[Extensions Toolbar] Don't show the "show button" for hidden browser actions

Since browser actions that are hidden are now just overflowed to the wrench
menu, we don't really need the show button anymore.

BUG=453152

Review URL: https://codereview.chromium.org/879213005

Cr-Commit-Position: refs/heads/master@{#313645}

chrome/browser/ui/webui/extensions/extension_settings_handler.cc

@@ -400,7 +400,11 @@ base::DictionaryValue* ExtensionSettingsHandler::CreateExtensionDetailValue(
   else
     extension_data->SetInteger("order", 2);
 
-  if (!ExtensionActionAPI::GetBrowserActionVisibility(prefs, extension->id())) {
+  // Don't show the "show button" for the browser action if the toolbar
+  // redesign is enabled, because "hidden" buttons are now just hidden in the
+  // wrench menu.
+  if (!ExtensionActionAPI::GetBrowserActionVisibility(prefs, extension->id()) &&
+      !FeatureSwitch::extension_action_redesign()->IsEnabled()) {
     extension_data->SetBoolean("enable_show_button", true);
   }