Economics and accounting are two very different courses of study. Economics is a liberal arts path and accounting is a business path. Other than the courses you take for your major, a big difference is that in a b-school you have a core curriculum of classes such as intro to accounting, finance, economics, IT, management etc. that you do not get as a liberal arts major. A number of classes in this business core are needed to get a CPA.
It is highly unlikely that you will be able to get that coursework as an economics major especially if you are not in Haas. It really depends on how many classes you can take in Haas and how much space in free in your schedule to take the classes. As an accounting major typically one only needs to take intro to macro and micro. The rest of your economics classes would likely be considered electives as far as the CPA exam is concerned.
You can look at your state accounting board to find the coursework you need to be eligible to take the CPA exam in CA. Here is something I found quickly. http://www.calcpa.org/cpa-career-center/cpa-requirements
To become a CPA one now needs 150 credits so many go on for a one year MS in Accounting. You could probably go for a two year MS in Accounting (or there are a few compressed MS programs for non-majors) and get all the classes you need that way.
Perhaps talk to the people you know at the Big 4 firm you have worked out and see if they can suggest a good path if you go the economics at Berkeley route. From what I know that is not as direct of a path (unless perhaps you have an "in’ to get a job in the consulting group, then you don’t need to be a CPA). IMO the more straightforward path to becoming a CPA would be UCLA as an accounting major and you can always minor in economics if that is an area of interest (keep in mind that economics gets very theoretical at the upper levels).
PS I’m a CPA and my S is a CPA currently working for a big 4 firm.