California Revenue & Tax Code Section 17955 covers your situation. Here is the text of that law:
https://codes.findlaw.com/ca/revenue-and-taxation-code/rtc-sect-17955.html
Note that dividends are NOT taxable to a non-resident of CA if "the taxpayer's only contact with this state is through a broker, dealer, or investment adviser located in this state."
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
