Add the Action to the Global Publisher Layout

When we created the canvas app, we opted to automatically create the action. In this step, we’ll add the action to the global publisher layout so that it shows up in the action bar in the Salesforce1 app.

In the Salesforce application, from Setup, enter Publisher Layouts in the Quick Find box, then select Publisher Layouts.
Click Edit next to the Global Layout.
This layout is the default for the publisher.
In the Salesforce1 and Lightning Experience Actions section, click override the predefined actions.
Drag the Shipify element into the Salesforce1 and Lightning Experience Actions section so that it appears as the first element.
Our warehouse workers are going to use this custom action a lot, so we’re putting it at the start of the list so it is one of the first actions they see in the action bar.
The canvas custom action was created automatically, so it used the name of the canvas app for the name of the action (in this case, Shipify). In a production scenario, change the action name to represent what the user can do. For example, we could change the name of this action to Ship Orders.
Note
Click Save.

Now that we’ve created the custom action and added it to the publisher layout, we’re ready to see it in action (no pun intended).

Salesforce1 Mobile App Developer Guide

Add the Action to the Global Publisher Layout