It wasn't even close. Had he played the ball with his studs, I'd consider that leading with 'studs up', but it's very difficult to make a sliding challenge without raising a foot from the floor (kind of gets in the way otherwise!). He plays the ball with a clean side foot and comes away with the ball at his feet. The write ups make it sound like Rooney got 99% of the ball and Bravo barely flicked it whilst clattering Rooney at the same time. I don't even think he makes contact with Rooney much does he?
It's the sort of challenge Zabba makes (used to make pre Pep) all the time. Plus, people would say Rooney is entitled to go for the ball because he senses a goal scoring opportunity. By the same logic, Bravo is more than entitled as he's (just about) in possession of it currently and trying to prevent a goalscoring opportunity.
I fully understand the concept of a dangerous challenge and had they been going directly at one another and Bravo had led studs up and played the ball with his studs then there's the potential for injury. But he's heading to the left touchline, Rooney is coming straight down the pitch, he slides and wins the ball cleanly with the side of his foot which means the sole of his boot is pointing in a different direction. The day they start giving fouls for clean challenges really will mean the end of tackling.