[AjithAntony]

The cache doesn't seem relevant but I could test that. Presently my breakdown is 189MB+21MB , App+data, and 13MB Cache.

   Uninstalled.

   Reinstalled.  (play store reports 30MB download)

   Before opening the app  65MB+4KB, 0MB cache

   First launch (no sync sign-in) 65MB + 10MB, 60KB cache

   Browsed Noisy SSL page (google plus feed):  65MB + 14MB, 13MB cache
   
   Signed into sync: no change  ( 10min later, no change)

   Browsed image heavy site (imgur): 65MB + 14MB, 25MB cache

Does chrome store the old versions on upgrade? That would perfectly explain why my fresh install is 64MB, and my older isntall was 3x that size.

[derefr]

It does on the desktop: Omaha, a.k.a. Google Updater, follows a "keep a few recent versions around and just symlink the current one" model to enable atomic upgrades and rollbacks of failed upgrades. If Android Chrome manages its own updates, it's likely using Omaha for them.