Implement SyncEngine::EnableOrigin/DisableOrigin

Test=Automated. Added SyncEngineTest.EnableOrigin
BUG=240165

Review URL: https://codereview.chromium.org/60733025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235323 0039d316-1c4b-4281-b951-d872f2087c98
added default res input and set default to 1280x720
I added the resolution as an optional constraint because we do not want failures if the camera cannot do HD, it will gracefully use a lower resolution.

BUG=NONE
TEST=Manual
NOTRY=TRUE

Review URL: https://codereview.chromium.org/61743022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235324 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235324