When trying to open a link directly within the gmail app, it opens in safari instead of chrome. This used work just fine until the latest update of gmail.
I looked in the gmail settings under google apps, to use the app instead of the browser. There is no option for Chrome where I imagine it should be.
I can't find any other option to make chrome the default browser instead of safari.
UPDATE: As of 11/26/2016, the problem seems to have been fixed. Links from my gmail app open up in chrome again.