[GCM] Adding a list of accounts present on the client to checkin request

We need to bind device id (profile specific) to accounts running in that
profile. For that reason we are grabbing all of the accounts as tracked
by the ProfileOAuth2TokenService and pass them to Initialize method of
GCMClientImpl. The list of accounts is then passed to CheckinRequest when
the request is happening.

Once the CheckinRequest is done more often than simply on login, we may want
to give a more updated list of accounts than the one present on startup of
Chromium. For now there is no reason to handle that case.

BUG=343203

Review URL: https://codereview.chromium.org/171513004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252759 0039d316-1c4b-4281-b951-d872f2087c98
Update hash to new toolchain rev

Matches toolchain update here: https://codereview.chromium.org/169053008/
to pull missing parts of MFC.

TBR=iannucci@chromium.org
BUG=345993

Review URL: https://codereview.chromium.org/169053009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252760 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252759
Cast: Re-enable End2EndTest.StartSenderBeforeReceiver

I was not able to re-produce the non-determism.

BUG=314233

Review URL: https://codereview.chromium.org/175213004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252761 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252761
Refactor user pods to use authType property for distinct authentication modes.

The authType of the user pod determines the authentication method to sign in
or unlock from the account picker screen. This refactoring aims to unify the
current two modes the user pod can use, and make the user pod more
extensible for other modes.

For example, the user pod may currently authenticate using a password or online
GAIA signin. This CL introduces a full-pod user click authType, and a PIN
code authType will be implemented in the future (see bug). This CL also adds
plumbing for the authType to be set by the ScreenLocker for the
chrome.screenlockPrivate API.

BUG=344179
TEST=visual inspection

Review URL: https://codereview.chromium.org/168813002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252762 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252762