Currently source actors are stored as part of the Source object directly. This isn't ideal for several reasons, but most importantly it means that makes source-actor-specific operations end up having to be aware of a specific Source object, which complicates working with them.

I'll probably use this as an initial opportunity to introduce the immutable vs mutable information distinction I've been proposing to see how it feels.

Depends on D27956

Depends on D27957

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&searchStr=os%2Cx%2C10.10%2Cdebug%2Cmochitests%2Ctest-macosx64%2Fdebug-mochitest-devtools-chrome-e10s-3%2Cm%28dt3%29&fromchange=9fe6de0bfd86fa9683cac4d76c5df5730cf25769&tochange=0fc9a9b3d76b963f858b87f151cbff584f83d117&selectedJob=241373567

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=241378220&repo=autoland&lineNumber=20209

Backout link: https://hg.mozilla.org/integration/autoland/rev/0fc9a9b3d76b963f858b87f151cbff584f83d117

05:38:41 INFO - TEST-OK | devtools/client/debugger/test/mochitest/browser_dbg-windowless-workers.js | took 23579ms
05:38:41 INFO - GECKO(881) | ++DOCSHELL 0x121eb4800 == 2 [pid = 883] [id = {49db683d-939b-6444-b222-038e2e2a1914}]
05:38:41 INFO - GECKO(881) | ++DOMWINDOW == 3 (0x121e2e020) [pid = 883] [serial = 170] [outer = 0x0]
05:38:41 INFO - GECKO(881) | ++DOMWINDOW == 4 (0x1120ea800) [pid = 883] [serial = 171] [outer = 0x121e2e020]
05:38:41 INFO - checking window state
05:38:41 INFO - TEST-START | devtools/client/debugger/test/mochitest/browser_dbg-worker-scopes.js
05:38:41 INFO - GECKO(881) | ++DOCSHELL 0x11519b800 == 1 [pid = 887] [id = {7cb0c82e-9087-9444-bad6-3cc5deeb6f76}]
05:38:41 INFO - GECKO(881) | ++DOMWINDOW == 1 (0x11c03a020) [pid = 887] [serial = 245] [outer = 0x0]
05:38:41 INFO - GECKO(881) | ++DOMWINDOW == 2 (0x10c2e6c00) [pid = 887] [serial = 246] [outer = 0x11c03a020]
05:38:41 INFO - GECKO(881) | ++DOMWINDOW == 3 (0x1151b6c00) [pid = 887] [serial = 247] [outer = 0x11c03a020]
05:38:41 INFO - GECKO(881) | --DOMWINDOW == 20 (0x11d180c40) [pid = 881] [serial = 632] [outer = 0x0] [url = chrome://devtools/content/debugger/index.html]
05:38:41 INFO - GECKO(881) | --DOMWINDOW == 19 (0x11739d5c0) [pid = 881] [serial = 629] [outer = 0x0] [url = about:blank]
05:38:41 INFO - GECKO(881) | ++DOCSHELL 0x117859000 == 6 [pid = 881] [id = {d6f4b9cd-6be2-e641-90bc-6ed5bc5b38a5}]
05:38:41 INFO - GECKO(881) | ++DOMWINDOW == 20 (0x1176a0c40) [pid = 881] [serial = 641] [outer = 0x0]
05:38:41 INFO - GECKO(881) | ++DOMWINDOW == 21 (0x1176f9000) [pid = 881] [serial = 642] [outer = 0x1176a0c40]
05:38:41 INFO - GECKO(881) | ++DOMWINDOW == 22 (0x121392400) [pid = 881] [serial = 643] [outer = 0x1176a0c40]
05:38:42 INFO - GECKO(881) | ++DOCSHELL 0x117287800 == 7 [pid = 881] [id = {9b42b8fd-c7f9-734c-aca5-42d93a9d837a}]
05:38:42 INFO - GECKO(881) | ++DOMWINDOW == 23 (0x11cd2bf20) [pid = 881] [serial = 644] [outer = 0x0]
05:38:42 INFO - GECKO(881) | ++DOMWINDOW == 24 (0x120bd0400) [pid = 881] [serial = 645] [outer = 0x11cd2bf20]
05:38:43 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_SUCCESS(rv, nullptr) failed with result 0x804B000A: file /builds/worker/workspace/build/src/extensions/cookie/nsPermission.cpp, line 41
05:38:43 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(principal) failed: file /builds/worker/workspace/build/src/extensions/cookie/nsPermission.cpp, line 53
05:38:43 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_SUCCESS(rv, nullptr) failed with result 0x804B000A: file /builds/worker/workspace/build/src/extensions/cookie/nsPermission.cpp, line 41
05:38:43 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(principal) failed: file /builds/worker/workspace/build/src/extensions/cookie/nsPermission.cpp, line 53
05:38:43 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_SUCCESS(rv, nullptr) failed with result 0x804B000A: file /builds/worker/workspace/build/src/extensions/cookie/nsPermission.cpp, line 41
05:38:43 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(principal) failed: file /builds/worker/workspace/build/src/extensions/cookie/nsPermission.cpp, line 53
05:38:43 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_SUCCESS(rv, nullptr) failed with result 0x804B000A: file /builds/worker/workspace/build/src/extensions/cookie/nsPermission.cpp, line 41
05:38:43 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(principal) failed: file /builds/worker/workspace/build/src/extensions/cookie/nsPermission.cpp, line 53
05:38:43 INFO - GECKO(881) | [ACTION] ADD_SOURCES - {"type":"ADD_SOURCES","cx":{"navigateCounter":0},"sources":[{"id":"sourceURL-http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-worker-scopes.html","url":"http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-worker-scopes.html","relativeUrl":"http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-worker-scopes.html","isPrettyPrinted":false,"sourceMapURL":null,"introductionUrl":null,"introductionType":"scriptElement","isBlackBoxed":false,"loadedState":"unloaded","isWasm":false,"isExtension":false}]}
05:38:43 INFO - GECKO(881) | [ACTION] INSERT_SOURCE_ACTORS - {"type":"INSERT_SOURCE_ACTORS","items":[{"id":"server1.conn96.child1/source20","actor":"server1.conn96.child1/source20","thread":"server1.conn96.child1/context18","source":"sourceURL-http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-worker-scopes.html","isBlackBoxed":false,"sourceMapURL":null,"url":"http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-worker-scopes.html","introductionUrl":null,"introductionType":"scriptElement"}]}
05:38:44 INFO - GECKO(881) | [ACTION] RESUME - {"type":"RESUME","thread":"server1.conn96.child1/workerTarget21/context1","wasStepping":false}
05:38:44 INFO - GECKO(881) | [ACTION] INSERT_WORKERS - {"type":"INSERT_WORKERS","cx":{"navigateCounter":0},"workers":[{"actor":"server1.conn96.child1/workerTarget21/context1","url":"scopes-worker.js","type":0}]}
05:38:44 INFO - GECKO(881) | [ACTION] CONNECT - {"type":"CONNECT","mainThread":{"url":"http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-worker-scopes.html","actor":"server1.conn96.child1/context18","type":-1},"canRewind":false}
05:38:44 INFO - GECKO(881) | [ACTION] ADD_SOURCES - {"type":"ADD_SOURCES","cx":{"navigateCounter":0},"sources":[]}
05:38:44 INFO - GECKO(881) | [ACTION] INSERT_SOURCE_ACTORS - {"type":"INSERT_SOURCE_ACTORS","items":[]}
05:38:44 INFO - GECKO(881) | [ACTION] SET_EXPANDED_STATE - {"type":"SET_EXPANDED_STATE","thread":"server1.conn96.child1/context18","expanded":{}}
05:38:44 INFO - GECKO(881) | [ACTION] SET_ORIENTATION - {"type":"SET_ORIENTATION","orientation":"horizontal"}
05:38:45 INFO - GECKO(881) | [ACTION] ADD_SOURCES - {"type":"ADD_SOURCES","cx":{"navigateCounter":0},"sources":[{"id":"sourceURL-http://example.com/browser/devtools/client/debugger/test/mochitest/examples/scopes-worker.js","url":"http://example.com/browser/devtools/client/debugger/test/mochitest/examples/scopes-worker.js","relativeUrl":"http://example.com/browser/devtools/client/debugger/test/mochitest/examples/scopes-worker.js","isPrettyPrinted":false,"sourceMapURL":null,"introductionUrl":null,"isBlackBoxed":false,"loadedState":"unloaded","isWasm":false,"isExtension":false}]}
05:38:45 INFO - GECKO(881) | [ACTION] INSERT_SOURCE_ACTORS - {"type":"INSERT_SOURCE_ACTORS","items":[{"id":"server1.conn96.child1/workerTarget21/source4","actor":"server1.conn96.child1/workerTarget21/source4","thread":"server1.conn96.child1/workerTarget21/context1","source":"sourceURL-http://example.com/browser/devtools/client/debugger/test/mochitest/examples/scopes-worker.js","isBlackBoxed":false,"sourceMapURL":null,"url":"http://example.com/browser/devtools/client/debugger/test/mochitest/examples/scopes-worker.js","introductionUrl":null}]}
05:38:45 INFO - GECKO(881) | [ACTION] SET_EXPANDED_STATE - {"type":"SET_EXPANDED_STATE","thread":"server1.conn96.child1/workerTarget21/context1","expanded":{}}
05:38:45 INFO - TEST-INFO | started process screencapture
05:38:45 INFO - TEST-INFO | screencapture: exit 0
05:38:45 INFO - Buffered messages logged at 05:38:41
05:38:45 INFO - Entering test bound
05:38:45 INFO - Adding a new tab with URL: http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-worker-scopes.html
05:38:45 INFO - Tab added and finished loading
05:38:45 INFO - Opening the toolbox
05:38:45 INFO - Console message: [JavaScript Error: "The character encoding of the HTML document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the page must be declared in the document or in the transfer protocol." {file: "http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-worker-scopes.html" line: 0}]
05:38:45 INFO - Buffered messages logged at 05:38:43
05:38:45 INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/debugger/src/components/Editor/Breakpoint.js" line: 29}]
05:38:45 INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/debugger/src/components/Editor/Breakpoint.js" line: 29}]
05:38:45 INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/debugger/src/components/Editor/Breakpoint.js" line: 29}]
05:38:45 INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/debugger/src/components/Editor/Breakpoint.js" line: 29}]
05:38:45 INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/debugger/src/components/Editor/ColumnBreakpoint.js" line: 26}]
05:38:45 INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/debugger/src/components/Editor/ColumnBreakpoint.js" line: 26}]
05:38:45 INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/debugger/src/components/Editor/ColumnBreakpoint.js" line: 26}]
05:38:45 INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/debugger/src/components/Editor/ColumnBreakpoint.js" line: 26}]
05:38:45 INFO - Buffered messages logged at 05:38:45
05:38:45 INFO - Toolbox opened and focused
05:38:45 INFO - Waiting on sources: scopes-worker.js
05:38:45 INFO - Finished waiting on sources: scopes-worker.js
05:38:45 INFO - Buffered messages finished
05:38:45 INFO - TEST-UNEXPECTED-FAIL | devtools/client/debugger/test/mochitest/browser_dbg-worker-scopes.js | a new breakpoint was created - Got 0, expected 1
05:38:45 INFO - Stack trace:
05:38:45 INFO - chrome://mochikit/content/browser-test.js:test_is:1325
05:38:45 INFO - chrome://mochitests/content/browser/devtools/client/debugger/test/mochitest/helpers.js:addBreakpoint:812
05:38:45 INFO - chrome://mochitests/content/browser/devtools/client/debugger/test/mochitest/browser_dbg-worker-scopes.js:null:33
05:38:45 INFO - chrome://mochikit/content/browser-test.js:Tester_execTest/<:1116
05:38:45 INFO - chrome://mochikit/content/browser-test.js:Tester_execTest:1144
05:38:45 INFO - chrome://mochikit/content/browser-test.js:nextTest/<:1005
05:38:45 INFO - chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:SimpleTest.waitForFocus/waitForFocusInner/focusedOrLoaded/<:803
05:38:45 INFO - Invoking in tab: startWorker()
05:38:45 INFO - Waiting for state change: paused
05:38:46 INFO - GECKO(881) | [ACTION] RESUME - {"type":"RESUME","thread":"server1.conn96.child1/workerTarget23/context1","wasStepping":false}
05:38:46 INFO - GECKO(881) | [ACTION] INSERT_WORKERS - {"type":"INSERT_WORKERS","cx":{"navigateCounter":0},"workers":[{"actor":"server1.conn96.child1/workerTarget23/context1","url":"scopes-worker.js","type":0}]}
05:38:46 INFO - GECKO(881) | [ACTION] ADD_SOURCES - {"type":"ADD_SOURCES","cx":{"navigateCounter":0},"sources":[]}
05:38:46 INFO - GECKO(881) | [ACTION] INSERT_SOURCE_ACTORS - {"type":"INSERT_SOURCE_ACTORS","items":[{"id":"server1.conn96.child1/workerTarget23/source4","actor":"server1.conn96.child1/workerTarget23/source4","thread":"server1.conn96.child1/workerTarget23/context1","source":"sourceURL-http://example.com/browser/devtools/client/debugger/test/mochitest/examples/scopes-worker.js","isBlackBoxed":false,"sourceMapURL":null,"url":"http://example.com/browser/devtools/client/debugger/test/mochitest/examples/scopes-worker.js","introductionUrl":null}]}
05:38:46 INFO - GECKO(881) | [ACTION] SET_EXPANDED_STATE - {"type":"SET_EXPANDED_STATE","thread":"server1.conn96.child1/workerTarget23/context1","expanded":{}}
05:38:47 INFO - GECKO(881) | --DOMWINDOW == 23 (0x121394400) [pid = 881] [serial = 636] [outer = 0x0] [url = about:blank]
05:38:49 INFO - GECKO(881) | --DOCSHELL 0x11afb0800 == 1 [pid = 883] [id = {17b3bdd2-b86c-cf43-bbfa-56f5e0445557}] [url = http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-windowless-workers.html]
05:38:49 INFO - GECKO(881) | --DOCSHELL 0x1291c8800 == 0 [pid = 885] [id = {bc2eb36f-0e72-3248-ae34-ac8e4a44bb18}] [url = about:blank]
05:38:49 INFO - GECKO(881) | --DOMWINDOW == 3 (0x121e2e200) [pid = 883] [serial = 167] [outer = 0x0] [url = http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-windowless-workers.html]
05:38:49 INFO - GECKO(881) | --DOMWINDOW == 1 (0x129136020) [pid = 885] [serial = 155] [outer = 0x0] [url = about:blank]
05:38:50 INFO - GECKO(881) | [ACTION] REMOVE_SOURCE_ACTORS - {"type":"REMOVE_SOURCE_ACTORS","items":[{"id":"server1.conn96.child1/workerTarget21/source4","actor":"server1.conn96.child1/workerTarget21/source4","thread":"server1.conn96.child1/workerTarget21/context1","source":"sourceURL-http://example.com/browser/devtools/client/debugger/test/mochitest/examples/scopes-worker.js","isBlackBoxed":false,"sourceMapURL":null,"url":"http://example.com/browser/devtools/client/debugger/test/mochitest/examples/scopes-worker.js","introductionUrl":null}]}
05:38:51 INFO - GECKO(881) | [ACTION] REMOVE_WORKERS - {"type":"REMOVE_WORKERS","cx":{"navigateCounter":0},"workers":["server1.conn96.child1/workerTarget21/context1"]}
05:38:51 INFO - GECKO(881) | console.warn: "Error while detaching target: undefined"
05:38:51 INFO - GECKO(881) | console.warn: "Error while detaching the thread front: No such actor for ID: server1.conn96.child1/workerTarget21/context1"
05:38:53 INFO - GECKO(881) | --DOMWINDOW == 22 (0x1176f9000) [pid = 881] [serial = 642] [outer = 0x0] [url = about:blank]
05:38:53 INFO - GECKO(881) | --DOMWINDOW == 21 (0x11d1ef800) [pid = 881] [serial = 634] [outer = 0x0] [url = about:blank]
05:38:53 INFO - GECKO(881) | --DOMWINDOW == 20 (0x120ace000) [pid = 881] [serial = 631] [outer = 0x0] [url = about:devtools-toolbox]
05:38:53 INFO - GECKO(881) | --DOMWINDOW == 19 (0x11d1f0800) [pid = 881] [serial = 633] [outer = 0x0] [url = about:blank]
05:38:53 INFO - GECKO(881) | --DOMWINDOW == 2 (0x11af81000) [pid = 883] [serial = 169] [outer = 0x0] [url = http://example.com/browser/devtools/client/debugger/test/mochitest/examples/doc-windowless-workers.html]
05:38:53 INFO - GECKO(881) | --DOMWINDOW == 0 (0x1193dfc00) [pid = 885] [serial = 157] [outer = 0x0] [url = about:blank]
05:38:54 INFO - GECKO(881) | --DOMWINDOW == 2 (0x10c2e6c00) [pid = 887] [serial = 246] [outer = 0x0] [url = about:blank]
05:38:55 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:38:55 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:38:55 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:38:55 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:38:55 INFO - GECKO(881) | --DOMWINDOW == 18 (0x11769fb60) [pid = 881] [serial = 635] [outer = 0x0] [url = about:blank]
05:38:55 INFO - GECKO(881) | --DOMWINDOW == 17 (0x11d180100) [pid = 881] [serial = 638] [outer = 0x0] [url = chrome://devtools/content/debugger/index.html]
05:38:57 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:38:57 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:38:58 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:38:58 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:38:59 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:38:59 INFO - GECKO(881) | [Parent 881, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/workspace/build/src/dom/events/DOMEventTargetHelper.cpp, line 318
05:39:06 INFO - GECKO(881) | --DOMWINDOW == 16 (0x11dccbc00) [pid = 881] [serial = 640] [outer = 0x0] [url = about:blank]
05:39:06 INFO - GECKO(881) | --DOMWINDOW == 15 (0x121397c00) [pid = 881] [serial = 639] [outer = 0x0] [url = about:blank]
05:39:06 INFO - GECKO(881) | --DOMWINDOW == 14 (0x121992000) [pid = 881] [serial = 637] [outer = 0x0] [url = about:devtools-toolbox]
05:40:11 INFO - Not taking screenshot here: see the one that was previously logged
05:40:11 INFO - TEST-UNEXPECTED-FAIL | devtools/client/debugger/test/mochitest/browser_dbg-worker-scopes.js | Test timed out -

Of course it's the patch that lands 8 hours before mine that introduces an issue :P

https://hg.mozilla.org/mozilla-central/rev/e5dee8a169f6
https://hg.mozilla.org/mozilla-central/rev/6bd8461e7a72
https://hg.mozilla.org/mozilla-central/rev/9e8b0b5f0d04