I’ve run into the same recently, while trying to build out a simple PoC extension. MV3 seems to be vague, and many of the changes specified do not seem to have actually been implemented yet. Such as chrome.tabCapture being namespaced to chrome.capture. Or these are bugs, it’s unclear.
It’s certainly odd that the schedule for moving to MV3 appears to be underway (not accepting MV2 extensions) when I’ve found the only way to enable my use cases has been to downgrade to MV2 (as the author also found)
Edit: The bug report I found, but unclear if it’s going to be fixed. As conflicting announcements else where state this api will be moved to the chrome.capture namespace for MV3. But neither presently works.
https://bugs.chromium.org/p/chromium/issues/detail?id=121484...