Sync the preference for surprise me, and pull from local if synced preference is unset.

BUG=331653

Review URL: https://codereview.chromium.org/145783005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249911 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249911
Add port mechanism for chooseDesktopMedia.

This is necessary in order to allow the page to
cancel the window picker before it returns a
source ID.

Review URL: https://codereview.chromium.org/157123003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249912 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249912