Is this the same story everytime that G. invents something, implements it in Chrome and then gains advantage, because takes it as standard and other browser hadn't implement it yet?
This wasn't developed and deployed in secret. According to the comments in https://bugzilla.mozilla.org/show_bug.cgi?id=366559, the GitHub repository has been public since at least November 2014.
You may not like Google, but insinuating evil plans every time they do something cool isn't helping anyone.
By the way, new features are generally created this way. They are added to browsers way before they are standardized. You see, convincing the other browser vendors isn't easy. You need very compelling arguments.
Take WebP, for example. It provides massive benefits. Especially if you can use lossy RGBA instead of PNG32 (easily 80% smaller). And yet, Mozilla shows little interest in implementing it.