[OriginChip, OSX] Delay origin chip hiding for SRP

If the omnibox displays search terms (or any other text) delay hiding
the origin chip until any typing by the user.

The shared code in the model is benign on non-OSX platforms in that it
doesn't lead to any behavioral changes - the chip is already off when
SetInputInProgress is hit.

BUG=349567
[email protected]

Review URL: https://codereview.chromium.org/198293003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257040 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed