Remove libchrome dependency from full_update_generator.h am: c485dddb59 am: f507e22d43

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3304095

Change-Id: I3d094c46819b0715b0405f3301e873053c3e8f86
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>