Add support for externally provided refresh tokens.

Add support for externally provided refresh tokens.

OAuth token cache file (as implemented by oauth2client library) stores refresh
token and can in theory be deployed via Puppet as the credential. But it is
mutated by the library (to store access tokens, rotated each hour), and so it is
not static and managing it via Puppet (or however else) is a big pain.

Instead, now depot_tools accepts --auth-refresh-token-json parameter with a path
to a static JSON file (with minimal body being {"refresh_token": "....."}). It
can be used to pass previously prepared refresh tokens of role accounts. It
will be used for blink DEPS roller account and similar @chromium.org accounts.

R=maruel@chromium.org
BUG=356813
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=294870

[Vadim Sh., 2015-04-17 01:44:05]

tl;dr we have "role accounts" (commit-bot@chromium.org, blink deps roller, etc.)
that are like service accounts (used on headless machines), but use refresh
tokens. We'd like to use puppet for managing these tokens. Thus this CL.

[M-A Ruel, 2015-04-17 01:49:50]

lgtm

https://codereview.chromium.org/1060193005/diff/1/auth.py
File auth.py (right):

https://codereview.chromium.org/1060193005/diff/1/auth.py#newcode274
auth.py:274: logging.warning('Failed to revoke refresh token: %s', e)
you don't set credentials to None in else / except?

[Vadim Sh., 2015-04-17 02:38:07]

https://codereview.chromium.org/1060193005/diff/1/auth.py
File auth.py (right):

https://codereview.chromium.org/1060193005/diff/1/auth.py#newcode274
auth.py:274: logging.warning('Failed to revoke refresh token: %s', e)
On 2015/04/17 01:49:50, M-A Ruel wrote:
> you don't set credentials to None in else / except?

If cached refresh token is invalid (for example revoked), revoke raises
client.TokenRevokeError. In such case "depot-tools-auth logout" would still show
message "Done" (and a warning), since logout() returns True (because it did have
some credentials in the cache, and it did remove them from there).

[Vadim Sh., 2015-04-17 02:38:50]

The CQ bit was checked by vadimsh@chromium.org

[Vadim Sh., 2015-04-17 02:38:50]

The patchset sent to the CQ was uploaded after l-g-t-m from maruel@chromium.org
Link to the patchset: https://codereview.chromium.org/1060193005/#ps20001
(title: " ")

[commit-bot: I haz the power, 2015-04-17 02:38:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1060193005/20001

[commit-bot: I haz the power, 2015-04-17 02:42:47]

Committed patchset #2 (id:20001) as
http://src.chromium.org/viewvc/chrome?view=rev&revision=294870