1468509 - Clean up threading for ScreenCapturer on OS X

Status: NEW

(Core :: WebRTC: Audio/Video, enhancement, P3)

Description

[Dan Minor [:dminor]]

At the moment, we call Initialize() while still on the VideoCapture thread when setting up screen capture on OS X. This results in event handlers being registered on that thread, rather than the ScreenCapture thread. Bug 1409018 added a variable to defer initialization until the ScreenCapture thread has started and added a call to spin the associated run loop on OS X. This could be made less hacky. We could likely dispatch an event to the ScreenCapture thread from the VideoCapture thread, and run the CaptureFrame method on a timer on the run loop.