[iOS] Fix page info description

If the URL scheme corresponds to Chrome on iOS, the icon shouldn't be
set.

Bug: 1038919
Change-Id: I3f23fd8a23a3c10accb139d341d75d952e6faae4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2096555
Commit-Queue: Ewann Pellé <ewannpv@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749660}

ios/chrome/browser/ui/page_info/page_info_description.mm

@@ -73,6 +73,10 @@
 }
 
 - (NSString*)pageSecurityStatusIconImageName {
+  // If the URL scheme corresponds to Chrome on iOS, the icon is not set.
+  if (self.URL.SchemeIs(kChromeUIScheme))
+    return @"";
+
   if (self.isOffline)
     return @"page_info_offline";