[M111] Add feature flag for preventing navigation

This new logic was added in crrev.com/c/4206652. Adding a new flag to be
used as a killswitch in case there are any unintended side effects of
this change which are not observed before stable.

(cherry picked from commit 7ab182a)

Bug: 1408799
Change-Id: I22110d7c4a5f1f839c9cb0dd3725e5a854947d5f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4215894
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Reviewed-by: Ali Juma <ajuma@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1100500}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4218202
Commit-Queue: Ali Juma <ajuma@chromium.org>
Auto-Submit: Mike Dougherty <michaeldo@chromium.org>
Cr-Commit-Position: refs/branch-heads/5563@{#126}
Cr-Branched-From: 3ac59a6-refs/heads/main@{#1097615}

ios/web/common/features.h

@@ -73,6 +73,9 @@ BASE_DECLARE_FEATURE(kLongPressSurroundingText);
 // the old one.
 BASE_DECLARE_FEATURE(kScrollViewProxyScrollEnabledWorkaround);
 
+// Feature flag to prevent navigation without user interaction.
+BASE_DECLARE_FEATURE(kPreventNavigationWithoutUserInteraction);
+
 // When true, user control for camera and/or microphone access should be
 // enabled.
 bool IsMediaPermissionsControlEnabled();

ios/web/common/features.mm

@@ -73,6 +73,10 @@
              "ScrollViewProxyScrollEnabledWorkaround",
              base::FEATURE_ENABLED_BY_DEFAULT);
 
+BASE_FEATURE(kPreventNavigationWithoutUserInteraction,
+             "PreventNavigationWithoutUserInteraction",
+             base::FEATURE_ENABLED_BY_DEFAULT);
+
 bool IsMediaPermissionsControlEnabled() {
   if (@available(iOS 15, *)) {
     return base::FeatureList::IsEnabled(kMediaPermissionsControl);

ios/web/navigation/crw_wk_navigation_handler.mm

@@ -391,7 +391,9 @@ - (void)webView:(WKWebView*)webView
   }
 
   // Ref: crbug.com/1408799
-  if (isMainFrameNavigationAction && isCrossOriginTargetFrame &&
+  if (base::FeatureList::IsEnabled(
+          web::features::kPreventNavigationWithoutUserInteraction) &&
+      isMainFrameNavigationAction && isCrossOriginTargetFrame &&
       !hasTappedRecently) {
     decisionHandler(WKNavigationActionPolicyCancel);
     return;