[Monorail] Implement "Switch accounts" via google.com/a/SelectSession.

[Monorail] Implement "Switch accounts" via google.com/a/SelectSession.

Changing the URL from '/accounts/ServiceLogin' to '/a/SelectSession'
always gives the user the chance to switch accounts, even if they
are currently signed into exactly one account.  Also, that account
selection page looks nicer.  The user will see both the google.com
and the GAE account selectors the first time for each account, but
it should not happen much after that if the user leaves "Remember
this choice for 30 days" checked.

R=seanmccullough@chromium.org
BUG=monorail:438
Committed: https://chromium.googlesource.com/infra/infra/+/15b9f61d90423bcb2d240736e4a9401efddba42f

[jrobbins, 2016-05-06 17:36:34]

Demo server
https://3994-a874cb1-tainted-jrobbins-dot-monorail-staging.appspot.com

[seanmccullough1, 2016-05-06 17:43:57]

seanmccullough@google.com changed reviewers:
+ seanmccullough@google.com

[seanmccullough1, 2016-05-06 17:43:57]

lgtm

Nice!

[jrobbins, 2016-05-06 21:52:43]

The CQ bit was checked by jrobbins@chromium.org

[commit-bot: I haz the power, 2016-05-06 21:52:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1954193002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1954193002/1

[commit-bot: I haz the power, 2016-05-06 21:54:16]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-05-06 21:54:17]

Try jobs failed on following builders:
  Infra Linux Trusty 64 Tester on tryserver.infra (JOB_FAILED,
https://build.chromium.org/p/tryserver.infra/builders/Infra%20Linux%20Trusty%...)
  Infra Presubmit on tryserver.infra (JOB_FAILED,
https://build.chromium.org/p/tryserver.infra/builders/Infra%20Presubmit/build...)

[jrobbins, 2016-05-06 23:10:27]

The CQ bit was checked by jrobbins@chromium.org

[jrobbins, 2016-05-06 23:10:28]

The patchset sent to the CQ was uploaded after l-g-t-m from
seanmccullough@google.com
Link to the patchset: https://codereview.chromium.org/1954193002/#ps20001
(title: "Rebased")

[commit-bot: I haz the power, 2016-05-06 23:10:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1954193002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1954193002/20001

[commit-bot: I haz the power, 2016-05-06 23:14:28]

Description was changed from

==========
[Monorail] Implement "Switch accounts" via google.com/a/SelectSession.

Changing the URL from '/accounts/ServiceLogin' to '/a/SelectSession'
always gives the user the chance to switch accounts, even if they
are currently signed into exactly one account.  Also, that account
selection page looks nicer.  The user will see both the google.com
and the GAE account selectors the first time for each account, but
it should not happen much after that if the user leaves "Remember
this choice for 30 days" checked.

R=seanmccullough@chromium.org
BUG=monorail:438
==========

to

==========
[Monorail] Implement "Switch accounts" via google.com/a/SelectSession.

Changing the URL from '/accounts/ServiceLogin' to '/a/SelectSession'
always gives the user the chance to switch accounts, even if they
are currently signed into exactly one account.  Also, that account
selection page looks nicer.  The user will see both the google.com
and the GAE account selectors the first time for each account, but
it should not happen much after that if the user leaves "Remember
this choice for 30 days" checked.

R=seanmccullough@chromium.org
BUG=monorail:438

Committed:
https://chromium.googlesource.com/infra/infra/+/15b9f61d90423bcb2d240736e4a94...
==========

[commit-bot: I haz the power, 2016-05-06 23:14:30]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/infra/infra/+/15b9f61d90423bcb2d240736e4a94...