[DevTools] Add notification of storage being limited in Incognito mode

Add a message telling users that storage quota is limited in Incognito
mode (why: crbug 800329 comment \#1). In non-Incognito mode, the quota
is in gigabytes. But in Incognito, the quota cap is no more than 120MB.

Bug: 794269, 800329
Change-Id: Ic0d9e9d40119424c0b44bdd314d1f836af4ed357
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1506462
Commit-Queue: Haihong Li (Harley) <hhli@chromium.org>
Reviewed-by: Erik Luo <luoe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#639677}
2 files changed