GitLab

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1. filter expired suggestions before loading from cache
2. assign default expiry timestamps (now + 72 hours), to those ones which don't have expiry timestamps, before storing in cache

BUG=387926

Review URL: https://codereview.chromium.org/423133003

Cr-Commit-Position: refs/heads/master@{#288375}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@288375 0039d316-1c4b-4281-b951-d872f2087c98