Eliminate Bookmarks dependence to bookmark_undo_utils.h.

Introduced a mechanism through BookmarkModelObserver to inform the
bookmark undo service to group a set of bookmark changes instead of an
explicit call.

This removes the dependence to bookmark_undo_utils that was recently
introduced in
https://src.chromium.org/viewvc/chrome?view=rev&revision=241973

BUG=126092
TEST=Added a unit_tests test to ensure that the BookmarkModelObserver is notified.

Review URL: https://codereview.chromium.org/155913004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252832 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252832