A module/library that contains logic responsible for managing and delivering resources essential for Android on-host rendering. While the logic might not be used exclusively to support rendering, it is important to keep it in a separate module because it is predominantly Android Studio agnostic. It is supposed to be used both from Android Studio (for the previews) and outside, for CLI execution or as a part of a Gradle task. The only exception is dependency on intellij-core library that contains a subset of studio (Intellij Idea) specific API.
Therefore, the module belongs to both tools/adt/idea and tools/base projects, having 2 separate targets. For more information on the examples of code can be share between tools/adt/idea and tools/base see android.sdktools.base.lint.cli and intellij.android.lint.