Remove EXTENSION_ALERT_ITEM_BLACKLISTED_PLURAL message

The plural message is the same as the non-plural
message so there's no need for this.

Bug: 1038797
Change-Id: I77b9a6a558fd4cfa4ceb70fb1ae98473d6c6a68d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2350344
Auto-Submit: Bettina Dea <bdea@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797100}

chrome/app/generated_resources.grd

@@ -3815,9 +3815,6 @@ are declared in tools/grit/grit_rule.gni.
       <message name="IDS_EXTENSION_ALERT_ITEM_BLACKLISTED_MALWARE" desc="A statement that an extension has been newly blacklisted for malware.">
         "<ph name="EXTENSION_NAME">$1<ex>Gmail Checker</ex></ph>" has been disabled because it contains malware
       </message>
-      <message name="IDS_EXTENSION_ALERT_ITEM_BLACKLISTED_MALWARE_PLURAL" desc="A statement that an extension has been newly blacklisted for malware.">
-        "<ph name="EXTENSION_NAME">$1<ex>Gmail Checker</ex></ph>" has been disabled because it contains malware.
-      </message>
       <message name="IDS_APP_ALERT_ITEM_BLACKLISTED_OTHER" desc="A statement that a packaged app has been newly blacklisted. https://support.google.com/chrome/answer/1210215 contains the language on which we're basing the phrasing.">
         The app "<ph name="EXTENSION_NAME">$1<ex>Gmail</ex></ph>" was automatically removed.
       </message>

chrome/browser/extensions/extension_error_ui_default.cc

@@ -58,9 +58,7 @@ std::vector<base::string16> GenerateMessage(
     int id = 0;
     if (disable_remotely_for_malware ||
         (blocklist_state == BlocklistState::BLOCKLISTED_MALWARE)) {
-      id = forbidden.size() == 1
-               ? IDS_EXTENSION_ALERT_ITEM_BLACKLISTED_MALWARE
-               : IDS_EXTENSION_ALERT_ITEM_BLACKLISTED_MALWARE_PLURAL;
+      id = IDS_EXTENSION_ALERT_ITEM_BLACKLISTED_MALWARE;
     } else {
       id = extension->is_app() ? IDS_APP_ALERT_ITEM_BLACKLISTED_OTHER
                                : IDS_EXTENSION_ALERT_ITEM_BLACKLISTED_OTHER;