Have a look at the picture
This is how Share button looks like in action bar.
Here's the code I use in menu xml file:
<item
android:id="@+id/menu_item_share"
android:showAsAction="ifRoom"
android:title="Share"
android:actionProviderClass=
"android.widget.ShareActionProvider" />
Is it possible to remove that border or change its color?
You need to use custom background.
This might help: https://developer.android.com/training/basics/actionbar/styling.html