I'm wondering if there's a way to bring focus to a process that's in "activity monitor".
Specifically, I've got a bunch of Google Chrome processes and I'm trying to figure out which process correlates to a particular browser/tab.
Not really. The thing is, most of the time, processes in Activity Monitor don't actually have a UI that you can 'switch' to. Using the Google Chrome example, think of those 'Google Chrome Renderer' processes as background tasks, and you just see the result of them in the main 'Google Chrome' process. Activity Manager does not have a way to identify how to tie these 'background tasks' to the parent GUI.
However, for your particular problem, Google Chrome actually provides you with a Task Manager that will help you out:
You can use this to identify which tab is using up too many system resources. You can also use the Process ID from the Chrome Task Manager to match the process up in Activity Monitor (Process ID == PID).
No - Activity Monitor merely shows you which processes have the ability to draw directly to the screen with an icon next to the name.
In your example, pid 464 is one such process that draws Chrome's output to the screen. You will need to mentally map that icon and perhaps use the task switcher key shortcut: CommandTab to switch the keyboard and pointer focus to that process.
The rest of the Renderer processes from your example are background processes that don't interact with the visual display directly and instead read or write data for another process to consume and display. Another answer here covers how to get the Chrome app to divulge more details on its internal task hierarchy, but from a Mac OS X perspective, the answer in general is no.