amazon-chime-sdk-ios: Video Tile modifications from Web not triggering on iOS

Various video tile notifications are not being triggered in the RealtimeObserver when the remote attendee is on web.

To Reproduce

1. Open web client and mobile client, and join the same meeting.
2. Toggle video on and off on the web client
3. The iOS client will receive videoTileDidRemoveWithTileState when the web client toggles their video off, but not videoTileDidAddWithTileState when the web client toggles their video back on. videoTileDidPauseWithTileState and videoTileDidResumeWithTileState are not called either.

Expected behavior I expected the iOS client to receive either videoTileDidAddWithTileState or videoTileDidResumeWithTileState.

Logs One log worth looking at is:

2020-09-10 20:36:48.442882-0700 rn[43046:4877775] [ERROR] NativeMobileSDKBridge - [789:559] [66563] (webrtc_video_engine.cc:3264): Absent receive stream; ignoring clearing encoded frame sink for ssrc 0

followed, after a little bit of inactivity, by:

[800:149] [67591] (video_renderer_adapter.cc:196): 10 metrics frames sent with 0 FPS; notify:video_remote_stream_unpaused_with_zero_fps [801:154] [67591] (video_renderer_adapter.cc:196): 10 metrics frames sent with 0 FPS; notify:video_remote_stream_unpaused_with_zero_fps [802:158] [67591] (video_renderer_adapter.cc:196): 10 metrics frames sent with 0 FPS; notify:video_remote_stream_unpaused_with_zero_fps [803:162] [67591] (video_renderer_adapter.cc:196): 10 metrics frames sent with 0 FPS; notify:video_remote_stream_unpaused_with_zero_fps [804:168] [67591] (video_renderer_adapter.cc:196): 10 metrics frames sent with 0 FPS; notify:video_remote_stream_unpaused_with_zero_fps [805:172] [67591] (video_renderer_adapter.cc:196): 10 metrics frames sent with 0 FPS; …

This is logged every time the web client toggles their video back on; so it seems likely that the event is indeed getting to the iOS client, but some error is causing it to not trigger up to the SDK.

Test environment Info (please complete the following information):

• Device: iPhone X
• OS: iOS 13.6
• Version AmazonChimeSDK: 0.10.0
• Version AmazonChimeSDKMedia: 0.6.2