Launch Linkedin app from Gmail link rather than browser Background
Currently, when I receive an email from LinkedIn, let's use the example of an invitation to connect, I'll select the link from the Gmail app which will open the mobile LinkedIn site via my default browser (Firefox).  Now, I have the LinkedIn app on my Android phone and I would expect these applications can talk to each other whereby the link would launch the app instead of the browser.
My Attempts to Fix
So my initial assumption was that something within the default applications settings got allocated to Firefox rather than LinkedIn for this type of link.  So here's what I've tried...

From App Settings &gt; Gmail &gt; clear defaults, clear cache, clear data
From App Settings &gt; Firefox &gt; clear defaults, clear cache

From here when I try again in the Gmail app I get the option of choosing between different browsers installed.  However, LinkedIn still does not appear as a choice for the default application.
Some Details

I'm running the latest versions of both Gmail and LinkedIn apps
On Android version 4.4.4

Have others had success here?  Is it possible this is not a current capability?
Sadly, This feature/functionality is NOT currently Supported by LinkedIn App. 

The best user can do is write a Feedback/Review in Google Play Store and request this feature to be added to the development team of LinkedIn. 

Hopefully, in newer version of LinkedIn App, this might be included.