Remove unloadSession command and sessionUnloaded message from the Replay protocol. Instead, unload sessions automatically when starting capture or switching sessions.
Start numbering session IDs from 1 instead of 0 (to match ReplayRecordings).
Create CaptureSession when ReplayController is created, so that a session is always loaded.
Remove log messages from CaptureSession ctor/dtor.
Fix recordingAddedToSession arguments in InspectorBackendCommands.
Consume session messages in frontend and create session objects.
Add simple mutation API to CaptureSession and corresponding messages and commands to the Replay protocol.