[GStreamer] Use GstBus sync message handler and schedule tasks to the main thread with RunLoop::dispatch

[Carlos Garcia Campos]

This way we would avoid all the GScource + polling mechanism that GST uses internally to handle messages asynchronously in the main thread.

[Carlos Garcia Campos]

Created attachment 264584 [details]
Patch

[Carlos Garcia Campos]

Created attachment 264591 [details]
Updated patch

I was assuming that sync message handler was always called from a secondary thread, but the main thread can also call gst_bus_post, so I've added a check to not schedule the message to the main thread if we are already in the main thread.

[Zan Dobersek]

Comment on attachment 264591 [details]
Updated patch

View in context: https://bugs.webkit.org/attachment.cgi?id=264591&action=review

Looks good, I'll leave it to Phil to approve it.

> Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp:1949
> +                    if (!weakThis)
> +                        return;
> +                    weakThis->handleMessage(protectMessage.get());

Nit: could be a two-liner.

> if (weakThis)
>     weakThis->handleMessage(protectMessage.get());

[Carlos Garcia Campos]

Committed r191948: <http://trac.webkit.org/changeset/191948>