Simply go to - admin/layout
Check the option - Custom HTML in <head> section of every page:
Paste the below lines of code (Source - http://stackoverflow.com/a/33193739/1691300 )
<!-- Chrome, Firefox OS and Opera -->
<meta name="theme-color" content="#4285f4">
<!-- Windows Phone -->
<meta name="msapplication-navbutton-color" content="#4285f4">
<!-- iOS Safari -->
<meta name="apple-mobile-web-app-status-bar-style" content="#4285f4">
( PS -: This should work but I have not tested this , please make sure you test it before you got to production )