Sandboxing for individual tabs
Ability to drag tabs between windows
Isn't each tab a process or something so when you close it memory is freed?
I am sure there are some other things. This is all I can think of off the top my head.
My point is that saying "Chrome came and shook things up introducing features no existing browsers had" is a bit of a stretch. When it came out Chrome was basically not very different from Internet Explorer 6 (feature-wise), and it seems to have stayed that way (I like full page translation but that's it).
We should be fair and say that Google Chrome has a large market share because it has Google behind it. It doesn't have much else going for it.
One process per tab is a feature. If a tab crashed in FF, typically the whole browser would need to restart whereas in Chrome the tab could be closed and re-opened without affecting the other tabs. I think that's a pretty significant feature.
Auto-updating every 6 weeks is another feature. As a developer, I don't have to worry when an update comes out since I know 90%+ will be on the new version.
While I think part of the reason Chrome has a large market share is clearly because of Google, I don't think it's the main reason. There are many other factors.
The problem here is that you trade a lot of performance for stability that you should have to begin with, so in the end you have worse overall performance just so that a fringe case is covered. What's the worse that can happen if Chrome crashed? You could lose all your tabs because the default setting is "open homepage" instead of "reopen the pages that were open last", but that's your fault.
But let's investigate this more deeply - browser crashes have two major causes - internal bugs and plugins. What used to happen was that Flash (or Acrobat Reader, or whatever) would crash and it would bring down the whole browser. The solution is (of course) one separate process for the plugins. Problem solved. Going beyond that and fitting every tab with its own process to account for the fact that your business isn't really building browsers is of little comfort to me; you shouldn't be dereferencing that NULL pointer to begin with.
Opera has auto-update as well. I guess we'll have to disagree on the reason Chrome has its market share.