When did the colloquial "bro" come into use?

I did research and came up with nothing. It only shows "brother". I'm talking about "bro" as a colloquialism, when reffering to a guy, like saying "dude". For example:

Pass the chips, bro.

Hey bro; you coming to the party later?

According to dictionary.com the expression "bro" as a short for brother dates back to 1830-40, but it is only arond the mid-20th century that "bro" began to be used outside the familiar or religious contexts:

The following extract from Oxfordwords.blog traces its origin and its more recent semantic changes:

• For centuries, it was merely a graphic abbreviation of brother (properly bro.), occasionally put to colloquial use, like sis, to refer to a person’s male sibling.

• It wasn’t until the 20th century that bro’s meaning began to stray from familial relationships and religious titles. More recently still, the word has taken on new life as a productive element forming new words and compounds, like brogrammer (a loutish male computer programmer), or curlbro (a gym rat who focuses too much attention on his biceps).

• Bro’s meaning had begun to expand by the mid-20th century. It came to refer simply to a man (a synonym of ‘fellow’ or ‘guy’), or sometimes more specifically a black man. The rock critic Lester Bangs wrote in 1976, “if we the (presumably) white jass-buffs couldn’t get with it maybe it was only meant for the bros.”

• Bro also became common as a term of direct address (“Hey, bro!”). These developments gave bro a bigger semantic footprint, but they didn’t completely sever the tie with brother, which had been used in similar ways even earlier.