Adding a button next to Share and Follow to open a application page

Question

I want to add a button like "Share" or "Follow" next to Share or Follow button.

I want button to open an application page preferably on same master page without redirect.

As visible in this picture

Answer 1

This can be done with a delegate control targeting the PromotedActions DelegateControl:

PromotedActions Delegate Control

The PromotedActions delegate control allows you to add your own content to the following area on a SharePoint site in the top-right section of the page

[..]

So what does the files look like for these parts of the project?

Elements.xml

<?xml version="1.0" encoding="utf-8"?>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">

  <!-- DelegateControl reference to the PromotedActions Delegate Control -->
  <Control ControlSrc="/_controltemplates/15/Zimmergren.DelegateControls/PromotedAction.ascx"
           Id="PromotedActions"
           Sequence="1" />

</Elements>

PromotedActions.aspx (User Control)

<!-- Note: I've removed the actual Facebook-logic from this snippet for easier overview of the structure. -->
<a title="Share on Facebook" class="ms-promotedActionButton" style="display: inline-block;" href="#">
    <span class="s4-clust ms-promotedActionButton-icon" style="width: 16px; height: 16px; overflow: hidden; display: inline-block; position: relative;">
        <img style="top: 0px; position: absolute;" alt="Share" src="/_layouts/15/images/Zimmergren.DelegateControls/facebookshare.png"/>
    </span>
    <span class="ms-promotedActionButton-text">Post on Facebook</span>
</a>

From Zimmergren

Or you could certainly accomplish it with a custom action injecting some script injecting a new element up in the Promoted Actions section