GCMClientImpl:
* dispatching of messages from the server (data messages, messages deleted event, send error event) with basic tests,
* wiring user checkin with test,
* wiring application registration with test

BUG=284553

Review URL: https://codereview.chromium.org/130983003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248076 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248076
Blink roll 166141:166176

http://build.chromium.org/f/chromium/perf/dashboard/ui/changelog_blink.html?url=/trunk&range=166142:166176&mode=html
TBR=
BUG=

Review URL: https://codereview.chromium.org/148513006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248077 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248078 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248078