Expose the proper TabAndroid object from the TabModel.

Instead of returning the SyncedTabDelegate from the TabModel, return
the proper TabAndroid and pull the delegate from there.

BUG=277135

Review URL: https://codereview.chromium.org/26343003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227809 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227809
Add actions for application shortcuts

CL for the actions landed in https://codereview.chromium.org/25657010

BUG=305723
NOTRY=true

Review URL: https://codereview.chromium.org/26605003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227810 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227810