The crazy linker requires that libchrome.so be page-aligned within the apk. To achieve this, rezip was written:
https://cs.chromium.org/chromium/src/build/android/rezip/RezipApk.java
Since that time, the functionality has been added to Android's zipalign tool via the -p flag.
The flag applies only to uncompressed libraries, and only to files that end with ".so" (so will apply only to the files that rezip targets).
There is no longer any need to have rezip.
Comment 1 by bugdroid1@chromium.org
, Dec 21 2016