This is actually a rather interesting strategy by Google. As you might have heard, Android Messages is also getting a dark mode (it was added, removed, and is now being added back again). It almost sounds like Google is slowly introducing dark mode across its own native apps which seems like a roundabout way of bringing dark mode to Android.
Dark mode for Android has been talked about and spotted a few versions ago. For example back in Android Marshmallow, during its developer preview settings for dark mode was spotted, but it obviously did not make the cut. The feature was once again spotted in Android Nougat, and we all know how that turned out.
There has been speculation that it could also be making its way onto Android Pie, but with Android Pie having been released, we haven’t seen the feature yet. However like we said, Google has been bringing the feature onto its various apps, such as YouTube, so we guess that’s probably the next best thing for now.