Prevented default backspace handler in File Browser Gallery

chrome/browser/resources/file_manager/js/util.js

Index: chrome/browser/resources/file_manager/js/util.js
diff --git a/chrome/browser/resources/file_manager/js/util.js b/chrome/browser/resources/file_manager/js/util.js
index 40c38ce390d284720efc37f35fced7b80b4ef25e..18fd9926c907d0a317381966849b4f74fd2447fb 100644
--- a/chrome/browser/resources/file_manager/js/util.js
+++ b/chrome/browser/resources/file_manager/js/util.js
@@ -474,5 +474,19 @@ var util = {
     }
 
     return element;
+  },
+
+  /**
+   * Returns a string '[Ctrl-][Alt-][Shift-][Meta-]' depending on the event
+   * modifiers. Convenient for writing out conditions in keyboard handlers.
+   *
+   * @param {Event} event
+   * @return {string}
+   */
+  getKeyModifiers: function(event) {
+    return (event.ctrlKey ? 'Ctrl-' : '') +
+           (event.altKey ? 'Alt-' : '') +
+           (event.shiftKey ? 'Shift-' : '') +
+           (event.metaKey ? 'Meta-' : '');
   }
 };