GitLab

Added LoadingErrorPage flag to NavigationContext to mark
LoadHTMLString: navigations which feed Error page to
WKWebView. These navigations will be ignored in
WKWebViewNavigationDelegate callbacks.

GoBackFromErrorPage and testGoBackFromErrorPage tests were
updated to cover this test case.

Bug: 725241
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I1a38685d96997328c4be2a250dcedb5837e76d77
Reviewed-on: https://chromium-review.googlesource.com/1093515Reviewed-by: Danyao Wang <danyao@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567281}