This completes the transition of moving control over the set of &quotstable&quot features from Content down into Blink and making it autogenerated.

      I also needed to add value-validation to InFile parsing for this change.

There is still more we could autogenerate here, but this covers most use-cases for contributors wanting to add experimental features to the tree and be able to easily turn them on/off.  (And for API OWNERS being able to tell what we're actually shipping as part of the &quotstable&quot API.)

I suspect we'll want to iterate on this file format further, once we've had some time to try it.  I expect that many other systems may want to read this file (including possibly layout tests and the chrome feature status dashboard).

We may want to change the default to be &quottest&quot instead of &quotoff&quot as most &quotoff&quot features actually end up enabled in some part of the product through other (non-standard or deprecated) ways up in Content.

I will announce this on Blink dev once it's successfully integrated into the tree.

BUG=237740
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/15018018

git-svn-id: svn://svn.chromium.org/blink/trunk@149923 bbb929c8-8fbe-4397-9dbb-9b2b20218538