I used this tutorial to facelift my Holo app for Lollipop: http://android-developers.blogspot.ru/2014/10/appcompat-v21-material-design-for-pre.html
What I have:
Just add these two lines to the theme:
<item name="actionModeBackground">@color/theme_primary_dark</item>
<item name="actionBarPopupTheme">@style/ThemeOverlay.AppCompat.Light</item>
This might also be helpful in addition to @Andrey Shcherbakov's answer if you want to have more control of each individual color.
<!-- action bar title text color, icon color (ie: back icon, icons when editing text)-->
<item name="android:textColorPrimary">#FFFF00</item>
<!-- action bar background color-->
<item name="android:colorBackground">#444400</item>
<!-- color of line under contextual action bar-->
<item name="colorControlActivated">#00CC00</item>