The whiole G20 thing went over the top, BUT... suppose she had mixed some other irritant into the bubbles? what if they werent just soap? soap in the eyes hurts enough.
The protesters that went carrying bats/pipes/bags of rocks and yes bubbles went looking for confrontation, and they found some.
Do I think the officer could have behaved differently? you go stare down a mob when you have no idea what they are carrying as offensive weapons and report back how you handle the situation.