Here Android L Keyboard for non root devices, i "modded" apk

- http://d-h.st/YmI

Uninstall google keyboard(Play Store one not AOSP), install this apk and change theme

Go to Android L Google Keyboard settings
Open “Advanced settings”
Select Color scheme “Material”

Tested on Moto G 4.4.2 no root

EDIT: Will not work on nexus stock no root,because google keyboard is a system app and you cant uninstall it

Moto G - ROM: Stock | Kernel: Stock
Galaxy Ace2 - ROM: CM 10.2 | Kernel: Stock