When a team has a supposedly world class forward line, you expect them to take a percentage of half chances.
Well yeah, especially when the team they're playing is staying completely negative.
Of course Barcelona is going to have the lion's share of possession, the majority chances and a lot of "half chances". Chelsea conceded that fact from the start.
The issue is that Barca failed to put any of those chances away, at home. Now it's even and Chelsea will probably use a similar tactic, though I expect them to counter a lot more, with a home crowd.
I don't really think it matters whether Barcelona had ten chances or fifty when Chelsea practically conceded the pitch for the entire match. If anything it says a lot about Chelsea's defense.