd78dc96155ccd91523b788db0&selectedJob=247146101

Backout link: https://hg.mozilla.org/integration/autoland/rev/777492b75f9745bd78dc96155ccd91523b788db0

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=247146101&repo=autoland&lineNumber=1695

[task 2019-05-18T00:46:25.750Z] 00:46:25 INFO - 123 INFO TEST-START | dom/tests/mochitest/general/test_interfaces_secureContext.html
[task 2019-05-18T00:47:07.826Z] 00:47:07 INFO - <snipped 2326 output lines - if you need more context, please use SimpleTest.requestCompleteLog() in your test>
[task 2019-05-18T00:47:07.827Z] 00:47:07 INFO - Buffered messages logged at 00:46:56
[task 2019-05-18T00:47:07.828Z] 00:47:07 INFO - 124 INFO TEST-PASS | dom/tests/mochitest/general/test_interfaces_secureContext.html | If this is failing: DANGER, are you sure you want to expose the new interface Comment to all webpages as a property on the window? Do not make a change to this file without a review from a DOM peer for that specific change!!! (or a JS peer for changes to ecmaGlobals)
...
[task 2019-05-18T00:47:07.882Z] 00:47:07 INFO - 222 INFO TEST-PASS | dom/tests/mochitest/general/test_interfaces_secureContext.html | ScopedCredentialInfo should NOT be defined on the global scope
[task 2019-05-18T00:47:07.883Z] 00:47:07 INFO - 223 INFO TEST-PASS | dom/tests/mochitest/general/test_interfaces_secureContext.html | StorageManager should NOT be defined on the global scope
[task 2019-05-18T00:47:07.883Z] 00:47:07 INFO - Buffered messages finished
[task 2019-05-18T00:47:07.887Z] 00:47:07 INFO - 224 INFO TEST-UNEXPECTED-FAIL | dom/tests/mochitest/general/test_interfaces_secureContext.html | U2F should be defined on the global scope
[task 2019-05-18T00:47:07.888Z] 00:47:07 INFO - SimpleTest.ok@https://example.com/tests/SimpleTest/SimpleTest.js:275:18
[task 2019-05-18T00:47:07.889Z] 00:47:07 INFO - runTest@https://example.com/tests/dom/tests/mochitest/general/test_interfaces.js:1337:5
[task 2019-05-18T00:47:07.889Z] 00:47:07 INFO - @https://example.com/tests/dom/tests/mochitest/general/test_interfaces.js:1347:1
[task 2019-05-18T00:47:07.890Z] 00:47:07 INFO - 225 INFO TEST-PASS | dom/tests/mochitest/general/test_interfaces_secureContext.html | UserProximityEvent should NOT be defined on the global scope
[task 2019-05-18T00:47:07.891Z] 00:47:07 INFO - 226 INFO TEST-PASS | dom/tests/mochitest/general/test_interfaces_secureContext.html | WebAuthnAssertion should NOT be defined on the global scope
[task 2019-05-18T00:47:07.892Z] 00:47:07 INFO - 227 INFO TEST-PASS | dom/tests/mochitest/general/test_interfaces_secureContext.html | WebAuthnAttestation should NOT be defined on the global scope
[task 2019-05-18T00:47:07.892Z] 00:47:07 INFO - 228 INFO TEST-PASS | dom/tests/mochitest/general/test_interfaces_secureContext.html | WebAuthentication should NOT be defined on the global scope
[task 2019-05-18T00:47:07.893Z] 00:47:07 INFO - 229 INFO TEST-UNEXPECTED-FAIL | dom/tests/mochitest/general/test_interfaces_secureContext.html | The following interface(s) are not enumerated: U2F - got 1, expected +0
[task 2019-05-18T00:47:07.893Z] 00:47:07 INFO - SimpleTest.is@https://example.com/tests/SimpleTest/SimpleTest.js:320:16
[task 2019-05-18T00:47:07.894Z] 00:47:07 INFO - runTest@https://example.com/tests/dom/tests/mochitest/general/test_interfaces.js:1343:3
[task 2019-05-18T00:47:07.894Z] 00:47:07 INFO - @https://example.com/tests/dom/tests/mochitest/general/test_interfaces.js:1347:1
[task 2019-05-18T00:47:07.895Z] 00:47:07 INFO - 230 INFO TEST-OK | dom/tests/mochitest/general/test_interfaces_secureContext.html | took 43711ms
[task 2019-05-18T00:47:07.895Z] 00:47:07 INFO - 231 INFO TEST-START | Shutdown
[task 2019-05-18T00:47:07.895Z] 00:47:07 INFO - 232 INFO Passed: 2430
[task 2019-05-18T00:47:07.896Z] 00:47:07 WARNING - 233 INFO Failed: 2
[task 2019-05-18T00:47:07.896Z] 00:47:07 WARNING - One or more unittests failed.
[task 2019-05-18T00:47:07.896Z] 00:47:07 INFO - 234 INFO Todo: 0
[task 2019-05-18T00:47:07.896Z] 00:47:07 INFO - 235 INFO Mode: non-e10s
[task 2019-05-18T00:47:07.897Z] 00:47:07 INFO - 236 INFO Slowest: 43708ms - /tests/dom/tests/mochitest/general/test_interfaces_secureContext.html
[task 2019-05-18T00:47:07.897Z] 00:47:07 INFO - 237 INFO SimpleTest FINISHED
[task 2019-05-18T00:48:21.045Z] 00:48:21 INFO - Failed to get top activity, retrying, once...
[task 2019-05-18T00:48:21.962Z] 00:48:21 INFO - wait for org.mozilla.fennec_aurora complete; top activity=com.android.launcher
[task 2019-05-18T00:48:22.168Z] 00:48:22 INFO - remoteautomation.py | Application ran for: 0:04:39.736009
[task 2019-05-18T00:48:22.790Z] 00:48:22 INFO - Stopping web server
[task 2019-05-18T00:48:22.799Z] 00:48:22 INFO - Stopping web socket server
[task 2019-05-18T00:48:22.820Z] 00:48:22 INFO - Stopping ssltunnel
[task 2019-05-18T00:48:22.843Z] 00:48:22 INFO - leakcheck | refcount logging is off, so leaks can't be detected!
[task 2019-05-18T00:48:22.843Z] 00:48:22 INFO - runtests.py | Running tests: end.

[Tracking Requested - why for this release]:

I'm out Monday the 20th, so assuming I miss the merge with the rework (it's on try and r? bz), we'll need to uplift this to 68 as part of the Fennec/WebAuthn support.

https://hg.mozilla.org/mozilla-central/rev/0b5457f89030

Comment on attachment 9065830 [details]
Bug 1552602 - Disable FIDO U2F API for Android r?keeler

Beta/Release Uplift Approval Request

• User impact if declined: Capability checking will assume the FIDO U2F API is available when it is not.
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: No
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): It's a pref-off and a test-flip. However, there's no way to test Fennec features in Nightly anymore, so we effectively must go straight to Beta.
• String changes made/needed:

Comment on attachment 9065830 [details]
Bug 1552602 - Disable FIDO U2F API for Android r?keeler

disable fido u2f api for upcoming fennec nightly and beta builds

https://hg.mozilla.org/releases/mozilla-beta/rev/fc4e6975d7fe