419d1b9cae
- Add the functionality to merge and unmerge MessageLoopTaskQueues This introduces a notion of a "owning" and "subsumed" queue ids. Owning queue will take care of the tasks submitted to both that and it's subsumed queue. - The tasks submitted still maintain the queue affinity - Same for the task observers - Also adds MergedQueuesRunner which grabs both the locks owner and subsumed queues in RAII fashion. - Also use task queue id to verify if we are running in the same thread. - This is to enable merging the backed message loop task queues to enable dynamic thread merging in IOS.