Reading List: Mark entry read when opening external app.

ios/web/web_state/ui/crw_web_controller.mm

Index: ios/web/web_state/ui/crw_web_controller.mm
diff --git a/ios/web/web_state/ui/crw_web_controller.mm b/ios/web/web_state/ui/crw_web_controller.mm
index 5204ae4a1656e50bb3cc2cd284f5a327bef4315b..e8bf409e64a0343e48e9b7ee79660eb592a3c730 100644
--- a/ios/web/web_state/ui/crw_web_controller.mm
+++ b/ios/web/web_state/ui/crw_web_controller.mm
@@ -3065,8 +3065,10 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
     }
 
     // Stop load if navigation is believed to be happening on the main frame.
-    if ([self isMainFrameNavigationAction:action])
+    if ([self isMainFrameNavigationAction:action]) {
+      [_delegate currentNavigationWillContinueInExternalApp];
       [self stopLoading];
+    }
 
     // Purge web view if last committed URL is different from the document URL.
     // This can happen if external URL was added to the navigation stack and was