[GCM] Adding retry logic to registration

* in certain cases, we want to repeat the registration if the first attempt fails, e.g. malformed response, or credentials not being propagated yet.
* also adding response parsing into a relevant status.

BUG=284553

Review URL: https://codereview.chromium.org/140433013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249904 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249904