Add API to control mock media devices

[youenn fablet]

This will allow improving testing

[youenn fablet]

Created attachment 343414 [details]
Patch

[youenn fablet]

Created attachment 343418 [details]
Patch

[youenn fablet]

Created attachment 343441 [details]
Patch

[youenn fablet]

Comment on attachment 343441 [details]
Patch

Patch is ready for a first round of review.
I need to beef-up the change log, especially the changes to MediaDevices to ensure it is not GCed while dispatching events.

[Radar WebKit Bug Importer]

<rdar://problem/41401524>

[Eric Carlson]

Comment on attachment 343441 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=343441&action=review

> Source/WebKit/UIProcess/API/C/WKMockMediaDevice.cpp:48
> +static inline std::optional<Properties> typeFromString(const String& type)
> +{
> +    if (type == "camera")
> +        return Properties { WebCore::MockCameraProperties { } };
> +    if (type == "microphone")
> +        return Properties { WebCore::MockMicrophoneProperties { } };
> +    if (type == "screen")
> +        return Properties { WebCore::MockDisplayProperties { } };
> +    return std::nullopt;
> +}

Nit: this is only used in one place. Is there a plan to use it in more place?

[youenn fablet]

Created attachment 343508 [details]
Patch for landing

[youenn fablet]

Created attachment 343517 [details]
Patch for landing

[WebKit Commit Bot]

Comment on attachment 343517 [details]
Patch for landing

Clearing flags on attachment: 343517

Committed r233162: <https://trac.webkit.org/changeset/233162>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.