What it does:
Adds a new function, TelemetrySession.getChildThreadHangs(), which returns a promise resolving to an array of threadHangStats [1], one per process.
Note that processes that spawn or die while the function's promise is created but not resolved may be excluded from the final result.
How we do this:
1. Parent sends a MESSAGE_TELEMETRY_GET_CHILD_PAYLOAD message to each child, promising the results of these messages.
2. Child processes respond to parent with a MESSAGE_TELEMETRY_THREAD_HANGS, which contains BHR stats in the payload.
3. Parent combines all the child responses together and resolves the promise.
Plus a bunch of synchronization stuff and handling of edge cases since the number of child processes can change at any time.
Also, there is a 200ms timeout since we can't handle all of these cases. Specifically, when a child dies without responding, after all other child processes have responded.
Why we do this:
* We can technically get thread hang stats by retrieving Telemetry pings (see requestChildPayloads() in TelemetrySession for details), but this is very slow and can only be done for one process at a time.
* TelemetrySession is responsible for various Telemetry IPC-related tasks, and so is a natural place to expose this function (i.e., the function blends in well with the rest of the API).
* Statuser [2] uses this for quickly obtaining child process BHR stats. This allows us to get realtime hang monitoring for child processes.
[1]: https://dxr.mozilla.org/mozilla-central/source/toolkit/components/telemetry/nsITelemetry.idl#146
[2]: https://github.com/chutten/statuser
Detecting if hardware decoding is available is an asynchronous operation/
The use of Promise allows the value displayed to be accurate on all platforms and not just windows.
This currently forbids unknown top-level schema properties, and unknown
permissions. In the future, I'd like to make those warnings rather than
errors, for compatibility purposes, but I think errors are fine for now.
This one's a bit weird. I was trying to avoid it for a while, but when we
start to support different sets of APIs on different apps, it's going make it
complicated to maintain a single, centralized manifest schema without some way
for them to directly extend it.
This takes the TLS Error Reporting functionality used in the aboutNetError.xhtml
and aboutCertError.xhtml error pages and moves it to its own component. This
allows us to make use of this same error reporting functionality from elsewhere.
Notably, this allows us to send error reports for issues that occur when loading
subresources.
The xpcshell test included is in security/manager/ssl/tests because we need to
make use of tlsserver functionality from the PSM tests.
