[ios] Fix logic for hiding navigation in history

Update |hidden| argument calculations as follows:
 - Remove GetError() check, because same check was made earlier in the
   method and results in early return
 - Remove "is main frame" check as unnecessary, because
   DidFinishNavigation is not called for iframe
 - Remove navigation_context->GetResponseHeaders()->response_code() > 600
   check, as it looks like a mistake which overrides correct comparison
   to status code 400 (range of HTTP status codes is [100, 599]).

Bug: 924298
Change-Id: I0dc570d34ef6aed0654f7d0742190f425b2ac966
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2535017
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Auto-Submit: Eugene But <eugenebut@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827031}

ios/chrome/browser/history/history_tab_helper.mm

@@ -165,18 +165,13 @@ void HistoryTabHelper::DidFinishNavigation(
       !content_suggestions_navigation &&
       referrer_url != kReadingListReferrerURL;
 
-  // Top-level frame navigations are visible; everything else is hidden.
-  // Also hide top-level navigations that result in an error in order to
-  // prevent the omnibox from suggesting URLs that have never been navigated
-  // to successfully.  (If a top-level navigation to the URL succeeds at some
-  // point, the URL will be unhidden and thus eligible to be suggested by the
-  // omnibox.)
+  // Hide navigations that result in an error in order to prevent the omnibox
+  // from suggesting URLs that have never been navigated to successfully.
+  // (If a navigation to the URL succeeds at some point, the URL will be
+  // unhidden and thus eligible to be suggested by the omnibox.)
   const bool hidden =
-      navigation_context->GetError() ||
       (navigation_context->GetResponseHeaders() &&
-       navigation_context->GetResponseHeaders()->response_code() >= 400 &&
-       navigation_context->GetResponseHeaders()->response_code() > 600) ||
-      !ui::PageTransitionIsMainFrame(navigation_context->GetPageTransition());
+       navigation_context->GetResponseHeaders()->response_code() >= 400);
   history::HistoryAddPageArgs add_page_args(
       url, last_committed_item->GetTimestamp(), this,
       last_committed_item->GetUniqueID(), referrer_url, redirects, transition,