Optionally pass --vmodule from yarn start

[garrettr]

Description

Chromium has tons of optional verbose logging, which can be a boon for tracking down errors in the interactions between our code and theirs. At the moment, it is possible to pass --v through to the Brave binary from yarn start, which enables the verbose logging at a given log level. However, this logging is extremely verbose and if you have an idea of what specific log messages you are looking for, it is easier to use --vmodule to only request verbose logging from specific files/modules.

--vmodule has a convenient and flexible syntax which is documented in a source code comment.

For example, I was just debugging an issue where the Firefox importer was importing cookies correctly, but they weren't actually being set. CookieMonster::SetCanonicalCookie had some helpful-looking VLOG statements, but they were all being logged at level 7. yarn start --v=7 creates such a torrential deluge of messages that I was waiting minutes just for Brave to load because it was bottlenecking on writing megabytes of debug log messages to my terminal. With yarn start --vmodule=cookie_monster=7, I found the info I needed in seconds 😎