Break the association between pipelines and browsing context actors.
Now there is one browsing context actor per actual browsing context,
and individual actors keep track of known pipelines as necessary.
There is also one console/performance/timeline/inspector/etc. actor
per browsing context.
This also centralizes more information in the browsing context actor.
Rather than duplicating state for the active pipeline in actors that
need to use it, each actor now remembers the name of its associated
browsing context actor and obtains that state whenever it's necessary.
DevTools - add Interrupt method to ThreadActor
This is one of three pull requests that allows the DevTools Debugger to render.
The two related prs are #21942 and #21943
In this pr, I introduced the `interrupt` method to the threadActor. This is arguably a carry-over from the firefox devtools, where the debugger server is running in the same event loop as the content scripts, and it can only update itself when the debugger server is paused. Depending on how debugging is, or how debugging will be implemented on servo, this method may need to be adjusted for "debugger events" and "script events".
After all three patches on this topic are merged, you should be able to see the debugger \o/ (but no sources yet)
<img width="900" alt="screen shot 2018-10-14 at 16 57 07" src="https://user-images.githubusercontent.com/26968615/46918408-35f30180-cfd2-11e8-9a98-8e1540adc894.png">
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____
<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/21944)
<!-- Reviewable:end -->
DevTools - add ListWorkers method to BrowsingContextTargetActor
This is one of three pull requests that allows the DevTools Debugger to render.
The two related prs are #21942 and #21944
This pr introduces a `ListWorkers` method, which the debugger relies on for startup. At the moment, we are returning an empty array, but later on we can return an array populated by all workers associated with a target.
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____
<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/21943)
<!-- Reviewable:end -->
DevTools - add DeviceActor and update Root to own global actors
This is one of three pull requests that allows the DevTools Debugger to render. This pr also introduces global actors to the root actor, the same as exists in FF devtools. At a later point I would like to reorganize this.
The two related prs are #21943 and #21944
This is the most significant change of the three. It introduces both Device and Performance as global actors, and leaves the Performance actor also as a target actor. It also introduces the concept of ownership to the root actor, with regards to the two Global Actors.
The Device actor as added to allow the JS Debugger to start up. This required the DeviceActor's `getDescription` method. `getDescription`, in the case of servo, returns a couple of basic fields that the debugger is interested in but doesn't use, specifically `apptype` -- which is returning a fake value of `servo`, and the version number `63.0`.
The version number is interesting because devtools has [dropped support for any versions below 2 version numbers from the current firefox](https://searchfox.org/mozilla-central/rev/3a54520d8d2319a4116866371ed3d9ed2ec0cc2b/devtools/client/debugger/new/src/client/firefox/commands.js#398).
This means that if we want the servo server to be supported, we will need to keep this number synced with FF's versioning. It isn't great, but hopefully we can introduce a different approach later on.
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____
<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/21942)
<!-- Reviewable:end -->
As part of [Bug 1172987](https://bugzilla.mozilla.org/show_bug.cgi?id=1172897) we renamed TabActor, as the actor does not represent tabs (as in a browser tab), it instead represents a browsing context as defined by the the [HTML standard](https://html.spec.whatwg.org/multipage/browsers.html#windows). In a later PR I will mirror the structure we have on devtools to have a targets folder, which contains all target types. At the moment it looks like servo only represents workers and browsing contexts.
Use try syntax for Option where appropriate
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes do not require tests because they are refactoring only
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/18968)
<!-- Reviewable:end -->
