Places got Async Expiration - More sleep, less work.

A better expiration component is now part of Places module Last week, on Friday, i've pushed the last pieces of the new Places Expiration component. This was one of the Firefox Projects intended for 1.9.3 branch, you can find more background on the start of this project in its wiki page. Some backgroundOriginally expiration was managed by History component itself on three major steps: after each v

[amino_acid9]

Firefox4の履歴管理、places.history.expiration.max_pageにて最大保存ページ数を設定

[Rockridge]

Firefox 4では履歴の保存期間の設定がなくなった。履歴の数や搭載メモリ量を考慮しつつ、3分ごとに非同期の期限切れ処理を行う。アイドル時やシャットダウン時の同処理はパフォーマンスに悪影響を与えないよう抑えた。