A test should be added to check that it works as expected

With Bug 1674336 fixed, we can properly clear worker messages.
A test is added to check this works as expected.

Depends on D138314

Backed out for causing devtools failures on browser_webconsole_console_logging_workers_api.js.

Push with failures

Failure log

Backout link

[task 2022-02-10T11:37:18.790Z] 11:37:18     INFO - Toolbox opened and focused
[task 2022-02-10T11:37:18.790Z] 11:37:18     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | We get the cached message from the worker - 
[task 2022-02-10T11:37:18.791Z] 11:37:18     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | The simple object is logged as expected - 
[task 2022-02-10T11:37:18.791Z] 11:37:18     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | undefined assertion name - 
[task 2022-02-10T11:37:18.792Z] 11:37:18     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | We get the cached message from the worker - 
[task 2022-02-10T11:37:18.792Z] 11:37:18     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | The message is logged as expected - 
[task 2022-02-10T11:37:18.793Z] 11:37:18     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | undefined assertion name - 
[task 2022-02-10T11:37:18.793Z] 11:37:18     INFO - Check that Symbol are properly logged
[task 2022-02-10T11:37:18.794Z] 11:37:18     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | Symbol logged from worker is visible in the console - 
[task 2022-02-10T11:37:18.794Z] 11:37:18     INFO - Buffered messages finished
[task 2022-02-10T11:37:18.795Z] 11:37:18     INFO - TEST-UNEXPECTED-FAIL | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | cached message was removed - Got [object HTMLDivElement], expected undefined
[task 2022-02-10T11:37:18.796Z] 11:37:18     INFO - Stack trace:
[task 2022-02-10T11:37:18.796Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:test_is:1422
[task 2022-02-10T11:37:18.796Z] 11:37:18     INFO - chrome://mochitests/content/browser/devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js:testWorkerMessage:87
[task 2022-02-10T11:37:18.796Z] 11:37:18     INFO - chrome://mochitests/content/browser/devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js:null:19
[task 2022-02-10T11:37:18.796Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:handleTask:989
[task 2022-02-10T11:37:18.796Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:_runTaskBasedTest:1061
[task 2022-02-10T11:37:18.796Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:Tester_execTest:1189
[task 2022-02-10T11:37:18.796Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:nextTest/<:978
[task 2022-02-10T11:37:18.796Z] 11:37:18     INFO - chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:SimpleTest.waitForFocus/<:1041
[task 2022-02-10T11:37:18.797Z] 11:37:18     INFO - Not taking screenshot here: see the one that was previously logged
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - TEST-UNEXPECTED-FAIL | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | as well as live message - Got [object HTMLDivElement], expected undefined
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - Stack trace:
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:test_is:1422
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - chrome://mochitests/content/browser/devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js:testWorkerMessage:92
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - chrome://mochitests/content/browser/devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js:null:19
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:handleTask:989
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:_runTaskBasedTest:1061
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:Tester_execTest:1189
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - chrome://mochikit/content/browser-test.js:nextTest/<:978
[task 2022-02-10T11:37:18.798Z] 11:37:18     INFO - chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:SimpleTest.waitForFocus/<:1041
[task 2022-02-10T11:37:18.799Z] 11:37:18     INFO - Close and reopen the console to check messages were cleared properly
[task 2022-02-10T11:37:19.063Z] 11:37:19     INFO - Opening the toolbox
[task 2022-02-10T11:37:19.073Z] 11:37:19     INFO - GECKO(1601) | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'DevToolsWorker'
[task 2022-02-10T11:37:19.075Z] 11:37:19     INFO - GECKO(1601) | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'DevToolsWorker'
[task 2022-02-10T11:37:19.076Z] 11:37:19     INFO - GECKO(1601) | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'DevToolsWorker'
[task 2022-02-10T11:37:19.080Z] 11:37:19     INFO - GECKO(1601) | console.warn: "IGNORED REDUX ACTION:" "AUTOCOMPLETE_CLEAR"
[task 2022-02-10T11:37:19.093Z] 11:37:19     INFO - GECKO(1601) | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'DevToolsFrame'
[task 2022-02-10T11:37:19.097Z] 11:37:19     INFO - Console message: [JavaScript Error: "NotFoundError: No such JSWindowActor 'DevToolsWorker'"]
[task 2022-02-10T11:37:19.098Z] 11:37:19     INFO - Console message: [JavaScript Error: "NotFoundError: No such JSWindowActor 'DevToolsWorker'"]
[task 2022-02-10T11:37:19.098Z] 11:37:19     INFO - Console message: [JavaScript Error: "NotFoundError: No such JSWindowActor 'DevToolsWorker'"]
[task 2022-02-10T11:37:19.100Z] 11:37:19     INFO - Console message: [JavaScript Error: "NotFoundError: No such JSWindowActor 'DevToolsFrame'"]
[task 2022-02-10T11:37:19.493Z] 11:37:19     INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome" line: 511}]
[task 2022-02-10T11:37:19.494Z] 11:37:19     INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome" line: 511}]
[task 2022-02-10T11:37:19.495Z] 11:37:19     INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome" line: 62}]
[task 2022-02-10T11:37:19.877Z] 11:37:19     INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome" line: 511}]
[task 2022-02-10T11:37:19.880Z] 11:37:19     INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome" line: 511}]
[task 2022-02-10T11:37:19.881Z] 11:37:19     INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome" line: 62}]
[task 2022-02-10T11:37:19.882Z] 11:37:19     INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome" line: 511}]
[task 2022-02-10T11:37:19.882Z] 11:37:19     INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome" line: 511}]
[task 2022-02-10T11:37:19.882Z] 11:37:19     INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome" line: 62}]
[task 2022-02-10T11:37:19.957Z] 11:37:19     INFO - Toolbox opened and focused
[task 2022-02-10T11:37:19.957Z] 11:37:19     INFO - Log a message and wait for it to appear so older messages would have been displayed
[task 2022-02-10T11:37:20.077Z] 11:37:20     INFO - Matched a message with text: "smoke", all messages received.
[task 2022-02-10T11:37:20.091Z] 11:37:20     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | Message cache was cleared - 
[task 2022-02-10T11:37:20.092Z] 11:37:20     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | Live message were cleared as well - 
[task 2022-02-10T11:37:20.562Z] 11:37:20     INFO - Removing tab.
[task 2022-02-10T11:37:20.563Z] 11:37:20     INFO - Waiting for event: 'TabClose' on [object XULElement].
[task 2022-02-10T11:37:20.575Z] 11:37:20     INFO - Got event: 'TabClose' on [object XULElement].
[task 2022-02-10T11:37:20.581Z] 11:37:20     INFO - GECKO(1601) | console.warn: "IGNORED REDUX ACTION:" "AUTOCOMPLETE_CLEAR"
[task 2022-02-10T11:37:20.602Z] 11:37:20     INFO - Tab removed and finished closing
[task 2022-02-10T11:37:20.623Z] 11:37:20     INFO - GECKO(1601) | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'DevToolsFrame'
[task 2022-02-10T11:37:20.624Z] 11:37:20     INFO - Leaving test bound 
[task 2022-02-10T11:37:20.635Z] 11:37:20     INFO - Console message: [JavaScript Error: "NotFoundError: No such JSWindowActor 'DevToolsFrame'"]
[task 2022-02-10T11:37:20.677Z] 11:37:20     INFO - TEST-PASS | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | The main process DevToolsServer has no pending connection when the test ends - 
[task 2022-02-10T11:37:20.689Z] 11:37:20     INFO - GECKO(1601) | ###!!! [Parent][PCompositorManagerParent] Error: RunMessage(msgname=PCompositorBridge::Msg___delete__) Channel closing: too late to send/recv, messages will be lost
[task 2022-02-10T11:37:20.689Z] 11:37:20     INFO - GECKO(1601) | ###!!! [Parent][PImageBridgeParent] Error: RunMessage(msgname=PImageBridge::Msg_WillClose) Channel closing: too late to send/recv, messages will be lost
[task 2022-02-10T11:37:20.693Z] 11:37:20     INFO - GECKO(1601) | ###!!! [Parent][PBackgroundParent] Error: RunMessage(msgname=PRemoteWorkerService::Msg___delete__) Channel closing: too late to send/recv, messages will be lost
[task 2022-02-10T11:37:20.703Z] 11:37:20     INFO - GECKO(1601) | MEMORY STAT | vsize 20992174MB | residentFast 1936MB
[task 2022-02-10T11:37:20.704Z] 11:37:20     INFO - TEST-OK | devtools/client/webconsole/test/browser/browser_webconsole_console_logging_workers_api.js | took 8422ms
[task 2022-02-10T11:37:20.753Z] 11:37:20     INFO - checking window state
[task 2022-02-10T11:37:20.808Z] 11:37:20     INFO - TEST-START | devtools/client/webconsole/test/browser/browser_webconsole_console_profile_unavailable.js

https://hg.mozilla.org/mozilla-central/rev/5a23bf196eb4