Omnibox: Discount Frecency Estimates for URLs with <10 Visits

Currently a URL calculates its frecency score using at most its ten most
recent visits.  This means for instance if a URL was visited once today
(and never any other times), the estimated frecency will imply the user
visits the URL once every day.  This is extremely optimistic.

This change introduces an experiment to alter this behavior.  In
particular, we now pretend the user has ten visits to the URL (even if
the actual count is lower), and simply have those additional "visits"
not count for anything.

This is the first bullet on the attached bug.

BUG=327085

Review URL: https://codereview.chromium.org/103783003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240454 0039d316-1c4b-4281-b951-d872f2087c98
[Mac] Always animate extension popup window size changes.

Something about the new window animation changed in 10.9 in a way that's
difficult to detect.

BUG=307912

Review URL: https://codereview.chromium.org/111493003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240455 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240455