This option is located in the Theme Options > Mobile Browser Color tab.
Sonnet can specifies theme color of Chrome on Android. (Fig. 1)
Starting in version 39 of Chrome for Android on Lollipop, you’ll now be able to set the toolbar color. This means no more gray toolbars!
Specify theme color for Chrome on Android. (Fig. 2)
Theme Color For Chrome on Android – Illustrated as A. Specify theme color for Chrome (and Samsung Internet Browser) on Android.