are you a Chrome committer ? if not, please review the documentation:
http://dev.chromium.org/developers/how-tos/install-depot-tools
(hint: use the http:// URL)
-mike
depot_tools is special ... very few people actually commit to that.
much more likely would be posting changes to the other source trees.
with Chromium and ChromiumOS, you don't have to be a "committer".
anyone can post a changelist (CL) for review/merging. you just need
to create an account on the respective codereview/gerrit websites.
-mike