GitLab

Pull out a generic TabModel class for Android.  It owns SyncedWindowDelegate
like Browser owns a corresponding instance.  This will allow us to eventually
implement TabModelAndroid.

We no longer need to keep SyncedWindowDelegateRegistry, as we were using that
in non-sync related places to reach the TabModel methods.

BUG=
TEST=


Review URL: https://chromiumcodereview.appspot.com/10701030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148798 0039d316-1c4b-4281-b951-d872f2087c98