Add Google Plus link to head
Create block and place in Header Top. Go to Structure -> Block -> Add Block, then in Block body, write custom HTML. Below block body, Text format should be in "FULL HTML" to display the image.

&lt;a href="https://www.google.com/.." target="_blank"&gt;&lt;img src="YOURIMAGE" width="64" height="64"&gt;&lt;/a&gt;


I think it will work.