[Nav Experiment] No need to handle cancelled error.

|handleCancelledError| currently reloads the last committed item if
the current provisional navigation is cancelled. This is not needed with
WKBasedNavigation because WKWebView will take care of restoring the last
committed state.

This explicit load is the cause of disappearing forward-history when
user taps on "back" in rapid succession. Each tap starts a new
navigation that is immediately cancelled by the subsequent navigation.
At the end of the chain, when the last committed item is loaded (NTP),
it causes forward history to be lost.

Bug: 841747
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I612a403ac1a7fbe40ea00196aafa2492a3345ce0
Reviewed-on: https://chromium-review.googlesource.com/1065052
Commit-Queue: Danyao Wang <danyao@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559917}
1 file changed