Not correct. AOSP source code has always included full source for android.view., android.widget., and so forth. Which are, by the way, Apache-licensed, not GPL. If you'd like to look for yourself, it's here:
In recent releases (4.x, a/k/a ICS and later), some of the low-level GPU drivers are included as binary blobs, but the GUI libraries built on top of them remain, at the very least, source-available.
https://github.com/android/platform_frameworks_base
in the "core/java" subdirectory.
In recent releases (4.x, a/k/a ICS and later), some of the low-level GPU drivers are included as binary blobs, but the GUI libraries built on top of them remain, at the very least, source-available.