Optimize the ripple effect on the navigation bar in Files app.

ui/file_manager/file_manager/foreground/js/file_manager_commands.js

Index: ui/file_manager/file_manager/foreground/js/file_manager_commands.js
diff --git a/ui/file_manager/file_manager/foreground/js/file_manager_commands.js b/ui/file_manager/file_manager/foreground/js/file_manager_commands.js
index 7f035d219d3e22983a6b55f4c69e72b0b43dc095..662c39f9f30550af197d0416e2185bdd2a254216 100644
--- a/ui/file_manager/file_manager/foreground/js/file_manager_commands.js
+++ b/ui/file_manager/file_manager/foreground/js/file_manager_commands.js
@@ -276,8 +276,11 @@ CommandHandler.prototype.updateAvailability = function() {
  * @private
  */
 CommandHandler.prototype.shouldIgnoreEvents_ = function() {
-  // Do not handle commands, when a dialog is shown.
-  if (this.fileManager_.document.querySelector('.cr-dialog-container.shown'))
+  // Do not handle commands, when a dialog is shown. Do not use querySelector
+  // as it's much slower, and this method is executed often.
+  var dialogs = this.fileManager_.document.getElementsByClassName(
+      'cr-dialog-container');
+  if (dialogs.length !== 0 && dialogs[0].classList.contains('shown'))
     return true;
 
   return false;  // Do not ignore.