UPDATE: ryebreadraz beat me to this in a comment in his fanpost from earlier this week.
I haven't seen this anywhere else yet, and correct me if I'm wrong, but the Bruins get the #1 seed in the Pac-10 Tourney with a win and a Washington loss no matter what now. Nothing else matters anymore, not even the Cal-Arizona State game.
Scenario #1: Cal beats ASU
This would put UCLA and Washington tied for first at 13-5, with the first tiebreaker being head-to-head, where the teams split. The next tiebreaker would be results against the next best team, which in this case would be Cal, finishing third. UCLA swept Cal, Cal swept Washington, so UCLA would get the #1 seed
Scenario #2: Arizona State beats Cal
In this scenario, UCLA and UW would be tied at 13-5 and would still be tied in the first tiebreaker, head-to-head. Cal and Arizona State would be tied for third at 11-7 and under Pac-10 rules, you take head-to-head results against tied teams as a group, and UCLA and Washington both went 2-2 against these schools. So the next tiebreakers would be head-to-head results against the next best team. Both UCLA and Washington would've split against Washington State, split against Arizona, swept USC, swept Oregon State, swept Stanford and swept Oregon.
Here's the Pac-10 tiebreaker rules from their media guide (PDF):
1. Two-team tie
a. Results of head-to-head competition during the regular season.
b. Each team’s record vs. the team occupying the highest position in the final regular standings, and then continuing down through the standings until one team gains an advantage.
When arriving at another group of tied teams while comparing records, use each team’s record against the collective tied teams as a group (prior to that group’s own tie-breaking procedure), rather than the performance against individual tied teams.
c. Won-lost percentage against all Division I opponents.
d. Coin toss conducted by the Commissioner or designee.
a) and b) would be even as I established already. For the whole season, UCLA would be 24-7 and Washington would be 23-8, so UCLA would get the #1 seed by tiebreaker c).
And to think, had Washington won one more non-conference game (or UCLA lost one more) -- this could've gone to a coin toss.