After doing some research, here are my findings:
Under Section 337j of the California Penal Code it is a misdemeanor to "deal, operate, carry on, conduct, maintain, or expose for play in [California] any controlled game" unless all required federal, state and local licenses have been obtained. Many local jurisdictions in California require licenses to be obtained in order to operate a cardroom in that jurisdiction. No online real-money poker website has a license from any California gaming authority.
A "'controlled game' means any game of chance, including any gambling device, played for currency, check, credit, or any other thing of value that is not prohibited and made unlawful by statute or local ordinance.... [But] does not include any of the following: (A) The game of bingo conducted pursuant to Section 326.5. (B) Parimutuel racing on horse races regulated by the California Horse Racing Board. (C) Any lottery game conducted by the California State Lottery. [or] (D) Games played with cards in private homes or residences, in which no person makes money for operating the game, except as a player."
Poker games that are not "percentage games," and assuming further that they are "games of chance," are lawful under Section 330, so the offering of such games is subject to the requirement of Section 337j. Of course, if the online poker game is a percentage game, then the offering of it would be unlawful directly under Section 330.