[M108 Migration] Remove EWK_BRINGUP from ewk_back_forward_list_private
This removes EWK_BRIRNGUP from the file and replaces deprecated
notification types with methods in WebContentsObserver as per the
reference in [1].
NOTIFICATION_NAV_ENTRY_CHANGED
-> WebContentsObserver::NavigationEntryChanged
NOTIFICATION_NAV_ENTRY_COMMITTED
-> WebContentsObserver::NavigationEntryCommitted
[1] https://chromium-review.googlesource.com/630420
Reference: https://review.tizen.org/gerrit/283901/
Change-Id: Ib980ae58958b734d3d1b92984095446e6dfb8f3f
Signed-off-by: Ayush Kumar <ayush.k123@samsung.com>