Google don't need to keep their in-home standards proprietary. For them it's enough to pump as much different features into Chrome as possible. No one except them can implement those standards simply because no one have development team of comparable size.

Then they just going to state something like: our service dont support Firefox because Chrome-only feature X is not fully implemented.

Right, Google is going the "regulatory capture" route of standards, where they're the only place capable of meeting the standards they wrote.