UPDATE
Same issue present in the latest Gmail app. I still don\'t understand why would Google make such unpleasant UI change. Obsessive in me goes cr
In case only the color is the issue, you can change it. Only to a fixed color resource.
@color/primary_dark
Obvious ?colorPrimaryDark will not work, not even on API 21.
The view responsible for the black status bar background is stored in AppCompatDelegateImplV7.mStatusGuard. You can get the delegate by calling getDelegate() from your activity and access mStatusGuard field by reflection. After starting the action mode you can get a reference to this view and customize it however you like.
This was found in AppCompat 24.1.1.