To be clear, what I meant is that projects with open stewardship (which I believe the Chromium Project is? unclear from the project website) don't tend to want employees of companies, in their capacity as employees-of-companies to be directors/core maintainers for the project. Which is different from being regular developers on those projects.
Open-stewardship projects tend to be happy to accept contributions from companies; and they tend to be happy to accept the stewardship of individuals who happen to work at companies; but they don't want to be beholden to the interests of those companies in their direction, so projects with community/foundation stewardship don't usually allow companies to pay their employees for their time spent sitting on that foundation's board. (I.e. they let companies pay employees to write code, but they won't allow companies to pay employees to do the work of deciding whether that code belongs upstream.)
Instead, the software foundations that manage FOSS projects usually legally restrict corporations or their representatives from participating in their capacity as representatives of corporations in directorship/steering committees/etc. for the foundation. Instead, they expect/require each person with decision-making authority in the foundation to have their own individual voice—to not be just a sock-puppet of a company, saying whatever the company wants you to say. When you vote for things in the foundation, you have to be able to vote for the interests of the project itself, even if those interests are against the interests of the company you work for—without that endangering your job.
Which usually means that employees of such companies must do their foundation maintainership "off the books" of the company they work for, e.g. at non-work hours using non-work equipment. Just as if they were trying to avoid IP cross-pollution.
Source: worked at a company with an "open core" product, where the core was an Apache Software Foundation project, and most of the ASF project's maintainers happened to be employees of the company. Those people could push a PR to the ASF upstream for consideration from their work account, as a representative of the company; but they then had to don their personal-gmail-account, separate-profile, no-corporate-affiliation hat to handle the PR and discuss it with the other maintainers.
Is that really the case, I always imagined they had a full time team on it.